Valiant boiler loosing pressure, 4 engineers later and no fix

R.Brown

Hello! I'm looking for some advice about my boiler that keeps losing pressure. 

Quick timeline: 

• Bought the place in Feb and had British Gas come out to do a boiler inspection (£100 later) and they said it was all good, have a certificate and all
• In May no hot water – it had lost pressure, which was no big deal. First engineer comes and repreusrises it, checks the boiler and says it looks pretty new, no issues
• Did it again in June after a cold snap and having the heating on, and called insurance. The second engineer came out and said to bleed the radiators, which I did 
• Happened end of August, after the heating was on... bit of a pattern starting. Thirds engineer came again, said it was wrong to bleed the radiators, it was the pressure balloon. Said he had fixed that 
• Then it happened again beginning of Sept, except this time, the heating hadn't been on all week. Had the heating on for a couple of hours Monday night, but only on Friday morning did the pressure tank. I ask if it could be a leak and told nope, if there's no water anywhere near the radiators then no leak.
• Fourth engineer comes and says nah, the other two were wrong, it's air in the system, i need to top it up 2 or 3 more times and it'll be fine. I ask again if it could be a leak and if he could check, he says no. 
• Happens again, 2 days later. Then started happening at first every two days, then every day. 

Now we get to today: fourth engineer comes back a week later to add leak sealant to the system (which was today). Apparently now he thinks it's a leak. 

He told me to leave the heating running for 30min, which i do – but before the time is up, the heating stops. I check the boiler and the pressure is too high this time! 3.3bars. I switch the heating off, and it drops quickly. I've checked it every couple of hours today and it's just dropped below the low pressure line.

I feel like if they had listened earlier, my problem wouldn't be such a huge mess now. It's definitely gotten worse. 

The engineer today told me i'll most likely have to "rip up all [my] floorboards and pay thousands for the fix". When i asked him how likely that was, he said he didn't know. When I asked if he had seen this before, he shrugged and said he wasn't sure. 

I went back to the insurance today, because this last visit was a joke. 

My question is: is this normal after putting leak sealant in that it should drop that quickly? Is this a bigger issue than a simple leak? Anything I should be asking for, or trying to do? 

tacpot12

I don't think it's a bigger issue than a simple leak. It could be a problem with the Pressure Relief Valve, but the engineers that have been out should have been able to spot this - water will be released to a drain somewhere and you will either hear it or see it.

The high pressure is a concern.The leak sealer can't have gummed up the Pressure Relief Valve (PRVs), it's desgned for systems that have PRVs; the particles in the leak sealer are quite small and only expand very slightly to plug the leak. The fact taht the system is still leaking suggests that the hole is bigger than the leak sealer is designed to fill -  which is good news -  a bigger leak should be easier to find. Check the ceilings for wet patches or warmth (if the boiler has been running recently). The high pressure might just be that the system has been overfilled and the expansion vessel might not be able to accomodate all the expansion. You should also check that the filling loop is completely turned off and disconnected so that no mains pressure can add to pressure in the system. If the pressure rises with the boiler off, the filling loop connecting would be the most likely cause. 

Try to find an engineer with a thermal camera to find the leak. If you can pressurise the system long enough to get hot water all the way around the system, the camera might be able to see where the hot water is leaking out. 

FreeBear

R.Brown said: He told me to leave the heating running for 30min, which i do – but before the time is up, the heating stops. I check the boiler and the pressure is too high this time! 3.3bars. I switch the heating off, and it drops quickly. I've checked it every couple of hours today and it's just dropped below the low pressure line.

The pressure relief valve should be cutting in at 3 bar for most boilers (would need to check the manual for your specific boiler).

As for boiler pressure, mine idles at 1.2 bar, rising to 1.7 bar when hot (I probably need to bleed the system). If you are getting more than 0.5 bar difference, you either have a lot of air in the system, or the expansion vessel is faulty. A regular loss of pressure suggests a leak somewhere that is letting air in, so you'll have to go hunting. Any pipes buried under concrete floors ?

ThisIsWeird

FreeBear said:

If you are getting more than 0.5 bar difference, you either have a lot of air in the system, or the expansion vessel is faulty. A regular loss of pressure suggests a leak somewhere that is letting air in, so you'll have to go hunting. Any pipes buried under concrete floors ?

