My water heater will over-pressurize and open the blow-off valve and
begin spilling water to the drain in the utility closet. I've tried
stepping down the temp. incrementally to find a position that it
likes, but nothing acceptable for showers will be acceptable for the
heater. We've since been turning off the water supply valve to keep
it from overflowing when we're not in need of hot water.

I called a plumber and the guy mentioned that they keep cranking up
water pressure through our area to supply the folks farther out with
decent pressure. He was wondering if we had a pressure reducing valve
in the unit and I was going to check on that before I had a plumber
physically come out. I believe it is more a problem with excessive
water pressure coming to the tank because if we shut off the cold
water supply to the unit it will not spew water even with the
temperature elevated.

Duke of Hazard wrote:

My water heater will over-pressurize and open the blow-off valve and
begin spilling water to the drain in the utility closet. I've tried
stepping down the temp. incrementally to find a position that it
likes, but nothing acceptable for showers will be acceptable for the
heater. We've since been turning off the water supply valve to keep
it from overflowing when we're not in need of hot water.

I called a plumber and the guy mentioned that they keep cranking up
water pressure through our area to supply the folks farther out with
decent pressure. He was wondering if we had a pressure reducing valve
in the unit and I was going to check on that before I had a plumber
physically come out. I believe it is more a problem with excessive
water pressure coming to the tank because if we shut off the cold
water supply to the unit it will not spew water even with the
temperature elevated.


If city pressure *is* high (over 80 psi, for example), you will
likely need a pressure reducing valve AND a thermal expansion tank.
http://www.amtrol.com/thermxtrol.htm

Jim

On Tue, 27 May 2008 10:43:24 -0700 (PDT), Duke of Hazard
wrote:

My water heater will over-pressurize and open the blow-off valve and
begin spilling water to the drain in the utility closet. I've tried
stepping down the temp. incrementally to find a position that it
likes, but nothing acceptable for showers will be acceptable for the
heater. We've since been turning off the water supply valve to keep
it from overflowing when we're not in need of hot water.

I called a plumber and the guy mentioned that they keep cranking up
water pressure through our area to supply the folks farther out with
decent pressure. He was wondering if we had a pressure reducing valve
in the unit and I was going to check on that before I had a plumber
physically come out. I believe it is more a problem with excessive
water pressure coming to the tank because if we shut off the cold
water supply to the unit it will not spew water even with the
temperature elevated.

Per home improvement show, you most likely have a one way valve in
your supply line that is the culprit.

On Tue, 27 May 2008 14:01:29 -0500, Duff2 wrote:

On Tue, 27 May 2008 10:43:24 -0700 (PDT), Duke of Hazard
wrote:

My water heater will over-pressurize and open the blow-off valve and
begin spilling water to the drain in the utility closet. I've tried
stepping down the temp. incrementally to find a position that it
likes, but nothing acceptable for showers will be acceptable for the
heater. We've since been turning off the water supply valve to keep
it from overflowing when we're not in need of hot water.

I called a plumber and the guy mentioned that they keep cranking up
water pressure through our area to supply the folks farther out with
decent pressure. He was wondering if we had a pressure reducing valve
in the unit and I was going to check on that before I had a plumber
physically come out. I believe it is more a problem with excessive
water pressure coming to the tank because if we shut off the cold
water supply to the unit it will not spew water even with the
temperature elevated.

Per home improvement show, you most likely have a one way valve in
your supply line that is the culprit.


Yes, the fix is simply to install an expansion tank in the cold
water line, after the back flow valve.

On May 27, 1:43*pm, Duke of Hazard wrote:
My water heater will over-pressurize and open the blow-off valve and
begin spilling water to the drain in the utility closet. I've tried
stepping down the temp. incrementally to find a position that it
likes, but nothing acceptable for showers will be acceptable for the
heater. *We've since been turning off the water supply valve to keep
it from overflowing when we're not in need of hot water.

I called a plumber and the guy mentioned that they keep cranking up
water pressure through our area to supply the folks farther out with
decent pressure. *He was wondering if we had a pressure reducing valve
in the unit and I was going to check on that before I had a plumber
physically come out. *I believe it is more a problem with excessive
water pressure coming to the tank because if we shut off the cold
water supply to the unit it will not spew water even with the
temperature elevated.

First step is to get a cheap pressure gauge with a telltale and
install it somewhere convenient to you. You should be able to buy one
at your local Big Box home improvement store, near the water heater
parts. It'll have a NPT to garden hose female fitting adapter already
included with it, so you just screw it onto a handy spigot somewhere.
Obvious choice would be the drain valve of the water heater, but if
you're not 100% confident that said valve is in good condition, I'd
suggest something else- perhaps a laundry sink (if the faucet doesn't
leak) or external spigot.

