1

I have a gas water heater and I'm thinking of moving to an electric water heater.

The exhaust pipe would then be free and I was thinking of reusing it for a dryer. Would that work? The pipe would be vertical, and the house is made of only one story

note: I saw Gas dryer water heater vent but the question is whether BOTH could be used at the same time (dryer and gas exhausts), whereas here I'm asking about just one of them

7
  • 2
    Gas or electric dryer? Dryer instructions should mention the length and vertical limits of the vent and type of vent needed.
    – crip659
    Jan 12, 2023 at 21:29
  • 1
    it's an electric dryer
    – Thomas
    Jan 12, 2023 at 21:48
  • Wouldn't count on it. Dryer vents do a very different job. Their job is to eject large volumes of heated, now very wet air. The operative word is "large volumes". It is way too much flow of air for a combution exhaust vent, and the vent going "up" is wasted on dryer vents. Since you're buying new appliances anyway, how about a ventless condensing dryer? They include an on-board dehumidifier so they condense their water. They also put the tumble drum in between the hot and cold side of the dehumidifier, so they get the dryer heat almost free LOL. Jan 12, 2023 at 21:54
  • 1
    A gas heater is usually MUCH cheaper to operate and reheats a LOT faster as well, why would you want to switch?
    – dandavis
    Jan 12, 2023 at 22:09
  • I was thinking of having a tankless electric water heater, to save space in the laundry room @dandavis
    – Thomas
    Jan 13, 2023 at 5:42

2 Answers 2

2

Wouldn't count on it. Dryer vents do a very different job. Their job is to eject large volumes of heated, now very wet air. The operative word is "large volumes". It is way too much flow of air for a combustion exhaust vent, and the vent going "up" is wasted on dryer vents anyway since they contain no combustion product.

Since you're buying new appliances anyway, how about a ventless heat pump dryer? They include an on-board dehumidifier so they condense their water. They also put the tumble drum in between the hot and cold side of the dehumidifier, so they get the dryer heat almost free LOL. And since air doesn't leave the building, you don't pay to re-condition it.

Normal electric dryers use inefficient electric coils (only 100% efficient; 300-600% efficiency is possible with heat pumps)... and they eject masses of air from the house, causing cold/dry or hot/wet air to be sucked into your house from outside via every leak in the house. Then you have to pay again for your heating or A/C to condition it to desired humidity and temperature.

4
  • 1
    One wrinkle: the ventless dryers i've seen all take a lot longer to dry, during which more power is used. They also don't eject their heat, so when using AC, you have to pay to re-cool every Calorie of heat it produces.
    – dandavis
    Jan 12, 2023 at 22:03
  • @dandavis -- old school condensing dryers are indeed dog slow, but heat pump dryers can put up reasonably respectable times (albeit slower than the brute force of a vented dryer) Jan 13, 2023 at 4:42
  • @Dan yeah I should've made clear that I meant heat pump dryers. I forgot "big radiator interchanging heat with room air" condensing dryers exist, makes no sense thermodynamically to me. Jan 13, 2023 at 4:48
  • @Harper-ReinstateMonica if the OP's existing WH vent duct is 4" why wouldn't it be fine? Is there a difference between dryer ducts and WH ducts? Obvs if the duct is 3", no bueno, since most (all?) dryers require a 4" duct.
    – Huesmann
    Jan 13, 2023 at 16:11
1

You need to check the instructions for your dryer. Water heater exhaust and gas dryer exhaust both have hot air, carbon dioxide and various pollutants from burning natural gas. An electric dryer just has hot air.

However, a dryer - gas or electric - also has a lot of water vapor and lint. Gases - hot air, CO2, water vapor, etc. - can travel through pretty much anything without a problem, as long as the duct work is able to handle the heat. But lint adds some serious concerns about how many bends,how much vertical rise and how much total length. In addition, a dryer vent needs to be cleaned periodically as there will always be some lint that gets past the filter but that doesn't get all the way outside the house. You can easily have a water heater vent that is not practical (i.e., without special equipment) to clean, and that would not be good for a dryer vent.

1
  • 2
    Or someone could convert it back to a combustion stack again, and have a lint fire the first day they light it off. Of course if it's a condensing furnace, the exhaust won't be warm enough to set anything on fire. Jan 12, 2023 at 21:59

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.