Non Combi boiler - low pressure?

Supernova

Hi all,

I have a 15 year old non-combi Glow Worm.

The radiator upstairs near the water tank is not heating up, the pilot light keeps gong out and there is no air or water pressure in the radiators - the ones downstairs are heating up but can't be bled.


The hot water takes all day to heat up but in the morning is barely tepid.

Can't see any evidence of leaks...

Any clues...or get BG engineers out?

Cheers!

S

Alex1983

Do you have a feed and expansion tank in the loft? If you have check the ball valve hasn't stuck and there's water in the tank, if that's all ok then possibly looking at a blockage somewhere, mostly likely where the cold feed joins the system.

Mutton_Geoff

Header tank in the loft empty by the sounds of it. Before refilling, it's a good opportunity to chuck a bottle of inhibitor into the tank to let it run into the system first before you fix/turn on the water.


It's the head of water in the tank that pressurises a normal vented ch system (hence the name header tank).


Sometimes stopcocks are put in the riser to the tank in a cupboard beneath to make access easier. Are you sure one hasn't been turned off?


Don't forget to exercise the stop cocks regularly (inc water main and any others you don't normally use) to stop them seizing up and not being available when you need them most.

Supernova

Thanks guys,

Here is the header tank next to the main one:



Should it be more full?

The stopcocks haven't been switched off. A couple are stiff, even after WD40.

S

Mr.Generous

Header tank is ok, what do you mean by low pressure? Is the pump set on high speed?

Supernova

Mr.Generous wrote: »

Header tank is ok, what do you mean by low pressure? Is the pump set on high speed?

By low pressure I guess I mean that there is no air or water coming from the radiators when I bleed them and the one upstairs just below the water tank doesn't come on at all.

Was getting a little hot water yesterday but today the boiler pilot light keeps going out after about 5 minutes. The pump hasn't been touched afaik.

Thanks!

S

Alex1983

The water looks a little high, if you can't bleed water or air out of the upstairs radiators you most likely have a blockage at the cold feed.

Mutton_Geoff

I reckon you have an air lock somewhere. Turn all rads off but one. Find the pump and turn it up to highest speed (usually marked I/II/III).


This may push the water through and clear the airlock. Repeat with each radiator in turn til you hear loads of gurgling.


Header tank looks OK but check there is nothing blocking the pipe out into your heating system at the bottom of the tank.

Supernova

OK thanks.

No apparent blockage in the tank. Pump was on II so set to III.

Tried each solo rad in turn and got some signs of life from the one next to the boiler downstairs. It gurgles and sounds like it's filling and heating up bit by bit, but the boiler cuts out after a few minutes.

Shall I just keep switching on again?

I have BG Homecare here tmw morning. When it was serviced a few months ago I pointed out that there was gurgling coming from the water tank area...

Cheers
S

Supernova

So...BG changed the pump to no avail.

Quoted £848 for a PowerFlush and said it might wreck the boiler, so will quote for a new closed system boiler (natch).

Any alternatives in NW London?

Cheers
S

Alex1983

You most have a blocked cold feed. You could back fill the system as a short term fix. You need the cold feed cut out and repiped or blockage clear to permanently fix.