Can't get any pressure in our heating system

TEssery

Fellow moneysavers please help!
We have a Glow Worm Ultracom hxi boiler running our central heating (our hot water is separate). We had some air in our radiators so a couple of nights ago I bled them. The next day the heating didn't come on. The boiler is working and has no error code, but when it fires the temperature shoots right up into the 90s then it cuts out. The pump appears to be working fine, but the pressure valve on the expansion vessel is showing zero and when we open the value to it no water flows in.
We had a similar problem a while back and got an engineer in; he said he bled the valve above the boiler to fix it, so we've tried that but no change. We also bled the valve on the front of the pump, but again no change. Any advice? Would like to avoid paying an engineer if it's something we can do ourselves!
Kind regards - and thanks in advance!
Tracey

Canucklehead

Hi.

Are there two valves on the filling loop? You need to open both, one fully , then the second carefully. Fill to 'one bar' when cold.

Otherwise you are looking for another valve somewhere that supplies the filling loop.

Is the lever on the filling loop broken? By that I mean does it actually turn the valve it's connected to.

Turn the boiler stat down to minimum until the air is cleared.

GSR.

TEssery

Thanks Canucklehead, appreciate your advice but we have only one valve to our filling loop. Last night we tested the water supply by removing the far end of the pipe and opening the valve to see if water flowed out. It did. So we definitely don't have a blockage in the water supply.
I agree with your final comment - it's probably an airlock. But it appears to be between the expansion vessel and the boiler, as it's quite obvious that when the boiler fires it finds only air to heat so it overheats and cuts out every time.
Still, at least the weather has warmed up!
Cheers
Tracey

Canucklehead

Hi.

So now you need to find out why the water doesn't fill the system.

I would stop dry firing the boiler before you damage it.

Once you have water in the system it should clear quite quickly.


GSR.

TEssery

We've turned the programmer off now, so the boiler is switched on but idle. No idea what else might be stopping the water from getting through other than an airlock. Judging by banging in the pipes recently this is quite likely! But how can we get it to move?

mikey72

Turn it off. even on idle it can still fire up to keep a reserve of water warm for when you turn the tap on.

Canucklehead

Hi.

Pressure gauge on zero. It will not circulate.You need water in the system. The only way to get water in the system is via the filling loop. Bleeding various air vents will serve no purpose until you have water / pressure in the system.

You have water to the end of the filling loop.

There can only be another lever valve or check valve (sticking?) between the heating system and the water you have at the fill loop. Can't see why this is such a problem.

Post a photo and all will be clearer.

GSR.


PS mikey it's a HXi not a CXi.

TEssery

@Mikey72 - our hot water is on another boiler, so no issue there

@Canucklehead, thanks for sticking with my problem. Will take a photo tonight and post tomorrow.

From memory, there are no other valves between the filling loop and the boiler, though.

Really missing my Dad on this - he was a retired builder and died in December 2010. He always fixed my home maintenance problems

gas4you

The end of the filling loop that you removed to test the water, may fix onto the non-return valve.

It could be this that has stuck shut.

Failing that, you could get a hose pipe and connect between an outside tap and a drain valve on the ch, probably under a radiator, make sure it is fully secured on the drain valve, open the drain valve, then the outside tap and re-pressurise the system from this.

This will get you going, but obviously not cure the root cause of the problem.

mikey72

Canucklehead wrote: »

There can only be another lever valve or check valve (sticking?) between the heating system and the water you have at the fill loop. Can't see why this is such a problem.

Post a photo and all will be clearer.

GSR.


PS mikey it's a HXi not a CXi.

Bit of a skim read this morning on the way out.

TEssery

Well, here are links to some pics, not sure if they'll help!

http://twitpic.com/9gihiq

http://twitpic.com/9giggo

http://twitpic.com/9gih5c

http://twitpic.com/9gihci

Really grateful for all your help!

Tracey