Drained & Refilled CH Yesterday. Today no heating!

[adamr7747]

Hi All,

Yesterday I drained and refilled my (open-vented) central heating to add some cleanser. The system has inverted pipe loops and I drained from all 4 drain valves (though the water came out very slowly from one).

After refilling & bleeding, the heating didn't work at first, but turning the hot water and heating on and off a couple of times resulted in a lot of gurgling from around the 3-way valve (next to the hot water cylinder) and then everything started working fine. The heating also came on fine this morning.


But this evening:
- only one radiator is getting hot
- the return pipe to the boiler is cool
- the 3-way valve seems to be working OK
- I've bled all the radiators fine
- the pump seems to be working (though making a high-pitched noise which I don't think it used to)

I'd be really grateful for any help & advice!

Thanks,
Adam

 

[Biguns]

See boiler & CH FAQs- bleeding a CH pump

 

[adamr7747]

Thanks a lot for the quick reply! I bled the pump. It didn't seem like much (or any) air came out and I thought it hadn't helped, but about half the radiators in the house warmed up.

I left the heating on and after about half an hour there was some serious gurgling and wooshing around the house and all of a sudden the remaining radiators started heating up

Strangely the return to the boiler is still only barely warmer than the surrounding room - but perhaps it never did get hot when the system was working before...

Anyway, thanks for the help, I'll just have to hope I don't go round the same circles tomorrow night!

Adam

 

[JohnD]

is the pump very hot?

does it pump downwards or upwards?

have you repeatedly bled everything?

 

[adamr7747]

is the pump very hot?

Yes. Is that good or bad?

does it pump downwards or upwards?

Hmm, how do I tell? It's mounted in the same orientation as the picture in the FAQ.

have you repeatedly bled everything?

I've just now gone round and re-bled the upstairs radiators and a lot of air came out.

At the risk of sounding stupid... all the new air must have come from somewhere in the system, so I'm guessing there was an air-lock or something somewhere. Is there anything I can do to avoid that happening again when I drain the system in a few weeks to get rid of the cleanser?

Cheers,
Adam

P.S. The return to the boiler is getting a little bit warmer now.

 

[dextrous]

The trapped air has worked it's way loose - there's every reason to assume that it will do so again when you come to drain down and refill. Doesn't really sound a problem.

 

[JohnD]

if the pump is not circulating water (e,g. it is jammed or full of air) it will be hotter than the pipes connected to it, so this is a bad sign, especially if it is too hot to put your hand on.

the pump body will have an arrow showing direction of pumping. It should pump upwards, not downwards, as this can trap air in it. with practice, you can also tell by looking at or feeling the "underneath" of the pump. You can make out the shape of the waterways, the outer one is connected to the output port, and the input pipe goes to the middle.

the high-pitched noise you heard might have meant the pump was spinning dry which will wear the bearings and might make it seize later

often air will move out of the way given time, or if you start and stop the pump repeatedly. Any motorised valves need to be open.