If you do put an ajax on the inlet to the low pressure tank, I'd fit TWO 6.7m relief valves. If the ajax fails and one single valve blocks then the resultant explosion will probably kill your entire family.
Personally, I'd stick to sorting the existing issue and KISS. I recently put a plastic one in place of the rusty galv one here and it folded OK. I think I got it from MasterTrade and the outlet pipe was tapered so easily hooked to the existing drain.
trade4us2,
Apr 21, 2:59pm
I had so many problems with the springs in relief valves going rusty that I took it off and put the original copper overflow pipe back up to the roof. That has solved all the problems (assuming people do what I have already mentioned).
tegretol,
Apr 21, 3:51pm
Yep I share that idea - there stuff all to fail. Have you ever seen a copper cylinder explode? I once hooked one up and put it 100m down the yard. Gradually crept the pressure up in 1psi increments. At 18psi, it turned into a very round ball shaped unit and at 40-ish psi it let go. I expected the folded end seams to fail but it split along the length of the side. Try the same with a 44g drum and the ends come out at about 8psi with an equally loud bang. But I certainly wouldn't want to be in a house with a cylinder that went bang. So open ppes suit me for sure. Again KISS.
trade4us2,
Apr 21, 4:14pm
As it happens, the roof of my house is about 7.6 metres above the bottom of the hot water cylinder, so the overflow pipe can be firmly attached to the house with copper saddles (which I made). If you don't have a tank on the top of the pipe, hot water usually overflows after you use a hot tap. It still does that with a pressure relief valve.
Since my house is very old and has finials, I made a 2 litre tank that looks like the other finials. I drilled 36 tiny vent holes around the top which have the same area as the pipe. Mosquitoes and seeds dropped by birds can't get in there. If the Ajax valve should fail, lots of water will fall down on my kitchen roof and attract my attention.
pauldw,
Apr 21, 4:47pm
What is the tank made of? The galv tray doesn't look too bad at the edges. Copper and galv must be kept apart or the galv will quickly corrode. We used to have a tank that sat on a layer of grease filled Denso tape.
doree36,
Apr 22, 9:44am
We live in a lovely 1958 brick and tile home. we had one of those things the ball cock used to stick and the water kept running all the time - we called a plumber who disconnected it and put in an ajax valve - no trouble since He is a friend of my son and he calls in every now and again to check its O.k
tegretol,
Apr 22, 12:10pm
I bet he does!
doree36,
Apr 23, 9:58am
What a sarcastic remark to make to make tegratol - he is a 68 year old man (one of the old school plumbers who is still working and doling a great job) my son is 52 and I am a 82 year old lady - so please dont judge others or compare him to these young blokes of to-day many of them who could not ,care less about the oldies! as long as they have been paid.
trade4us2,
Nov 21, 9:06pm
The rubber diaphragm in an Ajax valve perishes after 20 or 30 years. They cost only about $15. Mine has lasted 25 years so far with no problems. Maybe they have synthetic rubber diaphragms these days.
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