I have city water with no check valves. Electric water heater. Problem I have is with the Thermal Expansion Tank. As pressure builds it releases water back out to main. When pressure is needed again it brings water back in. Problem is, it does this all day long and I am paying for same water over and over. Has doubled our water bill. I isolated this along with a licensed plumber and he says he has never seen this before. Turn off the water heater (and water supply to heater) and the "diamond" shaped spinner on water meter absolutely stops. Turn water heater back on and it spins forward... then back slightly and then forward again several turns. I am reluctant to put in check valve as it could reduce psi 6-10 and pressure from city is not best to begin with. Heater is new (new house and heater is on 2nd floor making gravity drop even stronger?). T&P is also in place with drain tub and outlet. Is it better to keep tank and add check valve or remove tank all together? Thanks

Hi Tom

I don't know... would be a first for me, too!

My first thought after reading your post is that you don't have an issue with your expansion tank... you have a leak in a hot water pipe somewhere.

Is your house on a concrete slab? If so, can you chase out the hot water pipe(s) and see any go into the ground? If any hot water pipes go into the ground I would suspect that you have a leaking pipe underground and need to find it or pipe new piping above ground.

One other way to check all this would be to remove the expansion tank (plug tapping) and see if the issue continues. If it does, you definitely have a leaker... ;)

Back to you...

Mark

House is on slab and elevated home (Florida). I can see all the pipes and appears to be no leaks. Good idea on temporary removal of tank.

Thanks.
Tom

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Originally Posted by massplumber2008

Hi Tom

I don't know...would be a first for me, too!

My first thought after reading your post is that you don't have an issue with your expansion tank...you have a leak in a hot water pipe somewhere.

Is your house on a concrete slab? If so, can you chase out the hot water pipe(s) and see any go into the ground? If any hot water pipes go into the ground I would suspect that you have a leaking pipe underground and need to find it or pipe new piping above ground.

One other way to check all this would be to remove the expansion tank (plug tapping) and see if the issue continues. If it does, you definitely have a leaker...;)

Back to you...

Mark

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I agree with Mark, you have a leak somewhere on the hot water side. A check valve should not reduce the water pressure any measurable amount. What is the normal city water pressure? Must be awfully low for what you describe. The expansion tank would mitigate, not aggravate, the phenomenon since it absorbs some of the pressure created by the water heater.
If the water meter runs backwards due to the increased house pressure then that offsets original cost of the water coming in. Net cost to you is zero.

Easy way to know for sure about what is happening is to turn off the electric (or gas) to the heater and watch meter. If I am correct the meter will move forward only. Removal of the expansion will only force more water back through the meter.

Expansion tanks are almost always installed as a result of check valves or pressure reducing valves (PRV) being installed in the water main. Although Tom said there is no check valve, there may be a PRV, so I am having a real hard time buying the fact that water is going back through the main, 'cause as you said, Harold, that would not increase the bill, but would be offest and bill should remain about the same.

I've removed a lot of expansion tanks over the years and have never seen water go backwards into the water main (meter run backward) as long as PRV or check valve was present (or at any time that I can remember... can water meters run backward? ). What I have seen is water spill out through the temperature and pressure relief valve, so in this case where I suspect a leaker I would think that removing the expansion tank would lead to a leak at the T&P valve or nothing as the expansion may leak out at the leaker in the hot water pipe. Either way, the red pointer on the meter should be running forward.

I agree that it is even easier just to shut off the power and take thermal expansion out of the equation... I'm just not as patient as you, Harold... ;)

Since one of the complaints is low water pressure I assume no PRV. No check valve is stated. I've never seen it but I will accept that if the flow is backwards through the meter the meter will run backwards.

After giving it a little thought I will say that I was incorrect about the expansion tank. With no check valve and no PRV, in other words no restriction on back flow to the main, the expansion dank does nothing. That is nothing at any time. Any increased pressure due to the water heater is passed back to the main, the air to water ratio and the pressure in the expansion tank remains the same. The only time the air/water/pressure of the expansion tank changes is when the city pressure changes.

Think about this. If the city water pressure is in adequate to service the area and if Tom is sitting in front of the TV watching late night porn, and his neighbor comes home from the mill and takes shower. Tom's meter runs backwards briefly to equalize the pressure. When neighbor finishes shower Tom's meter runs forward.

Mark,
Just had to replace my PRV. Got the cheapest one I could find, A Watts X65B, figured it will last longer than I will.
Briefly looked at the literature, which I seldom do. States that if the house side pressure exceeds the supply by 10 lbs it releases back to the supply side. Negates the need for the expansion tank if no other restrictions exist.

Meters in my area won't read backflow. If they did, I can tell you I would be taking my meter out every month and blowing through it backwards to lower my water bill, lol. Okay, I wouldn't, but Im sure there are many folks that would, and they build these things (at least these days) to prevent this from being possible.

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taking my meter out every month and blowing through it backwards to lower my water bill, lol. Okay, I wouldn't

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No, but you probably piped around it. (Grins, grins)

Nope too lazy. Last thing I want to do after a hard days plumbing is to come home and do more plumbing. If I weren't so lazy, I would have a bypass on my water meter, gas meter, and electrical meter. Only thing I would have to figure out after that is how to bypass my Tax meter..

In all seriousness though, it is mighty easy to pop the head off my meter, hee hee. That backyard pool takes a bit of water..

