Possible fault APEX pressure relief valve? Is DIY replacement possible?

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PPAP

41 posts

Geek

#185528 26-Nov-2015 14:05

It still reliefs pressure as I can see water drains out when heating, about 500ml for 20 degrees rise.
But at the same time the black plastic hole (air return?) is leaking when heating too, it stops when the heating stops.

How much the repair job would be? It looks like a easy swap job, diy possible?

Fred99

13684 posts

Uber Geek

#1435414 26-Nov-2015 18:10

Can't really see what's going on there, but my guess if there's water coming out there, then there's a blockage in the outlet, not enough run-off, or the outlet drain is too long.
Or, is the air return vent just a hole - or is there a check-valve in it? If there's a check valve, perhaps it just needs a clean.
If in doubt though, call a plumber. If something actually is wrong with the valve, it might cause an expensive problem.

Aredwood

3885 posts

Uber Geek

#1435457 26-Nov-2015 19:26

Since you say that the water stops dripping when the heating stops. This means that the valve itself is fine. When everything is working normally they will drip approx 1% of the hot water you use. (As the amount that drips depend on the amount of water that needs to be heated, which in turn depends on the amount of hot water you use.

But the drain pipe on the valve is blocked or not installed properly. That plastic fitting is just an air vent, which is doing it's job - allowing the valve to still do it's safety critical functions even though the drain pipe is blocked.

The drain pipe must be made of copper, Must only run downhill, Must not have any kind of valve or other restriction in it. And must discharge somewhere noticeable. (Yes there are other rules but those are the main ones)

Find the other end of the drain pipe and have a look there. Have seen them going into gardens and getting blocked due to the garden getting raised and the end now being underground. If you cant unblock the pipe yourself or otherwise can't figure out why the pipe is not draining - call a plumber.

PPAP

41 posts

Geek

#1435562 26-Nov-2015 21:54

Aredwood: Since you say that the water stops dripping when the heating stops. This means that the valve itself is fine. When everything is working normally they will drip approx 1% of the hot water you use. (As the amount that drips depend on the amount of water that needs to be heated, which in turn depends on the amount of hot water you use.

But the drain pipe on the valve is blocked or not installed properly. That plastic fitting is just an air vent, which is doing it's job - allowing the valve to still do it's safety critical functions even though the drain pipe is blocked.

The drain pipe must be made of copper, Must only run downhill, Must not have any kind of valve or other restriction in it. And must discharge somewhere noticeable. (Yes there are other rules but those are the main ones)

Find the other end of the drain pipe and have a look there. Have seen them going into gardens and getting blocked due to the garden getting raised and the end now being underground. If you cant unblock the pipe yourself or otherwise can't figure out why the pipe is not draining - call a plumber.

Thanks very much indeed, Aredwood.

Yes I can access where the drain pipe ends. This was the amount of water for about a day. Yes the drain pipe is pretty much as your description except it is plastic outside the house. So I guess it is maybe a partial blockage?

If you don't mind me asking some more silly questions. Since the black plastic fitting is just a open vent, it doesn't have any complex mechanism inside. (not the copper side of the valve) That's why APEX website says it can be installed either vertically or horizontally. I guess when it is horizontally the opening have to be facing up. Do I understand these right?

I'll try to do it safely with some common sense otherwise I will make a call. :D

Aredwood

3885 posts

Uber Geek

#1435678 26-Nov-2015 23:37

Yes the vent needs to be facing up when the valve is horizontal. And since you have plastic pipe outside. It may or may not be allowed. (It depends on when it was installed) But when I started doing plumbing back in 2004 the rules at the time definitely required copper then. (Don't know exactly when the "must be copper" rule was introduced) If Im doing a cylinder replacement I always upgrade any plastic relief valve pipework to copper. (Unless practically impossible to do so)

A common problem with using plastic pipes for valve vent / drain lines. Was the pipes sagging or kinking, which causes exactly the problem you are having. Due to lots of uphill and downhill sections in the pipe.

And if a thermostat failure occurred, (fail permanently on) The plastic pipes can't handle the boiling water / steam. And would very easily kink from going very soft due to the heat. There have been cylinder explosions caused by plastic pipes on relief valves.

If you do get a plumber in, Ask them if they can replace all the plastic relief valve pipework with copper.

PPAP

41 posts

Geek

#1436842 28-Nov-2015 13:23

Got up early this morning to do the fix so if anything goes beyond control I can call a pro. :D

So I connected a garden hose to the drain pipe by a 1/2-3/4 adapter and gave the pipe a good flush. Before install back I did a visual check of the relief valve when heating to make sure it is working fine (and not damaged by novice me). It dripped about 800ml in an hour's heating.

Now its all connected back. Hope the flush was helping. I guess I should keep a close eye on everything these days just in case. :D

PPAP

41 posts

Geek

#1452716 17-Dec-2015 22:20

So far so good. Thank you Aredwood. :D