Combi Boiler losing pressure

magn8p

Sorry if I am reposting the same question but I couldn't find a suitable solution in the forum.

I have recently moved into a new house (a month ago). After 14 days into moving in, our Ideal Logic combi 35 boiler failed showing error code "1" followed by "F". After quick search online, I found that the problem was pressure drop - fell to 0.5 bar.

I have repressurised it and the boiler started work. I thought that was it, but then 10 days later it happened again (and I repressurised) and it happened again after 10 days (today).

I know that Combi boilers need topping up every 3 to 6 months but every 10-day topping up could mean there is a leak somewhere.

Everytime the heating starts, I can hear water droplets fall for 5 to 10 seconds from the roof. But I can't figure out where exactly the leak is because I can't see any signs of patch/damp.

My question is, if there is a leak, shouldn't it leak continously? Why do I hear the leak (water drops in the roof) only for the first 10 seconds after the heating kicks in?

What is the best way to track and trace the leak? Thanks in advance.

Chunks

Giving your post a bump. I am not a plumber (plenty on here) so in the meantime........ A few things I have seen since my boiler was installed ~10 years ago:

I have a condensing boiler (similar not the same as yours, obviously). In my case water drips from the flue from time to time, which is 'normal' I was told - I think this might be your 'water drops'.

There is a pressure release valve in the boiler that has let go in the past giving rise to a larger quantity of water flowing from the overflow pipe outside (bent 15mm copper pipe below the flue). Worth re-pressuring your system and checking the overflow pipe when the boiler fires up - keep checking. May not be the PVR itself but another issue causing the boiler to over pressurize.

My pressure vessel needed pumping up (pressure dropped to 0.5bar but stayed there). Plumber drained boiler, pumped the vessel back up, refilled.

Leak(s) in CH pipework itself - may be obvious if above ground level - damp patch(es) not so obvious if in the screed, lift carpets and inspect (last resort perhaps).

May well be other theories (likely) but expert MSErs along shortly.

dbriggs

I've got a similar issue with mine; I have to re-pressurise every couple of weeks.

The pressure drop in mine only happens in winter when the heating is used. When the boiler is just doing hot water for the taps the pressure takes 6 months to drop (just a little). I do worry there is a leak somewhere in the central heating pipes but without taking up carpets and floorboards, how would I know where it is? I can't see any damp patches on the walls or ceilings.

Crinkmeister

If the pressure is dropping over 2 or 3 weeks, then the rate of loss is so very small, you are going to find it difficult to spot as the water will evaporate on the warm pipes. A good telltale sign is green copper oxide on the pipe - assuming you have copper and not plastic!

southcoastrgi

Is your boiler in the loft ?

magn8p

Hi there,

No, the boiler is not in the loft, it's in our kitchen.

I am going to get the boiler serviced next week. I am planning to buy something like this and ask the Gas engineer to put it in the system to seal any small leaks, has anyone tried this before? Is it effective at all?

http://www.screwfix.com/p/sentinel-internal-leak-sealer-1ltr/99730

NectarCollector

My parents had exactly this issue. Eventually after several months and visits by British Gas we discovered a damp patch under the lino... there was a pin hole sized leak in the hot water pipe under the concrete floor.
They had the all the pipes reinstalled above the floor after that, no more leak, no more constant drop in pressure.

southcoastrgi

I can't quite understand that if the boiler is in the kitchen why you hear water dripping from the loft ?

TeamPlum

southcoastrgi wrote: »

I can't quite understand that if the boiler is in the kitchen why you hear water dripping from the loft ?

I believe he feels he/she can hear the leak (causing the pressure drop) from the upstairs pipes.

I wonder however, if these "drips" you can hear are simply the pipes warming up and expanding. Logically if it was an upstairs pipe, you wouldn't hear a drip because they're too close to the floor level to make a loud "drip".

Check your house insurance, some have a "trace and access" clause to find leaks, and will be covered under that. (Though more common on landlord insurance).

Otherwise it's a complex issue about putting air into the system and listening for leaks.

Grenage

magn8p wrote: »

I know that Combi boilers need topping up every 3 to 6 months but every 10-day topping up could mean there is a leak somewhere.

Ideally not; a sealed heating system shouldn't need topping up more than once a year - if at all. My old house didn't drop pressure over a two year period.

magn8p wrote: »

Everytime the heating starts, I can hear water droplets fall for 5 to 10 seconds from the roof. But I can't figure out where exactly the leak is because I can't see any signs of patch/damp.

Most likely expansion noises; it will either leak, or it won't.

magn8p wrote: »

What is the best way to track and trace the leak? Thanks in advance.

Check all visible pipework; most leaks will eventually become apparent. It could be the expansion vessel, although I'm not particularly savvy with boilers.

TBagpuss

I had an issue with pressure dropping after my very old back boiler was replaced with a combi boiler.
My plumber/heating engineer said it was probably a microleak somewhere and initially put some sealant(??) through the system - that didn't fix the issue and we then found it was a leak in one of the old pipes which couldn't take the new, higher pressure. I spotted it as it did creatte a slightly discloured patch on the ceiling below where hte leak was, but it wasn't obvious at first as the amounts leaking were so small, there were no drips or dampness. Once identified it was fixed fairly easily and (touch wood) I've had no issues since.

I'd speak to your plumber about what product to consider, rathe than buying something first nd asking them to add it.