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Power bill sky high, hot water leaking. Is my overflow valve wrecked?

I went to look at a friends house to see what was causing the electricity bill to be double the cost compared to last years.  What I found was that the hot water cylinder was (1) turned up too hot, and, (2)is constantly trickling out of the overflow pipe.

This cylinder isn't vented through the roof, it has a pressure doohickey on the top that vents water direct to the drain outside.  Is there a way to check that the pressure valve is working ok, or just get a plumber to replace it?


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kelseymh7 years ago
The "overflow" (pressure relief) valve sounds like it's working correctly.  If the water heater is turned up too high, then the pressure will push water out through the relief valve exactly the way it's supposed to.

Turn the temperature back down to where it should be (usually marked "A" on the thermostat).  Give it a while (at least an hour or two) for the temperature to come down, and the relief valve should no longer be "leaking." 

To speed up the process you can do something like turn the bathtub on full hot for about five minutes.  That should flush all the existing hot water out, and the heater will refill from the input with "cold" water.

If there is still water coming through the overflow pipe when the temperature is set correctly, then you should call a plumber to have it diagnosed.  For some of the consequences of messing around with safety systems on a water heater, check out the Mythbusters :-)
onrust kelseymh7 years ago
If it has been flowing a long time, the T&P valve may  never seal good again.
Gaark (author) 7 years ago
Thanks for all the feedback.  Im an electrician so I was making sure that the temperature wasn't too high (which it was) and making sure the element was ok. 

Turned the temp back to 60 degrees C, down from 70 (owch!) just have to have a look at that pipe again and replace the relief valve if like Onrust says, it could be toasted.
NachoMahma7 years ago
.  Your best bet would be to just go ahead and replace it.
.  If you have lowered the tank temp as per kelseymh and it is still leaking then try caarntedd's jiggle-the-handle trick. Probably won't work, but worth a  try.
.  If you've never worked on a water heater, it would be best to get someone with experience to do the job.
caarntedd7 years ago
Does the valve also have a manual operation lever? If so, operating this a couple of times may help it to seal again. (it also could make it leak forever)