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Water heater problem, I think

Posted by ladycfp (My Page) on
Sun, Jun 17, 12 at 17:08

I purchased a vacation home in a resort community in December. Home inspection clean. First clue, I noted that water coming out of cold tap was not really COLD, throughout home. Water bill arrives and it is a whopper. Utility company confirms this a usual bill for home. Prior to our purchase, home used heavily as short term rental, but we are there few days a month at best.

Handyman hired comes out rules out leak between home and water line by turning off water to home and monitoring meter throughout day. We then check toilets for leak and in turning them off I notice several of them handles on shut off warm to touch and water in bowls is also. Handyman decides several toilets leak and replaces fill valves in them. Also installs check valve in hot water heater (there are two tanks.) He mentions it could be bigger problem but this might work.

The water bill after toilet repairs is normal again ($35 for a month instead of initial $200) but warm water at cold taps persists. I have also noticed by now when I am there that the hot water heaters seem to run a LOT and make a loud fan noise when doing so. The running does not seem to coincide with use of hot water, either. By then our first gas bill arrives and it too is a doozy. We locate breaker for water heaters and turn it off when we leave and back on when we arrive. This continues and has helped gas bill but not the constant fan noise when on or warm water from cold taps.

I am told it could be as simple as a failed mixing valve anywhere (shower, kitchen sink, anywhere there is not a Hot and Cold tap) to (worst case) hot water and cold water plumbed wrong somewhere in the infrastructure. It is a large home, three stories and hot water heaters are side by side on first floor. There are four showers. Dishwasher, washing machine. Where would you start?

I intend to have a real plumber out to address issue but had hoped to isolate further and provide more specific info by being here more. I have visions of multiple visits without progress. All I know by being here couple days a week is it is a real problem. Everyone reports showers start hot then turn cold and by end of shower you have to practically have all the way to HOT for warm water. I suspect this why there are two hot water heaters, I imagine renters would have complained about not enough hot water. When we are here, we often come without kids and use the master shower only, it still runs colder quickly regardless.

Thanks for any insight and direction you can provide.


Follow-Up Postings:

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RE: Water heater problem, I think

Coincidentally, I'm watching a rerun of "Ask This Old House" where a homeowner describes a similar problem -- warm water coming through the cold water side of the bath faucet, and warm water filling the toilet tank.

In this case, the culprit was a scald-prevention shower valve, where the diaphragm separating the hot and cold water had failed. Richard replaced the diaphragm, and all was well.

Here is a link that might be useful: Ask This Old House


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RE: Water heater problem, I think

Are these gas HWHs or electric?

If gas, do they use powered exhaust vents? (the fan noise) If so, don't turn these off!

Is it possible there is a recirculation loop in the system? (recirculates hot from the tank to the fixtures and back through the cold side either by a pump or convection)


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RE: Water heater problem, I think

These are gas water heaters. And yes I do believe the noise is fans running. Can you tell me why I should not turn the breaker off when I leave? I think that is what is keeping my gas bill down until I get this figured out.

I am not sure about a recirculation loop, we do get hot water at taps on all floors very quickly, is this what you mean? I will try to post pictures but I am on an iPad and the image upload button is not working for me.


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RE: Water heater problem, I think

I believe what weedmeister was about to point out was if you do have a recirc line tied in to either of your heaters for the home, if it is either installed incorrectly without the proper check valves, check valves installed incorrectly, or possible check valve failure, any of these could be your culprit. This is just one of several different ways you could be experiencing this issue. I've seen direct cross connections of mains, scald guard cartridge failures, capped off bathroom faucets mixing across isolation valves, commercial kitchen faucets with prerinse faucets dropping temperatures causing restaurants to lose 180 degree water at their commercial dishwashers-----> You get the idea. What could leave you tearing your hair out can be figured out by a sharp, experienced plumber. Considering the amount of holes that somebody could make in your home not knowing where the usual suspects would be, you might want to find somebody reputable. This can sometimes be a challenge for the best of us if it's not something obvious. Good luck! =-)


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RE: Water heater problem, I think

With regards to the gas WHs: These are power-vent WHs. I'm not that familiar with them. Gas WHs must vent to the outside. A 'regular' gas WH does not use a fan but 'convection' of the hot gasses up the flue to the outside. It does not use electricity, the advantage being you have hot water when the power goes out. The only way to turn them off is to go to the unit and turn down the thermostat to the Off position.

A power-vented unit requires the fan to operate in order to push the hot gasses out of the house. If they don't go outside, then they go inside which would be a Bad Thing (CO poisoning).

I can only surmise that there is a safety interlock such that if there is no power to the fan the unit will not operate.


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RE: Water heater problem, I think

I too am having hot water coming out of the cold taps. We have had the entire house replumbed last fall and all faucets and fixtures are new. We installed an insta hot and a hot water recirculating pump. We are on a well. The problem only happens when we are watering the lawns. We feel the cold water line to the top of the WH and it is hot. This happens even when we turn the valve to the recirc pump line off. Does this sound like a check valve problem? But, why would hot water be sucked into the cold water side when we are running sprinklers? It does not seem to happen at any other time. The line to the faucet for the sprinklers is on the intake line from the well.The recirc pump is installed on the cold water side of the WH. The equipment on the holding tank from the well are existing - perhaps about 20 years old. The well pump is at about 60 ' and we get 6-8 gpm.

This post was edited by LAW047 on Tue, Jun 3, 14 at 11:33


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RE: Water heater problem, I think

I would turn off all the hot supplies to each fixture and see if the problem show up as you bring each fixture back on line. Take notes, because you may want to discuss this with the plumber who will eventually come out. It can be a lot of leg work. I had this happen once where a shower valve was piped backwards and drove us crazy.

Locate the recirc pump. If it is simply "plugged in" and runs all the time it will cost a lot in heat loss off the pipes. Shut the recirc pump off and see if that solves the cross flow issues.

This is one of those things that will/can drive you crazy. Good luck!


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