Tempering valve?

[bigshovel]

I recently watched my electric bill jump sharply. So I started the investigation process as to what is causing it. As it turns out the 65 gallon water heater that was put in circa 1984 had a bad thermostat. Instead of fixing I chose to replace this twenty plus year appliance. I was fond of the on demand system but without propane or gas I bought an 80 gallon Whirlpool lifetime warranty programable electric model. For some odd reason I actually pulled out the instructions and read through them." I know I broke all codes of being a man" and the instructions are recomending a tempering valve. In all my life I've never seen such a piece of plumbing, I know what its for but just never saw one. So the electronics on this heater have temperature limits you can set and I will but the tempering valve seems redundant to me. Any thoughts? All of our faucets and showers have temperature limits on them as well by design.

Brad

 

[TedLaRue]

bigshovel,

Your household demands some number of gallons of water delivered at some temperature per hour. You could meet this demand with a very large water heater set to about 125 degrees F, or with a smaller heater set to about 160 degrees F.

But the smaller heater set to 160 degrees creates a dangerous situation at the faucet if someone turns on the hot without also turning on the cold to mix with the very hot water. (bigshovel, you say your faucets and shower are already protected, so this isn't an issue for you.)

If you install a temperance valve (which automatically mixes the hot water with cold to achieve a set temperature), you can set your water heater to a higher temperature (e.g. 160), thus providing more water at 125 degrees without any risk of someone getting scalded by the 160 degree water.

You could also install the temperance valve for the faucets and bathtub or shower, and bypass it for the washing machine and/or dishwasher.

I'm not endorsing the use of a temperance valve nor discouraging its use. I'm just trying to explain why it's used.

 

[bigshovel]

Ted,

Thanks for the reply. You confirmed my suspicions. I don't need it. I do need union fittings and I'm back in hot water tonight.

Brad

 

[tallyho8]

I was wondering which way would use the less electricity, heating a small tank to 160 degrees or heating a large tank to 125 degrees?

 

[kenmac]

some codes require these valves to be installed. Along with an expansion tank. You are doing your own install & aren't getting an inspection so, you are ok

 

[Wayne County Hose]

We also put them before the toilets to prevent the tank from sweating. Here, our well water is so cold that the toilet tanks will sweat with condensation it the summer,

 

[bigshovel]

I was wondering which way would use the less electricity, heating a small tank to 160 degrees or heating a large tank to 125 degrees?

Well, my energy use guide on my existing unit is $519 annually at 56 to 65 gallon. The new one on energy mode 74 to 80 gallon is listed at $514 anually.
I don't see the difference other than capacity. New unit also has a vacation mode to maintain 50 degrees at rest.

Brad

 

[Wayne County Hose]

My plumbing/heating guy just installed my hot water/heating system in my new house. He said that the tank is lined with 4" of concrete then insulated. He said that with this system, he has turned these off on Monday, came back Friday and still had water at 100 degrees.

 

[TedLaRue]

My plumbing/heating guy just installed my hot water/heating system in my new house. He said that the tank is lined with 4" of concrete then insulated. He said that with this system, he has turned these off on Monday, came back Friday and still had water at 100 degrees.

This jumped out at me. I assume the concrete was added to supply thermal mass.

But water has twice the thermal mass of concrete (in other words, a cubic foot of water will store twice as much heat as a cubic foot of concrete). So I would have just made the tank 8" larger in diameter and left out the concrete. Or am I missing something?