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Old 09-21-12, 08:48 PM   #10
opiesche
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Join Date: Jul 2012
Location: Rohnert Park, CA
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Quote:
Originally Posted by Vlad View Post
opiesche,

Be careful when you select your HWT. All HWT have their minimum temperature unless it is a condensing one. If you just get regular DHWT and try to run it @ 80F you will end up with condensation problem.

For this reason if you use regular DHWT (non condensing type) you have to keep it @ minimum allowed temperature an install mixing valve.

I used special mixing valve I050C2R-2 - Taco I050C2R-2 - 1/2", 2 Way Outdoor Reset I-Series Mixing Valve w/ Sensor which works as thermostat as well. It is pricey but worth every penny. Check eBay for better deal but make sure you get exactly this model.
Thanks for the info, Vlad! I've been thinking about a mixing valve, but then I'd have to worry about what to do with the additional water I'd introduce into the system. In the end, I think I might go with a tankless natural gas water heater. They usually have energy factors of around 0.8, so are pretty efficient - and since I'm only going to need <30F rise of water temperature, a small model should do the trick. I'm looking at this one:

Eccotemp-FVI12-NG Indoor Tankless Water Heater

Which allows for individual control of gas and water flow, so I should be able to adjust this very well for my target temperature. This heater turns on when the water flows, so my pump circuit would automatically also turn on the heater if the water temp is below target.

Has anyone here had experience with tankless heaters for hydronic floors? I'd be interested in hearing some experiences!
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