leaking boiler

[sunama]

Hi,

Last night, I discovered a small puddle of water around my gas boiler. I traced the leak to what I believe is a pressure relief valve.

I took the following pictures and am hoping you can help me to identify the part that might be at fault and also possible cures. I have also shown the exact point where the leak is eminating from.

Would I be right in thinking that the leaking part is called the "Pressure Relief Valve"? Also would the job be as simple as replacing it?

My heating system is open vented.
There is no expansion vessel.
There is 1 cold water/storage tank,
a header tank for the open vented central heating system and
a big hot water storage cylinder.

The continuous leak happens regardless of whether the boiler is cool or is hot. It just keeps dripping.

Right now, I'm thinking of simply replacing the part that is leaking.

 

[ChrisR]

It's an Automatic Leak Valve not a prv.
Sorry I meant Automatic Air Vent!
They cost about £2.50 and are not very good.
I'd replace it with a manual one, like a radiator bleed valve. You can buy 1/2" male chrome ones in the likes of WIckes.
If this is a high point in the system, you may have to bleed it 2 or 3 times when you refill the system, but if you use another AAV it'll probably leak again sooner or later.

I presume you've tried screwing in the little black plastic finger-plug part where the water's coming from? If you find an identical AAV you could try just swapping that.

Or.....
If it separates at the red arrow you should in theory be able to remove the old valve and screw in a new one without losing more than a spoonful of water without draining down.

 

[Agile]

Clearly a DIY boiler installation!

Merely closing the black screw should stop the leak and will have converter it to a manual vent. Thats all you need to do it it stops leaking like that.

Tony

 

[sunama]

Hi gents.

The boiler was installed at around 2002, before I bought the property (in 2006).

I have tried the obvious - tighten the black plastic screw - but water continues to spew out of it.

I like the idea of replacing it with a radiator bleed valve, but would probably look into replacing it with an identical part, first.

Thanks for your help chaps.

 

[Agile]

They often leak hence the recommendation to replace it with a rad bleed valve.

I use gently force but that can snap them off.

If you can reduce the pressure or just get a little wet you could remove the screw completely and put a little silicone sealer in the hole before replacing the screw or put a little PTFE taps on the thread.

Tony

 

[sunama]

I actually did remove the screw yesterday, before wrapping with PTFE tape, but this didnt stop the leak competely. It did reduce it though. My gut feeling is that the plastic screw itself has worn out.

 

[Agile]

If the screw gets tight then its not worn out!

The actual sealing is done by the tapered tip. This has probably got a little distorted or the brass socket is corroded or worn.

The PTFE tape needs to be on the taper part rather than the screw thread!

Tony

 

[sunama]

Ive replaced the Automatic Air Valve. I didnt need to drain the system, but simply removed the old AAV and quickly replaced it with the new one. I used lots of old towels to prevent spillage.

Thanks for your help chaps.