Thermostats and Control heating

sva14

Cardew wrote: »

People are missing a fundamental point here.

The only reason the CH boiler turns off(i.e. stops firing) is because the water temperature has reached the temperature set on the boiler.(this can be 60C to 85C

Obviously when the wall thermostat temperature is reached the pump stops and the water in the boiler is not circulating so the boiler stops firing.

However even when the pump is running the water in the system(including radiators) will reach the set temperature and the boiler turns off.

With my method I turn off the hall radiator. The pump will keep running but when all the TRVs have reached the set temperature the radiators are shut off and the boiler will stop firing as there is very little water being circulated in the system.

There is nothing wrong with this system and people have reported on here they have old systems without any wall(room) thermostat - In effect I am doing the same by having mine always keeping the pump running. The new regulations say a room thermostat is required but even in some plumbing websites they recommend that you do as I do - turn it to max and forget about it.

Lastly, most modern CH systems have an (ABV Automatic Bypass Pressure Balancing Valve) which allows you to have TRVs fitted to every radiator - my 21 year old system has one.



So if you have any doubt get your system checked.

Another question my house still has some radiators not with TRV, so consindering what cardew is saying, the radiators with TRV will shut off when temp reached and reduce water circulation, but what about the rads without TRV, will they keep circulating, thus the ch pump and boiler still run all the time (Remember hall therm set high ).

Ps Where would the ABV be located?

Cardew

satish98 wrote: »

Another question my house still has some radiators not with TRV, so consindering what cardew is saying, the radiators with TRV will shut off when temp reached and reduce water circulation, but what about the rads without TRV, will they keep circulating, thus the ch pump and boiler still run all the time (Remember hall therm set high ).

Ps Where would the ABV be located?

Firstly you need to take advice from a plumber or someone with plumbing knowledge about your ABV when they have seen your system.

The radiators without TRVs would have water circulating through them and get hot - unless you turn them off.

The pump will run all the time but remember the boiler will shut off when the water in the system has reached the temperature set on the boiler. If little water is circulating then it will only fire for a very short time. It may be set to, say, 75C. So it will shut off at 75C and back on for a short while when the water temp drops to, say, 70C.

Bear in mind also that much of the time your radiators with TRVs will not be closed and they will be demanding heat.

bryanb

satish98 wrote: »

A good point, but I read in one website that the room thermostat should not be fitted in a room with a TRV. My lounge does have a TRV.

Just leave it wide open.

sva14

Another question.

Assuming I am just controlling my CH by turning on and off the boiler when my desired temperature has been hit. I.e I come home after work, put the CH on once my lounge is 20C, I turn it off. Then put it one again when it drops again for a while and then off etc.

Then will turning off some of my unsed radiators in bedrooms, bathrooms, help the boiler warm up the water quicker thus getting the lounge radiator warmer quicker, thus allowing me to turn of the CH quicker, which in effect is less gas used by boiler. OR does it not make any difference and I should just keep all radiators in unsed bedrooms open as it going to use the same amount of gas?

Cardew

satish98 wrote: »

Another question.

Assuming I am just controlling my CH by turning on and off the boiler when my desired temperature has been hit. I.e I come home after work, put the CH on once my lounge is 20C, I turn it off. Then put it one again when it drops again for a while and then off etc.

Then will turning off some of my unsed radiators in bedrooms, bathrooms, help the boiler warm up the water quicker thus getting the lounge radiator warmer quicker, thus allowing me to turn of the CH quicker, which in effect is less gas used by boiler. OR does it not make any difference and I should just keep all radiators in unsed bedrooms open as it going to use the same amount of gas?

Your assumption that it is going to use the same amount of gas regardless of the number of radiators turned on is completly wrong. - It costs a lot more to heat the 500 radiators in Buckingham Palace than 2 radiators in a bedsit.

Your boiler heats up the water circulating in the Central heating system.

Firstly if more radiators are turned on, more water is circulating in the system and it will take longer to get the water up to the desired temperature set on your boiler - just as it takes longer for a kettle to boil 2 litres of water than 1 litre.

Secondly, the more radiators that are turned on, the quicker the water in the system will cool as the radiators dissipate the heat(which is their function). the cooler the water, the more gas the boiler will use to keep the water hot.

savers_united

Get a digital wireless room stat with programmer, probably the best bit of kit I ever bought.
They even allow you to offset your temp, as my hall is 2 degrees lower than the rest of the house I offset it by 2 degrees, so it shows 18 degrees on the screen but it is infact 16degrees in the hall but 18 in the lounge.
I set my boiler stat to max, set each rooms TRV indivdually and then the desired temp for the house on the room stat for different times of the day, it works well and since fitting the stat use approx 2 units less per day over 8 hours.

jennifernil

I suggest that you invest some money in getting TRVs fitted to all your radiators except one (maybe the one in the hall if it is not huge), set them according to how warm you want each room, and do as Cardew suggested and turn the room stat in the hall right up and forget it. This way the TRVs can do their job as intended.

We run our system this way, but do not have a room stat at all. The radiator in the hall acts as a bypass as it is always on. It is small and the hall is very big.

We turn off the bedroom radiators as we prefer cool bedrooms, but leave the doors open so the heat from the hall takes the chill off them. It also allows air to circulate to keep the rooms smelling fresh.

You will need to experiment a little to find the correct TRV setting for each room to give the desired temperature. Ours go from "off" through 1 to 5 and full on, we find around 3 is good in the lounge.

Do you have a timer for your heating? This is an essential piece of equipment as it will let you set the heating to warm the house in the morning before you get up, and in the evening for you coming home. No point in heating it when you are asleep or out.

ic

Roll on the day when this system is affordable: http://www.inspiredheating.co.uk/acatalog/HONEYWELL_CM_ZONE.html

Each TRV is set digitally, and reports back to the main control unit whether or not it requires heat. The control unit uses this to decide whether or not the boiler should be run. Also means you can programme different rooms to be different temperatures during the day (say for example heat the kitchen around the times meals will be made, whilst bedrooms will be heated first and last thing in the day).

grumpycrab

Our house is very similar to the case discussed here. The main thermostat is in the hall which is very cold (non-double-glazed window where a door used to be). This has one rad with no TRV.
Living room has 3 rads (no TRV). Its a constant juggling act to keep the living room at 20C by tweaking the main thermostat. Its currently set at 15C.

sva14

savers_united wrote: »

Get a digital wireless room stat with programmer, probably the best bit of kit I ever bought.
They even allow you to offset your temp, as my hall is 2 degrees lower than the rest of the house I offset it by 2 degrees, so it shows 18 degrees on the screen but it is infact 16degrees in the hall but 18 in the lounge.
I set my boiler stat to max, set each rooms TRV indivdually and then the desired temp for the house on the room stat for different times of the day, it works well and since fitting the stat use approx 2 units less per day over 8 hours.

hi all,

Thanks for your advice, learnt alot.

I am considering getting a wireless room stat with programmer, to replace the exisiting Room Stat in the Hall and the Programmer in the Kitchen.

How easy is it to install on my current set up. Would I make my current Hall Stat dormat, and install the Receiver of the Wireless on the wires within the boiler and then use the Wireless Room stat in the Main Lounge?