Evohome continually bringing boiler on for one minute then off for 10 minutes

[colin_]

Hi

When the zones are near temperature (if far away it keeps boiler fully on instead) it seems that the Evohome is bringing the boiler on for 1 minute in every 10 (as some of the zones are reporting not at 0% even though the system is reporting that it is at temperature).

I believe (though not sure) that the control system is doing this to keep push some heat into the radiators so it keeps at temperature rather than dropping far and having to put boiler on full blast (TPI function), however it seems to be continually doing this. This means that it the equivalent of bringing the boiler on for 6 minutes every hour and so for 20 hour same as if boiler had been on full blast for 2 hours.

The issue I have is that the minute on is not enough for the water the boiler (Bosch Greenstar 8000 Life) pushes around to get to more than 36 degrees and so the radiators calling for the heat do not get more than slightly warm (could never get above the 36 degrees but in reality much less). I could set the min on time for longer (max is 5 minute) but this then means that the boiler will be on for half an hour every hour) and 5 minutes still will not produce much heat (it takes around 10 minutes to go from 36-70 degrees), all that I would achieve is the boiler on for 10 hours every 20 hours!

Resideo (Honeywell) say it is "learning" but so far never seems to bring it on longer than a minute unless temperature difference is around 1.5 degrees lower.

Does anyone have an Evohome and know whether this is normal operation on their system (and whether it really does learn) or anyone have any suggestions/experience as to why I seem to be having issues (at the moment I regret changing my simplistic 3 zone controller that just brings it fully on when drops 0.5 degrees below set point).

Thanks
Colin

 

[EvilDrPorkChop]

Hi

When the zones are near temperature (if far away it keeps boiler fully on instead) it seems that the Evohome is bringing the boiler on for 1 minute in every 10 (as some of the zones are reporting not at 0% even though the system is reporting that it is at temperature).

I believe (though not sure) that the control system is doing this to keep push some heat into the radiators so it keeps at temperature rather than dropping far and having to put boiler on full blast (TPI function), however it seems to be continually doing this. This means that it the equivalent of bringing the boiler on for 6 minutes every hour and so for 20 hour same as if boiler had been on full blast for 2 hours.

The issue I have is that the minute on is not enough for the water the boiler (Bosch Greenstar 8000 Life) pushes around to get to more than 36 degrees and so the radiators calling for the heat do not get more than slightly warm (could never get above the 36 degrees but in reality much less). I could set the min on time for longer (max is 5 minute) but this then means that the boiler will be on for half an hour every hour) and 5 minutes still will not produce much heat (it takes around 10 minutes to go from 36-70 degrees), all that I would achieve is the boiler on for 10 hours every 20 hours!

Resideo (Honeywell) say it is "learning" but so far never seems to bring it on longer than a minute unless temperature difference is around 1.5 degrees lower.

Does anyone have an Evohome and know whether this is normal operation on their system (and whether it really does learn) or anyone have any suggestions/experience as to why I seem to be having issues (at the moment I regret changing my simplistic 3 zone controller that just brings it fully on when drops 0.5 degrees below set point).

Thanks
Colin

It is normal, however I have set mine to 2 minutes rather than 1. How long has the system been installed? It takes 3/4 weeks to fully learn the system, and tbh it does it's own thing. I've told customers to just leave it in this initial period and allow it configure itself. After this you can then start tweaking settings. Do you know which software version you are running?

What's you system configuration?

 

[John.g]

Colin seems to say that even with the boiler firing continuously for 10 minutes that "it takes around 10 minutes to go from 36-70 degrees", can you think of any reason for this?.

 

[EvilDrPorkChop]

Colin seems to say that even with the boiler firing continuously for 10 minutes that "it takes around 10 minutes to go from 36-70 degrees", can you think of any reason for this?.

His boiler has a 1:10 modulation range, I can only imagine that it's modulating accordingly to the system demand.

The only other issue is that it could be return through the automatic bypass too quickly when the TRVs are on a low demand. Hence why I prefer a manual bypass. For me i'd set the auto bypass on the highest setting.

 

[John.g]

A bit of a puzzle alright though as one would think that it should reach its target temp of 70C even if it then exceed it.

 

[colin_]

Hi

Sorry for the late replies but been somewhat tied up this weekend.

As far as I can tell the system is OK when it has over 1 degree to heat up, it will bring the boiler on 100% and things will get warm.

The issue is when it is near set point as I think it is trying to maintain some low temperature in the radiator and it brings the boiler on for 1 minute and then off for 9 minutes.

I have noticed that my new Worcester boiler will by itself take around 5-10 minutes to warm from 30 - 70 degrees even if radiators are fully open (it modulates low and starts ramping up over time).

This means that in the 1 minute on/ 9 minutes off mode that the boiler does not raise the water to much over 36 degrees and coupled with the fact that the HR92 valves are near closed, the radiator stays coolish. It thus never exceeds the desired set temperature and so is always in the cycling on/off mode (unless hot day and sun warms up the rooms). It is worse in the fact that when it does this and goes to the off part I can hear water gurgling in the system from one of the radiators (I am still trying to bleed all the air out of the system 2 weeks later) that is in the bedroom which makes it hard to fall to sleep.

Even if I set it to 2 minutes on (8 minutes off) it does not change much as it is still ramping slowly up (36 degrees is the most I have ever had in this 2 minute on/ 9 minutes off mode. I could set it to 5 minutes by I suspect that will not help much and just mean that the boiler is on for 12 hours a day!

