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Help with Puzzling pressure loss

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weejoe

I would be great-full if any one has any advise on pin pointing where I could be losing pressure in my CH system.

I have a 2 1/2 year old Sabre 29 HE Condensing Boiler which seems to be losing pressure by the day, approx 3/4 Bar.

Before I noticed this the system usually needed a wee top up every 3 months or so but not a lot.

I've checked the RV pipe outside and it shows no sign of the valve passing.
I've checked the pipework under the ground floor (All wooden) and I see no obvious sings of water/dampness. The pipework below consists of a mixture of HEP20 and copper, the newer HEP20 is lagged with foam insulate and I've checked all runs for signs of Rodent damage.

At the rate the pressure is being lost I had expected to see obvious signs of a leak somewhere, to my disappointment I have found nothing.

The only place I find dampness of any sort is from the condensing pipework outside but given that it's clear looking and the CH radiator water is a cloudy grey I'm assuming it's just condensate. ?

I've just stuck 500ml of Fernox sealer into the system but I'm not holding out much hope at the rate I'm losing pressure.

Any idea's where I could be losing the pressure from ?
Should I expect to see dampness at the location of the leaking pipework (If that's what's wrong)

I haven't lifted any upstairs floors to check the pipes because quite frankly I'd have expected to see a dirty damp stain on the downstairs ceilings had the leak been upstairs.


Your help and advice would be appreciated :)
 
disconnect your condensate pipe you should then turn off your boiler for a few hours any water present would point to your heat exchanger main if band a recuperater if band b
 
gas man said:
disconnect your condensate pipe you should then turn off your boiler for a few hours any water present would point to your heat exchanger main if band a recuperater if band b
Click to expand...

Off to try this

I'm assuming that in two hours time there should be no sign of water whatsoever ?

If this was the issue should the water be coming out at a constant dripping rate or less ?
 
there may be condensation but you will easily tell the difference,if theres water running or constantly dripping theres your leak
 
gas man said:
there may be condensation but you will easily tell the difference,if theres water running or constantly dripping theres your leak
Click to expand...

No sign of a constant drip or worse from condensate pipe or relief valve pipe, I can remove the bend of the Cond pipe and look right into it, there are only droplets of condensate on it's walls, nothing running.

I have noticed a small orange "Rusty" staining on the floor below the boiler, it's completely dried up though, I would have expected that if this was the position of the leak then surely at the rate I'm losing pressure there would be evidence of leakage at least when the system is off and cold.
 
what you need to do next is isolate the boiler flow and return (i have no idea if your boiler has quality isos) leave it for a good few hours if it drops its on the boiler if it stabilises its on the system
 
gas man said:
what you need to do next is isolate the boiler flow and return (i have no idea if your boiler has quality isos) leave it for a good few hours if it drops its on the boiler if it stabilises its on the system
Click to expand...

My boiler does have flow and return isolation valves (ball valve type) should I isolate when the system is cold or will it make no difference hot ?

Will there be any loss of pressure simply from the isolated water in the boiler cooling down or should the gauge sit steady regardless ?

thanks for your help by the way :) Appreciated :)
 
if they are the ball type leave well alone,they could leak unless you have used them and they are reliable should do this with a cold system
 
Valves seem reliable , i'll let the system cool down for two hours then shut in the boiler, leave it overnight then report my findings.

Many thanks !
 
Personally I wouldnt touch the isolation valves on any boiler, you could end up with just more problems.
 
Last night I let the system go cold, pressured it up to 2 bar then locked in the boiler by closing the two isolation valves at the CH flow and return.

When I checked it this morning there was no sign of pressure loss at the boiler side and when I opened the boiler isolation valves back up there was a pressure drop of 3/4 Bar.

With the above findings I'm pretty convinced the issue is not the boiler but the radiators/pipes, what's confusing me though is that I checked all pipes on the ground floor and couldn't find anything.

Can anyone suggest any further steps/techniques that I could try to help me find the problem ?
 
Apart from using a tracer (and I've never seen this done in domestic plumbing!) you're just going to be checking all the pipework and radiators I'm afraid. I presume your boiler is a combi, so the problem can't be with a hot water cylinder, so you've proved that the drop is somewhere in the rads or their pipework.

Sorry I can't offer you a silver bullet :(
 
I have had occasional boilers that showed no sign of a leak but lost pressure. I bumped up the pressure to just below 3 bar and that showed it up. Then of course you would try and fix leak or report its where abouts and then drop pressure back to normal.

Doesn't always work perhaps, but a simple free test.

After all a sealed system is only a balloon and if its got a hole in it, it will loose pressure. Except of course if you are topping up with water that has high air entrainment.
 
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Cheers folks :)
I'll try letting the system cool down then pressuring up to 3 bar to see if a leak is picked up.
I'll report back my findings :)
 
weejoe said:
I'll try letting the system cool down then pressuring up to 3 bar to see if a leak is picked up.
Click to expand...

just below - the PRV will usually be set to open at 3 bar and it's not a good idea to let this happen in case it doesn't seal shut again. :)
 
Success !!

Last night I pressured the system up to just under 3 Bar and found the leak

Surprisingly it was upstairs, surprisingly even more were the findings I encountered.....
photo-1-1.jpg

The nice people who installed the original system over 15 years ago had ran the CH flow and return pipes over a joist in a very shallow cut-out. Approx 3 years ago when I decorated that bedroom I attempted to fix a squeaky floorboard with an additional wood screw, that said screw had penetrated the smaller of the pipes and stayed sealed for 3 years, corrosion must have finally snapped the screw head off its shaft and left it in the pipe.

I always wondered how I got a pipe against wood sound everytime I stood on that still loose floor board, looks like the screw actually pulled the pipe upwards and was being slapped back down every time it was stepped on.

Nothing's ever simple in my house :lol:

Anyways, pipe has been rerouted, ceiling has survived, just a wee lick of emulsion required, all is good :)

Thanks to everyone for the advice :)
 
Cool hope thats the only leak! For what it's worth, the notch you see is a pretty standard size - take much more out and you weaken the joist too much.
 
Notching out is a big problem. I have lost could of the over deep notches I have seen. Its a wonder the floors stay up. But lets be honest on price work how many do it the right way?

How many center the notch in the middle of the Tand G width, drill a proper sized hole at the correct depth in the joist then vee cut into it, and a bit of insulation to stop it rubbing on the joist?

Lets be honest what you usually get is a quick pass with the circular saw then a bang with the hammer. That'll do they can always fit a soil pipe in as well if they want to.
 
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