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Looking for a heat source for my new Radiant Slab

Basically I have a 480sq ft 24x20 foot slab I just poured with (2) 300ft 1/2" PEX lines running though it, insulated with 2" rigid pink foam board on the bottom and sides. No windows, 1 7x8ft insulated garage door and a 36x80 door. 12' ceilings. Will be well insulated - R19 on walls and R38 in Ceilings. This is a small garage so I am trying to find a unit that will give me the most space possible. Will be run on propane.



I like the idea of tankless units because I can mount it on the wall out of the way, I have a Tankless DPW Quiteside in my house for heat and hot water, So I was thinking maybe a ODW in the garage and using it for the radiant heat but I called Quiteside and they pretty much said it would not work, something with flow switches and stuff - I like the idea of the condensing unit with PVC discharge and the ODW unit is in my price range - DPW unit is now out of my price range. I see a lot of people use Takagi units but they don't seem as efficient as the Quiteside but look like they are designed on the same principles.

Another option would be a tank heater but this is starting to take up more room, but if it is my best option then it is what it is, I can't afford the $2000+ plus ones everyone talks about, this is my detached garage I want to keep at like 60-65* year round. I will probably only be living at this house for another 5 years or so, so a very expensive boiler would not pay itself off for me plus it would take up a lot of space.



What do you guys suggest for me?



Kyle

Comments

  • hot_rod
    hot_rod Member Posts: 15,031
    do you know the load?

    assume 480 sq. ft at 20 BTU/ sq. ft. would be a load of 9600 BTU/ hr at design conditions. Do a load calc if you can with any of the radiant design software available online, to get your exact load..



    With that small load could electric be an option? A small electric tank water heater with a 3000W element = 10,230 BTU/ hr.



    Or a small gas/ lp fired water heater, there are some stubbies available that could be shelf mounted to save floor space.



    Either electric or convential water heaters may be more expensive to operate than a 90% boiler or tankless but depending on how cold your climate is and how often you heat the space???



    hr
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • oceanstatetuning
    oceanstatetuning Member Posts: 2
    .

    True, I would like to stay with a more efficient unit BUT my load is so small that it's probably not even worth it. Electric is not a bad idea, I like the idea of not needing a hole in the side of my garage for the vent. Heat would be going on roughly end of November to probably May or so. I went on here:

    http://www.climate-zone.com/climate/united-states/rhode-island/providence/

    Coldest month, January is 19* average lowest with a average temp of 36*, It gets cold here but nothing extreme... I think I only say it hit the single digits a hand full of times last winter. Although it would suck to get a $1000 electric bill.
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