The automatic bypass is on 0.4 and is not getting warm (initially it was set to 0.15 for some reason), I will set it higher as a test (I sometimes hear a "clunk" after the boiler has stopped)

The system has been in for around 3 weeks and according to Resideo it should have learned by now (I am not sure as it had been warm until recently and so HR92s off). Unless it does learn then I cannot see it being useful as the boiler is on for 6 min x 24 => 2.5 hours without foing anything useful (initial readings show it on target to use approx 25% more gas than any other year for this month). So far worst decision I have made for heating control.

I have 12 zones in use and some of them are set for single room with multiple HR92 units. I have noticed for the sinlge room multi HR92 that when the controller says that the value % is say 20% that when some heat eventually gets in it is just one radiator so I presume that the others are fully closed and only one of them thinks it needs heat.

The software is the latest one as Honeywell pushed it for the installer when they tried to ascertain why it is not working correctly.

Does anyone know how the HR92s are used by Honeywell

1. The system tells them the temperature and they decide how far to open. If this is the case I cannot see how it could learn.
2. The system tells them the heat and how far to open. This way the system could learn but then I would have thought that all the HR92s bound as a single room zone would then open that far and they do not (as only one gets slightly warmer and different radiators in that zone do it).

Any information/ suggestions would be most welcome.

Thank you
Colin

 

[colin_]

It is normal, however I have set mine to 2 minutes rather than 1. How long has the system been installed? It takes 3/4 weeks to fully learn the system, and tbh it does it's own thing. I've told customers to just leave it in this initial period and allow it configure itself. After this you can then start tweaking settings. Do you know which software version you are running?

What's you system configuration?

Hi

If set for 2 minutes does that means that twice as much gas will be used (on for 12 minutes every hour => 4.8 hours as opposed to 2.4 if one minute - as in this mode mine never seems to get out of it unless the littel sun we have heats up the room a little)

When yours is in that mode, do the radiators get hot or just stay luke warm (mine never get hot when it is in that mode as the boiler takes up to 5 minutes to get from around 30 degrees to 50 degrees as it modulates up).

Thanks
Colin

 

[EvilDrPorkChop]

I think you're getting confused. It won't run 2 minutes every hour unless it needs to.

My radiators never get hot once the system is up to temperature as the system just learns and keeps topping the system up. In winter I leave mine on all day at set points and unless I boost a zone the radiators are generally luke warm.

If you've only just started using the system for heating then it won't have learnt enough over the past 3 weeks. I'd say you need a good 4 weeks in full heating use to give it the ability to calibrate itself correctly.

The main panel tells the HR92s what to do and what % to open close.

In terms of the radiator in the room you're saying it's warm enough. Is it near the set point, and if you boost it up to say 23oc does the radiator get hot then?

Honestly the biggest problem I usually find is people watching/messing with it too much in the early days. You need to let it do it's own thing.

 

[colin_]

I think you're getting confused. It won't run 2 minutes every hour unless it needs to.

My radiators never get hot once the system is up to temperature as the system just learns and keeps topping the system up. In winter I leave mine on all day at set points and unless I boost a zone the radiators are generally luke warm.

If you've only just started using the system for heating then it won't have learnt enough over the past 3 weeks. I'd say you need a good 4 weeks in full heating use to give it the ability to calibrate itself correctly.

The main panel tells the HR92s what to do and what % to open close.

In terms of the radiator in the room you're saying it's warm enough. Is it near the set point, and if you boost it up to say 23oc does the radiator get hot then?

Honestly the biggest problem I usually find is people watching/messing with it too much in the early days. You need to let it do it's own thing.

Hi

Many thanks for the reply.

I think my concern at the moment is that when the boiler is in this mode and is on then the radiator in one of the rooms demanding heat appear to not be warming up at all, indeed it appears as cold as the ones that are not demanding heat.

I have looked at the boiler display when it is heating for the minute and it has raised the temperature from say 30 degrees to 32 degrees which does not seem to be much. I have noticed that, even when zones are 100% on and valves fully open, the Worcester boiler will take around 10 minutes to go from 30 degrees to 70 degrees heat (it starts low and as time goes on you can hear the boiler working harder as it modulates up), now this may be normal but in this case I was wondering if the lack of heat and valves near closed was causing an issue. It may be that increasing the on time to 2 minutes (so we have 2 minutes on, 8 minutes off) may be helpful with this boiler but I am trying not to change anything whilst it is learning (as well as being on twice as long may use twice as much gas)

I asked Resideo about the learning and they said it should have learnt after 2/3 weeks even if the heating not required. Now I cannot see how this can be the case as the valves would always be at 0% and nothing to learn, hence I presume I have to wait the 4 weeks from now (as the weather being colder means the valves will be moving).

I have one room where it is not up to the desired temperature, the Evohome does its 1 minute/9 minute cycle but it never gets to the set temperature on the Evohome display (it was still cycling 1/9 10 hours later and that room was the only one not getting up to temperature, this appeared worse as it was happening at night and I still have water gushing noises that are being heard as air slowly bled out over last week and counting). The HR92 has been changed in that room and the stroke is set to 1 (setting to 1 was recommended by Resideo and seems to help in the other rooms). If the temperature is set to say 1.5 degree above what is required then it will get hot (and wireless realy to boiler will read 100%) but it never quite reaches the set temperature (usally 0.5 degrees below) and the radiator will go cold. I am hoping from what you say that the Evohome will eventually tell it to open more and/or bring the boiler on for longer than the 1 minute in every 10.

