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chauncedog60 · Dec 16, 2007, 02:55 AM

Old house, bottom of a steep but beautiful canyon, that isolates it from the otherwise urban maze of Los Angeles, burst into a geyser through a remnant leg of the old galvanized water supply pipe, right after the first good rain of the season. Up the mountain, they had a burst water main, locally isolated mudslides, but several miles from us.
Most of the extensive network of plumbing at the place (3 units; 3 kitchens, 3 1/2 bathrooms, lots of landscape irrigation, and two gas water heaters), had been redone not to long ago, in copper, but the rusty old iron section was hidden underground until it erupted shortly before we arrived from a week of long distance moving. We quickly found a shutoff valve for that section, and considered ourselves lucky it was outside, only to open the door of the front unit, to see the pressure relief valve on the water heater gushing furiously. The water was hot, so this must've happened just before before we got there, so we shut of the gas and the supply gate for it thinking "what a coincidence"
The next morning after it was cool, we turned the water supply back on, and the pressure relief valve triggered instantly, though only cool. Thinking the relief valve defective, we replaced it, only to have the same thing happen. We went up to check the other hot water heater in the back unit, and it too, though stone cold, triggered instantly upon opening the supply gate for IT... My only conclusion is that something happened to increase the water pressure to the whole place beyond the limit of the relief valves, even though cold, which is quite a bit of pressure! I know anybody reading this who has weak water pressure is probably shaking their head, but this is a new one on me. What model of regulator do I need to install, and will it require a separate gauge to calibrate it, or is this the responsibility of the water company? Thanks for listening:confused: :confused: :confused: :confused: :confused: :confused: :confused:

iamgrowler · Dec 16, 2007, 10:34 AM

You need to install a pressure reducing valve, no doubt about it.

It is possible you already have a pressure reducing valve somewhere, but because of age or a build up of minerals, has decided to go points up.

Being gas fired, the H/W tanks should have expansion tanks as well.

As for the relief lines, do yourself a favor and run them outside.