If the gauge telltale is within an acceptable range - the instruction
card will likely say 60 PSI but I'm running about 70 PSI consistently
in my house without issues - your problem is simply a failing T/P
valve. Replace it. It's cheap and should fix you up for years to
come (I had this issue in my house, and in my case, a new T/P valve
has been installed and working fine since late last year.) At the
same time I would recommend replacing the cheap plastic spigot that is
the drain valve on your water heater with something like this:

http://waterheaterrescue.com/pages/W...sh-Kit-PP.html

the "ball valve drain assembly" is simply, from the water heater out,
a 3/4" dielectric nipple, a 3/4" NPT ball valve, a 3/4" NPT male to
garden hose male adapter fitting, and a brass garden hose cap (in case
you inadvertantly kick the lever on the ball valve.) You can buy all
those parts at your local hardware store; that and a small container
of pipe dope (which you'll need anyway to replace the T/P valve) will
fix you up. Reason I suggest this is if your heater has been
installed for any length of time, you will either a) not be able to
open the drain at all or b) you'll open it, a chink of sediment will
get caught in it, and you won't be able to close it again. This is
the voice of experience talking At a minimum I would recommend
picking up a couple of garden hose fitting caps even if you don't want
to replace the drain valve just in case it doesn't shut you can cap it
off so you can turn the water back on without flooding your basement.

If the pressure is generally within an acceptable range but you have
pressure spikes close to the max rating of the T/P valve - I think
something around 150 PSI - then you have more serious issues. I would
suspect that there is a backflow preventer (e.g. check valve)
installed on the water line going into your house but no expansion
tank.

If the pressure is simply high all the time, you'll probably want to
install both a pressure reducing valve and an expansion tank, as I
believe that a BFP is integral to most pressure reducing valves.

The reason for the expansion tank is that while water is
incompressible and relatively stable in volume WRT temperature, it
*does* expand somewhat - ever so slightly - when heated. So if you
have water incoming at 65F and you heat it to 130F and don't open a
tap during this process - like, say, if you take a hot shower and then
leave for work - the water will be trying to expand in your system and
if it can't expand back into the city water line because of a BFP it
will raise the pressure in your system until the T/P valve pops off
and lets a little water out to relieve the pressure.

I hope this is helpful...

nate

Duke of Hazard wrote:
My water heater will over-pressurize and open the blow-off valve and
begin spilling water to the drain in the utility closet. I've tried
stepping down the temp. incrementally to find a position that it
likes, but nothing acceptable for showers will be acceptable for the
heater. We've since been turning off the water supply valve to keep
it from overflowing when we're not in need of hot water.

I called a plumber and the guy mentioned that they keep cranking up
water pressure through our area to supply the folks farther out with
decent pressure. He was wondering if we had a pressure reducing valve
in the unit and I was going to check on that before I had a plumber
physically come out. I believe it is more a problem with excessive
water pressure coming to the tank because if we shut off the cold
water supply to the unit it will not spew water even with the
temperature elevated.

Replace the T/P valve under the theory that the most likely culprit is the
one that shows the symptom.

On May 27, 4:03*pm, "HeyBub" wrote:
Duke of Hazard wrote:
My water heater will over-pressurize and open the blow-off valve and
begin spilling water to the drain in the utility closet. I've tried
stepping down the temp. incrementally to find a position that it
likes, but nothing acceptable for showers will be acceptable for the
heater. *We've since been turning off the water supply valve to keep
it from overflowing when we're not in need of hot water.

I called a plumber and the guy mentioned that they keep cranking up
water pressure through our area to supply the folks farther out with
decent pressure. *He was wondering if we had a pressure reducing valve
in the unit and I was going to check on that before I had a plumber
physically come out. *I believe it is more a problem with excessive
water pressure coming to the tank because if we shut off the cold
water supply to the unit it will not spew water even with the
temperature elevated.

Replace the T/P valve under the theory that the most likely culprit is the
one that shows the symptom.

I agree but my post was intended to cover all possible bases

I forgot a reminder - exercise those T/P valves annually, at the same
time that you do a sediment flush and anode inspection (you do do all
that stuff, right? RIGHT?)

nate

I forgot a reminder - exercise those T/P valves annually, at the same
time that you do a sediment flush and anode inspection (you do do all
that stuff, right? �RIGHT?)

around here exercising the valve means replace it

sediment flush gains nothing

anode inspection a great way to generate a leak.

water very hard, causes corrosion.. draing tank waste of time,.

how old is the OPs tank? if its gas and near end of life, say 10 years
just replace it. new tank will be more efficent, and messing with old
ones will likely cause leaks..........