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I moved into my home in the winter of last year after the house had been vacant for 1 - 2 years. In the summer during bouts of rain for 2 - 3 days, humidity levels in the house increase dramatically. The humidity in the basement was 85%, and there was growth on things like cardboard, clothing items, etc. in the basement. I bought a stand alone dehumidifier for the basement, which got the humidity levels down to 45% or 50%.

Notably, the upstairs of my house also gets extremely humid during long bouts of rain, which results in a funky smell that gets noticeably worse. I recently heard about "whole-house" dehumidifiers that can be installed directly into HVAC systems. This solution seems like it would work for me rather than installing ~4 noisy, stand alone dehumidifiers throughout my house.

From what I can tell, whole-house dehumidifiers seem to be linked with an AC system. My house does not have central air, but it does have ducts for the heating system. Will I have to install central air in order to achieve my ultimate goal of installing a whole-house dehumidifier?

geoscience123
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    If you had AC you wouldn't need one (there's a reason the coil on the inside is called *the evaporator*). You *would* need like twenty grand though.... Set the Nest : **stir setting** 60 minutes per hour. – Mazura Sep 11 '23 at 19:36

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You could just put the furnace on "fan" mode and run one dehumidifier anywhere in the house that the air circulates from the central system.

i.e other than perhaps the capacity being low, you could do this with what you have now, if the basement is part of the conditioned air path from the furnace, by just setting the thermostat to "fan" and letting the air circulate, while the dehumidifer runs. If your furnace offers a choice of fan speeds, a low one would be quieter and waste less power, while still circulating the air around.

If it's not already set up to auto-drain, you might want to arrange for that.

For a conventional central solution I expect a heat pump or AC is required.

Ecnerwal
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  • Unfortunately I have a nest thermostat which does not allow for a fan only mode (wtf). Looks like I'll be going back to a normal thermostat to try this. – geoscience123 Sep 11 '23 at 18:29
  • As "not enamored of allegedly *smart* thermostats" I approve of this solution to that dumb "feature" (it's bug, but if you call it a feature you don't have to fix the bug...) Don't know if it would upset the Nest, but you could also put a switch between the correct wires (G&R if normal) to force the fan to run. – Ecnerwal Sep 11 '23 at 18:33
  • It is very dumb. Before I go and buy an old-fashioned thermostat, do all furnaces have the continuous fan option? – geoscience123 Sep 11 '23 at 18:51
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    It's normal/common. "All" might be a stretch. But it may be worth saving the cost of a new stat and trying to just jumper G to R and see if that works on your furnace, and does not cause the Nest to have a hissy-fit. – Ecnerwal Sep 11 '23 at 19:30
  • Replace the Nest with an Ecobee. The Lite model is only $150. The Ecobee has a "run (just) the fan for X minutes every hour" setting. – Huesmann Sep 12 '23 at 13:08
  • @Huesmann Per comment on the question by Mazura, evidently there's a "stir" setting on the Nest which should solve it without spending additional money. – Ecnerwal Sep 12 '23 at 13:22
  • @Ecnerwal I believe the stir setting only exists on older models. If it is on my model, it is very difficult to find. – geoscience123 Sep 13 '23 at 12:36
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    "If your forced air system has a separate fan wire in your Nest thermostat's G connector, you can run the system fan when it's not heating or cooling. If not, your fan will only run automatically when your system is heating or cooling." https://support.google.com/googlenest/answer/9296419?hl=en – Huesmann Sep 13 '23 at 13:16
  • I'm using the Nest Learning 3rd Gen which allows me to run the fan daily for X minutes during any hours I specify. Is that the same one you're using? @geoscience123 – eszed Sep 20 '23 at 00:38
  • @eszed No, I just have the poor-man's equivalent. The base model titled, "Nest Thermostat." – geoscience123 Sep 20 '23 at 15:31
  • I see. Just to be sure, when you open the Nest app and tap your Thermostat do you see Fan Schedule under Options? – eszed Sep 20 '23 at 16:10