Thread: Hot Water Cylinder Pressure Relief Piping

Should be all downward, but I have seen them with a slight rise then dropping. The problem is that although there is pressure on the tank side as soon as the water is past the valve it relies on gravity to drain. If you go up then the water will build up in the lowest part until it gets to the down bend.

But you should check out whether the valve and tank is working as intended. In normal use you should see very little coming out of that valve and sometimes none at all. Mostly water will come out while the element is on then stop while the water is simply being stored ie: cycling with the heater element.

Three things to check:

1. The valves can corrode and start leaking with age - especially because most owners do not regularly check them and do a regular manual release - so the seats get damaged. If the valve is leaking a little all the time then it probably needs replacing.
2. The rating of the valve might be too low for the water pressure in your house supply. Often your water supply utility can tell you what the likely pressure is at your residence - check that it is well below the rated pressure of the relief valve. I once had to replace a 650Kpascal valve with one rated 1150Kp because my supply was regularly at 900Kp. Alternatively you can get a pressure reduction valve installed on the inlet to the heater.
3. Check that the temperature stetting is not too high. For storage tanks the recommended is 60-65 degrees to prevent bacterial growth, but older ones might be set as high as 75 degrees or the thermostat might be faulty.

Fixing it is a job for a plumber friend, but the above checking can be done by you (although to check the the thermostat requires the removal of the cover and that exposes 240v wiring not all that well protected - so turn the heater off and remove the fuse before checking or get a sparky to do it for you if you have never done it before).

They must be run with fall and terminate 1m away from the heater.

Make sure it has the pressure reduction valve in water inlet line. Home handymen/women sometimes neglect to put them in.

Originally Posted by Claw Hama

Make sure it has the pressure reduction valve in water inlet line. Home handymen/women sometimes neglect to put them in.

This will depend on your incoming water pressure off the main.

in response to the suggestions so far....

1 - the heater and plumbing was done by a plumber, however, a lot of the other work he did, i have had to have repaired as it was not done to a decent standard, so i have no reason to beleive that this has been done properly either!!! (he didnt use an offest pan collar on the toilet, and simply stretched a rubber boot over it, hence it split after a few weeks, and the toilet started pouring water all over the floor and through the wall behind for example!!!)

it DOES have a pressure reducing valve on the inlet. i had to have it replaced recently, as the old one was faulty, and restricting water flow a lot.

the drain pipe runs almost directly down the side of the cylinder, and then runs about 30-40cm through a brick wall from under the house to outside, and then drips directly onto the ground almost against the bricks.

the whole setup is less than 6 months old, as i had a renovation done last year. there have been numerous issues with the whole job, and the plumbing was just one of them.
because the plumber didnt change the old pipes into the cylinder, all the filters got a LOT or crap in them, and i am wondering if this could possibly be a part of the problem with the relief valve draining...

even if we do not use much hot water throughout the day, we seem to get a fair bit if water on the ground from the overflow. it is getting the ground REALLY wet, and starting to get the brick foundations damp as well.

is there anyway i can check this valve, to make sure it is closing properly. i was thinking i might put a small container under the drain over the weekend, and measure exactly how much water comes through in the two days.