Combi Boiler Pressure Question

[julesapple]

We have a combi gas boiler, it's about 6 years old. It's been a pain ever since uncle landlord's pet plumber guy fitted it incorrectly and flooded it out. Anyhooo.....

Every day we have to re-pressurise the thing. The idiot uncle landlord keeps sending his pet plumber around (he is qualified to do gas) and he's changed the valves underneath and replaced a radiator that he said was leaking. This solved the problem until we had to click the switch from hot water over to hot water & heating. Now we are re-pressurising half a dozen times a day.....so they'll have to come back and look for other reasons - the rads aren't leaking, we've checked - and I'm guessing the leak, if that's the problem, is in the pipes under the floorboards somewhere.

My question is; how much extra money on our energy bill do you think this inefficient boiler is costing us, do you think?

[Potstubsdustbins]

Its not costing you any extra on your gas bill.

It maybe a leak but from what you describe I would say not.

Easy to find out, next time you have to re-pressurise the system bring it up to 1 bar, turn on the central heating and watch the pressure gauge for about 10 minutes it should rise to about 1.5 bar. If it goes beyond this up to about 3 bar the safety valve will open and the water will be blown off out side.

If this happens it is your expansion vessel that's the problem it will need recharging or even changing.

Let me know and I will offer some advice that you can pass on to said plumber, in fact you will amaze him.

Potty

[Bigmallly]

I remember having to regularly pressurise our boiler which turned out to be a leaking joint under the house. Luckily there was a 3 foot gap under the house that had a floor trap which I could crawl under to check the pipes. It may not be as easy for you.

[julesapple]

BM, I do hope Pots is right. There is no way we can get under the floor. When they took out the old system and put in the combi, new pipes & rads, I remember having to get one of our cats out from under the floor. We have floor boards a foot (or possibly less) above soil! There may or may not be a damp course - if it rains we get damp carpets......

Colin, I'll try that - usually we have to bring the pressure down from 3+, but sometimes we get the E19 error message too.

When the pet plumber and his 'team' put our central heating system in, they plumbed the safety valve to the outside into a drain which we clearly told them was a soak away that backed up in heavy rain. Two weeks later we had a torrential downpour at 11pm on a Saturday night. The water backed up the soak away downpipe and poured into our kitchen through the boiler. We were told to phone the boiler manufacturers as it was under guarantee. Before the manufacturer's chap came out, one of the pet plumber's team arrived, disconnected the safety valve pipe from the soak away downpipe and turned the s/a downpipe around to hide the hole. The manufacturer's chap arrived, took one look, open the back door and turned the downpipe around to find the hole - he'd quite obviously seen it all before and was wise to cowboys

[Snadger]

I remember having to regularly pressurise our boiler which turned out to be a leaking joint under the house. Luckily there was a 3 foot gap under the house that had a floor trap which I could crawl under to check the pipes. It may not be as easy for you.

So you had a three foot deep underfloor swimming pool..........

[veggiechicken]

........probably just reached BM's knees..........

[Potstubsdustbins]

Jules,

I think that would be the condensate drain you are talking about. The safety discharge pipe is only 15mm, usually copper and would not be connected to anything.

What is the make and model of the boiler as they all have different fault codes.

Colin

[Potstubsdustbins]

Just reread your second post.

You say you have to bring the pressure down, can you tell me how you do that.

Can I still presume you are loosing pressure and the boiler fails and then you have to add water to the system in order to reset it.

Colin

[Bigmallly]

So you had a three foot deep underfloor swimming pool..........

Not quite Snadge. Because the pressure dropped almost immediately, it pointed to a leak. Luckily I could commando crawl underneath the house and fit a new joint.

[julesapple]

Just reread your second post.

You say you have to bring the pressure down, can you tell me how you do that.

Can I still presume you are loosing pressure and the boiler fails and then you have to add water to the system in order to reset it.

Colin

Sorry Colin - I fell asleep....

We have to turn a square brass screw on the pipework underneath and 'bleed' it until the pressure drops. It's a Maine Combi Eco boiler. When the E19 message comes up we have to let water into the boiler using the tiny black tap things underneath.

You can tell I'm not technical..........

[Bigmallly]

BM, I do hope Pots is right. There is no way we can get under the floor.

Sorry Jules, I didn't mean to worry you.........I too hope it is a faulty part in the boiler that can easily be replaced. I know how bad it is being without heating at this time of year........good luck.

[julesapple]

Oh, no...sorry, my fault - we have got heating. You just have to watch the boiler like a hawk. It's becoming second nature; go into kitchen, switch on the one cup boiler & coffee machine, check boiler, get tea & coffee bags, make drinks, check boiler, leave kitchen....

[julesapple]

Jules,

I think that would be the condensate drain you are talking about. The safety discharge pipe is only 15mm, usually copper and would not be connected to anything.

What is the make and model of the boiler as they all have different fault codes.

Colin

Just been outside and had a good look - there is a copper pipe and a plastic pipe. The plastic pipe (condensate drain) was the one they connected to to soak away and caused the backed up water to flood out through the boiler. We had about 2" on the floor.

Just now the pressure was at almost three and the copper pipe just had a drip, nothing else. The pressure wasn't going down. We had to discharge it manually.

[Potstubsdustbins]

Hi Jules,

Only three things can cause the pressure to rise in the system.

The first is quite natural, that is when the system water expands due to heating up the central heating waters. The pressure will rise about half a bar on the pressure gauge, when the heating goes off the pressure should fall again to its original level.

The second is that the filling loop tap is not turned off correctly or it has failed and is passing water even when in the off position. Very simple quick job to change the tap, we actually carry spares on the van to save having to fetch them.

The third is the nasty one, the expansion vessel has failed. The symptoms for this are that you would have to top up the system waters before you can use the boiler. There would then be a rapid rise in pressure when you turn on the central heating. The pressure will continue to rise until the safety discharge valve operates blowing water off through the small outside copper pipe, lowering the system pressure to a safe level. The problem then comes when the heating switches off, the system waters will cool and contract lowering the system pressure such that the boiler will not fire.

If you do not have to top up the system pressure it will be the filling loop tap.

If you have to constantly top up the pressure to get the boiler working it will be the expansion vessel.

There should not be any drip on the discharge pipe unless the system pressure is to high and 3 bar is to high.

If I can help further please let me know.

Colin

[Piggle]

Just to chip in- mine makes a noise like it's going to explode sometimes..... But only when it is on and you try to run the taps! Scares the life out of me.
If I try to raise the pressure to 1.5 if goes on a mad one, the valve goes off and it re- pressurises itself back to about 0.8.
I should call the boiler people but you know when you just can't be arissed.


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