Real world testing example of Condensing Boiler in older home

[ShaunCorbs]

Would be best practice

 

[JC22024]

Would be best practice

Yes that's OK I will make that good before I proceed - will try to get that done on Sat and system going again then balance on Sunday.

Since the upstairs and downstairs zones are programmed independently, I will balance them independently too.

This is a good video on the subject FWIW. Not how to balance but the theory of the efficiency and why it is important. A band aid to get a further rad to heat may be to turn pump speed up but as they explain it makes it worse even if that rad heats.

 

[John.g]

Any (if) build up of sludge in the rad itself has a huge effect on rad dT, I find that to make any appreciable difference in flowrate and dT that I would have to throttle in (either) one valve to only ~ 1/4 turn open, it seems, on my system anyway that I will only start increasing the dT by throttling from say 1/2 turn open, down.. Even with both valves fully open my rads have a dT of ~ 7C to 10C with a pump head of ~ 3.5M.

 

[JC22024]

This is a domestic Boiler Energy Manager I also got on ebay. They are about £200 from supplier but a guy on ebay has a few new ones for £50 so worth a try at that. At £200 probably wouldn't have bothered but interested to see if / how it may reduce oil consumption/ boiler cycling.

Energy Minder Auto | Total Energy Controls

 

[JC22024]

I checked the radiator valves and only a couple have the TRV on the return side. They are bi directional TRVs but all the same I will move them.

But thinking more about the 11c ideal temperature drop - how obtainable is this really? The Delta radiator temperature drop would be directly linked to the heat disapated into the room.

So the room temperature / weather would also be important.

It's very mild at present with temperatures outside at or near 7-10c. So in that case I think turning the boiler stat up for the balancing will provide better results unless the weather drops when I get to it.

Do you guys agree with what I'm saying in principle? If my rooms are 18c now, 7c outside and I am seeing 4 or 5 c drop max across a radiator then perhaps that is all it would achieve unless the room temperature dropped.

Maybe open the windows for balancing 😀

 

[John.g]

All my TRVs are on the returns and I can certainly balance/reduce rad outputs by throttling the lockshields, but as I said I reckon I would find it extremely difficult to get all rads to a dT of say 10C or 15c or whatever, having TRVs on all rads, once they throttle in will give a variable dT depending on the room temperature(s). I have watched my boiler return over the past few days and it never goes below 42/43C and probably averages more like 45/46C. I really think the best way to get a relatively constant low (but not below 38/ 40C for oil firing) is to use flow temperature control. You could get limited return temperature control by controlling the flow with a smart circ pump but this only allows a minimum rad output of ~ 58% whereas flow temperature control (if achievable) allows rad outputs as low as 30% with return temps not falling below ~36/38C.

 

[JC22024]

All my TRVs are on the returns and I can certainly balance/reduce rad outputs by throttling the lockshields, but as I said I reckon I would find it extremely difficult to get all rads to a dT of say 10C or 15c or whatever, having TRVs on all rads, once they throttle in will give a variable dT depending on the room temperature(s). I have watched my boiler return over the past few days and it never goes below 42/43C and probably averages more like 45/46C. I really think the best way to get a relatively constant low (but not below 38/ 40C for oil firing) is to use flow temperature control. You could get limited return temperature control by controlling the flow with a smart circ pump but this only allows a minimum rad output of ~ 58% whereas flow temperature control (if achievable) allows rad outputs as low as 30% with return temps not falling below ~36/38C.

View attachment 73023

Controlling the return temperature would be good- but I am not a huge fan of smart pumps. On my house at least. Because some radiators drop out altogether. The pump now fitted does a great job.

But what I was thinking is wouldn't it be great to have a thermostatic device on the return pipe to the boiler which could sense the 50c return temp etc and maintain it. Eg throttle down automatically if the flow temp tries to climb above 50c but in all other instances normal flow. (Since I like 70c flow setting then 50c is what my system would be good at)

There must be something available along these lines. At a quick glance maybe something like this that can be set to thermostatically control a flow.

MTCV-CCR2

Danfoss MTCV thermal balancing valves – reduce the risk of legionella, long waiting times and high energy consumption in drinking water applications.

www.danfoss.com

Get radiators balanced as precisely as possible first then something like this to provide precise control on return.

 

[John.g]

Rad stats give individual room control so why throttle the main if the room stats are set properly and operating properly?. The boiler return temp will then be at its lowest possible but individual rad returns will vary from say 50/55C downwards, consistent with your requirement for a 70C constant flow temp, my rad stats give excellent individual room control.

 

[JC22024]

Rad stats give individual room control so why throttle the main if the room stats are set properly and operating properly?. The boiler return temp will then be at its lowest possible but individual rad returns will vary from say 50/55C downwards, consistent with your requirement for a 70C constant flow temp, my rad stats give excellent individual room control.

