Radiators And Thermostat

[Scarlett]

I’ve turned off my radiators in my flat (gas central heating) apart from the two in my main room. At night I switch them to off (the little snowflake icon) but when I do this, one of them hisses for ages. What is happening to the radiator to make it hiss when I turn it down/off? Is it okay?
Also- is it cheaper to just heat one room? It seems mad to heat the rooms I rarely go into like kitchen and bathroom!

[tonyav]

Regarding the hissing noise make sure that the bleed valve is fully closed if that is okay check for a pin hole leak, when the rad as cooled have a feel on the floor under the rad for water also feel the underside of the rad for water.

[Hopkirk]

Are you turning all the radiators off, while leaving the heating running? The pump will be running with nowhere for the water to go.

[Scarlett]

All the radiators are off apart from the two in my room. So those two were on 3 whilst the thermostat in the hall was on 18 but the temperature in the hall is 16 (as the rest of the flat is cold). I turned the two rads to 0 as I was going to bed, and they both hissed really loudly all night. Like the heat was discharging. Just checked and they are still hissing! Not sure what’s going on. Maybe I need to turn more radiators on as the system isn’t coping with just the two trying to get the thermostat up?

[bhg481]

If you turn all the radiators off (as you do at night) but leave the heating on, when the temperature in the hall gets below 18 the boiler will light and the heating will be switched on. The pump will be trying to pump the water round the system but, with all the radiators turned off, it will be pumping against a closed system, hence the noise. In any central heating system you should always have one radiator switched on; one in the same room as the wall-thermostat is best.

[donny48]

There should be one radiator fitted with lock-shield valves to prevent the situation that BHG describes.

[bhg481]

Why do you have your heating ON overnight? Changing your timer to turn if off at bedtime is your best option and then have it come back on in the morning an hour before you get up.

[donny48]

Why don't you leave the two radiators in your room as they are and turn off at your wall thermostat, if you don't wish to use your timer.

[ZebuSanctuary]

Assuming your radiators all feel equally hot (test with the open palm of your hand) then another problem can be the pump is running too quickly. CH pumps are manufactured with various speed settings.

You might consider this alternative way of heating your home. Leave the 2 radiators turned on, then turn the thermostat down to 5 degrees just before retiring to your bed.

[bhg481]

At 8:26 I said you should always have one radiator switched on. If all your radiators have TRVs then one should be FULLY on. If, as donny says, one radiator does not have a TRV then that is the one to leave on but it is not necessary to have it fully open; just don't have it fully closed.

[SnowGoofy]

Radiators often make hissing sounds when they cool down, which is typically normal.
Heating just one room can be cost-effective, especially if you spend most of your time there. Managing your heating system efficiently is a great way to save on energy costs. For more tips and insights on optimizing your heating setup, you can check out https://www.radiatorvillage.co.uk/ . Whether it's last year or today, staying warm while being mindful of expenses is always a smart approach.