You mention that the main panel says what % to close the HR92 actuator, in the single room with multiple HR92s I have noticed that even though it says a % (and all the HR92 units read the same valve position) that only (usually) one of them (in the cylcing mode) is slightly warm. I presume that even though they all say the same, they are saying what the Evohome globally thinks for that zone and this is normal operation.

I will let it think for 4 weeks and if all is well I will also update here in case anyone else has the same issues. If it has notlearnt by then I am unsure of what to do next.

Thanks
Colin

 

[John.g]

"I have noticed that my new Worcester boiler will by itself take around 5-10 minutes to warm from 30 - 70 degrees even if radiators are fully open (it modulates low and starts ramping up over time)."

I think this is also part of your problem, any of the few gas boilers that I have seen will get the boiler flow temp up to SP in a minute or two except from a completely cold start, this doesn't mean that the rads will though which is correct in the Evohome case?.
I read up a bit about the system and it seems to me that the HR92s do the PI learning and tell the controller what to do and in some cases can even control themselves like a true TRV?.

 

[EvilDrPorkChop]

Hi

Many thanks for the reply.

I think my concern at the moment is that when the boiler is in this mode and is on then the radiator in one of the rooms demanding heat appear to not be warming up at all, indeed it appears as cold as the ones that are not demanding heat.

I have looked at the boiler display when it is heating for the minute and it has raised the temperature from say 30 degrees to 32 degrees which does not seem to be much. I have noticed that, even when zones are 100% on and valves fully open, the Worcester boiler will take around 10 minutes to go from 30 degrees to 70 degrees heat (it starts low and as time goes on you can hear the boiler working harder as it modulates up), now this may be normal but in this case I was wondering if the lack of heat and valves near closed was causing an issue. It may be that increasing the on time to 2 minutes (so we have 2 minutes on, 8 minutes off) may be helpful with this boiler but I am trying not to change anything whilst it is learning (as well as being on twice as long may use twice as much gas)

I asked Resideo about the learning and they said it should have learnt after 2/3 weeks even if the heating not required. Now I cannot see how this can be the case as the valves would always be at 0% and nothing to learn, hence I presume I have to wait the 4 weeks from now (as the weather being colder means the valves will be moving).

I have one room where it is not up to the desired temperature, the Evohome does its 1 minute/9 minute cycle but it never gets to the set temperature on the Evohome display (it was still cycling 1/9 10 hours later and that room was the only one not getting up to temperature, this appeared worse as it was happening at night and I still have water gushing noises that are being heard as air slowly bled out over last week and counting). The HR92 has been changed in that room and the stroke is set to 1 (setting to 1 was recommended by Resideo and seems to help in the other rooms). If the temperature is set to say 1.5 degree above what is required then it will get hot (and wireless realy to boiler will read 100%) but it never quite reaches the set temperature (usally 0.5 degrees below) and the radiator will go cold. I am hoping from what you say that the Evohome will eventually tell it to open more and/or bring the boiler on for longer than the 1 minute in every 10.

You mention that the main panel says what % to close the HR92 actuator, in the single room with multiple HR92s I have noticed that even though it says a % (and all the HR92 units read the same valve position) that only (usually) one of them (in the cylcing mode) is slightly warm. I presume that even though they all say the same, they are saying what the Evohome globally thinks for that zone and this is normal operation.

I will let it think for 4 weeks and if all is well I will also update here in case anyone else has the same issues. If it has notlearnt by then I am unsure of what to do next.

Thanks
Colin

What is your system configuration? Are you on a combi or System, heat only boiler you didn't state, just that it's an 8000. If the latter has the zone valve for the heating been removed? Are you using the boiler relay?

I think you've been misinformed by Resideo. As an installer I know this is definitely incorrect, the system cannot calculate warm up/cool down times and room atributes when it isn't heating said room!

Regarding the flow temperature, I think you need to look at the boiler configuration and the flow round the system. The boiler is obviously isn't getting going as it should.

In a room with Multiple HR92s have you got it set on Multi Room or Single room in the configuration?

 

[colin_]

"I have noticed that my new Worcester boiler will by itself take around 5-10 minutes to warm from 30 - 70 degrees even if radiators are fully open (it modulates low and starts ramping up over time)."

I think this is also part of your problem, any of the few gas boilers that I have seen will get the boiler flow temp up to SP in a minute or two except from a completely cold start, this doesn't mean that the rads will though which is correct in the Evohome case?.
I read up a bit about the system and it seems to me that the HR92s do the PI learning and tell the controller what to do and in some cases can even control themselves like a true TRV?.

I have sent an email to Worcestor technical asking if the slow start up is normal and if so is there anything that can be done to make it quicker (I outlined the 1 minute on time that Evohome is doing). I will update if I get an answer from them regarding it.

I am tempted to try 3 cycles per minute and 4 minutes on to see if it helps but as per EvillDrPorkChop recommendation, I am leaving "as-is" for 4 weeks to see if it sorts itself out (unless EvillDrPorkChop recommends otherwise)

Thanks
Colin

 

[colin_]

What is your system configuration? Are you on a combi or System, heat only boiler you didn't state, just that it's an 8000. If the latter has the zone valve for the heating been removed? Are you using the boiler relay?

I think you've been misinformed by Resideo. As an installer I know this is definitely incorrect, the system cannot calculate warm up/cool down times and room atributes when it isn't heating said room!

