Boiler/central heating pressure loss

Bammo

Hi everyone,

I no next to nothing about plumbing and so feel a little lost with all of this.

We've recently been having pressure loss on our ideal combi boiler. I've been able to top the system up but it kept falling. We've signed up to British Gas homecare and had the boiler serviced on Monday. The engineer said that the expansion vessel was full, drained it of water and repressurised it. That should have solved the problem but he said if the pressure dropped again then we may have a leak.

The pressure has indeed dropped again. The issue I have is that he also took a look at the radiators. 2 of them have never heated properly since we moved in last December. The engineer recommended we have the system power flushed and quoted us nearly £800.

My concern is that if we pay them (or anyone else) to do the power flush then not only will it not solve the problem of the pressure dropping, it could flood the house if there is a leak somewhere.

Unfortunately, as these may be classed as pre-existing problems we may not be covered by British Gas as they don't cover anything that occurs within the first 14 days. The engineer did out on the paperwork that there were no major leaks in the system so that may help.

Can anyone advise if the power flush should be done or if the leak should be found first? I'm assuming it's the leak (if there is one) but as I said, I know nothing about plumbing!

Thanks for any advice.

Le_Kirk

Not knowing your piping layout nor your boiler type it is difficult to advise how to find a leak. If the BG engineer sorted your expansion vessel and the water pressure relief valve is not passing (check the outlet pipe outside by putting a container under it and seeing if it catches any water) assume there is a leak in the pipe work so check visually for water wherever you can see a pipe. Turn off all your radiators at both ends and repressurise your system. Does the pressure hold? If so, the leak is in a radiator, so eliminate them one by one by turning them on one at a time until your pressure drops.

southcoastrgi

Plastic bag taped over the end of the copper pipe outside so no rain water can get in it, turn the boiler off at the mains electric, turn off the valves on the bottom of the boiler going to the heating (normally the two valves towards the sides, one left one right), see if the pressure drops over night,

water in the bag outside = prv
Pressure drops but no water in the bag & no leaks from the boiler = heat exchanger ie new boiler unless you can get BG to do it foc
no pressure drop = leak on the heating system

Bammo

Thanks for the advice. I'll give them a go and see if I can find anything out.

Bammo

An update:
I checked each radiator and it turns it that almost all of the valves needed tightening! Placing tissue around them meant it was fairly straightforward to locate which were actually leaking. As far as I can see, none of them now leak.

What I now have is a bit of a puzzle. We have 4 radiators on (living room, dining room, landing and bedroom) and the pressure remains stable. When I turn on a 5th radiator, the pressure remains stable (I check every hour) and then drops quickly to zero. I've tried 4 different ones now so it seems to be an overall problem rather than a specific radiator.

Could it be an issue with the boiler? Any advice is gratefully received.

Thanks.

Alias_Omega

When you turn on the 5th rad, the pressure drops?

Assuming there is not a hole in this radiator, I would probably guess that this radiator is empty and turning it on the pressure from the boiler is filling this radiator.

If the radiator was empty, and there is now no pressure, you would need to restore pressure in the system, bleed the radiator, and restore the pressure again...


PS - British Gas will always tell you need a Powerflush. I once had Homecare, they quoted for a Powerflush. I cancelled the scheme and had a full refund. I then paid them the 1 off fee for a boiler repair (£79) and the SAME engineer came and fixed it without the need.

If your with Halifax Bank, they have free boiler/heating cover with the Ultimate Account (£15 per month account fee).

macman

No possible connection between pressure loss and possible sludging, BG try it on every time...

SGM1

The flush was recommended for the radiators not working.

Not a good a time of year but it is possible to isolate the system to see if it's the boiler or CH system.
Ive heard of quite a few issues with those heat exchangers, it could be that leaking but it will run out of the condense so you won't see that there is a leak

Bammo

Thanks for everyone's advice. There has been some progress since Tuesday...

The pressure was still OK but we turned the heating off, allowed it to cool down, turned all of the radiators off then bled them. All were full. Then we turned the heating back on. Since then it has been consistently at 1.3-1.5 when cold and 1.8-2 when heating. I've regularly checked it (somewhat obsessively!) and it seemed to be fine.

Then at 3am this morning, the pressure dropped to 0.

I'd have thought with a leak it would drop either immediately or gradually over time. What we seem to have is it working normally for days then it dropping suddenly.

It's difficult to isolate the boiler as we have a baby but we're all away Saturday night. The problem is I'm not certain how to isolate it properly!

Thanks

edgex

Bammo wrote: »

Thanks for everyone's advice. There has been some progress since Tuesday...

The pressure was still OK but we turned the heating off, allowed it to cool down, turned all of the radiators off then bled them. All were full. Then we turned the heating back on. Since then it has been consistently at 1.3-1.5 when cold and 1.8-2 when heating. I've regularly checked it (somewhat obsessively!) and it seemed to be fine.

Then at 3am this morning, the pressure dropped to 0.

I'd have thought with a leak it would drop either immediately or gradually over time. What we seem to have is it working normally for days then it dropping suddenly.

It's difficult to isolate the boiler as we have a baby but we're all away Saturday night. The problem is I'm not certain how to isolate it properly!

Thanks

You bleed radiators whilst the heating pump is on, as you need the pressure to force any air in the radiators out.
Go around & do all of them in one session, then check the pressure. If youve had air come out of any of them, might need to put more water into the system.
Do this multiple times (once a day till you have no more air coming out)

Rubidium

edgex wrote: »

You bleed radiators whilst the heating pump is on, as you need the pressure to force any air in the radiators out.

Another 'armchair expert' - the pump does not pressurise the system, it simply circulates the water!

The boiler/pump should be OFF when bleeding with all radiators ON.