Boiler vs tankless? electric vs NG?

Old 06-19-14, 02:57 PM
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Boiler vs tankless? electric vs NG?

I am looking to replace an undersized NG boiler in my house. Here's the current scenario:

Two floors - main floor has hydronic radiant heat on underside of the wood subfloor. Basement has hydronic baseboard heat.

Domestic hot water
Output from boiler runs through a storage tank to heat water. Water is heated either when a zone calls for heat or the tank itself does.

I should also mention that I live at 8700 feet, so we lose about 25% efficiency right off the bat.

My plumber calculated that I need 141k btu output based on my house volume (current boiler is less than 100k). Also said that I should have a system that provides two different temps of output: 120-140 degress for the infloor portion and 180+ for the baseboard. These sound right based on what I've read.

What I am considering:
Isolating the infloor (upper level) system. I would love to find a tankless water heater (maybe even electric) that I could use for this since the infloor needs a lower water temp and we sometimes heat some of this area with a wood stove as well. Seems like even a small boiler is overkill and the tankless water heaters are pretty reasonable price wise.

Replace current cast iron boiler with a tankless one to service the lower level baseboard and domestic HW. Also wondering if electric would be better considering our altitude.

Any thoughts on the pros and cons - and better alternatives?

Thanks - Ron
Old 06-19-14, 03:45 PM
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I always recommend a true boiler over using a DHW maker for space heating.
They are designed for low flow high delta T loads, these are not what our space heating loads are.

Get a good condensing boiler, designed and installed by someone who knows multi zone heating.
Your appliance will last as designed and not fail on you a few years in.
Old 06-19-14, 06:02 PM
Tolyn Ironhand's Avatar
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I might be wrong, but I don't think you have enough flow for a tankless heater to fire.

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