Potterton Performa 24 leak from bottom of DHW PDV

[otherparty]

Hi guys
The other day my boiler started leaking quite badly from the bottom of the DHW PDV. That is, water was almost pouring out for a short time. However water is now only dripping out occasionally. I thought it must be a seal of some sort, but, having opened it up, the only 'seal' i can see is the diaphragm itself. The diaphragm looks ok, but i haven't changed it for a few years so could it be the cause of the leak? FYI - hot water is fine (so diaphragm is doing its job) and there is no leak thru the (microswitch-activating) spindle hole.

 

[Gas2Air]

Do you mean the brass flow valve? Or the Hydraulic outlet with proving switch diaphragm?

 

[otherparty]

Do you mean the brass flow valve? Or the Hydraulic outlet with proving switch diaphragm?

Sorry, not sure what you mean. See fig. 83 (p. 44) here:
http://www.potterton.co.uk/docs/Pot..._HE_Installation_and_Service_Instructions.pdf

The water is leaking from the bottom of this unit. Does that make sense?

In the past i've had water leak out of the hole where the pushrod (spindle) exits - a fairly common problem i think - but that bit is fine now (after replacing the part).

 

[Gas2Air]

The brass valve that has 8 screws on it, with a micro switch. With 2 tubes connected to it? Or just behind there is a proving switch, brass and has 4 screws, both have diaphragms.

 

[otherparty]

The brass valve that has 8 screws on it, with a micro switch. With 2 tubes connected to it? Or just behind there is a proving switch, brass and has 4 screws, both have diaphragms.

Ah i see.
It's the front part (brass valve), with the microswitch.

 

[Gas2Air]

You certain it's leaking there? Thought you'd changed it? Change the flow valve complete, instead of diaphragm, pic would be helpful if you're still struggling.

 

[otherparty]

You certain it's leaking there? Thought you'd changed it? Change the flow valve complete, instead of diaphragm, pic would be helpful if you're still struggling.

Yep, deffo coming from there, and it's dripping a lot now again (even with HW off) - see pic. I last changed diaphragm about five years ago! Could it be caused by anything other than the diaphragm?

Untitled

• otherparty
• 4 Jan 2014
• 1

 

[Gas2Air]

Up to you, diapragm for cheap chips or flow valve for £70. You're right, the only seal in there is the diaphragm. I'd try diaphragm first clean all of it out and make sure screws are not threaded.

 

[otherparty]

Fingers crossed; looks like a new diaphragm has done the trick - thanks!