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

[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.