Steam in expansion pipe CHeating!

[Michele]

This seems to happen when the thermostat switches the pump off. I get a rumbling sound in the pipes and the sound of gushing water. I have been locked in the loft for the past hour until it happened again. The rumbling starts followed by a rush of water into the expansion/feeder tank in the loft. The last bit of it was steam so I assume it was either boiling or certainly very hot water.

Help!

 

[breezer]

ignore 2 & 5 but see this

 

[Michele]

1. Gas fired Glow-Worm space saver 50 balanced flue boiler, serviced every year

3. I've not changed anything. My service blokey said to go in the loft and empty out the tank until the ball valve started letting water in. I did that about 2 months ago.

4. Been having this problem for since last September, got better when I did the bucket trick as above, but now its back to gurgling. It started again about 3 days ago. Seems to be much worse at night time when the whole system goes off.

6. Old system but I've drained and flushed two or three times in the last 8 years.

7. You guys are quick!

 

[oilman]

If the pump switches off when the boiler stops, it might be a fault as the pump might be meant to run for a few minutes after the boiler stops. Unfortunately I don't know the details of gas boilers, but pump overrun is a common technique and even where it's not fitted, the addition might cure the problem.

 

[boxster]

It sounds like air. try pulling stat and wait for a splatter in the head tank. The pipes will get hot so watch it. The pump overrun would sometimes cause it but unlike the apollo it sounds like a basic air lock.
Also the pump is supposed to run after the boiler shuts off but are you 100% sure it cuts off as soon as the boiler reaching temp? you would also get steam in the header tank. Go to your boiler switch it on, pull the stat out and get a bucket of COLD water cool the end of the stat down. let the boiler reach high temp and listen for a rumble in the loft, dont panic this will be loud. the pipes will bang like crazy but keep it going for a little longer and re-inset that stat on the gas boiler. The glow worm boiler 50 balanced flue is VERY common for this. Fully pumped is the worst for air! If you dont feel ok with this get a plumber to do it, it should only take about 10 mins

 

[Potterton Man]

Yes Oil Man is correct this boiler requires pump to be wired back to boiler and a permanant Live supply if this is correct check pump overun stat i think newer modles the pump overrun is provided by pcb timed delay

 

[boxster]

I dont see how the wiring can be an issue. It will already be wired back to the boiler. I really think you should try the stat thats ALL it can be i have worled on these for years

 

[Michele]

Do you mean the boiler thermostat or the room thermostat? The boiler goes from 120 to 180 and I've turned it right down to 130 (from 140). The room thermostat is set at 20 degrees and I've left that one alone for now. I'm not sure about the pump. It does clatter when the whole system shuts off with the timer switch at midnight. Would/should the pump carry on running after the timer switches off?

 

[Michele]

Sorry jumped in too quick! Didn't read the bit about the boiler stat!

 

[Michele]

Apart from that how do I get the air out? Would draining and flushing again be a good idea? I had building work done a 2 years ago which was the last time I did it. I had 3 new rads fitted then but I thought it was too long ago to have caused this problem!

 

[Potterton Man]

I have seen plentey of boilers that require pump overun, but it has not been wired in sometimes 10 or more years old some one turns boiler stat up and hay presto faults I always find (and i have worked on a help line for a few years start at basics then move on from there don't asumme anythink

 

[boxster]

the amount of calls i get explaining they have just had a flush out by a company and there system is banging is unreal. I hate flush outs they create more airlocks than enough. I aint a plumber but i am a gas fitter. Removee the BOILER stat, its a long copper coloured pole that goes in the boiler, pull it out, the air will find its way to the vent. It will make a loud noise which had been described as a plane landing on your roof but it will rmoe the airlock. Thats all it can be, all these posts about wiring and pumps cant be the problem. A pump should run after the boiler cuts off to remove any heat. The pump over run can be the cause but it normally blows. try the airlock first, by draining down and refilling can fix it but you must fill it by BACK FILLING the system. I have found this helps. strap your ball valve up and find a drain off, attach a hose pipe and another end on the cold tap and turn it on. Get a friend to vents the rads then shut it off or wait for your tank to spurnt over the overflow. THIS WILL remove the airlock. never vent rads when a boiler is on, MAJOR AIR PULLER!

try to do it without spurting out the overflow as it may not be tight.

I agree with potterton man maybe it hasnt been right from day one and a simple turn up fired it off.

 

[breezer]

don't asumme anythink

does that include spelling?

 

[oilman]

The pump over run can be the cause but it normally blows.

Is this the opposite of "it sucks". It just doesn't make sense to me, can you explain?

 

[boxster]

sorry when i mean blow and mean BANG! they 80% of time trip. i can understand how you though blow and suck were related LOL