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Diesel Boiler VS Propane Inline Hot Water Heater

Currently have a diesel fueled boiler or hot water heater. Thinking about switching to propane inline water heater as I use propane for many other things  and with diesel prices rising it just makes more sense.

However, I'm trying to figure out if the inline propane heaters have the

same output  of hot water as my diesel one. Want to make sure it can keep up with/ produce as much hot water as the one I have before I invest in switching. I'm at a loss for how to figure that out. Have tried calling local places that sell them both...no help. Have "googled" and came across "waterheaterrescue.com" who referred me to this site.

Hoping there will be someone who can help :) even if just to point me in the right direction.

Thanks much!


  • chapchap70
    chapchap70 Member Posts: 139
    Not sure of what you have

    I don't hear the term "Diesel Boiler" too often because no. 2 heating oil and diesel are basically the same thing; is there something different about your particular boiler?

    The heating content of one gallon of propane is about 91,000 BTU's.

    The heating content of one gallon of heating oil is about 137,500 BTU's.

    If you have hot water storage for your boiler, remember that you won't have that with the inline heater.  Hopefully, you have documentation with your boiler that tells the recovery rate for the hot water making device (whatever it is; tankless coil, indirect, etc.) 

    There are a variety of inline/tankless propane heaters with different hot water flow capacities.  Generally, the ones that make more hot water cost more.
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