V. Old Underfloor Heating mostly cold

[Fraiquin]

Hi,

We have lived here for 11 years now, and the guy who we bought the house from, built his own extension and fitted underfloor heating himself. There are no fancy thermostats or control boards - I think it basically works like a long radiator!

I have no paperwork for the heating, we changed the boiler 3 years ago, but the flooring did work fine until this winter.

I've noticed this year that the floor of the extension doesn't feel at all warm - it used to feel warm to the foot when worked. I had a look at where the pipework is, and there's basically a hot pipe running into a white 'valve' that can be turned (it is all the way at +) that then goes under the floor. This does feel very warm and where it runs under the floor for a little bit, the floor is properly warm. But the rest of the floor feels cold.

The other pipe has a small brass valve, but is stone cold, as is the copper pipework it feeds back to.

I've attached pics of the set up.

IMG_4594

• Fraiquin
• 21 Dec 2016

IMG_4592

• Fraiquin
• 21 Dec 2016

IMG_4589

• Fraiquin
• 21 Dec 2016

Is there a way of bleeding the system? Or can anyone offer advice as to what the problem could be?

Many thanks in advance.

 

[Roger928]

You could try shutting off one valve and open the compression nut to see if any air comes out.
Manifolds are fitted with the necessary taps to facilitate purging air with a mains powered hose pipe or on a sealed system just use the filling loop.

Looks like an old copper system and no tempering valve. Systems like this can give floors a proper roasting.

 

[Fraiquin]

Hi,

Thanks for your response - I closed off the white valve all the way to the '-' position. The pipe that ran from that definitely got cooler. So I turned the small 'key' that sits on the end of the cold pipe, but couldn't hear or feel any air escaping.

 

[Roger928]

'key' that sits on the end of the cold pipe

Key??
Is this "key" you refer too an actual air vent that's not in the images you posted?
Or are you referring to the angle valve in your image that has the cover removed?

 

[Fraiquin]

Hi, yeah - my terminology isn't very good! I'm referring to the uncovered end at the bottom of the first image, that has a small bit that turns.

I can't find any other control or pipework for the underfloor heating. The boiler is working perfectly fine for all the other rads in the rest of the house, and no pressure loss there.

 

[Roger928]

OK. Well that's not an air vent.
Its an angled radiator valve, possibly used in this case as a "lockshield" valve in order to balance the system along with the radiator circuit and the cap has never been replaced or it was just lost. Now its been fiddeled with the balance will be upset.

 

[Fraiquin]

Ahh - I have no idea which way the rads run in our house - whether the underfloor heating is the last or first! It was fully off when I started fiddling with it.

 

[muggles]

If it's lashed in like that it most likely wasn't treated with the correct chemicals and may well now be full of sludge. Can try bleeding it but I suspect a powerflush may be required

 

[Roger928]

It was fully off when I started fiddling with it.

I had a geezer a while back who said the radiator I fitted had stopped working.
When I checked it, the valve that was fitted to one end of the radiator was turned off.

 

[Fraiquin]

Thanks for your advice - managed to get a bit of heat going again, hopefully doesn't get too cold until Spring!

 

[Fraiquin]

How would I go about bleeding this particular system? Would it be to loosen the return valve to let the air out - then tighten up once water comes out?

 

[mcmoby69]

Yes, some system cleanser wouldn't go amiss!