Regarding the flow temperature, I think you need to look at the boiler configuration and the flow round the system. The boiler is obviously isn't getting going as it should.

In a room with Multiple HR92s have you got it set on Multi Room or Single room in the configuration?

It is a Worcester Greenstar 8000 Life condensing boiler (GR83000iW 30S).

The old zone valves have all been removed and it is using the Evohome wireless relay box.

I have emailed "[email protected]" asking if it is normal operation and I am awaiting a reply.

I have the multiple HR92s set for single room. There seems to be confusion on multi room operation as the Honewyell website says you can but then says it needs to be set to heating type "Zone valve" to do so (rather than "radiator valve") but when I queried Resideo they said set it to "radiator valve" and it would be ok to set to mutli room but an installer has spoken directly with Honewell and they have been told that I cannot set my configuration to multiroom ....

Thanks
Colin

 

[ShaunCorbs]

I can confirm it will soft start and after 3-5 mins it will ramp up aslong as the ntc/ sensors agree

 

[colin_]

I can confirm it will soft start and after 3-5 mins it will ramp up aslong as the ntc/ sensors agree

This may be an issue with use on the Evohome as it is bringing it in for 1 minute only and water temeprature not going up much (a couple of degrees at most) before it turns off. It may be that the Evohome will learn this as it goes on and leave it on for longer but only time will tell (and at the moment it has been doing its 1min/9 min cycling for the last 6 hours)

Thanks
Colin

 

[EvilDrPorkChop]

It is a Worcester Greenstar 8000 Life condensing boiler (GR83000iW 30S).

The old zone valves have all been removed and it is using the Evohome wireless relay box.

I have emailed "[email protected]" asking if it is normal operation and I am awaiting a reply.

I have the multiple HR92s set for single room. There seems to be confusion on multi room operation as the Honewyell website says you can but then says it needs to be set to heating type "Zone valve" to do so (rather than "radiator valve") but when I queried Resideo they said set it to "radiator valve" and it would be ok to set to mutli room but an installer has spoken directly with Honewell and they have been told that I cannot set my configuration to multiroom ***.

Thanks
Colin

The only other issue I can see if it's returning to quickly and not ramping up, as Shaun says it'll only do this if the sensors agree. You need to check your pump setting on the boiler too, it's possible this isn't helping your cause.

Regarding EvoHome. It'll bring the system on and off as it requires. It'll not just keep bringing it on for a minute, otherwise the house would never get warm. It'll more than likely learn that a zone isn't heating correctly and that it requires more heat. You need to leave it on 2 minute minimum on time, and 6 cycles per hour.

The HR92s , when you've got multiple in one room you need to leave it on Radiator valve setting, and set to Multizone. Otherwise the master HR92 will control the other HR92s, when you want each to operate independently.

The room you are having an issue with, is this a room with multiple HR92s in by any chance?

 

[colin_]

The only other issue I can see if it's returning to quickly and not ramping up, as Shaun says it'll only do this if the sensors agree. You need to check your pump setting on the boiler too, it's possible this isn't helping your cause.

Regarding EvoHome. It'll bring the system on and off as it requires. It'll not just keep bringing it on for a minute, otherwise the house would never get warm. It'll more than likely learn that a zone isn't heating correctly and that it requires more heat. You need to leave it on 2 minute minimum on time, and 6 cycles per hour.

The HR92s , when you've got multiple in one room you need to leave it on Radiator valve setting, and set to Multizone. Otherwise the master HR92 will control the other HR92s, when you want each to operate independently.

The room you are having an issue with, is this a room with multiple HR92s in by any chance?

Hi

Not sure what the pump setting is but from the manual I have "Pump range map" and default is set for Constant pressure 250mbar but I will need to get the installer to check as they may have changed it (it can do "pump output proportiional to the thermal output as well as constant values of 150,200,250,300,350,400 mbar)

If other boilers were put on for a minute (or 2), what would be the expected rise in temperature out of the boiler (from say 30 degrees -> ???) as the Worcester mostly gets to only 33 degrees and 35 if lucky.

When the temperature is well away from set point it heats up nicely (albeit 10 minutes to get rads to 70 degrees) but when near set point and requesting a small amount of heat it seems to stick in this 1/9 cycle and never alter the on time.

The reason I left it at 1 minute was if it was cycling continually 1/9 as it is now then 2/8 would use more gas, but it is something I can try.

I am unsure of the single vs multi room setting for multiple HR92 on one zone. It is currently set to single room and when near to temerpature and requesting heat then usually only one gets slightly warmer (can be any one). I was going to have it set to multi-room but according to the installer, when he rang and spoke with Honeywell they said that my system cannot use multi-room, but I was offered no explanation as to why not, especially when it can be set in the menu.

The room I am having an issue with is by itself in a single zone.

As an aside, does Evohome work better with new radiators that heat up quicker (and los heat quicker) than the older radiators (take a while to heat up but lose heat slower) as I have a few old style radiators (20+ years old) - unfortunately not in the room I am having an issue with.

Thanks
Colin

 

[colin_]

Just a further update.

As far as I can tell it is looking like my issue is due to the slow start of the boiler itself as in one minute it barely raises a couple of degrees and once that is pushed around and lost in the pipes then not much goes to the radiator.

This morning the system was calling for heat on several radiators and the Evohome doing its one minute on/9 minutes off and the radiators were still cold.

