Hot water question.

[pullmytrigger]

since Im in the business people cant believe I dont have an on demand water heater.......

my reply is......."the last thing in the world I would want to do is let the women in my house know there is unlimited hot water......."

[Chris]

That's how my daughter knows her shower is done- the water starts running cold. Literally.

I have actually considered plumbing in a solenoid valve on the hot feed line so I can connect it to a timer. If they want hot water, the turn the dial- in another room of course.

[gerritm]

Sounds like a preassure equlization problem. Kinda what Chris said.
Sometime you use one heater, hot... sometime form the other that may be cool but higher preassure. You need a better plumber.
You might able to installa crossover copper pipe, to use both the same time. Longer duration of hot water source, but the output preassure has to be the same. It almost sounds like you only using one heater.

If you pipe the heaters the way I explained you will never have this problem, the #1 tank preheats the water for the #2 heater and you will never run out of hot water. If he has 2 -- 80 gallon heaters then he will have a true 160 gallons based on recovery rate of the heaters and the temperature rise of the incoming cold water. But this way he would be hard pressed to ever use that up. There will be no equalization or pressure problem. That is why you pipe them this way, if they are piped parallell you will commonly find this problem. Unless they are perfectly hydrostatically balanced, one heater will always be dominant and used more than the other. Water seeks the path of least resistance.The house is brand new, why would you take a couple of thousand dollar water heaters out and replace them with a Rinnai? Although the Rinnai's do work well and are very efficient. I think there is something wrong with the piping,thermostats, or the dip tubes. Get your contractor/plumber back and make him fix the units under warranty.

Chris, you live up north and the one you had installed was probably not sized correctly based on the incoming cold water temp. They had a lot of problems with this in the northern states when the Rinnais first came out. Your water probably enters the house at 50 degrees or less, where here in Texas the water comes in @ 70 degrees or better. If you have a competent plumber size, buy, and install one correctly, they work well.

[Chris]

Well water. Deeeeeep well. It's cold alright.

[nwpc]

Go to the bathroom in the unfinished area and shut off the tub/shower valve, or make sure the plumber didn't tie water stub-outs together. If you have a recirc on you water heater it may be tied into a cold line for return. Somewhere you have hot and cold water mixing. Let us know.