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StonesFan 06-03-2009 07:39 PM

Instant Hot Water Puzzle
We are in a small house on a slab. The plumbing is in the slab. We have a 40 gallon natural gas hot water heater that is approximately 40 feet from the bath tub. There is another half bath (no tub) on the other side of the wall making it about 45 feet from the heater.

We have noticed that every once in a while, hot water is instantly available at the tub when the hot water is turned on. This occurs without having recently run hot water from any of the other faucets. Normally, we have to run the water about 30 seconds to get hot water to the tub.

We have found no leaks and have not had any plumbing work in two or three years.

It happened this morning, and no one had been up for 8 hours.

Can someone suggest an explanation.

Redwood 06-04-2009 09:12 AM

Do you have a recirculation system installed?

Without any water running check your meter to see if it is turning indicating a leak. You may have a leak under the slab.

StonesFan 06-04-2009 06:37 PM

We don't have a recirculation system installed. Also, there is no movement in the meter when the water is turned off. The hot water is not always immediately present at the tub. The frequency of the problem is greater than monthly, but we really haven't kept track.

Redwood 06-05-2009 10:08 AM

Are there any single handle faucets particularly Moen or, Mixet?
You may have hot/cold cross over that is doing something similar to a recirculation loop when you run cold water somewhere.

Moen and Mixet have a particular knack of doing this.

Also do you have anyplace where there is a faucet that has a possibility of both hot and cold being turned on at the faucet but the spout of the faucet can be turned off?

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