Have Boiler on Constant or on Timer?

[SirGalahad]

I am trying to work out what is best.

At the moment I have my boiler set to 16 constant and the house is warm and maybe between 7.30am to 9am I turn it upto 19 and then from 5pm to 10pm to make it cosy.

Now someone is home during the day - have a one year old so house needs to be warm. So is it more efficient to cycle the boiler on and off via a timer or to keep it on constant?

 

[ericmark]

Switching the temperature up and down or on and off needs the lock shield valves set very well, or needs eTRV fitted. I have the latter, but would not sing their praises, of course house design is also important, so there is no one system fits all, however the standard system is.

The boiler sends hot water around the system and measures the return temperature and adjusts flame height to suit, the return temperature of the water is controlled by the lock shield valves and the thermostatic radiator valve, when the return water is too hot the boiler turns off, after a set time it turns on again, plus some anti-cycle software in the boiler that adjusts that set time.

You may note no wall thermostat, in theory not required, in practice however often they are.
When a timer turns off the heating all TRV will in time open, so once the timer turns on again all radiators want hot water, now if the lock shield valves are set correct every room will start heating, if not rooms may be heated one by one. However once every room has hit the set temperature the lock shield valve setting has little effect. The TRV has taken over control.

So likely it is more efficient to keep it on 24/7 because you can tweak each TRV so each room is exactly the right temperature, where if switching on and off it's far harder to set the lock shield valve to work A1 at reheating the house in an even manor. However not sure what theory says?

My problem is sun and wind, the direction of wind, and if the sun is shinning or not changes how much heat is needed in the two down stairs rooms, odd but not noted a problem up stairs. I have tried all sorts to stop the main living room getting either too hot or too cold. Nothing seems to work in the house I am living in now.

However old house simple programmable thermostat worked nearly A1, simply down to when the sun comes into the windows. The bay windows in house I am in now I am sure are the major cause of the problem.

 

[SirGalahad]

Switching the temperature up and down or on and off needs the lock shield valves set very well, or needs eTRV fitted. I have the latter, but would not sing their praises, of course house design is also important, so there is no one system fits all, however the standard system is.

The boiler sends hot water around the system and measures the return temperature and adjusts flame height to suit, the return temperature of the water is controlled by the lock shield valves and the thermostatic radiator valve, when the return water is too hot the boiler turns off, after a set time it turns on again, plus some anti-cycle software in the boiler that adjusts that set time.

You may note no wall thermostat, in theory not required, in practice however often they are.
When a timer turns off the heating all TRV will in time open, so once the timer turns on again all radiators want hot water, now if the lock shield valves are set correct every room will start heating, if not rooms may be heated one by one. However once every room has hit the set temperature the lock shield valve setting has little effect. The TRV has taken over control.

So likely it is more efficient to keep it on 24/7 because you can tweak each TRV so each room is exactly the right temperature, where if switching on and off it's far harder to set the lock shield valve to work A1 at reheating the house in an even manor. However not sure what theory says?

My problem is sun and wind, the direction of wind, and if the sun is shinning or not changes how much heat is needed in the two down stairs rooms, odd but not noted a problem up stairs. I have tried all sorts to stop the main living room getting either too hot or too cold. Nothing seems to work in the house I am living in now.

However old house simple programmable thermostat worked nearly A1, simply down to when the sun comes into the windows. The bay windows in house I am in now I am sure are the major cause of the problem.

Thanks for that brilliant and detailed explanation. I have TRV fitted on all radiators plus one which does not. I have a wireless Room thermostat thats in hallway which I have set to 16 and then turn up and down as needed. I live up north so its cold and windy most of the time.

So In the summer would I leave it the same temp as during summer I hardly if ever need to have the heating on or do I adjust down?

 

[Ted777]

Same here I work from home and keep my home at 16c during the day which is comfortable for me whilst working. Now im in the lounge for the evening it's up to 20c, I will drop it down to 14c when I go to bed. So for me to keep my home comfortable for 24hours my nest thermostat normally shows I've ran the heating for about 2-3 hours a day that's when it's around 0c outside. According to my smart meter display I spend around £1-£1.50 a day on gas that includes the 21p a day standard charge thing. I think around £35 a month to keep warm is worth every penny.

 

[ericmark]

I find the eTRV is about set about 4°C colder than you want room at night, and 2°C during the day. It would seem it gradually shuts off the water over a 2°C range, the thermostat in the hall is at moment left at 20°C, not worried about cost, just want it right for my mother.

I have theorised about control, and a thermostat which gets morning sun could ensure house is not heated on the days when it is going to get hot, and a programmable thermostat can also auto adjust the temperature. However my wireless programmable thermostat was a failure, it seemed to have two very basic faults.

1. There is no indicator to say how good the wireless signal is.
2. Should it not receive the signal it seems it's not resent.

The result was the system could get stuck on heating or cooling, I would think "It's cold in here" look and find at 16°C when set to 20°C and the animated icon said it was calling for heat, but looking at the receiver the green heating lamp was not on. I would also think "It's hot in here" and find at 26°C when set to 20°C and animated icon off so not calling for heat, but green lamp on the receiver was on.

I found if I removed the sender off the wall and put right next to receiver it did not switch even with inches between them, to get it to switch I would need to alter temperature to above or below what it showed and back again for it to work, even waiting 15 minutes it did not activate unless I moved the setting. This has put me off the cheaper programmable wireless thermostats, the non programmable wireless thermostat works fine. The more expensive units Nest, Hive etc. have two way coms, so are more reliable but then cost goes up. I looked at the EvoHome which seems to be bees knees, but it gets expensive, and one has to draw the line somewhere.

It seems the eTRV I am using is designed to follow the Nest thermostat, not sure what it means by follow? If it means when Nest set 2°C down then eTRV also set 2°C down then great, but if it means when Nest set at 20°C the eTRV also set to 20°C then not really what I want, as hall seems to need to be at different temperature to rooms, so don't want it to mirror hall temperature.

As with many things, the more technical it gets, the more likely to fail, already had a failure due to non heating problem, my wife unplugged the hub, the hub uses a standard USB power feed, and my wife has loads of tablets, phones and watches etc which all need to be charged from USB, even with two USB sockets so 6 USB outlets, she still unplugged the hub to charge something. Also had her unplug router, but she realised no internet so plugged it back in. Lucky not down stairs as mother will fiddle with anything she can, including the main thermostat. At the moment she has not found pressing button on eTRV for 2 seconds gives 1 hour at 21°C boost.

So at what point do you stop with central heating control? Up stairs with simple mechanical TRV all works A1, but not down stairs, I now blame bay windows and morning sun. But only a guess. I moved into this house in 1954, left around 1976 and returned last year, parents have lived in house since 1954, you would think by now we would have worked out how to heat it? But it has moved from open fires to fires with doors designed to burn coke, then central heating with thermo syphon heating hot water, them Combo boiler. To my mind having 4 radiators without TRV's is wrong, one in hall, one in airing cupboard, and two towel rails one in kitchen one in wet room. But that is what I have. If I fit a TRV in hall then where do I put the thermostat? Without the thermostat kitchen and wet room will get too hot. So I think until summer I will just monitor and see if it all settles down!