Once the hot water requested heat from the boiler it ramped up (after ~ 10 minutes) to 70 degrees and all the radiators that were requesting heat got hot (so valve definitely open enough, simply not enough heat from the boiler in one minute).

It is looking like this boiler will not work with the Evohome (which is a shame as the same installer installed both the boiler and the Evohome) as even if I set the time to the max 5 minutes min on time on the Evohome it will still only raise it a paltry 13 degrees (and that would mean the boiler was on 5 minutes, off 5 minutes, on 5 minutes . . . . which would be a big waste of gas).

The heating data from this morning was

Time offset in minutes	Degrees on boiler	Degrees increase from initial	Degrees increase from previous time point
0	27	-	-
3	30	3	3
5	40	13	10
7	50	23	10
9	60	33	10
11	66	39	6
12	69	42	3
12.5	70	43	1

 

[John.g]

Is your boiler a combi and what is its rated output.?

Will have a look at your numbers above when I return but they seem to be broadly in line with what Shaun Corbs is saying in post#14 "I can confirm it will soft start and after 3-5 mins it will ramp up as long as the ntc/ sensors agree" is it the Evohome that's causing the soft start or the boiler itself? in which case it will always take ~ 10 minutes to ramp up, so not great even if heating a HW cylinder.

 

[colin_]

It is the boiler that that does the soft start and takes ages to heat its output water to 70 degrees. The hot water will go from ~45 degrees to 60 degrees in around 20-25 minutes (dependent upon what else it is heating at that time)

Thanks
Colin

 

[colin_]

If another boiler without the soft start function comes on, what temperature does the output from the boiler get to (from 30 degrees) in 1 minute and in 2 minutes?

Thanks
Colin

 

[ShaunCorbs]

You get the full rated output within 20 seconds ish

 

[John.g]

It is the boiler that that does the soft start and takes ages to heat its output water to 70 degrees. The hot water will go from ~45 degrees to 60 degrees in around 20-25 minutes (dependent upon what else it is heating at that time)

Thanks
Colin

You will have to try and get that soft start sorted out, ironically, there are numerous posts around re gas boilers firing up at 70/80% of output for up to a minute before modulation and actually cutting out on high flow temperature, you can't win.

 

[colin_]

You get the full rated output within 20 seconds ish

So the boiler I have will probably not play well with the Evohome if it expects the full heat well within the minute (as it needs up to 10 minutes!)

Thanks
Colin

 

[ShaunCorbs]

So the boiler I have will probably not play well with the Evohome if it expects the full heat well within the minute (as it needs up to 10 minutes!)

Thanks
Colin

No boiler will do that you should be able to change the perimeters of evo to adjust this

 

[John.g]

That definitely makes sense.

 

[colin_]

No boiler will do that you should be able to change the perimeters of evo to adjust this

Hi

I adjusted the evo to keep on for 2 minutes but all that happens is it gets to ~40 degrees before tunring it off (nowhere near the 70 degrees set on the boiler).

Near the end of the 2 minutes you can hear the tone of the boiler change as it starts to modulate up, ust in time for the Evohome to tell it to stop.

Not sure I want to go longer than 2 minutes as gas usage will go up rather than the heat.

There appaears to be a parameter 5-A3 "Minimum boiler output (heating and DHW)" whose default is 10% (and max is 50%). I will be asking the installers (who did the boiler and Evohome) whether this needs to be set higher (perphaps 20-25% or higher?) so the boiler does not modulate so low at the start (especially as the Evohome will be in control)

Thanks
Colin

 

[ShaunCorbs]

Need to go longer else you will knacker your boiler as there designed to run longer

 

[colin_]

Need to go longer else you will knacker your boiler as there designed to run longer

The default of the Evohome is 1 minute on time (max is 5 minutes) when it is in the cycling mode (6 timers per hour).

I rang Worcester technical several days agao and he said the boiler would be happy doing it!

The boiler has the Worcester 12 year warranty so hopefully all should be well on that score.

When set for 2 minutes it only gets to 46 degrees before it turns it off again.

I have set it for 3 minutes now and when it came on it was still only 46.3 after 3 minutes - I am still (unfortunately) monitoring it.

I am waiting to see what the installers think after contacting Worcester technical about what the 5-A3 "Minimum boiler output (heating and DHW)" does and the ramifications of increasing it.

Thanks
Colin

 

[John.g]

The majority of boilers only modulate 5 or 6:1 but yours is 10:1 so maybe to replicate these boilers increase the min output to 25/30% (5-A3) and see how it goes, can't do any harm. and can always revert.

 

[colin_]

The majority of boilers only modulate 5 or 6:1 but yours is 10:1 so maybe to replicate these boilers increase the min output to 25/30% (5-A3) and see how it goes, can't do any harm. and can always revert.

I have asked the question of the installers (still waiting an answer) and I was thinking of having it changed from 10% to 20-25% as a test (can put heat on full and see how it performs)

I can eventually manage to get the temerpature to 60 degrees if I let the boiler come on for 3 minutes min time and off for 7 minutes (it cycles every 10 minutes) and this at least lets the radiator get warm (at the expense of gas) after about 4 cycles (so 12 minutes gas)

Hopefully if the change to 20% ish makes the boiler start modulating higher this will help the Evohome system and I can probably back off the 3 minutes to 2 (it should eventually learn what is what) and also get the heat up to 70 degrees quicker when the zones are fully open.

