Hi there,

I hope someone can help me with this. I'm having difficulty with my
heating system. Basically, I had the gas guy in recently to service the
bolier and he discovered that my pressure was down at zero bar so he
filled up the system to 1.5 bar from the mains as it is a closed
system. After about a day the gauge was down to zero again.

I filled it up again and the same thing. The gas bolier just cuts out
when I put it on, due to the fact that there's no water in the system I
suppose. There is no evidence of a leak anywhere in the house so I am
guessing that there is a leak under the living room floor (which is
concrete). Has anybody any suggestions. They would be much appreciated.

Regards,
Rory.

RoryC wrote:
Hi there,

I hope someone can help me with this. I'm having difficulty with my
heating system. Basically, I had the gas guy in recently to service the
bolier and he discovered that my pressure was down at zero bar so he
filled up the system to 1.5 bar from the mains as it is a closed
system. After about a day the gauge was down to zero again.

I filled it up again and the same thing. The gas bolier just cuts out
when I put it on, due to the fact that there's no water in the system I
suppose. There is no evidence of a leak anywhere in the house so I am
guessing that there is a leak under the living room floor (which is
concrete). Has anybody any suggestions. They would be much appreciated.

Regards,
Rory.

You do get a bit of loss due to outgassing..bleed and repressurise until
it settles down.

RoryC wrote:
Hi there,
Has anybody any suggestions.

Defective pressure relief valve?
Check 15mm discharge pipe going to outside after refilling, whilst
boiler warms up.

No air in the expansion vessel? Did gas man check this?

In an earlier contribution to this discussion,
RoryC wrote:

Hi there,

I hope someone can help me with this. I'm having difficulty with my
heating system. Basically, I had the gas guy in recently to service
the bolier and he discovered that my pressure was down at zero bar so
he filled up the system to 1.5 bar from the mains as it is a closed
system. After about a day the gauge was down to zero again.

I filled it up again and the same thing. The gas bolier just cuts out
when I put it on, due to the fact that there's no water in the system
I suppose. There is no evidence of a leak anywhere in the house so I
am guessing that there is a leak under the living room floor (which is
concrete). Has anybody any suggestions. They would be much
appreciated.

Regards,
Rory.

It's very likely that the pressure vessel is either duff or has lost its
charge pressure. The result is that, when the system heats up and the water
expands, it has nowhere to go - so discharges through the pressure relief
valve. When it cools down you have zero pressure.

Check the charge pressure in the pressure vessel with the water system
depressurised. You need a car tyre pressure gauge to do this. The pressure
should be about 0.7 bar (10 PSI). If it's low, pump air in with a car foot
pump, operated by hand. Then re-pressurise the water system to 1 bar using
the filling loop.

This may fix the problem. If it doesn't, it suggests either that the
pressure vessel is completely duff and needs to be replaced, or that the
pressure relief valve is faulty. Find the outside pipe through which water
discharges when the relief valve operates, and hang a jam jar under it to
see whether any water comes out.
--
Cheers,
Roger
______
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Another thought;

RoryC wrote:


Basically, I had the gas guy in recently to service the
bolier and he discovered that my pressure was down at zero bar so he
filled up the system to 1.5 bar from the mains as it is a closed
system. After about a day the gauge was down to zero again.

Strange that the water leak wasn't bad enough to cause the boiler to
lock out before his visit. Or was it?

Did he drain the system, for example to check & re-plenish the air
charge in the expansion vessel?
If so, did he connect a hose to drain it, or did he drain it by
operating the pressure relief valve easing lever/knob?

On Fri, 16 Jun 2006 00:25:49 -0700, RoryC wrote:

Hi there,

I hope someone can help me with this. I'm having difficulty with my
heating system. Basically, I had the gas guy in recently to service the
bolier and he discovered that my pressure was down at zero bar so he
filled up the system to 1.5 bar from the mains as it is a closed
system. After about a day the gauge was down to zero again.

I filled it up again and the same thing. The gas bolier just cuts out
when I put it on, due to the fact that there's no water in the system I
suppose. There is no evidence of a leak anywhere in the house so I am
guessing that there is a leak under the living room floor (which is
concrete). Has anybody any suggestions. They would be much appreciated.

Everything you need to know and then some is in the Sealed CH FAQ.
You probably have a failed expansion vessel.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards