Radiator Thermostat Help Please

cyclonebri1

awesome2 wrote: »

Hi
I have just had a ew boiler and new thermostats to all of my rads. I have not had them before so I am quite confused. When I put my heating on and the rad in the dining rm is set to 2 the rad gets really hot so I turn it down to 1.5 the rad then goes cold so I then turn it up to 2. This makes it go hot again (really hot) There seems to be no difference in heat between 2 and 5 this also happens to my kitchene no happy one. Should this happen there seems to be no happy medium. When they installed my boiler there is a dial on the front which they turned on full I was told that it controlled how hot the rads felt to the touch bt surely thermostats do this?
I have put the kitchen and dining rm on low as we dont use these rooms often bu cannot seem to get the heat on the rad right.
Could someone please ofer any advise.:beer:

Unless something has changed in building regs it was always good practise and recommended to leave one radiator without a trv, just to ensure that they could never all be closed at the same time thus overloading the pump etc

macman

Any rad in the same zone as the room 'stat should not have a TRV fitted.

cyclonebri1

macman wrote: »

Any rad in the same zone as the room 'stat should not have a TRV fitted.

Thanks macman:money:

latecomer

But if it does then presumably it shoudl be set to a higher temp than the room thermostat and hence effectively always on when the room stat is.

andrew-b

yes you'd open up the TRV on a radiator in a room where there is a roomstat to full (or at least a higher temp) else you'll struggle to achieve the temperature set on the roomstat. The TRV then becomes redundant as the room stat will take control.

Newer or updated systems have an auto-bypass valve (ABV) to ensure there is always a circuit from flow to return which will protect the pump (an integral part of combi-boilers; non-combis require a dedicated ABV) so it's not as critical to have a rad without TRV in the room with room thermostat. Without ABV, the old theory is a bit flawed anyway as a lone NON-TRV'd radiator might have to be isolated for decorating at some point.

Canucklehead

Good morning: the most reliable source of info on 'Basic' and 'Best' Practice in gas central heating i.e CHeSS 2008 is available here. Btw, modern system boilers eg. Vaillant Ecotec Plus 615, also have built-in bypasses. Vaillant also advises for best fuel economy where TRVs are used they must be used in conjunction with a boiler control interlock. eg. programmable room thermostat or a separate timer and room thermostat will ensure complete boiler shut down when the heating demand is satisfied. The radiator in the room containing the room thermostat should not be fitted with a TRV....always best to follow manufacturer's instructions.;)

HTH

Canucklehead

awesome2_2

Good Evening

Going back to my original post (sorry to be so thick) I have set my trvs to 3 and I dont seem to feel them cookling down or heating up at intervals at all. Should they go cold when the rad reaches the number on the trv or just cool slightly. Is this because the rads are not reaching the temp set on the trv? If so why not I dont thingk the rads are too small for the rooms. Does it matter which end the trv is put on? I thought puting trv's on would make them more efficent rather than befrore when they jus blasted the heat out but when I touch them they seem constantly hot excpert when the thermostat shuts the boiler down. ARRRG Help Feel like I am going mad!!!

DVardysShadow

awesome2 wrote: »

Good Evening

Going back to my original post (sorry to be so thick) I have set my trvs to 3 and I dont seem to feel them cookling down or heating up at intervals at all. Should they go cold when the rad reaches the number on the trv or just cool slightly. Is this because the rads are not reaching the temp set on the trv? If so why not I dont thingk the rads are too small for the rooms. Does it matter which end the trv is put on? I thought puting trv's on would make them more efficent rather than befrore when they jus blasted the heat out but when I touch them they seem constantly hot excpert when the thermostat shuts the boiler down. ARRRG Help Feel like I am going mad!!!

You try to leave them alone, you adjust them in small steps and although when you open them the rad can heat up quickly it can take quite a few minutes to cool down.

So when they are working properly, they just constrict the hot water flow a bit until a stable balance is reached where the rads are quite warm but not fully on. You will not tell this by feeling the top of the radiator, you will see it more if you feel the outlet pipe of the radiator. If the radiator size is well matched to the room and the TRV is set to a sensible temperature you will find the outlet pipe of the rad will be much cooler than the inlet - indicating that the radiator flow is quite low. Once again, when everything has reached temperature, the radiator will not and should not go cold.

keystone

Did your installer balance the system as the last thing he did?

There should be NO TRV in the room with the roomstat because if there is the two will fight one another and you'll probably end up using far too much gas.

Cheers

DVardysShadow

keystone wrote: »

Did your installer balance the system as the last thing he did?

There should be NO TRV in the room with the roomstat because if there is the two will fight one another and you'll probably end up using far too much gas.

Cheers

Or far too little and freezing