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Pressure loss (Read 10983 times)
TrevorP
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Pressure loss
Oct 31st, 2016, 11:41am
 
Few months back had new boiler and tank fitted, as weather fine did not require heating until now, but find the pressure constantly dropping, as much as 0.6bar per day.
I have checked all rad valves, boiler safety, vent, and any signs anywhere for a leak, but found none.
Am now suspecting an under floor leak, but the downstairs flooring is an asphalt screed, so my problem is finding it, has anyone any ideas? as I cannot see any damp patches yet.
Also have found that the pipework to radiators in the asphalt is not lagged, is asphalt corrosive to copper, as concrete?  
Any advise appreciated.
TP
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Re: Pressure loss
Reply #1 - Nov 1st, 2016, 9:43am
 
All I can suggest is isolating sections of the system and doing a pressure test on each section.
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thescruff
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Re: Pressure loss
Reply #2 - Nov 1st, 2016, 12:38pm
 
As above is the only painfull way.

But first isolate the boiler pipes and electric and check whether the pressure still drops over night, maybe be an internal leak and exiting via the condense pipe.

If it is the heating it maybe less disruptive to repipe the lot, if corrosion is the problem you'll eventually need to anyway.

Talking of corrosion do not keep topping the boiler up as it will only make the corrosion worse and trash the new boiler with it.
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Headrush
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Re: Pressure loss
Reply #3 - Nov 1st, 2016, 6:19pm
 
Strange that it should suddenly start losing pressure when you started using the heating. Maybe it's just trapped air working it's way out or a joint is leaking somewhere only when it's hot and expanded. In which case the leak often evaporates away and is difficult to locate. Check the valve stems where they screw into the radiators, leaks here are quite common after a period of time.

Just out of interest, after topping up the pressure and running the heating, does the pressure start to rise sharply? It shouldn't really go much above 1.5bar.

Having said all that you haven't actually changed anything other than the boiler and I assume you meant HW cylinder, so it's a bit of a mystery..
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thescruff
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Re: Pressure loss
Reply #4 - Nov 2nd, 2016, 12:04am
 
may have been an open vented system, changed to a sealed pressure system, sure way to find any weak joints.

Boiler make and model may help with a few clues, as could the size of the system, number of rads etc.
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Re: Pressure loss
Reply #5 - Nov 2nd, 2016, 11:13am
 
Thanks for coming back, my plumber has checked all the points you guys list. The problem finding the leak is the pipes are laid in a channel, with sand and fine rubble on top, then a layer of about 50mm concrete over, and on top of this is a 20mm asphalt damp proof screed. So any leak would not show or be detected with a damp meter.
Its a good idea you mentioned about isolating the upstairs from down, so my plumber is coming to fit two valves, and like you said this should show which area at least the leak is in.

I saw on the internet some company that uses nitrogen to fill the system then use a sniffer to detect any leaks, anyone know if this is a good idea?, I know the cost is very high, but am not really in favour of surface piping the whole downstairs.

Thanks for all advice.
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woodsmith
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Re: Pressure loss
Reply #6 - Nov 2nd, 2016, 1:37pm
 
Firstly, I'm a chippy so I may be rambling,, but I did replaced my own central heating last year. Lots of the pipework was concealed and when I had finished I had a constant but small pressure drop and air getting into the system somehow. I've had two heating engineers look at it and we have never found the problem. Last engineer recommended putting some leak sealer into the system and now, a year later, the problem seems to have resolved itself so last resort may be to add some sealer??

Another thought about tracing the leak especially if it is more substantial than mine, would be to get all the water out of the system and pressurise it with air to about 2 bar, then you may well be able hear the air escaping.
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Re: Pressure loss
Reply #7 - Nov 2nd, 2016, 8:01pm
 
I did suggest this to the plumber, as I  had used the leak sealer on our previous property with very good result.  But the plumber has said its a no no, as I would lose the warranty on the boiler.
So I will see wait and see what happens after the valves have been fitted, at least I'll know if its ground floor or upstairs.

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Re: Pressure loss
Reply #8 - Nov 2nd, 2016, 11:19pm
 
woodsmith wrote on Nov 2nd, 2016, 1:37pm:
Firstly, I'm a chippy so I may be rambling,, but I did replaced my own central heating last year. Lots of the pipework was concealed and when I had finished I had a constant but small pressure drop and air getting into the system somehow. I've had two heating engineers look at it and we have never found the problem. Last engineer recommended putting some leak sealer into the system and now, a year later, the problem seems to have resolved itself so last resort may be to add some sealer??

