Best way to heat a radiant floor? [Archive] - Home Construction Forums

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Dream shopper
10-07-2009, 04:09 PM
I have built my new 2700 sq.ft. workshop with 10 loops on two zones in the 6"-8" concrete pad (lots of insulation on the edges and under the pad!) and now I'm looking for ways to heat it with propane for the next 3-5 heating seasons in Ontario Canada (cold!).
When the budget allows, it will be heated with geo-thermal as I am located on 20 acres with no hope of natural gas. So until then I will need a boiler of some sort with a low up front cost. (Not looking for as much efficiency right now, rather a good reliable, fairly low upfront cost system.) I've been doing a lot of research on boilers......floor mount, wall hung boilers and tankless water heaters and would really like as much advise or feed back as I can get with your opinions.
First off, what is the difference between a tankless water heater and a tankless boiler? (besides price).
2nd: whats the difference between a floor boiler and a wall hung, are they both tankless and/or instant?
I have learned that a tankless water heater can be dialed in for the lower temps. that are required for a radiant floor where as a boiler would need a mixing valve to regulate the temp.
I also have learned that tankless water heaters are not manufactured for the most part for heating applications and would/might void the warranty of the unit. Although a few manufacturers have made tankless water heaters that are specifically designed for recirculating applications. ex.Bosch GWH 450 ESR.
When I talked to their rep., they recommended it be used with an external tank which would put me back at the boiler price tag.
Any help on this is greatly appreciated.
My Dream Shop,
Terry.

bkrahmer
01-12-2010, 09:27 PM
I would install a Navien condensing on-demand (wall-hung) water heater. This unit claims 98%+ efficiency, it's easy to vent with 3" pvc/abs, and is not that expensive at ~$1500. In fact, I just ordered one today for my house. I will use it for domestic hot water through a heat exchanger, as well as all of my heating, including the garage, driveway, and hot tub. I think it would be true that a water heater would be designed for optimum efficiency at 120 degrees, which also is a great temperature for radiant. Sorry, but I can't shed any additional light on your boiler questions. I have wondered several of them myself, reaching no conclusions.

cheers,
brian

Dream shopper
01-13-2010, 06:08 AM
Thanks for your input Brian.
I ended up going with a Vitodens 100-W made by Viessmann. Its a wall hung boiler designed for radiant heat. It too is a wall hung so very compact and I didn't pay much more for it than I would of for a water heater.
I'm in the middle of plumping it in now so I can't say how it is as of yet.
I will keep you posted though,
Terry.

Don_P
01-13-2010, 02:21 PM
I'd appreciate hearing your experiences with both of them.