Any help is appreciated.

I came home from work last night and the CH was not working. The water
pressure was at 0.5 bar and there was water on the floor below the boiler.

I refilled the system to 1.0 bar and the boiler fired up. I then had a
constant drip of boiling hot water coming out of the reduced pressure zone
valve as the heating was running. When the heating went off it turned into
more of a trickle and the pressure went down to zero. I had to look in the
manual to find out what the leaking part was. It is definitely not the
pressure release valve as this discharges outside.

For my second repair of the night I got the foot pump out the van and tried
the expansion vessel. The air pressure was at zero and I inflated it to 0.5
bar as per specs in the manual. Water ****ed out of the RPZV as I added the
air and then ****ed out water again when I repressurised the water side. All
seemed well and the boiler worked fine until I went to bed. This morning the
pressure was at zero again and the floor was wet through.

The only two things that are different with my combi to normal installations
are
1) it is not used for HW (it will be next year)
2) it has not been connected to the main cold water supply for the 2 years
it has been installed. It was filled up 2 years ago when installed and has
never lost any pressure.

So what is the faulty part, the expansion vessel or the RPZV?

Cheers

Adam

On Thu, 13 Dec 2007 21:41:58 +0000, ARWadsworth wrote:

Any help is appreciated.

I came home from work last night and the CH was not working. The water
pressure was at 0.5 bar and there was water on the floor below the
boiler.

I refilled the system to 1.0 bar and the boiler fired up. I then had a
constant drip of boiling hot water coming out of the reduced pressure
zone valve as the heating was running. When the heating went off it
turned into more of a trickle and the pressure went down to zero. I had
to look in the manual to find out what the leaking part was. It is
definitely not the pressure release valve as this discharges outside.

For my second repair of the night I got the foot pump out the van and
tried the expansion vessel. The air pressure was at zero and I inflated
it to 0.5 bar as per specs in the manual. Water ****ed out of the RPZV
as I added the air and then ****ed out water again when I repressurised
the water side. All seemed well and the boiler worked fine until I went
to bed. This morning the pressure was at zero again and the floor was
wet through.

The only two things that are different with my combi to normal
installations are
1) it is not used for HW (it will be next year) 2) it has not been
connected to the main cold water supply for the 2 years it has been
installed. It was filled up 2 years ago when installed and has never
lost any pressure.

So what is the faulty part, the expansion vessel or the RPZV?

Cheers

Adam

I open the manual and searched for the RPZV (thinking it must be the name
for some common component but SD have given it a fancy one).

There is little info on it. Guessing, and looking at the photos and the
description for its replacement it might be some sort of valve that
prevents too much pressure being put into the primary circuit?

Anyway if it's leaking then a repair or replacement is called for.
You might find that it's leaking due to a bad O-ring.

If the expansion vessel is at fault then pressure will rise on heating
and the discharge pipe open up, which it isn't. The RPZV is not a synonym
for the Pressure Releif Discharge Valve,


--
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

"Ed Sirett" wrote in message
...
On Thu, 13 Dec 2007 21:41:58 +0000, ARWadsworth wrote:

Any help is appreciated.
Adam

I open the manual and searched for the RPZV (thinking it must be the name
for some common component but SD have given it a fancy one).

There is little info on it. Guessing, and looking at the photos and the
description for its replacement it might be some sort of valve that
prevents too much pressure being put into the primary circuit?

I wondered (had suggested to me) if it was some sort of back flow device as
there is no filling loop on the SD. The F30E has a "filling tap" built in to
the boiler.

Anyway if it's leaking then a repair or replacement is called for.
You might find that it's leaking due to a bad O-ring.

The water comes out of a hole in the bottom of the valve not at a joint (if
that makes any difference?)

If the expansion vessel is at fault then pressure will rise on heating
and the discharge pipe open up, which it isn't. The RPZV is not a synonym
for the Pressure Releif Discharge Valve,

Pressure is definately not rising. I have put a plastic bag on the discharge
pipe and this has no water in it. I have no idea if it did do before the
first failure of the boiler and before I repressurised the air in the
expansion vessel.

The good news is I have refilled the boiler with water and it has worked for
over 48 hours this time. The pressure has dropped from 1.0 bar to 0.8 bar
during the 48 hours but at least I am warm.

I might phone SD to see what the RPZV actually does. All the plumers I have
asked said they have no idea why a combi would have one (apart from the
check valve idea from one of them).

The only other info on the RPZV in the manual is "on install there may be a
small discharge from the RPZV"

Thanks for your time Ed.

Adam