Home>Discussions>PLUMBING>New Expansion Tank/T&P Valve Still Leaking
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goldhiller
Re: New Expansion Tank/T&P Valve Still Leaking

Yeah, ........but.....(there's always a "yeah,but"...right?)

In theory, an out-of-control heating element could definitely be the cause, but....is everyone in the household asleep at the wheel as regards that temp thingie?

I would like to think that if that was happening (the cause)...that someone would have noticed the scalding hot water comin' outta the faucets by now.

And so....I'm gonna ask what the unregulated pressure is on the city supply line. 140 psi, maybe? This *could* be a PRV problem yet.

Edit: One way I can see the out-of-contol thermo/element being the problem and not being noticed is *if* the WH is also plumbed in backwards. This would mix the incoming cold with the outgoing hot. My neighbor did that and LEFT IT that way for 25 freakin' years ...even after I pointed it out to him! Said it was "too much trouble to mess with". Aye, carumba. Instead, they turned the thermo up as high as possible and went to watch TV. LOL Put a new WH in there for them this last winter while they were gone to AZ. Ain't hooked up backwards no more. LP consumption has gone way down. Imagine that.

(Or *maybe* (big maybe) an out-of-control thermo would go unnoticed *if* there is a major cross connection somewhere in house plumbing. Like maybe... one of them thar Y-thingie mixers on a faucet set with both lines open to it. But this would make for some very warm "cold" water and someone shoulda/woulda noticed that by now, too.)

(Or maybe one of those Moen single-handle bath/shower cartridges that are reknown for cross-connecting when parts wear out inside.)

mpriley05
Re: New Expansion Tank/T&P Valve Still Leaking

We haven't noticed any scalding hot water. I'll check the temp with a thermometer tomorrow. Is there a way the heater is staying on and increasing the pressure, but not the water temperature?

I don't think there are any crossed lines. Hot is hot and cold is cold in every faucet.

I know the WH isn't plumbed backwards.

I'll have to check and see what the incoming city pressure is. I assume the water dept. will have to check for me. I'm a firefighter by trade, so I could borrow a hydrant pressure gauge from work and check the pressure in the hydrant line, although this won't necessarily tell me the incoming pressure into the house (or will it?). There could be a PRV between the primary distribution line and my house supply, right?

goldhiller
Re: New Expansion Tank/T&P Valve Still Leaking

Heck...the city water department should know what the pressure is. *Should*, anyway. A simple phone call should answer the question.

You might also check to see if your PRV has a backflow device. If it does and it's not functioning properly, this could be the cause...or a contributing cause. Yeah, the expansion tank *should* negate the need for that backflow relief, but.... something or *things" is causing this problem and nothing should be taken for granted or overlooked now.

BTW, I'm curious as to how you're determining that the ET is taking on water and then leaving it out. How is it connected to the plumbing line and where does it reside? (Physically speaking. Already know it's hooked up to the cold side of things) Couple pics maybe?

mpriley05
Re: New Expansion Tank/T&P Valve Still Leaking

I'll give them a call.

The tank is connected via a braided hose to a tee fitting on the colds side. The tank sits atop the cabinet in the bathroom. I can pick it up to see whether it is full or not.

I'll take a peek at the PRV tomorrow and see if I can determine anything.

Blake
Re: New Expansion Tank/T&P Valve Still Leaking

Do you have any other appliances or connections to your water lines that may be causing the excess pressure? Maybe the water heater isn't the problem, it is just the point where the pressure is relieved.

goldhiller
Re: New Expansion Tank/T&P Valve Still Leaking
mpriley05 wrote:

I'll give them a call.

The tank is connected via a braided hose to a tee fitting on the colds side. The tank sits atop the cabinet in the bathroom. I can pick it up to see whether it is full or not.

I'll take a peek at the PRV tomorrow and see if I can determine anything.

That is kinda what I suspected. Haven't seen one yet with a clear housing. ;)

goldhiller
Re: New Expansion Tank/T&P Valve Still Leaking
Blake wrote:

Do you have any other appliances or connections to your water lines that may be causing the excess pressure? Maybe the water heater isn't the problem, it is just the point where the pressure is relieved.

Interesting notion. :)

mpriley05
Re: New Expansion Tank/T&P Valve Still Leaking
Quote:

Do you have any other appliances or connections to your water lines that may be causing the excess pressure? Maybe the water heater isn't the problem, it is just the point where the pressure is relieved.

Nope. There are no other heat or pressure producing appliances hooked up to the water line.

It sounds like the options here are to either:

1. Get a new water heater to eliminate the possibility of a broken thermostat or heating coil that won't shut off (and make sure there are no heat traps or check valves in the new heater)

or

2. Get a new PVR that permits backflow into the city system (assuming the city system is less than 140 PSI)

Blake
Re: New Expansion Tank/T&P Valve Still Leaking

The city may have a backflow preventer at the meter setter, if this is the case a new PRV will not change any thing.

canuk
Re: New Expansion Tank/T&P Valve Still Leaking
goldhiller wrote:

Yeah, ........but.....(there's always a "yeah,but"...right?)

In theory, an out-of-control heating element could definitely be the cause, but....is everyone in the household asleep at the wheel as regards that temp thingie?

Dang ... it was early in the morning when I came up with that .... hadn't had my coffee yet .... does that count?:D

I'm wondering ... if you put a pressure gauge on the cold water supply to the tank to check the water supply pressure to see if the water pressue is spiking .... in other words maybe the PRV is starting off at 40 psi and spiking at a higher pressure which might cause an imbalance to the air charge pressure to the expansion tank. So by shutting off the power and water to the tank ..... running water from a tap somewhere and see if the water pressure rises.

This would fill the expansion tank with cold water and not allowing any room for the hot water to expand to .... increasing the pressure and not necessarily the temperature is tripping the T&P valve.

Just a guess.

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