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Original poster

Boiler completely losing pressure every morning - help!

22 replies

Crackstone · 03/01/2023 18:21

We have a new (less than 18 months old) oil boiler. House is fairly large and on a zoned system so we have upstairs, original downstairs and extension as the three zones.

We have had some sort of issue since it was installed. The highest radiator in the house frequently needs bleeding. It will typically need bleeding every couple of weeks. Other upstairs rads have the same issue but not to the same extent as the highest one.

For the past couple of weeks the heating system pressure drops down to zero overnight. All the lights go out to the system and the label says if lights go out check pressure. The pressure is on zero. I have to top it up every morning and then the boiler will start.

Clearly we have a problem but does this sound like its just to do with settings or something easy to fix or do I need to get a heating engineer out? I'm worried that large amounts of water must be going somewhere since Im topping it up literally every day.

OP posts:
Hopingforno2in2023 · 03/01/2023 18:22

We had that and it was a leak. Unfortunately it was incredibly difficult to find so months of British Gas digging up our flooring. Hope it is much easier for you!

NCForQuestions · 03/01/2023 18:22

Your pressure vessel is probably shot to hell. You'll need to contact a gas fitter. It's possible it just needs to be repressurised and then it'll be fine but it's also possible it needs replacing. We had ours topped up and it lasted another 3 years before we had to replace the whole boiler, but we were warned it might not last more than a few days so we got lucky.

thistimelastweek · 03/01/2023 18:23

Sounds like you have a leak somewhere.
Check pipes and radiators.
Worst comes to worst there are companies that specialise in leak detection but they are pretty expensive.

Roselilly36 · 03/01/2023 18:24

That’s definitely not right, leak somewhere? I would get an engineer out. I hope you get it sorted out, is the boiler still under warranty?

Roselilly36 · 03/01/2023 18:25

It’s a oil boiler not gas.

Stardustkid · 03/01/2023 18:25

Leak or valve issue, good luck

Wombats67 · 03/01/2023 18:27

Leak somewhere. It was after a new boiler was fitted and the higher pressure caused a pipe that had been crimped, rather than capped, to leak under the floor.

It was an utter ballache finding it, took months of chasing the original plumber, eventually gave up.

You need a very tenacious plumber.

We were trying to sell the house and had to find the leak and eventually we got a guy in who crawled under the floorboards, tracing all of the pipes...

Wombats67 · 03/01/2023 18:29

The other issue with filling it up each day is that there is no inhibitor left in the system and it will rust faster.

I did fill ours up for months tho!

Original poster
Crackstone · 03/01/2023 18:32

Oh gosh this will be a nightmare if its a leak somewhere in the house. I'm assuming we would know if it was an upstairs leak and all the downstairs floors are solid with brand new parquet glued on top of them Sad.

The new boiler is an external one so if it is a leak then I'm praying its in the 1m stretch between the boiler and the house...

OP posts:
Wombats67 · 03/01/2023 18:48

I'd actually waited to put the flooring down, jic of a leak. The leak started the day after it was all fitted.

I got really good at taking a section up!

And yes, I figured we'd know about it if the leak was upstairs, it was downstairs under the kitchen floor. A very difficult time!

Original poster
Crackstone · 03/01/2023 18:48

Now panicking and checking every radiator. Presumably we'd be able to see from water marks on the ceiling above if it was an upstairs pipe or radiator

OP posts:
TequilaNights · 03/01/2023 19:07

Definitely sounds like a leak of some kind, Check there isn't water leaking from your condensate pipe, it could be a faulty expansion vessel, PRV, or heat exchange rather than a leak on a pipe.

Is your pipe work under the concrete copper?
If they were not installed with correct protection, that could also be your issue, as the pipes corrode in concrete.

You can hire leak detection specialists which would help locate an underfloor leak with minimal damage.

Good luck.

Taxistaxing · 03/01/2023 19:26

I have a gas boiler so I appreciate it's not the same, but I had similar and it wasn't a leak, it was a sensor (pressure or heat I can't remember) that's was faulty and it forced expulsion of water from the overflow and this meant the pressure dropped and boiler wouldn't start up.

Ilovefishcakes201 · 03/01/2023 19:33

You need to find a way to add strong aftershave/perfume into the system.

One way to do it is drain the system a little, normally the lowest radiator in the house with a radiator drain valve.
Remove the bleed valve from a towel rail or the highest radiator in the house and pour in the aftershave.
Shut everything and pressurise the system.

Then follow your nose after the boiler has been running for a while.

Felicity42 · 03/01/2023 19:55

Check all the rads for tiny leaks. Especially at the valves and along the bottom edges. It could be a leak at the boiler too. You should be able to take the side door off the boiler and see if there is a puddle of water out there.
We had this in our new house.
The plumber replaced something in the boiler and it was fine then. So don't panic just yet!

SweetPetrichor · 03/01/2023 20:35

We’ve just had this issue too - for us it was a leaky radiator. Hopefully you find the leak easily, I was very stressed imaging having to take up the floors!

17CherryTreeLane · 03/01/2023 20:45

We had the same for years! So annoying, and I had visions of our foundations being ruined and the house floating away. A new boiler and everything works fine though.

choppychopper · 03/01/2023 20:47

Leak for us too. House insurance covered the company who specialises in finding leaks and any replacement flooring required. It didn't cover fixing the actual leak which was the boiler in our case.

Wombats67 · 03/01/2023 22:13

Taxistaxing · 03/01/2023 19:26

I have a gas boiler so I appreciate it's not the same, but I had similar and it wasn't a leak, it was a sensor (pressure or heat I can't remember) that's was faulty and it forced expulsion of water from the overflow and this meant the pressure dropped and boiler wouldn't start up.

I've had this too, in a different house, yes I know, I'm doomed.

That's the pressure reduction valve, you tend to know if that goes off as it shoots the water out the side of the house (or flat into furious neighbour's garden, in our case.) I suppose if it's a house tho, it might be down a drain.

I do like the perfume idea! I was going to say go look for a damp patch but we never found one.

GasPanic · 04/01/2023 10:43

If you have a hot water cylinder remember to check around that as well, as the water heating circuit for the radiators is often the same one as for the hot water - it's just switched in and out by diverter valves.

Augend23 · 04/01/2023 10:48

Mine used to leak under the boiler itself - just the pipes coming out. A nylon washer had got ruined so it leaked round it. Mine still needs repressurising occasionally but only about once every 6 months. Goodness knows why or where it's going but no consequences for the house so far...

BlueMongoose · 04/01/2023 20:09

You need pigletJohn -is he around?

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