Method or madness in this CH installation?

[ATTQ]

It depends on what you call a "room thermostat"?

I was assuming meant wall thermostat. Thanks for the explanation. I'm not sure if we'd benefit much by having wall thermostats in each room and i prefer to keep it simple. We have a gas fire in the living room which is drawing the family to use that space together more which is nice, rest of house cooler which saves money. Can't have the thermostat in the living room of course as you say with alternate heating. Or the kitchen. We also don't have another room without external door. Hallway heat goes up so seems a poor choice.

Individual TRVs as you say seems fine and a boiler on a timer just modulated by the return temperature rising when the TRVs are shut. Its what we're doing now. Can bring the max temp of the boiler down as it gets warmer season so its a more steady heating. Seems very simple but will take a good bit of time to get perfectly balanced and set up I guess. Will be a new law in the house that no one fiddles with them without first consulting me about it. I'm not even sure if the TRVs work still, most are ancient and covered in paint and dust. On my list of things to do, just been assuming will change all of them

Once its set up best i can I'll assess if the rads would benefit from being more effective convecting ones. There's nothing in the way of sludge in the system, they are all singles and old but then maybe having ones that give off the heat more quickly would have a drawback in causing more of this

 

[ericmark]

I installed my own central heating (Gas) around 1980, there were a few teething problems, but in the main it worked well, so I never really considered how to control it, open-plan house, a thermostat between the dinning room and living room worked well.

It was much latter when my dad had his second system fitted, and I realised it was not working very well. The hall had the ramp for mother's wheelchair, and allowed most of the heat to raise up the stairs, so I fitted a curtain around the bottom of the stairs, but also the installers had not set any lock shield valves.

The use of TRV heads which displayed both target and current temperature helped, and I got it running reasonably well, the thermostat was not suitable.

It had a mark/space system to stop overshooting, which would have worked great in this house with an oil boiler, but for the modulating gas boiler it was not very good, but I never got around to changing it.

Soon after my mothers' death, we moved here, by this time I was a bit of a big head, and thought I knew all about central heating, but no, it did not matter how carefully I tried to set the lock shield valve, TRV and wall thermostat (Nest Gen 3) I could not get it to work as I wanted, I realised the problem was not the heating, but the cooling, the hall cooled too slowly, only way was to have multi thermostats to turn on boiler, and Nest USA has multi sensors, but not Europe Nest. So either Hive and Wiser seemed to fit the bill, but Hive will not accept a demand for heat over 22ºC, so decided to go for Wiser.

Only after buying did I realise it will work without a wall thermostat, but two thermostat which will run the boiler seems to have cured the problem in the main, still want to fit a linked TRV in wife's bedroom, but in the main now runs OK.

 

[ATTQ]

What would be useful is an outdoor temp reader linked which changed the target temp of the boiler. It wont work on mine as no way to control that other than a manual pot (or does it?) but I can imagine it would be a useful way to do macro adjustments to the system

 

[ScottishGasMan]

What would be useful is an outdoor temp reader linked which changed the target temp of the boiler. It wont work on mine as no way to control that other than a manual pot (or does it?) but I can imagine it would be a useful way to do macro adjustments to the system

Thats a completely normal way of running a condensing boiler. It's called weather compensation.

The radiators need to be X degrees when its -5 outside, but the dont need to be as warm as X when its -2 or +10 degrees outside as there is less heat loss from the building.

Weather compensated controls have an outdoor sensor that makes tiny adjustments to the boilers flow temperature based on variations of the outdoor temperature.

A system which needs say 75 degree flow when its -3 outside would only need about 55 degrees flow temperature when its 7 degrees outside. Telling the boiler to alter its flow temperature stops the system cycling on and off as much, and more importantly reducing flow temperatures increases condensing within the boiler increasing efficiency.



As far as your original post is concerned: It's unlikely it was plumbed that way to increase return temperature. If that radiator on its own run was responsible for say 10% of the heat demand in the property, then it should have been balanced so that it only had 10% of the water flow from the boiler. When the 10% of the water from that radiator returns to the boiler it mixes with the 90% of the water from the rest of the system so doesn't effectively increase the return temperature.

Systems that could increase the return temperatures were certainly used for big commercial equipment, but not on a normal domestic combi.

 

[ATTQ]

Thats a completely normal way of running a condensing boiler. It's called weather compensation.

is it possible with an old non-condensing boiler? https://www.vokera.co.uk/wp-content..._installation_and_servicing_-instructions.pdf

then it should have been balanced so that it only had 10% of the water flow from the boiler.

it was just fully open when we got here and was very noticeably raising return temp as soon as it started while the rest of the return took much longer to come back warm.