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Direct Vent?

JIMBO_2 Member Posts: 123
With a small gas-fired boiler (apx 100k BTUs), is it more effictive & efficient to power vent? Before I go any further with this project (house is owned by family menber, so every decision is complex).

The existing furnace is oil-fired. But now, we'll be switching to gas-fired fin-tube. Any suggestions. I'm thinking MZ, EK or similar unit.


  • Constantin
    Constantin Member Posts: 3,782
    Direct Vent with Gas should work great...

    I'm just a homeowner but I posted a similar question along the lines of oil heat a few weeks ago. With oil, the consensus is to use a chimney if you have one, as direct venting may be objectionable from time to time (smell and noise).

    On the gas side of things, it's a lot simpler. For one, any condensing boiler/furnace will produce gases that are safe around the house exterior. Noise should be OK as long as you don't have to add a powerventer. If the gas is making funny smells, you better have your relations call you...

    The only other thing I'd caution about is the actual location of the intake/exhaust terminal and its design. I once designed a outdoor gas waterheater that did not benefit from a blower or other assist device. This made me very conscious about the role of proper vent terminal design - get it wrong and a gust of wind can cause all sorts of mischief. To my eyes, many terminals on the market today are not wind-neutral (i.e. a ΔP develops across the intake and exhaust when a gust of wind hits the terminal).

    Also, plan on maintaining at least 4' clearances from windows, other intakes, etc. to keep the inspector happy.
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