Getting Rid of Humidity and Condensation from Heat Pump
LESLIE: Tony in Virginia, you’ve got The Money Pit. How can we help you today?
TONY: Last winter, in January, we got rid of our oil furnace and we got a 16 SEER HVAC, 3-ton unit. And this year, we noticed that there was condensation on our windows, so the first thing we did was we turned off the humidifier. In fact, I actually disconnected the line. And then we got a humidity gauge. We also ran a dehumidifier. We can’t get the humidity down below 45 percent in the house. It’s staying between 45 and 48 percent and it seems not to make any difference to anything that we do.
TOM: OK. So, the difference between the heat pump and the oil furnace you had before is pretty significant. When an oil furnace heats up and heats the air, it’s going to deliver that air at somewhere around 140 degrees or so. And when a heat pump delivers the air, it’s delivering it at 96, 97, 98, maybe 100 degrees. And so that 40-degree difference means that you’re going to have a lot more humidity stay in the air that the warmer oil furnace would have taken out. So that explains why you’ve got humidity now where you didn’t have it before.
So, what can you do about that? Well, you have to look at strategies to try to reduce the moisture load inside your house, turning off – the humidifier was an obvious one because, frankly, you rarely need those with heat pumps, for the reason I just explained. Secondly, taking steps to try to reduce the way moisture gets into your house can help.
So, for example, you can regrade the soil at the foundation perimeter: just the first 3 to 4 feet so that you don’t hold any rainwater against that foundation. You can make sure your gutters are clean and the downspouts are extending 3 to 4 feet from the foundation. You can make sure you have proper attic ventilation so that you have open soffit vents and open ridge vents, so that air is not getting trapped in the attic. And this way, you’re moving the vapor pressure, reducing the amount of vapor that gets into the foundation, works its way up into the house and gets out at the attic space.
Now, mechanically, you can add a device called a whole-home dehumidifier. You already have a ducted system. A whole-home dehumidifier is a product that would work both in the winter and in the summer in your location. And it would take a lot of water out of the air. But there’s an expense, obviously, to purchase it and to operate it.
So, what you’re explaining is not surprising to me. You’re just going to have to take some additional steps to try to reduce the amount of humidity. Does that make sense?
TONY: Yes. How about – the basement’s our first floor and it’s been dry when many of our neighbors have had water in the basement.
TOM: That’s a good sign.
TONY: So, I have to tell you, I’m a little reluctant to fool with the dirt outside. But what about – we have a fireplace down there. How about if I run the fireplace occasionally?
TOM: It’s not going to be a very efficient thing to do just to run your fireplace to try to dehumidify your house. It’s like it’s a lot of work to dehumidify, you know what I mean, using a fireplace. But if you were to use a whole-house dehumidifier, then you would have total mechanical and automatic control of that humidity level.
Take a look at the whole-home dehumidifiers by Aprilaire: Aprilaire.com. They make a pretty good one and then you could check with some local contractors and see what it will cost to have it installed.
TONY: Thank you very much.