recurring low pressure in new sealed system

NickNickleby

I'm back, because I always get helpful answers from you guys!


Not my house, but as an 'interested party' I notice these things.

New heating system installed in old house. Combi - boiler with 9 rads. Sealed system.

During a recent visit, I noticed a flashing alert on the boiler, and walking over to it I saw it was a pressure problem "0.4Bar". Told occupant to turn on heating to see what would happen. They did and the system fired up, but then the message changed to "0.3Bar" whereupon the system shut down, but then the reading went to "0.4Bar" and the system refired and continued to work. Told them to shut it down immediately and call plumber on Monday. Bear in mind this system is only weeks old.

Anyway, the plumber returns and repressurises the system and away we go. He was unperturbed by the pressure drop - explaining it as some sort of bedding in and to be expected. (I'm obviously paraphrasing someone who reported it to me- Chinese whispers).

Two weeks later I'm in the house and sneakily take a peak at the boiler. Its reading "0.7Bar". Asked the owner was this how the plumber left it. He said no, it had been brought up to 1.1Bar by the plumber. So I suggested this is quite a significant drop in just two weeks. He said the plumber had left instructions as to how to refill in future. So I said, well do that if you like, but make sure to record the pressure readings and dates every time. I said it was my understanding that introducing fresh water into the system on any kind of regular basis is likely to impair the system eventually (corrosion due to oxygen - am I right?). The homeowner said that the plumber put something into the system to prevent this, but I'm sceptical (not that he put it in, but that it'll be effective in a leaking system).

So now to my question(s).
1. Should the refilling procedure be followed in the hope that eventually this will resolve itself?
2. Is 0.4Bar drop in a fortnight excessive?

The downside is that since the system was installed, new wooden (and worse) some tiled, floors have been laid over the pipe runs. The runs are qualplex, I noted that during the build, but there are elbows under the rads, and copper is run for the last few inches to each valve. I'm assuming that one of these joints must be leaking, but thankfully there's no wet patches on the ceilings, so with 'luck' it'll be under the ground floor (floorboards on joists). I'm pretty sure a pressure test was done during the installation, so will that mean hands can be washed, so to speak???

Thanks in advance for any and all comments.

NickNickleby

Popped into the house today, and its now down to 0.4Bar, so that a drop of .3Bar in 3 days.

Anyone care to offer anything on this?

THe reason I'm asking a question to which it might be assumed I should know the answer because its staring me in the face, is because I don't want to find myself raising the issue of lifting brand new floors to new homeowners, unless its likely to be unavoidable.
On the other hand if someone comes along and says that in their experience it can be like this while new system beds in, then I won't open my mouth to the people involved - they've enough to be getting on with.

Also, I'm not looking for ammunition to fire at the plumber, my concern is with fixing the problem - if there is one.

cheers

sullzz

NickNickleby wrote: »

Popped into the house today, and its now down to 0.4Bar, so that a drop of .3Bar in 3 days.

Anyone care to offer anything on this?

THe reason I'm asking a question to which it might be assumed I should know the answer because its staring me in the face, is because I don't want to find myself raising the issue of lifting brand new floors to new homeowners, unless its likely to be unavoidable.
On the other hand if someone comes along and says that in their experience it can be like this while new system beds in, then I won't open my mouth to the people involved - they've enough to be getting on with.

Also, I'm not looking for ammunition to fire at the plumber, my concern is with fixing the problem - if there is one.

cheers

For sure a leak somewhere, id be advising them to get the plumber back.

NickNickleby

sullzz wrote: »

For sure a leak somewhere, id be advising them to get the plumber back.

Hi sullz,

Thanks for taking the time to reply.

Yeah, that's pretty much what I expected to hear. My better half doesn't want me to go all melodramatic and talk about lifting floors that were only put down in the last 3 weeks and the heating was completed about 5 weeks ago. Its my daughter's house, and we don't want to rain on her parade. But.... I feel that small problems can become big problems if not dealt with in time.

