Some radiators heat up when CH is set to Off Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[chachafrisk]

When my Hot Water control is set to On, but the CH is set to be permanently Off, some radiators still heat up. Any suggestions as to why this may be please? I got a huge Gas bill last time - much much bigger than in previous quarters and am not sure if the rads heating up when they shouldn't be could be anything to do with that?

[plumbbob]

Heating rads unnecessarily is going to cost more, but there could be other reasons why.

Fuel prices have increased, the heating could have been on longer possibly due to a faulty timer or the boiler could be in need of a service.

If this symptom is new then you could have a faulty zone valve or programmer. If it has always been this way, it could be intentionally plumbed for this to occur or could simply be caused by the system design.

[chachafrisk]

[quote="plumbbob"]Heating rads unnecessarily is going to cost more, but there could be other reasons why.

Fuel prices have increased, the heating could have been on longer possibly due to a faulty timer or the boiler could be in need of a service.

If this symptom is new then you could have a faulty zone valve or programmer. If it has always been this way, it could be intentionally plumbed for this to occur or could simply be caused by the system design.[/quote]

Thanks. The system (which has twin boilers) is about 12 years old now and the random 'radiators coming on when they shouldn't' problem has only been occurring for about 3 -6 months. I have turned off the valves (on the left hand side, bottom, of the rads) in order to stop them heating up when they shouldn't, and that worked. Not sure if that will stop the rise in bills though - I had one for £1300 for Jan, Feb & March!!. It sounds like a job for an expert to me (unfortunately), and one which I should get done before the next bill comes.