PS. I wish I had a backyard pool, or a sprinkler system, or any reason to actually pop the meter head off. As it stands, I never use enough water to exceed the minimum water service fee.

This statement, "If the city water pressure is in adequate to service the area and if Tom is sitting in front of the TV watching late night porn, and his neighbor comes home from the mill and takes shower. Tom's meter runs backwards briefly to equalize the pressure. When neighbor finishes shower Tom's meter runs forward" is exactly why I don't think water meters can run in reverse. If this was the case then as landlords, as an example, we could play all kinds of games with our meters, or when the neighbor fills his pool we would have the water company owing us money!! :)

Anyway, some PRVs have check valves in them... maybe your doesn't, Harold?

Finally, I still think Tom has a leak in his hot water pipe... can't wait to see result on this one!

Thanks for all the input. Meter does not "deduct" on the return to main. Plumbing company did confirm it's the Thermal Tank. The town water engineer confirmed it as well. No leaks as it's easy to detect as it is a Florida "stilt" home. No check valves for sure, but at this time plan to put one in. Manufacturer of Thermal Tank estimated a 5 psi drop. Normal pressure in our area is 65. Thanks

And thank you for the update. Please let us know if the tank replacement or removal indeed solves the issue.

I don't understand...

What exactly is the Town engineer and plumber suggesting? Are they suggesting that you have a defective expansion tank, i.e. that the tank is filled with water? If that was the case then you would need to replace the defective thermal expansion tank and that would reolve the issue. I'm still betting it won't!

Very difficult to make sense of this... especially from here!

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I don't understand...

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I agree.

I'll stick by my "no effect" position on the expansion tank. That doesn't mean that the water heater couldn't cause the little needle on the meter to turn backwards. BUT, if it did, you would have to wait a very long time to see it move forward because of the cooling of the water in the tank.

Tom, please let us know the final outcome.

I agree with the "no effect" position, Harold. In most homes that I know of, there is no check valve nor any thermal expansion tank and the thermal expansion from the water heater is released to the water distribution system with no positive or negative FLOW... pressure is ABSORBED, but doesn't cause flow, right?

Hopefully, Tom will keep us posted!

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"Has doubled our water bill. I isolated this along with a licensed plumber and he says he has never seen this before. Turn off the water heater (and water supply to heater) and the "diamond" shaped spinner on water meter absolutely stops. Turn water heater back on and it spins forward...then back slightly and then forward again several turns."

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Hard to imagine how the relatively long periods of heating/cooling in a water heater could be responsible for that. Even harder to imagine how it could double a water bill. Makes me wonder if it is not associated with something going on "downstream" of this house that increases/decreases water system pressure. Your expansion tank could be absorbing that change and allowing the water to slightly flow in/out as it absorbs those changes in pressure. When you turn off the water to the water heater, does it also isolate the expansion tank from meter?

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Originally Posted by jlisenbe

Hard to imagine how the relatively long periods of heating/cooling in a water heater could be responsible for that. Even harder to imagine how it could double a water bill. Makes me wonder if it is not associated with something going on "downstream" of this house that increases/decreases water system pressure. Your expansion tank could be absorbing that change and allowing the water to slightly flow in/out as it absorbs those changes in pressure. When you turn off the water to the water heater, does it also isolate the expansion tank from meter?

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Yes it does. The shut off valve to heater does isolate heater and thermal tank. Spoke with neighbor last night. 2 people like us and similar house size. We have high efficient washer and dish washer, but no need to run these much. Low flush toilets as well. His bill last month was $92 and ours was $187. I wonder as well if it is something else, but when I shut off the water heater and have no water running, the meter stops 100%. Leave everything else off and turn water back onto water heater and the meter spins forward non-stop except for about a 3/4 turn slowly back and then fast forward again. Thanks

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Leave everything else off and turn water back onto water heater and the meter spins forward non-stop except for about a 3/4 turn slowly back and then fast forward again. Thanks

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I'll let the guys who actually know what they're doing do the rest of the talking, but I just cannot imagine how a water heater heating up and down in LOONNNGGG intervals would cause such a thing. You might try one more thing. Turn off the breaker to the hot water heater. That turns it into simply a big pipe - no more expanding/contracing. Once it cools down, see if the meter keeps turning. If it stops, then the plot really has thickened.

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Originally Posted by jlisenbe

I'll let the guys who actually know what they're doing do the rest of the talking, but I just cannot imagine how a water heater heating up and down in LOONNNGGG intervals would cause such a thing. You might try one more thing. Turn off the breaker to the hot water heater. That turns it into simply a big pipe - no more expanding/contracing. Once it cools down, see if the meter keeps turning. If it stops, then the plot really has thickened.

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I did that as well. Same thing happens. Meter stops running. Left it off for an entire day. Turned back on and meter went spinning again! Crazy stuff and costing me plenty! Thanks

OK...

A little far-fetched here, but if you had a cross-connection somewhere where the mixing cartridge is failing (shower valve as an example) AND your toilet or toilets were leaking past the flapper you could end up wasting hot water into the toilet tanks (would arrive as cooled water)... maybe?

Try this real quick:

Drip about 20 drops of a dark food coloring into your toilet tanks and then wait an hour and see if the colored water shows up in the toilet BOWL(s). If colored water shows up in the bowl(s) then we probably found the source of the leak. If that is the issue, pop back and we'll see if we can help you to isolate the offending mixing valve!

Back to you...

Mark