Thanks yes not a great idea then was just throwing it out there as an alternative means to obtain the magical 20c drop if radiator balancing alone can achieve it.

Probably a case of do what you can with rad balancing and it is what it is. Eg 10c delta on boiler, if that's what you get then no more to reduce it by. But on colder days and warmup it will in realty be a greater delta.

 

[John.g]

Just read in a UPS 2 8M pump replacement post that a Dab Evoplus & a Grundfoss Magna 3 are suggested, you might be interested from the point of view that the also do temperature control, might be worth a look?.

 

[ShaunCorbs]

Prob is the magna3 eg dt controlled with all the kit ends up around £600

 

[JC22024]

Just read in a UPS 2 8M pump replacement post that a Dab Evoplus & a Grundfoss Magna 3 are suggested, you might be interested from the point of view that the also do temperature control, might be worth a look?.

Prob is the magna3 eg dt controlled with all the kit ends up around £600

I must read up on those but again I think my house suits a single speed pump.

Aka imagine some of the TRV valves start to close around the house. A smart pump would sense this and reduce the pressure or if it senses heat and modulates flow based on that then it would also throttle back the flow. And thus other radiators may fall dead again even when calling for heat.

It would work well no doubt in a new installation where the pipes and rads etc are properly designed installations but retrofitting into an old and somewhat unknown system / sizing probably won't give desired results IMO

 

[John.g]

Thinking more about it, would be inclined to agree with you, anyway when you balance your system you can just throttle the valve again until you get a average return temp of say 40Cish? and see how the system performs. if it is OK, then far cheaper maybe just to install a thermostatic valve in the line?. if it doesn't work you can just open it fully.

 

[JC22024]

Thinking more about it, would be inclined to agree with you, anyway when you balance your system you can just throttle the valve again until you get a average return temp of say 40Cish? and see how the system performs. if it is OK, then far cheaper maybe just to install a thermostatic valve in the line?. if it doesn't work you can just open it fully.

Yes I'll balance it properly first and see where the temps are at then.

Then run when I can monitor run time and burn time for a few days. Then downsize nozzle and repeat for comparison.

Then add the boiler energy manager and see if that reduces cycling etc. If it does then I'll probably leave it set up like that.

The BEM company can't give good advice on the wiring FFS! Asked a few times and the emails back don't make sense. They appear confused if it should link before or after my boiler stat. So I'll probably have to test that too and see which setup works best.

 

[ShaunCorbs]

If you can put up some instructions / wiring diagram will have a look later on

 

[JC22024]

If you can put up some instructions / wiring diagram will have a look later on

Thanks for that, I attach the PDF manual and also an extract of the wiring diagram below:

I have a CH wiring centre in my boiler room so no worries there. I understand their diagram also. But when I was simply asking that when installed on an oil boiler might it be best to link in before the boiler stat per diagram or go in between the stat and burner. Their reply was:

sorry for the delay responding, the black/grey cbles of the energy minder would smply wire in series with one of the cables from the boiler stat or their shoud be a link on the control panel for an external control wich would be removed and the black/grey cables wired into their place.

which doesn't help at all really they didn't understand what I was asking. I sent wiring diagram and photos of my boiler also. Anyway I'll follow their diagram and link thier black wires in between my "call live" wire from 240v zone valves switches and the boiler stat.

 

[JC22024]

I was just thinking that if the logic in the board of the BEM would function better before or after the boiler stat.

If it goes before the stat then there will be instances where it will be calling for heat and the boiler stat is satisfied. Burner not firing.

If it goes between burner and boiler stat then only when the burner demand is being called by heating system and boiler stat will it get signal and be able to control without the boiler stat interfering.

Personally I think the later may be the better setup- what do you guys think? Not knowing the logic of the device fully means however I should prob follow their diagram all the same!

 

[JC22024]

Not to confused things but I also did receive the Vector works BEM also. No instructions available for this one its top secret jobbie 🙄

On opening it, the connections are labeled. And it only has a power in, stat and boiler connections. No temperature monitoring aparantly. Not that I am qualified to comment but that hasn't stopped me before- appears limited for the high cost.

 

[JC22024]

Since the connections on the Vector unit were so simple I went ahead and wired it in temporarily at least. Boiler stat outlet going to "Stat" on its board. Burner wires connected to "boiler" on the board. Perm power added to remaining connection.

It appears to be working now. Upper figure is the call time of the boiler. Lower counter is the actual time it is firing the boiler.

So let's see if the house heats as well and the timers show a saving 🤔

 

[John.g]

Havn't read all the posts yet so basically is it monitoring the cycle times and then by means of a relay interrupting the switched live to the boiler?. If so, what determines the optimum cycle time?.