I understood that air in the system would help maintain the pressure, and not make it increase?

Ie, if your EV is kaput, a get-out could be to half empty a rad, and shut off the flow end.

ThisIsWeird

R.Brown said:

Hello! I'm looking for some advice about my boiler that keeps losing pressure.
Quick timeline: 

Bought the place in Feb and had British Gas come out to do a boiler inspection (£100 later) and they said it was all good, have a certificate and allIn May no hot water – it had lost pressure, which was no big deal. First engineer comes and repreusrises it, checks the boiler and says it looks pretty new, no issuesDid it again in June after a cold snap and having the heating on, and called insurance. The second engineer came out and said to bleed the radiators, which I did Happened end of August, after the heating was on... bit of a pattern starting. Thirds engineer came again, said it was wrong to bleed the radiators, it was the pressure balloon. Said he had fixed that Then it happened again beginning of Sept, except this time, the heating hadn't been on all week. Had the heating on for a couple of hours Monday night, but only on Friday morning did the pressure tank. I ask if it could be a leak and told nope, if there's no water anywhere near the radiators then no leak.Fourth engineer comes and says nah, the other two were wrong, it's air in the system, i need to top it up 2 or 3 more times and it'll be fine. I ask again if it could be a leak and if he could check, he says no. Happens again, 2 days later. Then started happening at first every two days, then every day.
Now we get to today: fourth engineer comes back a week later to add leak sealant to the system (which was today). Apparently now he thinks it's a leak.
He told me to leave the heating running for 30min, which i do – but before the time is up, the heating stops. I check the boiler and the pressure is too high this time! 3.3bars. I switch the heating off, and it drops quickly. I've checked it every couple of hours today and it's just dropped below the low pressure line.
I feel like if they had listened earlier, my problem wouldn't be such a huge mess now. It's definitely gotten worse.
The engineer today told me i'll most likely have to "rip up all [my] floorboards and pay thousands for the fix". When i asked him how likely that was, he said he didn't know. When I asked if he had seen this before, he shrugged and said he wasn't sure.
I went back to the insurance today, because this last visit was a joke.
My question is: is this normal after putting leak sealant in that it should drop that quickly? Is this a bigger issue than a simple leak? Anything I should be asking for, or trying to do?

Hi RB.

Model of boiler, please? Any idea of age? Still under warranty? And it's a combi type?

Ok, in a modern condensing boiler such as yours, the leak  - if there is one - can be narrowed down to two areas; from within the boiler, or outwith the boiler. See? Narrowed down...

If it's from within the boiler, then the leaking water has limited exit points from where it can escape unnoticed. These are:

1) From the Safety Release Valve and Discharge Pipe. This is the most common, and is also the easiest to ID (which it should have been by the engineers). Find the 15mm copper pipe that exits through your house wall adjacent to the boiler. It should terminate either by bending back on itself to point at the wall, or else go down low and aim at the ground (if it 'discharges' in anger, you don't want it pointing at you). Ok, get a wee clear plastic bag, and rubber-band it over the end so that you will catch anything that comes out. No water should come out if it's working ok. Water should only come out if the pressure exceeds ~3bar, but sometimes it can 'let-by'. So check.

2) Via the condensate pipe, which is the larger, 22mm, white plastic pipe which is likely coming out near the safety pipe. This one should aim into a drain, or on to the ground via a bag of chips. This one is more difficult to monitor, since it will be giving out repeated glugs when the boiler is in use. Not really sure how you can monitor this for leakage, other than adding a dye or smell to the system water...

3) The leak is small enough to be vaporised inside the combustion chamber, and ejected out t'flue. This is unlikely, certainly for the sizeable pressure drops you appear to be experiencing. No real way to monitor this other than adding a smell to the system water.

4) Going in to the Expansion Vessel, replacing the half that should be air. This has seemingly been checked, and in any case it can only carry on doing this for a limited time before the EV is full of water. At this point, the system pressure will be soaring when the boiler is running hot - and then point (1) will likely happen.

5) From a physical leak from the boiler, which should be obvious on any surface underneath it.

