Pressure drops but no leak

smp50 · 25 Feb 2019

Hello. This heating system keeps seeing pressure drops (down to zero) every few months but now increasing in frequency. It can be successfully re-pressurised with the filling loop, but then drops again over a period of time.

There are absolutely no discernible leaks, inside or outside the house. Can anyone suggest what the problem may be?

It is the sort of system with a boiler, hot water cylinder, but no header tanks.

Thanks,

Diyisfun · 25 Feb 2019

Pressure vessel. Im not a plumber.

smp50 · 25 Feb 2019

Diyisfun said:
Pressure vessel. Im not a plumber.

What about it, a leak of some kind? There's definitely no water leaking. By the way, a plumber and I looked around for this "pressure vessel" once but couldn't find it anywhere. How big is it, could it be hiding in insulation? Header tanks are easy to spot, but not this.

Jackrae · 25 Feb 2019

Water being 'consumed' in the conversion of steel radiators to iron oxide, carbon sludge and hydrogen together with the expansion vessel having failed ?

dilalio · 25 Feb 2019

Find the discharge pipe and go from there. Or its leaking internally (via hex) and out through condense. Or there is a leak and you just haven't found it.

dilalio · 25 Feb 2019

smp50 said:
It is the sort of system with a boiler

Is it a "white" one?

Madrab · 26 Feb 2019

Get a engineer in to trace and fault find, if it's a sealed system then it has to be going somewhere.

ianmcd · 27 Feb 2019

what boiler do you have

smp50 · 15 Apr 2019

This is still an ongoing issue - I have had a plumber round and he dug about in the loft and swears there is no "pressure vessel", and there's certainly no water leak that we can detect. But, every few days/weeks the pressure drops to nearly zero and needs refilling.

ianmcd · 15 Apr 2019

As you have already been asked what is the make and model of the boiler and we will tell you where the expansion vessel is

dilalio · 15 Apr 2019

If the vessel is inside the boiler and your plumber couldn't work that out, I'd suggest a different plumber, or perhaps a heating engineer

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Pressure drops but no leak

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