The plumber said he would install a new pressure relief valve and I just want to check that he has done it as I don't know what to look for.
snoopy221,
Jun 15, 12:14pm
Nope ajax is adjustable pressure used on input pressure relief is used on out put -as against a vertical open ended pipe that relieves at a set pressure by height (water being 1/2 a pound pressure by foot of standing head height)
lythande1,
Jun 15, 2:08pm
Ajax is an old term for an old valve. They are either Nefa or Apex these days.
nzmax,
Jun 15, 5:07pm
Did plumber say pressure relief valve, or pressure reducing valve?
headcat,
Jun 15, 5:33pm
If fitted to a hot water system they are the thingy that stops your cylinder exploding if your water boils.
trade4us2,
Jun 15, 6:16pm
Why is he replacing the pressure relief valve? Did the old one have a problem?
I don't actually know if it was replace or fit. But I'm guessing from the replies in this thread above the cylinder is where I need to look.
bit,
Jun 15, 8:40pm
That's helpful thanks. Now I have an idea what I'm looking for. Does it allow you to increase the pressure of water going into the cylinder, effectively increasing the pressure at the hot water taps?
bit,
Jun 15, 8:43pm
I'm not actually sure to be honest. But I'm pretty sure it would be relief. It's not a mains pressure system anyway.
gamefisher,
Jun 15, 9:32pm
Should have both if it's not mains pressure as one is a pressure reducing valve an the other is pressure relief valve for safety if something goes wrong eg to much inlet pressure or if the thermostat fail and the water starts boiling.Can post a photo of our if need be.
trade4us2,
Jun 15, 9:48pm
Plumbers are delighted to have a regular source of income every few years by replacing badly designed pressure relief valves that have failed. An ordinary overflow pipe up to the roof is more reliable.
pauldw,
Jun 16, 4:23am
Is that what you asked the plumber to do? He may have added a relief valve to your existing vent pipe to increase the cylinder pressure. Look for a fitting on the end of the pipe on the roof.
pauldw,
Jun 16, 4:30am
In 32 years I've had to replace the valve once. Why do you have so many failures?
trade4us2,
Jun 20, 4:37pm
Maybe Nefa valves are unsuitable for Auckland water. I won't be buying any of their products again.
tegretol,
Jun 20, 5:41pm
Eh?
Surely a low pressure (ie non-mains) system is vented to the sky with a pipe of the required length sticking out of the roof? Why would that system require a relief valve?
The OP must be referring to a reducer - how would anyone know that a relief valve had failed unless there was an explosion to prove it?
gabbysnana,
Jun 20, 7:26pm
wondered this as well, have nada on my low pressure system but I have one of those relief value pressure things on top the short pipe out the roof (did have a very tall one, but high winds took it out).
Why does a low pressure system that's vented to the sky need a relief valve?
pauldw,
Jun 21, 12:59am
As gabysnana says to increase the effective pressure without having a pipe sticking up as high as it would have to be if left open.
gamefisher,
Jun 22, 4:10pm
It doesn't if it is open vented like in time past there use to be a pipe above the roof and the height was related to the pressure of the system and acted as a safety vent but these day it is mostly done by mechanical ways with a pressure relief valve e.g. water pressure increases 0.1bar (1.4psi) per meter head.
gamefisher,
Oct 28, 2:14am
Your set up sound like the top diagram in the link I posted.
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