And from outside the boiler, there's everything else - pipes and radiators. Such significant pressure losses should leave obvious traces on the floor, such as stains and green verdigris. If it's under the floor, then...

You can determine which of these two areas is responsible by isolating the boiler from the pipes/rads. Under your boiler are isolating valves - you'd shut off the CH flow and return. Then you'd not run the CH for obvious reasons, but would run the DHW - which should work. You set the cold pressure to, say, 1.5bar first, and then monitor it after some DHW use, after allowing it to cool again.

If the pressure has dropped, the 'leak' is from within the boiler. If it hasn't dropped, then keep an eye on the needle as you open the isolating vales again - any drop then?

R.Brown

tacpot12 said:

I don't think it's a bigger issue than a simple leak. It could be a problem with the Pressure Relief Valve, but the engineers that have been out should have been able to spot this - water will be released to a drain somewhere and you will either hear it or see it.

The high pressure is a concern.The leak sealer can't have gummed up the Pressure Relief Valve (PRVs), it's desgned for systems that have PRVs; the particles in the leak sealer are quite small and only expand very slightly to plug the leak. The fact taht the system is still leaking suggests that the hole is bigger than the leak sealer is designed to fill -  which is good news -  a bigger leak should be easier to find. Check the ceilings for wet patches or warmth (if the boiler has been running recently). The high pressure might just be that the system has been overfilled and the expansion vessel might not be able to accomodate all the expansion. You should also check that the filling loop is completely turned off and disconnected so that no mains pressure can add to pressure in the system. If the pressure rises with the boiler off, the filling loop connecting would be the most likely cause. 

Try to find an engineer with a thermal camera to find the leak. If you can pressurise the system long enough to get hot water all the way around the system, the camera might be able to see where the hot water is leaking out. 

Every engineer said they've checked the boiler itself and it looks relatively new (was installed about 3-4 years ago, according to the neighbours) with no leaks. Apparently the pressure relief balloon was faulty, but no one mentioned the PRV? 

I dont have any wet patches on the floor, or the walls, near the radiators. 

I'm getting the the point where I'm too scared to even try and switch on the heating to see what happens. I'm checking the boiler about 5 times a day to watch it drop. It dropped below pressure last night, topped it up to about 1.7b and it's down to 1.2b this morning – whether that's it just fluctuating between the showers and washing up this morning, I don't know. But I'm frustrated and tired of no one being able to solve the issue. 

ThisIsWeird

The PRV and EVessel are related in function. 
If the EV has lost air, it won't be able to keep the system pressure steady, so it'll rise as the boiler heats up (and fall again as it cools down).
If it exceeds around 3bar, you can expect the safety valve to open, and it'll discharge excess system water out the pipe I mentioned, outside your house. Any such discharge is easy to ID, so that's the first move - monitor that pipe.

Annemos

https://forums.moneysavingexpert.com/discussion/6499054/vaillant-ecotec-plus-lost-pressure-reason-a-faulty-schrader-valve#latest

Please see my post last year. It was the Schrader Valve in my case. The expert knew exactly what it was and replaced it in 5 minutes. 

Just to add... I believe they get clogged up. Also they need to sit exactly in the right position (not wonky!). 

R.Brown

Annemos said:

https://forums.moneysavingexpert.com/discussion/6499054/vaillant-ecotec-plus-lost-pressure-reason-a-faulty-schrader-valve#latest

Please see my post last year. It was the Schrader Valve in my case. The expert knew exactly what it was and replaced it in 5 minutes. 

Just to add... I believe they get clogged up. Also they need to sit exactly in the right position (not wonky!). 

Thank you!! I'll make sure to ask at visit number 6 on Monday 🫣 I had to top it up last night and now again this afternoon 

ThisIsWeird

R.Brown said:

Thank you!! I'll make sure to ask at visit number 6 on Monday 🫣 I had to top it up last night and now again this afternoon 

Have you bagged yer wee safety pipe?

R.Brown

ThisIsWeird said:

R.Brown said:

Thank you!! I'll make sure to ask at visit number 6 on Monday 🫣 I had to top it up last night and now again this afternoon 

Have you bagged yer wee safety pipe?

What's the safety pipe?