dual thermostats

[triggamike]

i was wondering if anyone could tell me if i can run 2 thermostats on a girarde tankless water heater. i just bought the new unit and it came with one which i didnt think it did. I ordered one so now i have 2. thought about putting one in the kitchen for really hot water and i can put one in the shower area so i can change the temp while in the shower. From what i have read you need to change the temp by the thermostat and not by adding cold water. Please Help

[Witch Doctor]

I would think that you would need to add a relay, no system will allow two stats to work at the same time. You would need to lock one out, they both can’t work at the same time.

[triggamike]

Thanks for replying back. I understand you cant run both at same time. My thoughts are will it hurt to have 2 control panels hooked up to the unit. My idea is one in the kitchen for hotter water and one in the bathroom for the shower. I can mount mine in the bath so you can open the door and adjust temp because what i have read you cant add cold to adjust so i can just turn up the adjustment. And the kitchen control would be off. As long as one of them is turned off would that work?

[Retired JSO]

Why would you need 2 water heater temps? You would still adjust the outflow temp with the single or dual handle faucets just like at home.

[triggamike]

You cant add cold water to adjust temp. you have to set the temp on the control panel.

[Witch Doctor]

I can’t say without seeing a wire diagram, you need power to the stat correct? I assume 12 volt. You can’t do it If it runs that way you have to isolate the stats you do that with a relay such as a single pull double throw, take a picture of the wire diagram and post it. You need to be able to switch power to the stat independently

[triggamike]

Thanks for the help. I know what i need to do now. I was worried about the computer board have 2 control panels but with a relay i can set them up independent. Awesome thanks for you help.

[Witch Doctor]

Your welcome it’s pretty easy to do but they do have to be isolated. We use to call them peanut relays, you can find one on the Grainger site.

[ependydad]

Originally Posted by triggamike

You cant add cold water to adjust temp. you have to set the temp on the control panel.

Have you tried it?

My family of 4 all prefer different water temperatures. I can't imagine having to adjust the water heater when someone goes to get into the shower. Much less expecting my 8 year old to do it before he heads in.

[Retired JSO]

Demand and regular water heater work the same way as to temp. Tank water heater and demand heater should be set at 120 degrees. 120 degree water flows on the hot line to the mixer, faucet. Cold is added to make warm/hot/cold. This is not rocket science.

[NMWildcat]

Originally Posted by Retired JSO

Demand and regular water heater work the same way as to temp. Tank water heater and demand heater should be set at 120 degrees. 120 degree water flows on the hot line to the mixer, faucet. Cold is added to make warm/hot/cold. This is not rocket science.

Nope, not rocket science, but your description of how on demand water heaters work is not even close.

[Retired JSO]

I have one set at 120 degrees. Hot water valve turned on, hot water, add cold have warm. Simple

[NMWildcat]

Originally Posted by Retired JSO

I have one set at 120 degrees. Hot water valve turned on, hot water, add cold have warm. Simple

I also have one. Doesn't work that way at all. They are not all the same.....

[ependydad]

Originally Posted by NMWildcat

I also have one. Doesn't work that way at all. They are not all the same.....

Can you really not have anything but full hot?

I'm completely dumbfounded by this...

[NMWildcat]

Originally Posted by ependydad

Can you really not have anything but full hot?

I'm completely dumbfounded by this...

I have two control settings, one for low (27k btu) or auto, which is either 27k btu or 34k btu.
To more finely control temp, you adjust the flow rate with the hot water valve. More flow (full open) is cooler, less flow is warmer. For these type, if you introduce cold water, the temp becomes sporadic. The newer models have much better adjustment features. The next on demand I will have is the newer Truma.