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Boiler for radiant floor heat

toyotatech
toyotatech Member Posts: 6
in Radiant Heating
Just curious what your suggestions for a boiler would be. I have a 2600 square foot shop with an estimated heat load of 78,000 BTU/HR. The boiler would be used for heating the radiant floor. The floor is insulated with 2 inch foam board around the perimeter  and also all the way across the floor also with 2 inch foam board. I appreciate any and all suggestions.

Comments

  • NRT_Rob
    NRT_Rob Member Posts: 1,013
    fuel?

    what are your fuel options?
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
  • toyotatech
    toyotatech Member Posts: 6
    boiler for radiant floor heat

    NRT Rob,

    Thank you for replying, our options are electric or propane,we do not have natural gas in this area. I am currently comparing cost between electric and propane. Do you know what the electrical load in amperage would be for either electric or propane. The shop will be used for automotive use and will have a 200 amp panel.
  • Ironman
    Ironman Member Posts: 7,510
    Electric vs. Propane

    78k btu's = 22,853 watts or 22.9 kw / 240v = 95amps. That would require a single 125amp circuit or two 60amp circuits (95 x 1.25 = 118.75) The NEC requires the circuit to be sized @ 125% of the full load. A 200 amp service can only be loaded to 160 amps, but there are reductions for diversity. What is your cost per kw?



    Watts x 3.413 = btu's.



    A gal. of propane produces 92k btu's x boiler efficiency = output.

    What's your cost per gal?
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Zman
    Zman Member Posts: 7,610
    Nice spreadsheet

    This slick spreadsheet let's you compare any fuel and efficiency you want.

    http://www.eia.gov/neic/experts/heatcalc.xls

    I would be surprised if a propane Mod/con isn't the best bet but check it out.

    You could also look at wood,pellets or heat pump depending on you region.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • toyotatech
    toyotatech Member Posts: 6
    electric and propane costs

    Thank you to all that have replied. The cost of electric in this area is .057per kw/h, after 900 kw/h it goes down to .046. The cost of propane is $2.00 per gallon. Looks like propane is going to be the way to go if my math is correct. Can someone please explain the mod/con boilers and the outdoor re-set. Also if you could recommend reputable boiler manufacturers, cost is an issue but as as always I realize you get what you pay for. I forgot to mention the pex is non oxygen barrier. 
  • Zman
    Zman Member Posts: 7,610
    Firetube HX

    There are whole bunch of which boiler is better posts on the wall. To some extent they become" ford ,chevy,dodge" conversations. The non O2 barrier changes things a bit. I would find a boiler with high quality stainless. You need to eliminate all cast and steel components from your system. This includes airscoops,fittings flanges and ideally even the pumps.Also be aware that DHW heat exchanges like the Triangle Tube Smart have steel on the boiler side. personally I would install a triangle tube solo 110 boiler. There are now several other good firetube hx boilers on the market. The new dunkirk vlt also looks interesting. I would stay away from aluminum  exchangers because of the tubing.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • kcopp
    kcopp Member Posts: 4,462
    In that case....

    It looks like you will need a Heat exchanger of some type. A brazed plate is most common. For the boiler it all depends on what you want to spend. You could go conventional ans install a cast iron unit like a Weil-McClain CGs of you could go all out and go w/ a wall hung condensing. personally i like the Smith GC160/ Embassy Onex. The Triangle tube prestige is fine too. I personally don't like the Alum block units either.
  • Zman
    Zman Member Posts: 7,610
    Check with the manufacture

    I know Triangle tube has no concerns with the O2 in the boiler. Companies like heat-flow are OK with it in their DHW tank. I would not bother with a heat exchanger to isolate the boiler. Just buy components that won't be effected.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • NRT_Rob
    NRT_Rob Member Posts: 1,013
    I'd say electric wins

    3412/5.7 = 598 BTUs/penny

    92000*.9= 82800/200 = 414 BTUs/penny.



    looks like electric will be a cheaper install and cheaper operating costs than propane to me.
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
  • Zman
    Zman Member Posts: 7,610
    I agree

    Electric prices should be less volatile also. Were do you live were electricity is so cheap?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • kcopp
    kcopp Member Posts: 4,462
    edited January 2012
    You sure....

    about the TT used w/ non barrier pipe? Page 1 of the install manual warns against fresh water/ O2  in excess.... it really shouldn't matter if the O2 is getting in by a leak adding water fresh or non barrier tubing.... still is O2.
  • toyotatech
    toyotatech Member Posts: 6
    location

    We live in a small town called Bonner Springs located in Kansas, Thank you all for the greart information, you all have been a tremendous help.
  • toyotatech
    toyotatech Member Posts: 6
    location

    We live in a small town called Bonner Springs located in Kansas, Thank you all for the greart information, you all have been a tremendous help.
  • Gordan
    Gordan Member Posts: 891
    For what it's worth...

    The 110 and the Excellence have circs in them, and those are iron. The rest is copper or stainless. The fresh water warning may have to do with things other than oxygen, such as sediment or minerals. We're not talking about an open system here, but a closed system that lacks oxygen diffusion protection.
  • Zman
    Zman Member Posts: 7,610
    Triangle Tube

    That came from Rick Mayo, the western rep and trainer for triangle tube.You can not heat DHW directly but non O2barrier tubing is OK.The pumps bring up a great point. For reasons unknown I have seen cast pumps do very well in O2 environments and I have seen pumps literally eaten in a short period of time. I am guessing it has more to do with chemistry of the water and how the O2 effects it. The safe thing to do is go with Brass or Stainless.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • toyotatech
    toyotatech Member Posts: 6
    hard water

    we also have water with a hardness of 25. Would it be a good idea to run  a water softener to help protect the boiler? Or we could fill the system with water from the house that already has a water softener. I have read that hard water is not good for boilers. Thanks again for all the great information
  • Zman
    Zman Member Posts: 7,610
    Good Thought

    I would preflush the system then fill with the best water possible. There are also inhibitors that can be added, with or without glycol.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
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