Another thought about tracing the leak especially if it is more substantial than mine, would be to get all the water out of the system and pressurise it with air to about 2 bar, then you may well be able hear the air escaping.


Modern boilers have small water ways leak sealer is a very big no no or you'll be wanting a new boiler again.

Air testing anything is particularly dangerous as air compresses and can explode in a second, high risk of someone getting killed and frowned upon by the HSE, on an old system it could quite easily blow the lot to bits  in  a blink of the eye.
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Re: Pressure loss
Reply #9 - Nov 2nd, 2016, 11:21pm
 
TrevorP wrote on Nov 2nd, 2016, 8:01pm:
I did suggest this to the plumber, as I  had used the leak sealer on our previous property with very good result.  But the plumber has said its a no no, as I would lose the warranty on the boiler.
So I will see wait and see what happens after the valves have been fitted, at least I'll know if its ground floor or upstairs.



You'd be better doing what I suggested first  Roll Eyes
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Re: Pressure loss
Reply #10 - Nov 2nd, 2016, 11:45pm
 
TrevorP wrote on Oct 31st, 2016, 11:41am:
Few months back had new boiler and tank fitted, as weather fine did not require heating until now, but find the pressure constantly dropping, as much as 0.6bar per day.
I have checked all rad valves, boiler safety, vent, and any signs anywhere for a leak, but found none.
Am now suspecting an under floor leak, but the downstairs flooring is an asphalt screed, so my problem is finding it, has anyone any ideas? as I cannot see any damp patches yet.
Also have found that the pipework to radiators in the asphalt is not lagged, is asphalt corrosive to copper, as concrete?  
Any advise appreciated.
TP


Lastly, apply lateral thinking.

Ok you don't say whether you used the boiler to heat the tank or not, but lets assume you did and the pressure was constant blah blah etc.

Now the problem I have, is it's the same water heating the tank as the radiators so whats changed. ? nothing, so what have you done to get the radiators hot. 0.5 bar is probably a bottle of water depending on the size of the system, nothing more than a weep on a rad valve or nut.

You should be checking every nut, fitting, pipe insight when the system is cold, it is also common for a leak to be internal to the boiler or something the rgi has done as new work.

Don't waste time and money chasing shadows, isolate the boiler, if the pressure hols over night open the valves and see whether it drops instantly.

Is the cylinder new, the coil could be pinholed or damaged and the water is going into the storage tank. Is the stored water hot/warm if not used overnight.

Lots of easily checkable jobs before you even think to look ander the floors.
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Re: Pressure loss
Reply #11 - Nov 3rd, 2016, 7:53am
 
thescruff wrote on Nov 2nd, 2016, 11:19pm:
Modern boilers have small water ways leak sealer is a very big no no or you'll be wanting a new boiler again.


That's a worry! and it was Worcester Bosch's own engineer that recommended using leak sealer, I should have got him to put that in writing
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Re: Pressure loss
Reply #12 - Nov 3rd, 2016, 9:36am
 
You would probably know by now if it caused a problem K.
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Re: Pressure loss
Reply #13 - Nov 3rd, 2016, 11:19am
 
thescruff wrote on Nov 3rd, 2016, 9:36am:
You would probably know by now if it caused a problem K.

Thanks. It's an oil boiler, perhaps they have bigger waterways?
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Re: Pressure loss
Reply #14 - Nov 3rd, 2016, 11:43am
 
They do.  Smiley
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Re: Pressure loss
Reply #15 - Nov 5th, 2016, 10:10am
 
Perhaps put some dye in the system?

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Re: Pressure loss
Reply #16 - Nov 5th, 2016, 2:27pm
 
Hi all,

The boiler is a Valliant eco plus 630, its a sealer system, and the HW tank was replace at same time as boiler fitted.

Cannot isolate the boiler itself as no valves, but have try'd turning heating off and just running HW, still a pressure drop, but I suppose this does not prove anything as there are no valves on the return side.

I do now have two valves fitted to the downstairs now, so will now isolate this area, and show if its the HW/upstairs heating causing the drop.

I will check with the plumber if its ok to put the dye in system, but not sure if he would be agreeable to this?

Thanks for help, will keep you informed of progress.

TP
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