On the pstat assembly, does anyone happen to know whether the little outlet that has the plastic tube on it (pointing down) is the safety valve or the vacuum breaker?

Here's a picture of the entire unit



and the piece that is leaking:

That is the safety valve

The vacuum breaker is something on the boiler to release air when the water begins to boil

One side is the safety valve and one is the vacuum breaker. The question is which is which.

I'm guessing from your answer that the view of the piece removed from the unit suggests to you that it's the safety valve.

Kjetil wrote:That is the safety valve

Kjetil: Are you sure of that? Looks like an anti-vac valve, and I think the safety valve is in the other fitting (the one at the top in the photo.) The safety valve would have a good spring inside, pushing the valve closed until the 1.8 bar of boiler pressure forces it open.

leeherman99: When in the machine, was that leaking valve oriented so that the tube outlet faced up?

It was horizontal. Condensate could have flowed down into the drip tray.

Homeburrero: Does the exposed view of the part look like A/V valves that you have seen?

leeherman99 wrote: Homeburrero: Does the exposed view of the part look like A/V valves that you have seen?

Yes it does. When under just a little pressure from the boiler side that red oring is supposed to seal tight. Is that part with the oring a little loose so that If you blow on the hose, air goes thru, but when you press it closed and suck on the hose it seals tight? That's the way an anti-vac works.

Sometimes you can replace the oring if you can find the right size. Worst case is you'd need to spring about a hundred bucks for a whole new unit, which may not be a bad idea - that way you'd have a new pStat, relay, safety valve, and A-V valve (and keep the old one around for spare parts.)

I'm hoping that I can just replace the AV valve, or worst case replumb so that each piece can be replaced separately. I hate all-in-one units.