Is adding something to the water a reasonable approach, or is it better to find the leak and just fix it??

cheers, and thanks again.

sullzz

NickNickleby wrote: »

Hi sullz,

Thanks for taking the time to reply.

Yeah, that's pretty much what I expected to hear. My better half doesn't want me to go all melodramatic and talk about lifting floors that were only put down in the last 3 weeks and the heating was completed about 5 weeks ago. Its my daughter's house, and we don't want to rain on her parade. But.... I feel that small problems can become big problems if not dealt with in time.

Is adding something to the water a reasonable approach, or is it better to find the leak and just fix it??

cheers, and thanks again.

I'm guessing what the installer was referring to was inhibitor to prevent corrosion to the system. I wouldn't go down the road of adding any type of leak sealer to the system.
Its a newly installed system, the installer must stand over it
Your daughter has a log of dates of pressure drops, simply ring the installer and demand the leak is traced and repaired.

NickNickleby

thanks again, sullz.

the question about leak sealer was my own, the installer never mentioned it as a remedy (to my knowledge). So, I'll advise her to say she's not happy to have 'gunge' added to her brand new heating system. He's a nice chap, so hopefully this won't be an unpleasant process.

Fingers crossed its not under the tiled area :eek:.

cheers and thanks!

NickNickleby

Hi sully,
Watching brief at the moment. They're going to refill a couple of times and keep record, and if the problem persists they're going to get him back.

However, I was told something odd. The lad was refilling the system, and when it reached 1.1bar, he shut off the water. But... for the next 30 minutes the pressure continued to rise till it reached 1.5bar. Then it gradually dropped back to 1.1bar. During all this time, the heating was off, by which I mean it was powered up, but the timer wasn't calling for heating.

Does that sound strange?

Cheers.

John.G

NickNickleby wrote: »

Hi sully,
Watching brief at the moment. They're going to refill a couple of times and keep record, and if the problem persists they're going to get him back.

However, I was told something odd. The lad was refilling the system, and when it reached 1.1bar, he shut off the water. But... for the next 30 minutes the pressure continued to rise till it reached 1.5bar. Then it gradually dropped back to 1.1bar. During all this time, the heating was off, by which I mean it was powered up, but the timer wasn't calling for heating.

Does that sound strange?

Cheers.

Have you noted the boiler pressure both when cold and then after its up to full temperature with all rads in service?.

Edit: Reason for my query is :The exp vessel pre pressure may not have been checked prior to the initial fill, if it had no pre pressure or had excessive pre pressure then the PRV will lift when the boiler is up to full temperature....unlikely I know but worth checking out before tearing the floors up, the PRV will also lift if the exp vessel is under sized, also when boiler up to temperature i would run a hot water tap or shower and see if pressure is any different.

sullzz

NickNickleby wrote: »

Hi sully,
Watching brief at the moment. They're going to refill a couple of times and keep record, and if the problem persists they're going to get him back.

However, I was told something odd. The lad was refilling the system, and when it reached 1.1bar, he shut off the water. But... for the next 30 minutes the pressure continued to rise till it reached 1.5bar. Then it gradually dropped back to 1.1bar. During all this time, the heating was off, by which I mean it was powered up, but the timer wasn't calling for heating.

Does that sound strange?

Cheers.

Possibly filling via a filling loop fitted after a Pressure reducing valve/auto filling valve, can you take a picture of any pipework associated with where they refill it from.

NickNickleby

Thanks JohnG and Sullz for your replies.

I will attempt to get this information asap. can't be seen to be interfering too much, so treading softly :pac::pac::pac:

with a bit of luck I'll get the photos today, and ask them to record pressures as per John G's question.

Ffrom recollection, I think in the day or two after refilling to 1.1Bar, the system reaches 1.5Bar* under normal operation, and falls back to 1.1Bar when cold.

edit : this is not to be confused with the 1.5Bar observed shortly after refilling - I have definitely confirmed this rise happens when the system is not operating and only the once (per refill).

I'll see how to persuade them to record the pressures over a few days, you know, by letting them think its their own idea

cheers.