Thanks
Colin

 

[John.g]

I can't see any reason for a increase in gas usage, your house requires a certain amount of energy to keep it at a set temperature, the only reason that Evohome is range rating the boiler is to prevent too much setpoint room temperature overshoot?.

 

[colin_]

I can't see any reason for a increase in gas usage, your house requires a certain amount of energy to keep it at a set temperature, the only reason that Evohome is range rating the boiler is to prevent too much setpoint room temperature overshoot?.

Hi John

I think my concern was that if it was on for 6 x 1 minutes and I set it for 6 x 3 minutes then I am using 3x the amount of gas.

However if the 1 minute does not warm the radiator (above say 32 degrees) then it is probably never going to stop the cycling (until Evohome learns?) whereas the 3 minutes one will (after about 4 or attempts => 40 - 50 minutes get it up to around 60 degrees (at the end of the 3 minutes) so may be better.

I am waiting for them to get back from confirming with Worcester that changing the mosulation to say 20-25% (from the 10 it is now) will make it heat quicker and if so then all should be OK.

Thanks
Colin

 

[ShaunCorbs]

Set it to the maximum run time

 

[EvilDrPorkChop]

Your issue isn't the boiler as i've previously said. It's the on time rate from Evohome not working correctly, probably because of the algorithms it uses, thrown in with the fact it's been installed in a time when heating wasn't being used. Any boiler won't ramp up in 1 minute, Vaillants take about 2 mins to get going also. When you say the zone isn't meeting the set point, what temperature is the zone and what should it be?

I'd suggest deleting the troubled zone and resetting it back up. This will reset the learning for that zone. I'd also suggest looking at the flow rate to the rad, making sure the TRV on the rad is working correctly. Have you had all new TRVs throughout with the new EvoHome system?

 

[colin_]

Your issue isn't the boiler as i've previously said. It's the on time rate from Evohome not working correctly, probably because of the algorithms it uses, thrown in with the fact it's been installed in a time when heating wasn't being used. Any boiler won't ramp up in 1 minute, Vaillants take about 2 mins to get going also. When you say the zone isn't meeting the set point, what temperature is the zone and what should it be?

I'd suggest deleting the troubled zone and resetting it back up. This will reset the learning for that zone. I'd also suggest looking at the flow rate to the rad, making sure the TRV on the rad is working correctly. Have you had all new TRVs throughout with the new EvoHome system?

Hi

I have set the on time for 3 minutes and the water will eventually get up to around 60 degrees after 4-6 cycles of the 3 minutes on/ 7 minutes off which at least lets the radiators get warmer now (it still spends a significant time on lower modulation and lower temp before hitting the 60 mark at the end of 3 minutes - after sevral cycles of it to get there).

The set temperature was 18 degrees, the Evohome said it was 17.5 and never previously got to 18. With the on time at 3 minutes it eventually gets there (after around 30-40 minutes of the cycling on/off).

That zone was deleted as a new HR92 was fitted on it but it still misbehaved until 3 minutes on time set.

There was also a new zone set with multiple HR92s (with one as sensor) but this has started to misbehave. When the hot water zone comes on, one of the raidators in that zone can also be hard on (gets very hot) and the temperature ramps up (read with a min/max temeprature unit) from the set point of 18.5 degrees to 21 but the zone says it is still requesting heat (all the other HR92 units in that zone are cold) and thinks the read temerpature is 18.5 even though clearly it is not.

I had this in the recent past (as new system) when there were 6 radiators in a zone but when the zone was split, a HR92 was replaced as it was thought to be the cause. I have tonight changed the HR92 with another radiator in the zone to see if it follow the HR92 or remains at the radiator.

Now the installer says that my zone with multiple HR92 units cannot be set to multiroom (can only be used single room) as the person he contacted at Honeywell says that my system cannot do this (I have had no explanation as to why).

Thanks
Colin

 

[EvilDrPorkChop]

Hi

I have set the on time for 3 minutes and the water will eventually get up to around 60 degrees after 4-6 cycles of the 3 minutes on/ 7 minutes off which at least lets the radiators get warmer now (it still spends a significant time on lower modulation and lower temp before hitting the 60 mark at the end of 3 minutes - after sevral cycles of it to get there).

The set temperature was 18 degrees, the Evohome said it was 17.5 and never previously got to 18. With the on time at 3 minutes it eventually gets there (after around 30-40 minutes of the cycling on/off).

That zone was deleted as a new HR92 was fitted on it but it still misbehaved until 3 minutes on time set.

There was also a new zone set with multiple HR92s (with one as sensor) but this has started to misbehave. When the hot water zone comes on, one of the raidators in that zone can also be hard on (gets very hot) and the temperature ramps up (read with a min/max temeprature unit) from the set point of 18.5 degrees to 21 but the zone says it is still requesting heat (all the other HR92 units in that zone are cold) and thinks the read temerpature is 18.5 even though clearly it is not.

I had this in the recent past (as new system) when there were 6 radiators in a zone but when the zone was split, a HR92 was replaced as it was thought to be the cause. I have tonight changed the HR92 with another radiator in the zone to see if it follow the HR92 or remains at the radiator.

Now the installer says that my zone with multiple HR92 units cannot be set to multiroom (can only be used single room) as the person he contacted at Honeywell says that my system cannot do this (I have had no explanation as to why).

Thanks
Colin

Your multi room HR92s need to be set to Multi Room (Zone Configuration>Said Zone>Parameters>Single/Multi Room Zone>Multiple).

Advanced Load Scaling> Is this set to None?

