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Want opinions on heating detached garage

I'm heating my house and detached garage with outdoor wood/coal boiler now. I'm getting up in age and want to get away from wood and coal. I switching to  NG  boiler in my house . My garage has radiant floor heat, 28 X 42. 8ft ceilings. well insulated. I can think of 3 ways to continue radiant floor heat in garage.1  tankless water heater,2  tank water heater,  3 boiler.  which would be best ? which would be most dependable ? least maintenance and long lasting ? one contractor wants to install mod/con  Bosch 57 boiler.  Are they a good boiler ? He calculated that I only need 23K BTU's.  Cast iron boiler seem to be longest lasting, few problems. but I can't find anything that only puts out 30-35 BTU s.  Your thoughts appreciated. thanks


  • ScrewLooseScrewLoose Member Posts: 20
    garage heating

    Without knowing the issues of your system, I would say that the best solution for longevity and simplicity would be to make the garage it's own zone off the main house boiler system.

    Is that contractor suggesting that boiler *JUST* for the garage, or for entire property heating system?
  • HEFF653HEFF653 Member Posts: 5
    garage heating

    The garage does have it's own zone. My house and garage are getting hot water from outdoor furnace for now until I switch to natural gas. My house will have it's own boiler.  trying to decide what's best way to heat garage. tank, tankless or boiler. Garage will have it's own heating system.
  • RobGRobG Member Posts: 1,850

    If the garage is its own zone, why not use the boiler for the house to heat it? Even if it is a detached garage it may be cheaper to run insulated pex underground than to install its own heat source.

  • SnowmeltSnowmelt Member Posts: 750
    Garage heat

    I would install a gas water heater direct vent, then maybe just put a

    Little sink to wash your hands.

    I'm going to assume the manifolds in the garage.

    I would just install something with. 50,000 btu's
  • HEFF653HEFF653 Member Posts: 5

    I've thought about using one boiler. from the house to send water to garage. The pex pipe from my garage goes right pass my house to outdoor furnace. if I use the house boiler I'd have to dig the line up and reroute it back into my house. I'd have to break thru concrete. I'd rather get a second boiler for garage. from my house to garage is about 100ft. I'd be losing heat underground.
  • HEFF653HEFF653 Member Posts: 5
    Garage heat

    Would a water heater last longer than tankless or a boiler ?  is tankless definitely out of the question ? Pretty much every water heater I looked into only has an effiency rating of 59 to 62 . .  If it were in 85 to 95 range I'd consider it.  At 68" tall by 22" dia. takes up a lot of space. especially compared to Bosch 57 mod / con.. manifold is in garage . yes.
  • SnowmeltSnowmelt Member Posts: 750
    edited March 2014
    Cash flow

    It's all about how much you want to spend

    I have a takagi doing a 3 loop radiant and 1 zone baseboard at 140 degrees of water just finishing it's 5th year.

    I have my own drive way with 11 loops at 130 degrees with a takagi tk3

    So the answer would be no it's no out of the question.

    If you to to ao smith vertex, that would work

    Could go with the navien combo unit that way you can run domestic also so you can run your hands

    The navien has nice venting, but p/s loop has to be good, or should I say ran correctly.

    Any boiler would work it's all what the installer has a relationship with.
  • HEFF653HEFF653 Member Posts: 5
    Reply to Snowmelt

    I did some research. Takagi has a lot of good reviews. And so does AO Smith Vertex. but leaning toward a Takagi tankless due to taking up less space. What model should do the job ? Was told garage only needs 23K btu but to put in no less than 40 K btu.  T-K4  11k-190K btu or would a Heavy Duty T-D2 be a better choice. or something smaller ?   One negative thing about Takagi is there is no dealer close by. from what I'm reading I won't have a warranty If I get one thru internet.  Would it take much (Gas Wise) to heat water when the water going in is already preheated ?  
  • SnowmeltSnowmelt Member Posts: 750

    Where do u live that you can't find a supply house that installs them, I am going to assume this is for next years project, if you tell me where you live I could try to find one for you. I have a pretty good relationship with them. Ao smith bought them out. I can probably hook you up with a material list and a diagram to do this job.

    As far as taking up energy the answer is not much. The delta tee from the return would be much higher then ground water so the tankless will modulate on low fire, therefor using much less gas and making the unit real nice.

    There is a few things you need to know like 009 pump minimum, serving valve, back flow preventer but no pressure reducer air scoop and your exhaust isn't that cheap.

    So where do you live again & look me up
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