Oil Boiler PRV / Check Valve leak

monseiur · 29-05-2025 12:04AM #1

I have an indoor Firebird Super Q 50/90 boiler which is over 20 years old. The flow & return pipes are on the right hand side. On the left there's a drain valve fitted on the bottom port and on the top there's a PRV (or Check Valve ?) which is leaking for some time based on damage but just noticed Monday as it's in a corner near wall - it's a slow a constant drip, drip.

I searched on line for a replacement and came across something similar in brass - it what was described as a Check Valve, part no. ACC034FMC Which valve should be fitted here a PRV or Check Valve ? I guess there's a difference but not a plumber obviously !

Plumber unable to come for a least 2 weeks, hoping if I had the right part got some local handy lad may fit it. My local plumbers suppliers only stock the PRV with the red plastic knob which looks totally different to what's there at the moment.

Wearb · 29-05-2025 10:19AM

Can you post a picture. It's most likely a prv (pressure release valve). (BTW pressure reducing valve are sometimes referred to as prv also 🙄)

Is yours a sealed system?

monseiur · 30-05-2025 09:21PM

Thanks for reply, apologies for delay in replying.

Unfortunately I'm unable to post a picture. The system is an open one, there's a small tank in the attic supplying it.

The boiler is a corner and there's just an 7'' gap between the wall & boiler so it's not possible to see the 'face of the fitting' At first glance it looks like a blank cap but I can feel a hole in the front of this cap and the water is dripping from this. I came across a similar looking valve/fitting on line - in Heating Parts Warehouse, it's described as a 3/4'' Firebird Check Valve part no. ACCO34FMC It says that the check valve will help water system maintain pressure when the pump shuts off, also prevents backspin, upthrust & water hammer.

I tried to contact Firebird in Cork numerous times but only managed to get an automatic answering machine.

Would it be OK to replace it with a standard PRV - the ones with the red plastic knob ? They are the only ones my local plumbing supplier stocks for oil boilers.

Wearb · 30-05-2025 11:41PM

How can you replace it if you can't even photograph it?

It's most likely one of those red knob type prv's, but you have seemingly identified it as possibly something different.

declan b · 31-05-2025 03:30PM

its a standard 3 bar 1/2 inch pressure relief valve

monseiur · 31-05-2025 08:34PM

https://www.boards.ie/discussion/comment/123501513#Comment_123501513

It's possible to photograph it but I'm unable to upload a photo.

It's most definitely not one of those red knob prv's. There's roughly a 7'' gap between boiler & wall so I guess the plumber will be able to reach it as it's near the top. The valve describe on the Heating Parts Warehouse web site as a ''check valve'' I mentioned earlier is almost identical to what's there. If you Google Check Valve ACCO34FMC a photo is in the Heating Parts Warehouse.

It is possible that the plumber fitted one of these instead of the standard red knob prv's at the time. I guess the best thing to do is get one of each and let the plumber decide.

Wearb · 31-05-2025 09:32PM

While it's most likely a 3 bar prv (some of them have a visible spring beneath a brass nut), I've seen enough unusual stuff over the years to prevent me from confirming what you have without more info, ie photo.

Strange that you can't upload a photo 🤔

declan b · 01-06-2025 12:17AM

https://www.boards.ie/discussion/comment/123503553#Comment_123503553

that valve in heating parts warehouse is not for an oil boiler.

Oil Boiler PRV / Check Valve leak

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