Swapping HR92s will only confuse the learning, but you can give it a try.

You also didn't answer my question regarding the TRVs, are they new valve bodies or existing?

Is the Evohome system been installed new with the boiler or existing.

 

[colin_]

Your multi room HR92s need to be set to Multi Room (Zone Configuration>Said Zone>Parameters>Single/Multi Room Zone>Multiple).

Advanced Load Scaling> Is this set to None?

Swapping HR92s will only confuse the learning, but you can give it a try.

You also didn't answer my question regarding the TRVs, are they new valve bodies or existing?

Is the Evohome system been installed new with the boiler or existing.

Hi

Advanced load scaling is set to disabled.

The installer changed all the radiator valves and fitted new HR92 and the Evohome system.

They also fitted the new Worcester boiler.

According to the installer, he says that he has rung Honeywell and my system should only be set to Single room as multi room is not supported on my system (without giving any reasons as to why it is not supported). I have filled in the form on Resideo asking why there is conflicting information on whether it can or cannot be based upon who in Honeywell/Resideo is answering (the online instructions also say to set it to zone valve and not radiator valve for some reason) but I have not had a reply back from them yet.

The systems consists of 12 zones (2 of which have multiple HR92 units), a hot water sensor and wireless relay box for it, and another wireless relay box for bringing the boiler on.

At the moment I can hear the boiler come on for 3 minutes and off for 7 minutes (for the last hour) as it thinks that one of the zones with multiple HR92s want heat even though none of them are warming up.

I am currently wishing I had never changed from the simple 2 zone solution I had as at least it worked, hopefully if I can get the Evohome working I will learn to like it (worst case get them to remove it and go back to the simple system).

Regards
Colin

 

[EvilDrPorkChop]

It's not hard to change it and try it, but so be it. Wait for your reply.

Good luck getting the system sorted.

 

[colin_]

It's not hard to change it and try it, but so be it. Wait for your reply.

Good luck getting the system sorted.

Thanks, I think I'll need it. (hoping the system will not be 3 minutes on/ 7 minutes off for the rest of the night as may be tempted to turn the boiler off.

I have set to multiroom on this zone to see if anything changes.

 

[colin_]

It's not hard to change it and try it, but so be it. Wait for your reply.

Good luck getting the system sorted.

Thank you for your help and assistance.

Regards
Colin

 

[John.g]

Thanks, I think I'll need it. (hoping the system will not be 3 minutes on/ 7 minutes off for the rest of the night as may be tempted to turn the boiler off.

I have set to multiroom on this zone to see if anything changes.

Your house must require some level of heat to keep it warm so even though you are not seeing any rise in room temp this just proves in a way that the evohome is working by just firing the boiler long enough to keep the house exactly at your required temperature by keeping the rads at the required temperatures.
Except that your rads are at the room temperature then they must be emitting some heat so even if they are only at 25C and the rooms temperature is 18C then they will still emit ~ 8% of their rated output say 1.6 to 2 kw of a 20kw rating which isn't going to break the bank.

 

[colin_]

Your house must require some level of heat to keep it warm so even though you are not seeing any rise in room temp this just proves in a way that the evohome is working by just firing the boiler long enough to keep the house exactly at your required temperature by keeping the rads at the required temperatures.
Except that your rads are at the room temperature then they must be emitting some heat so even if they are only at 25C and the rooms temperature is 18C then they will still emit ~ 8% of their rated output say 1.6 to 2 kw of a 20kw rating which isn't going to break the bank.

Hi John

I think the main issue is that the boiler starts up at its min modulation (10%) which means 3KW of heat to warm up the water. It remains at this level for several minutes before ramping to the next level. It keeps ramping up and it can take over 12 minutes to get to 70 degrees.

I heave set the Evohome for a minimum on time of 4 seconds and iduring this time it can barely raise the water temerpature to 45 degrees (from around 30). It thus keeps coming on for 4 minutes in every 10. It eventually gets to around 60 degrees but that takes arind 5-7 cycles so around an hour. It is worse if more radiators want heat.

I suspect that the system will work much better if the start modulation is set higher (20% -> 6KW) and I am waiting on the installer to get back to me and set it as a test.

Thanks
Colin

 

[John.g]

Yes, understood, but Evohome seems to be saying so that as long as the the room temp is within 1.5C of its setpoint that whatever minimum time you have set is in fact a fixed time and not just a minimum?. So if the temperature offset is 0.75C then the controller just looks for the TRVs to be open say 50% or something like that and during this x weeks learning curve if the room temperature isn't rising then it might look for 75% opening or whatever but has no effect on the actual run time?

Is this your understanding of how it works?

 

[colin_]

Yes, understood, but Evohome seems to be saying so that as long as the the room temp is within 1.5C of its setpoint that whatever minimum time you have set is in fact a fixed time and not just a minimum?. So if the temperature offset is 0.75C then the controller just looks for the TRVs to be open say 50% or something like that and during this x weeks learning curve if the room temperature isn't rising then it might look for 75% opening or whatever but has no effect on the actual run time?

Is this your understanding of how it works?

Hi John

I think that when near temperature the Evohome is supposed to know how long to bring the boiler on to get the desired temperature (it is supposed to learn this over several weeks).

In the settings you can set the minimum time that the Evohome will bring the boiler on for, the defualt is one minute every 10.

I have had to set this to 4 to even get the radiators warm (it gets the temperature from the boiler to ~50-55 degrees in an hour of cycling 4 minutes off, 1 minute on).

