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Help the industrial/commercial guy select a 45MBTU boiler

Solid_Fuel_ManSolid_Fuel_Man Member Posts: 1,978
After posting about a Biasing B-3 and staying with oil, I've been talking to other guys who do more residential heating. I think I'm going to switch to propane. Looking for some modcon advice. A popular install around here is Pensotti which looks to be a run of the mill Giannoni HX and 5:1 turndown. My design templates is 45MBTU on a -40F day, so I would like a high turndown boiler, and will end up with the smallest boiler of a given manufacturer I'm sure. I have a 115gal indirect so no worries about a small boiler for DHW.

Wood gasification is my primary heat source, but with family considerations I'd like to have something efficient if wood ever were not possible. I do industrial/commercial heating controls for a living, so I'd like a boiler with less electronics as I already have a substantial control system for my existing backup oil boiler in place.

Thinking firetube, but not necessarily.

Thank you for the informed perspective this forum provides which is NOT taken for granted.

Serving Northern Maine HVAC & Controls. I burn wood, it smells good!


  • MikeSpeed6030MikeSpeed6030 Member Posts: 69
    So you just want a back-up to wood? With your tiny design heat loss, I would consider electric baseboard. It's 100% efficient, but the higher cost per Btu will be offset by its limited use as only a backup heating source and its low installation cost.
  • hot_rodhot_rod Member Posts: 13,477
    Are price and features part of the decesion?

    The Lochinvar KHN 80 has the best control that I have seen if control tinkering is in the cards. It has outputs to drive smart pumps and the ability to add the Conxus system for remote monitoring and adjusting. Warranty is great.

    I believe the HX is larger, more mass and fluid than some of the other small fire tube designs.

    I have had good luck with Giannoi style, just care for them properly.

    Local support and parts supply could help decide, I don't know of any terrible boilers in that range if you stay with name brands.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
    delta T
  • Solid_Fuel_ManSolid_Fuel_Man Member Posts: 1,978
    I have large radiant slab and would like to heat that and not have cold floors. Also our Electric rates are high at 0.165 kWh I had considered an electric boiler. Want something affordable to operate if something ever happens to me.

    Looking for input of very small output condensing boilers with high turndown ratios. Like a 5,000 -50,000 btu/hr or similar. Will talk to our local suppliers and see what is available.

    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • Solid_Fuel_ManSolid_Fuel_Man Member Posts: 1,978
    Looking at Lochinvar WHN055, looks like a nice unit. We have installed a few Loch 300+ MBTU boilers, but never anything this small. Looks to still be a 5:1 turndown though. Whadda think? Experience? Suggestions?

    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • SWEISWEI Member Posts: 7,356
    KHN series has 10:1 turndown, but not on the 055. The 085 and the 085 have essentially the same minimum firing rate.
  • Solid_Fuel_ManSolid_Fuel_Man Member Posts: 1,978
    Doesn't look like there are many (if any) with much less than 8,000 min firing rate. As many other threads have stated before, I wonder why. 5,000 to 50,000 would be a nice small boiler IMHO.

    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
    SWEIHatterasguyrick in Alaska
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