pressure problem?

Dan_29

I recently had to replace my two year old GE Smartwater (Rheem) 50 gallon hot water heater (12 year warranty) after only two years due to a leaking tank.

When I called Rheem to order a replacement, they indicated that the failure might be due to high water pressure. They suggested installing an expansion tank to reduce possible excessive pressure.

I asked my plumber about this and he said he has only installed an expansion tank in 1% of his hot water heater installs. It was most likely a defective hot water tank.

The previous hot water heater was an AO Smith Conservationist and lasted 12 years on a 10 year warranty.

I attached a water pressure test gauge to the drain valve on the hot water heater the average pressure over a 48 hour period is 63 psi although it spikes as high as 80 psi when a washer or dishwasher valve closes.

Rheem suggests an expansion tank. My plumber is skeptical. The water pressure test gauge company (Watts) suggests something called a "Watts Governor 80",which apprears to be an expensive toilet tank flush valve which reacts to high pressure by releasing water into the toilet tank as necessary.

I am confused. Is my pressure to high? Would you install an expansion tank, toilet valve governor or do nothing? What should a vigilant homeowner do?

Dan

Brad White

Bull-Dung Problem

Water heaters are rated for 150 PSIG. Plumbing codes in most jurisdictions stipulate 80 PSIG maximum in a residence. You have somewhat less than that most times.

An expansion tank will only help or be of benefit if there is a check valve in the CW line for example, or some means of fixing the volume in the system without room for thermal expansion. If you have HW recirculation, you may well have this situation.

If, like most systems yours is open to the street source, the expansion tank is the great outdoors ultimately. Your pressure cannot exceed that outside your home. If your volume is captive on the hot water side, expansion is exponential, relieved only by opening the tap.

Absent better information, I think the manufacturer is playing "Human Weathervane" myself.

Tony_30

Check in water heater

Some new water heaters are being shipped with a check in the cold supply tap. I know A.O. Smith is starting to come this way. A thermal expansion tank on the oulet side of the heater is the best way to protect the system. It may also help with the surge from the washing machine.

Tony

Brad White

Always something new, Tony

Thanks for that; I did not know that. I agree that a TX tank makes a good hammer arrestor too. Still, the situation seems a little squirrely to me. :P

lee_7

Around here, water companies are putting in back flow preventers as part of new digital water meters. They tell you after it is installed to have an expansion tank installed. All of my water heaters come with an expansion tank. Helps with any pressure issues and helps keep faucets from dripping.

Big Ed_3

Odd

The thermal expansion company wants their tank between the water meter and the hot water heater . Now the hot water heater company is installing checks valves at the tanks inlet , Seems like they want to protect the tank in a drop of pressure....If thats the case...... The hot water heater company should be installing built in vacuum breakers instead of check valves in my view.

Al_19

I believe that the check valve that Tony is referring to is to prevent hot water from gravitating out of the tank. It takes the place of a thermal trap in the piping. It's not meant to protect the tank from any specific pressure conditions.

The expansion tank that is being recommended is to protect the tank from the expansion that takes place when the water is heating up. So even if you are within acceptable pressures(the tested 60-80 psi range), the literature that I've read says that the constant decrease/increase in temperature, and corresponding changes in pressure, will cause the tank to flex and leak. This pressure change happens now because of the meters and backflow preventers with check valves that weren't commom years ago.

Again, this happens even though 80 psi is acceptable. I think you can't go wrong investing in the expansion tank.

Lyle C

GE W/H

Dan, I have checked the Mass. plumbing board web site . According to the site GE has no state approved Water Heaters.
But Rheem has many approved water heaters . Did this water heater come from a big box store or a regular plumbing heating supplier?
Also I do agree many water heaters need Exspantion tanks due the fact the pressure can rise as high as the street pressure. I have a condo complex I take care of where the street pressure is 145 psi . All tanks at this site get exspantion tanks.

Unknown

last time I checked

The GE water heaters are made by Rheem/Ruud company and sold by Home Depot. I installed exp tank on heaters that have backflow preventer on water supply. Whether the city required them or not. Its save me the griefs of going back on extended warranty on these crappy made heaters as its the expani son and contraction shorten the lives of all heaters. Water heater on well water most likely to lasts longer than city water system.

Darrell

Maybe I missed something...how will an expansion tank reduce street water pressure? The entire system, including the expansion tank, will rise to the supplied pressure in stasis...all points in the system will record the same pressure minus elevation variances. An expansion tank will only provide expansion/relief in a closed system...a water system with a checkvalve or water meter/check valve combo on the street side of the water heater. An expansion tank may help to eliminate water hammer if it happens to be in the right place.

Eighty pounds shouldn't damage a water tank...be interesting to strip it and find the computer weld that failed...and show it to the rep.

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mtfallsmikey

All the above are true

Bradford White (any relation Brad?)was the first to use ball-type checks on the inlet (I believe...??)about 15 years ago, but rjbphd hit the nail on the head. I installed a GE heater in my wife's house, with expansion tank, lasted not quite 2 years...it is a crappy heater with crappy t-stats that cause the temps. to overshoot.

zeke

I checked my Boch HWH and found that it is tested to 300 psi and the allowed working pressure is 150 psi so I would think that if the pressures got that high you would see other evidence like leaking or burst pipes elsewhere before the HWH should have let go.

Looks like a defective unit to me.

Al_19

I think we're making this way too complicated. The expansion tank that they're recommending really has nothing to do with test pressures, allowable working pressures, or normal street pressure. It's not to protect against an over pressure condition. The relief valve would cover that.

The expansion tank just accounts for the pressure cycling up and down in response to the water heater cycling between higher and lower temps. All normal operation, and within acceptable temps and pressures. But the constant cycling causes the heater tank to constantly flex, and shortens the life of the tank. With the expansion tank installed, the heater tank doesn't see the flexing. Thats all.

Aidan (UK)

Expansion tanks

All unvented water heaters over here have expansion tanks and a check valve on the cold inlet.
The expansion tanks are to prevent the waste of water. The water heater pressure increases as the water heats up; it's not allowed to expand back up the cold feed pipe to prevent contamination of the mains supply. The water would otherwise be discharged from the pressure relief valve. The expansion tank reduces the pressure that the water heater tank is subjected to.


The expansion tanks are fitted on the cold feed pipe so the diaphragm is only exposed to low temperatures.

Dan_29

pressure problem

Thanks for your replies on this problem.

I am going to put an expansion tank on the water line to the hot water heater. I do not want SmartWater-Rheem to have an excuse to deny any future warranty claims.

DAN

Tilmon

hot water heater short life

If you are connected to a well you do not need an expansion tank. The holding tank connected to the well pump will act as the expansion tank. If you live in an urban area and you get water from the municipality/city (any source except a well) than yes you need one.

The real reason most hot water heater don't last is because the anode is never checked and replaced as needed. I need to change mine about once a year, (I am connected to a well and have hard water) some anodes may last as long as 15 years. It all depends on the water. The anode will "sacrifice" it's self to prevent corrosion to occur on the tank. When the anode is gone the unit will begin to corrode and shorten the life of the unit. When the anode is completely corroded it leaves a steel core, if your hot water is yellowish (but not your cold) when you draw a bath it means the steel is exposed and you need to replace the anode.

I have seen this problem many times. I have had costumers in your situation before (needed to replace unit every 2 yrs.) that now have units over 20 yrs. still going because of regular anode verification/replacement. This is often overlooked by plumbers and home owners simply because they don't know.

And yes, every hot water heater on the market has one.