Worcester 24i Over pressure

[NeilV]

Hi All
just to set the scene, I am not a plumber and if I need our boiler repairing I would normally get our Landlord to fix it but it's Xmas eve and I can't get hold of anybody.

When I woke up this am to a feezing cold house, I checked the gas supply, OK, went to look at the boiler in the garage and the flue fan was running but the water pressure was reading 0. I switch off the system, repressurised to about 1 bar, switched back on & the boiler didn't fire up, just the fan running. Since the last call to a plumber resulted in 30 mins to find the reset on the top of the boiler, I switch off again, pressed this in, switched back on and the boiler fires up, pressure mounts to about 3 bar (at which point I was backing away quickly!) then it cuts out and the pressure dial sinks back to 0 (or close to)

Is there anything I can do, as a non plumber to get some heating back for the christmas period. until I can get a plumber in, via the landlord!

Any suggestions would be GREATLY appreciated.

 

[ianniann]

Possibly your expansion tank is empty (of air). Pressure rises as the water heats up, your relief valve (or something else!) blows, and the pressure drops. Did this happen suddenly?

Look for water somewhere. Your PRV might be plumbed into other pipework, but they might just terminate outside, or even under the boiler in your garage!

If the expansion tank needs refilling you could conceivably do it yourself with a pump, but it involves taking the boiler casing off and sometimes more.

 

[NeilV]

Thank you ianniann!

I'm not afraid to take the case of the boiler, i've done it in the past to see if the fault was easily rectified but I don't remember seeing an expansion tank! I think it went wrong suddenly last night, I did hear a bang but I thought it was the dog bashing up against the garage door! but now it happens within 10 seconds of resetting the boiler and switching it back on. it's quite alarming watching the pressure gauge rising from below 1 to over 3 before it cuts off!

 

[ianniann]

If it happens that fast it may be something else, something more serious.

 

[hi1]

The pressure vessel on this boiler is at the back of the boiler. I had to stand on a chair to see over the top of the boiler. You will see a shreader valve sticking up, like the one on a car tyre. If there is a cap remove it and depress the centre pin off the valve, quickly release it if you do not have the following, car foot pump or electrical equivilant and tyre pressure gauge. There should be a hiss of air escaping like a tyre. If there is no hiss and you have the equipment above then continue to depress the valve until the hissing stops. If water then comes out of the valve it means the expansion vessel has an internal fault and the vessel will have to be replaced. If no water comes out then the vessel has just lost its charge of air. In effect it needs to be pumped up like a car tyre. You need to make sure you are not pumping against the water pressure in the system, that is the pressure shown on the dial which you see rising from 1 to 3 bar. To do this you need to let water out of the system, there may be a drain under the boiler you can use or drain out of a radiator until the pressure reads zero. Attach your foot pump to the shreader valve and pump until you get a reading of 1 bar on your tyre pressure gauge not the dial on the boiler. Try and let some more water out, if it comes out you will need to re pump the expansion tank up some more. you need to do this untill no more water comes out when you open the drain cock/radiator. This shows that the water in the expansion tank has bee expelled and the pressure reading you are getting on the tyre gauge is the true pressure in the tank. Re pressurise the water pressure so that the reading on the dial is about 1.5 bar. The boiler should work again. The over pressued water was let out of the boiler by a pressure release valve. These often don't reseal properly so you may still lose pressure over time depending on how big a leak it is. If you had water come out of the shreader valve then the expansion tank will need replacing. The boiler has to come off the wall for this, not diy stuff. You could get another expansion vessel fitted into the pipery somewhere to avoid this but its still call a heating engineer for this i would suggest. Good luck.

 

[NeilV]

Thank you all for your replies. I was not online over the Xmas break so wasn't able to respond.

Was able to get a plumber out on Xmas EVE but he was gone by the time I got home with only a garbled message to my partner to explain what had happened. All OK Xmas day but failed again Boxing day!!!! I left it for about 4 hours, turned off and bled the upstairs rad which didn't give any water so I am assuming the pressure in the system is not enough to push all the air out. Reset and fired up and it has been OK ever since (touch wood) so I'm hoping it will hold out until I can get my landlord to fix it. Will keep you updated incase anyone else is following this thread!!

Thank you All