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Old 09-23-12, 02:42 AM   #17
Vlad
Apprentice EcoRenovator
 
Join Date: Aug 2010
Location: Windsor ON Canada
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Quote:
Originally Posted by opiesche View Post
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!
Using tankless HWT for low temperature application is going to be a real pain. It will short cycle on and off. With tank you just take as much water as you need and return water goes back to tank. Water mass in the tank will be like a buffer it will prevent short cycling. Short cycling is always bad because usually equipment efficiency is reached after some time not right away after starting.
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