I am now on its max setting of 5 (so boiler spending 50% of its time on whilst doing this - but presumably ok as modulated down to say 10% for firt couple of minutes).

So far the Evohome has not worked out that it needs to adjust the on time.

I do believe from what others have said is that the Evohome tells the HR92 how far to set its actuator.

Thanks
Colin

 

[fronty]

Another evohome user here, been reading this thread with interest, I do believe when evohome is doing this TPI thing (eg firing for 1 minute in every 10), the flow temps are not supposed to get up to anywhere near what you'd expect, it's literally just warming the water slightly to dump a small amount of heat into that zone, the idea is to prevent an overrun.

My system seems to work quite well as it will maintain the temps in each room once the set point has been reached. However what I did find is that some rads did not get warm at all despite calling for heat. It seems than for low demands of 10-20% when the boiler is firing as per TPI schedule, the valve does not open enough inside the TRV to let any water pass, I found that on a couple of rads I had to set the HR92 stroke parameter (setting 6) to 1. That seemed to fix the problem and even on low demands I can feel some heat in the rad, it's not hot just warm..

I don't think anyone has mentioned this so give it a try.

 

[colin_]

Another evohome user here, been reading this thread with interest, I do believe when evohome is doing this TPI thing (eg firing for 1 minute in every 10), the flow temps are not supposed to get up to anywhere near what you'd expect, it's literally just warming the water slightly to dump a small amount of heat into that zone, the idea is to prevent an overrun.

My system seems to work quite well as it will maintain the temps in each room once the set point has been reached. However what I did find is that some rads did not get warm at all despite calling for heat. It seems than for low demands of 10-20% when the boiler is firing as per TPI schedule, the valve does not open enough inside the TRV to let any water pass, I found that on a couple of rads I had to set the HR92 stroke parameter (setting 6) to 1. That seemed to fix the problem and even on low demands I can feel some heat in the rad, it's not hot just warm..

I don't think anyone has mentioned this so give it a try.

Hi

I am not sure what the system is supposed to be doing when in TPI mode but it seems that if I put the on time of the boiler to 4 minutes then the radiators will get hot (obviously as more time to heat) and that allows the system to get to/past the set temperature quicker and after a few cycles of that it will no longer need to come on every 10 minutes as no longer calling for heat.

My situation is made worse by the fact that the bathroom radiator is, at the moment, fully open and being used instead of an automatic bypass and if I do not have the boiler hotter then any heat that is output (even at 3 minutes, hence move to 4 minutes) is lost into this radiator and does nothing for the radiators that are wanting the top up heat.

I also have a Worcester boiler that seems to slow start. It comes on at a minimum modulation (default 10%, mine now 20%) and will stay there for several minutes before deciding it needs to up its modulation. This again means I have to set the minimum on time high. I hate to think what the gas usage is going to be like (Honeywell mention that the system will use less gas but in my case it looks like it will be much more).

So conflicting system needs and trying to get it sorted is a nightmare (Honeywell connected specialist installed it - they say they have escalated it with Honeywell). It would have been nice if Honeywell state what happens in TPI mode, especially with what the boiler is expected to do.

[Q1] When in TPI, do you happen to know what temperature your boiler is getting up to when it is turned on - when I had mine at 3 minutes it barely got to 40-45 degrees out of the boiler and so much less at the radiators?

[Q2] When in TPI mode you mention that the radiators are only warm, on yours is the most warm near the top of the radiator with the rest simply warm or is it evenly distributed around it?

[Q3] When in TPI mode, I presume that it takes many 10 minute cycles before the HR92 units are demanding 0% (hence why mine seemed to be coming on every 10 minutes for 4-5 hours)?

BTW: I had to put all my HR92 into full stroke mode to ensure that they opened far enough given what little heat was being given out.

Thanks
Colin

 

[John.g]

This means so that its opened more for any given HR92 deltaT?,

I never see any mention of the position of the HR92, ie on the rad flow or return as if installed on the return will give a more representative room temperature, obviously doesn't make any difference with a cold rad and a few bursts of 1 minute boiler run time.

 

[colin_]

Dear John

I think the Evohome may decide (as part of its learning process) to open it up more if the temperature has not moved in the last 10 minutes so that next time it gets more heat through it but that is just conjecture on my part as not looked closely at that yet.

Thanks
Colin

 

[John.g]

Talking generally,

"Normal" PI control integrates the (proportional) error over given time, for example if the error was looking for 10% valve opening then with a 1 minute integral time the valve opening will increase by another 10% in 1 minute (if the error remains constant) eventually and would be 100% open after say 9 minutes, normally the error is reducing as the valve opening increases so the integral add on progressively reduces until there is no error and the valve will stop opening, eventually the measured value may be > the SP value (integral overshoot) so the integral effect starts reducing the valve opening until eventually the SP value is achieved.

EH must clearly interrupt this integral effect when the boiler is not (EH) switched on otherwise all the HR92s would be 100% open irrespective of their room temperatures after a relatively short period and certainly after a overnight boiler shutdown.
If, as you think, the EH does not increase/decrease the valve opening with integral effect until there is a change in temperature after a certain time then that is not true PI control so maybe this is why its called timed PI control and doesn't increase/decrease the valve opening until each burst of run time unless the temperature has actually changed.
Or maybe the EH integral time is just the on run time/cycle.

Still a bit confusing to me IF it doesn't increase the valve opening to 100% say overnight whatever way I look at it.