Furnace replacement recommendations

[Maxt]

Something that came up dealing with a couple of friends furnaces in the last while. With the switch to high efficiency appliances with a dedicated fresh air direct vent install where the air intake is now sealed to the combustion chamber instead of drawing air from the basement, it causes the Radon levels to skyrocket inside. Turns out pulling the combustion air from the basement does a nice job of ventilating the basement and keeping the radon levels down.
If you change to high efficiency, I would keep the old style combustion air bucket vent, and just do a one pipe (exhaust) only install on the furnace. If existing is 2 pipe sealed combustion, I would do a radon check in the house.

[sabad66]

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Something that came up dealing with a couple of friends furnaces in the last while. With the switch to high efficiency appliances with a dedicated fresh air direct vent install where the air intake is now sealed to the combustion chamber instead of drawing air from the basement, it causes the Radon levels to skyrocket inside. Turns out pulling the combustion air from the basement does a nice job of ventilating the basement and keeping the radon levels down.
If you change to high efficiency, I would keep the old style combustion air bucket vent, and just do a one pipe (exhaust) only install on the furnace. If existing is 2 pipe sealed combustion, I would do a radon check in the house.

Interesting… you’d think this would be more widely known/talked about.

With your suggestion to keep the old one, is that allowed in terms of code? I’m getting close to having to replace mine so taking notes on things to watch out for.

[suntan]

I thought the reason for sealed intake was because the newer furnaces need a lot of air.

[Darell_n]

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I thought the reason for sealed intake was because the newer furnaces need a lot of air.

Only the supercharged ones.

[dj_rice]

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Hey all, anyone have experience with a Daikin brand furnace?

The Carrier one I have right now has a cracked heat exchanger.

Daikin good. Japanese! I actually don't know about their furnaces but my co-worker likes his Daikin A/C. Daikin owns Goodman

[J.M.]

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Daikin good. Japanese! I actually don't know about their furnaces but my co-worker likes his Daikin A/C. Daikin owns Goodman

Forgot to update here. Ended up replacing the old Carrier furnace with a new one. Daikin 80k BTU furnace - luckily install was next day after initial estimate.

[Maxt]

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Interesting… you’d think this would be more widely known/talked about.

With your suggestion to keep the old one, is that allowed in terms of code? I’m getting close to having to replace mine so taking notes on things to watch out for.

As long as the old combustion air is big enough and the appliance allows for one pipe installs, non direct vent install in the instructions. Some appliance state that the exhaust and intake have to be in the same pressure zone together and don't allow for one pipe installs.
The radon problem seems to only boiled up in Canada since building codes have mandated tighter structures, and more energy efficiency, less air movement, higher readings.

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I thought the reason for sealed intake was because the newer furnaces need a lot of air.

In theory, on a furnace, the excess air not needed for the draft hood should mean a high efficiency should require less air. Excess air cools combustion too, like on direct vent hot water tanks that use excess air to cool the flue gases down so you can use plastic pipe on the venting.
Most of the reason for sealed combustion is stopping cold air spillage and loss up the stack to meet the energy ratings. It's also good for when the air in the structure is contaminated. On the 2 pipe systems, the dirty flame rod isn't really a thing anymore, less fouling sucking fresh air. But I would sacrifice a little off the furnace rating and a little more maintenance for lower radon readings.