radiant floor heat/domestic hot water units
I failed with a longer post I tried to submit, so will keep this short and expound on it if warranted. Basically, I just wanted to know if a radiant floor/domestic hot water combination unit was more or less efficient in actual practice than having stand alone boiler and hot water heater. I live in northern Illinois, and this concerns new construction. My thinking is that trying to make one boiler do two purposes means the unit will not be at peak efficiency most of the time…but then again maybe he difference in working temperatures might mean better recovery of heat in the combination unit (?) Any pertinent comments? Thanks.
Jeff
Replies
Two separate systems is my recommendation without knowing more about the size of the house, number of occupants, etc.
Depending on the heat load, a 2nd domestic WH can be dedicated to just the radiant heat, and although its efficiency is not equal to some of the boilers, it is far cheaper, and much of its lost heat goes into the house anyway, and it is far less complex.
A separate system also eliminates the complications that result from the code requirements to keep the potable water from being contaminated by the radiant system because the radiant system can be a closed-loop system, meaning that it's not connected to the potable system. This also means it can operated at a low pressure, and any leak would be very small since the volume of system water available would be very small.
Thanks for the insights. I think I'll go with separate systems, partly because I can locate the water heater next to the two bathrooms (located at one end of the house), but the radiant boilers (primary heat for the house) will be central to the floors being heated by using two seperate mechanical rooms. Any thoughts on hyro-air combination units? I was thinking about using a split system (Mitsuibishi) as backup heat and airconditioning, but now that I'll have to meet the new code requirements of having a air exchange unit I'll have ducting anyway.
im starting a project and was wondering the same thing and kept reading about the diakin altherma unit, very interested in hearing more about it. seems like a complicated system to get to work flawlessly especially if also hooked up to solar like they show but if you could afford the initail cost and it did what they say... seems pretty awesome!
we are using the Altherma to heat/cool our shop here in Gardiner Maine. we love it and are a distributor for the units now to trained professionals.
typically if you can use 120 deg water or less, and you have a 35,000 BTU load or less, in a cold climate you can expect to run at about half the cost of propane or oil. close to natural gas and pellets.
great for radiant floors, ceilings, panel radiators. I am not a booster of the solar integration but I do think doing DHW with it is a no-brainer.