Rads are warm when heating is off

paintpot · 2 October 2008 at 8:05PM

I know this has been asked before but I can't find the relevant info

Can someone please explain in simple terms why some radiators can remain warm even when the heating is off.

It happens in my own house but a new tenant has mentioned it is happening in a house and I can't explain properly the reason why so they probably think I am talking nonsense to say that it is "normal".

Is there any way to stop it happening? It annoys me in the summer to have warm rads.

thanks

EliteHeat · 2 October 2008 at 8:12PM

Reverse circulation caused by improper piping.

Turn the radiators off if you don't want them to warm up.

paintpot · 2 October 2008 at 8:20PM

I am pretty sure the odd one still gets warm even when turned off. My rented house has TRVs but as is quite normal I think there is always one rad with no TRV and it is this one that is always warm. I checked and it was off I am sure because it was annoying me as the weather was warm and I was sweating.

What's reverse circulation and what's wrong with the piping to cause it? I am interested to understand.

Ephemera · 2 October 2008 at 8:22PM

Do you have a combi boiler? Could be a faulty valve inside the unit that is pushing hot water into the rads. You will most likely find the rads closest to the boiler will warm up first.

paintpot · 2 October 2008 at 8:27PM

My own home where it happens, no combi boiler, boiler is in the garage and its an upstairs bedroom getting warm with a TRV.

Rented house, combi is in the loft, it's the radiator at the bottom of the stairs with no TRV and it was off but tenant states one of the bedrooms too (I didn't notice that but it has a TRV which is probably on) and I know the boiler is set to hot water only at the moment. Oh and the boiler is only 12 months old

Ephemera · 2 October 2008 at 8:36PM

Hmm, can't help with that as not a plumbing or heating engineer, just had a problem with a combi a few years back. The only thing I can suggest is to check your rads are bled properly of air, that your system is properly balanced and give the system a good run. If it hasn't been cleaned in a few years you can do it yourself with Fernox cleaner, a bit of a messy job but not impossible for someone with a basic knowledge. Have a look in the library for heating maintenance books to give you an idea of what you are looking for and what to do.

Alternatively, get an engineer in...!

Volcano · 3 October 2008 at 11:27AM

One of my radiators is plumbed directly into the hot water tank and is completely separate from the other radiators. When I put the hot water only on, it heats up.

I have read somewhere that this is done to provide some kind of 'overflow' for excess heat when heating up your hot water, no idea exactly why though. If it hasn't got TRV then it's likely that you have the same set-up as me. It's really annoying as it's the radiator in the kitchen, so having the boiler on and cooking in summer means the kitchen is boiling hot!