Saunier Duval- dripping reduced pressure zone valve

[danb]

Hi all, first post on here, prob more to follow because of the brand of boiler I have as I know they are prone to leak.....if only they made showers!!!!!!

So, it sprung a leak yesterday and it turned out to be a crack in the flow sensor (on the box it says 'bulex'). I released some pressure from the system, once turning the water supply off, and set about replacing the part (for the first time I might add). Afterwards I turned the blue knob to re-pressurize the system up to .8, as it was before. It then began to drip from the reduced pressure zone valve, which it has done in the past when refilling the system but overnight it's continued. Its only a slight drip, but a drip all the same.

Don't know if it's related or not but, when the job was initially finished, it was leaking also from a valve near the part I replaced, another component with a hand screw on top. After I tightened it, it stopped. I thought that was ok until I read in the manual this morning where it states on commissioning the boiler the valve should be left open??? So I have just opened it again a little and it now seems fine......touch wood.

So why is the RPZV still dripping, any ideas???

Thanks in advance,
Danny

 

[petej]

Saunier Duval is not a boiler I have had any dealings with (luckily) but most combi's are very similar so here goes.

Is it the PRV (pressure release valve) that is dripping outside ? and did you use it to reduce the pressure ? . Most engineers do not disturb this valve as they often do not seal again after use.
if this is your problem you could try opening the valve a few times to see if you can get it to re-seal or just replace it. It is a common fault on most combi's once disturbed.
With your other leak it sounds like it may be an auto air vent with a small cap on top of it (again not an uncommon problem) you can replace it but most people would just use it as a manual air vent and close it after use.
Good luck
Pete

 

[danb]

Cheers for your response Pete. I can confirm its on the inside. I have had previous dealings with the pressure release valve and leaking on the outside. On the inside there is a gold coloured component, next to the pressure release valve, called a reduced pressure zone valve. A copper pipe coming from the filling tap goes into it at the front, then underneath is a threaded opening, as though something should screw onto it but it doesn't. This is where its leaking from. It may be a seal that's got dirty when I refilled the system with water, maybe?

 

[danb]

Bump............

 

[petej]

Hi danb
Looking at a diagram of a Saunier Duval boiler F24 and F28 boiler I see the valve you mean (why its called a zone valve I don't know). On the boilers I have had dealings with, some have had a similar arrangement and from what I can tell it is a device that prevent dirty water in the system passing back into the water mains.

An air break is required by the water authorities between the mains water and the heating water when the system is not being filled.

Different manufacturers have different ways to achieve this.

If it is only dirt on the valve seat you could try operating the valve a few times but most likely the valve will need changing.
Pete.