Saunier Duval isofast condens f35e - leak from boiler

[alwaysproblems]

HI, I'm wondering if any kind persons on this site will help me identify the part which I believe is causing the loss of pressure from the boiler. There is a threaded pipe under the boiler which leaks during operation. With it being a closed system I can only imagine this is causing the drop in pressure. I'm not sure if it should have a cap on it or if it is a valve which is faulty.
Pictures attached, from the bottom you can just see the open thread, top view is the part with my finger on.

Thanks for your help.

 

[Agile]

It is a valve which is kind of meant to leak while boiler is being filled.

Does yours leak all the time?

Tony

 

[holty]

Its a disconnector, a crude form of rpz valve. As used on some glowworm boilers. It does leak when topping up then stabalize. This is normal. But sometimes they just carry on and need replacing.

 

[holty]

Agile beat me to it

 

[alwaysproblems]

Thanks for the prompt replies. Yes it does leak while topping up, normally a dribble when I close the top up valve. It does leak during operation though as I have to keep a small cup underneath. Would this cause the pressure to drop?

Any estimates on cost to replace, thanks

 

[Agile]

They are about £40 but fairly easy to replace.

By chance, I have one to replace on a dreaded S-D boiler tomorrow!

Unless its a big problem I would suggest ignoring the drips.

Tony

 

[alwaysproblems]

It's a reasonable problem in that I have to top the boiler up pretty frequently. Although it can vary from every other day to once a month.

Thanks will get a plumber out.

 

[holty]

Great advice tony be it a glowworm or sd not a very tasking job. Both the same with the likes of the thema classic, isofast etc. cant believe your advising the OP to just put up with topping the boiler up.

 

[Agile]

Until now we had no idea how often he is topping it up.

BUT we don't know what other leakages there are in his system. He might spend to replace the valve and find other leaks are still requiring frequent topping up. Checking the vent on the pressure release valve would be a good idea.

For those who don't know, there are always small leaks in a system mostly from the shafts of rad valves. Ideally topping up from 1.0 to 1.5 bar is required from every 2 months to 6 months. But it depends on several factors including how effective the expansion vessel is.

If only there was an easy way to bung the vent then I might be suggesting that.

Very silly things! Even Worcester fit two valves!

Tony