Humidifier for ducted heat pump?

Questions on how we spend our money and our time - consumer goods and services, home and vehicle, leisure and recreational activities
Post Reply
Topic Author
NYCaviator
Posts: 2827
Joined: Sat Apr 09, 2016 5:06 pm
Location: NYC

Humidifier for ducted heat pump?

Post by NYCaviator »

Our Mitsubishi installer said that our current bypass Aprilaire humidifier won't work well with our new ducted heat pump and recommends getting rid of it. I guess it's an older model humidifier and the bypass models work best when you are dealing with really hot air from a gas furnace vs. less warm air from a heat pump. I guess the heat pumps don't get as hot (but run more constantly) which really affects the ability of a bypass unit to add humidity to the air. He said we'd really just be wasting water without seeing a difference in the humidity in the house. He recommended a fan based humidifier, but it would run about $1k.

Does anyone else with a ducted heat pump have a humidifier hooked up? If so, what kind?
User avatar
firebirdparts
Posts: 4763
Joined: Thu Jun 13, 2019 4:21 pm
Location: Southern Appalachia

Re: Humidifier for ducted heat pump?

Post by firebirdparts »

I use a steam humidifier.

Aprilaire 800 series is probably leading the market now. Before it came out, you simply couldn't keep a steam humidifier working. It's the first reliable one that I am familiar with (I had 3 prior, all honeywells)

They don't use RO on the water feed, although they could, so it has to blow down wastewater. You really need 240V power (technically optional). And of course you have the steam injector into your ductwork. That dictates what the install will cost. I have a honeywell humidistat hooked to mine that I really like. I have not ever used the one that comes in the box, but it may be awesome.
This time is the same
Sweaty
Posts: 27
Joined: Sat Nov 11, 2023 7:10 am

Re: Humidifier for ducted heat pump?

Post by Sweaty »

I have not had good luck with humidifiers in the ductwork - ineffectual, clogging, leaking, maintenance. I decided to not have one when I replaced my heat pump.
cmcdows
Posts: 5
Joined: Wed Jan 11, 2023 6:10 pm

Re: Humidifier for ducted heat pump?

Post by cmcdows »

I'm not a big fan of humidifiers on heat pump systems. The reason is heat pumps don't dry the air out like a traditional furnace. For example if your existing room temp is 68 with your thermostat set on 72, the heat pump will produce air around 83-88 degrees (or 15-20 degrees higher than the return air to the unit). A typical furnace with a gas, oil or electric heat exchanger will produce air around 140-150 so it has been heated quite a bit more and is lower in humidity. If it's really cold outside and the emergency heat is running, the air temp will be higher and it will be drier but you can alleviate that with a small stand alone humidifier that is much cheaper to buy and easier to clean.
Soobs
Posts: 107
Joined: Sun Nov 01, 2020 10:38 pm

Re: Humidifier for ducted heat pump?

Post by Soobs »

cmcdows wrote: Thu Jun 13, 2024 8:14 am I'm not a big fan of humidifiers on heat pump systems. The reason is heat pumps don't dry the air out like a traditional furnace. For example if your existing room temp is 68 with your thermostat set on 72, the heat pump will produce air around 83-88 degrees (or 15-20 degrees higher than the return air to the unit). A typical furnace with a gas, oil or electric heat exchanger will produce air around 140-150 so it has been heated quite a bit more and is lower in humidity. If it's really cold outside and the emergency heat is running, the air temp will be higher and it will be drier but you can alleviate that with a small stand alone humidifier that is much cheaper to buy and easier to clean.
Just found this thread because I'm looking into adding an Aprilaire 800 onto our house. I just wanted to add I have a heat pump with gas furnace that kicks in if the heat pump can't keep up. Our house is very tight and built by a small green home builder. The indoor humidity drops to 15%-20% pretty regularly in the winter and that's with the heat pump. So, depending on your location (and altitude) a heat pump will certainly drop your indoor humidity.
MCST
Posts: 278
Joined: Mon Aug 21, 2023 7:03 pm

Re: Humidifier for ducted heat pump?

Post by MCST »

Wanted to bump this thread to see if anyone had luck or experience with one of the fan powered Aprilaire humidifiers with a ducted heat pump? I've heard mixed things about the steam powered humidifiers and how much energy they use. The fan powered ones are supposedly "next gen" and save a lot more water/electricity.
bmsuter
Posts: 33
Joined: Thu Jan 01, 2015 2:48 pm

Re: Humidifier for ducted heat pump?

Post by bmsuter »

MCST wrote: Tue Oct 29, 2024 6:47 am Wanted to bump this thread to see if anyone had luck or experience with one of the fan powered Aprilaire humidifiers with a ducted heat pump? I've heard mixed things about the steam powered humidifiers and how much energy they use. The fan powered ones are supposedly "next gen" and save a lot more water/electricity.
It depends on how big your house is. I have the Aprilaire 800 on a heat pump with propane backup. I believe it is rated for 4,000 square feet. It works very well. I've got the Aprilaire 700 on my other unit which is only a heat pump. I would say if your house is 3,000 square feet or above I would go with the steam humidifier if you have a good spot in the return to put it. It also works well if you have a water softener. My canister lasts two years and there are now aftermarket canisters available. If you are under 3,000 square feet, I think you can get by with the Aprilaire 700. The Aprilaire 700 does need a pretty large area cut in the return to get it mounted so If you're in a tight space, that could be a dealbreaker.
Legoman666
Posts: 24
Joined: Mon Jun 10, 2024 6:44 pm

Re: Humidifier for ducted heat pump?

Post by Legoman666 »

I have a Mitsubishi heat pump and an Aprilaire 800.

Steam costs the same to run as an evaporative humidifier. Think about it. There's no free lunch. You want to turn water in to vapor. Heating the water directly costs x. Evaporating the same amount of water will cool the air down, which will cause you have to heat the air back up. Still costs x to achieve the same humidity.

Evaporative humidifiers suck. The filter gets clogged and nasty, they are slow.
Legoman666
Posts: 24
Joined: Mon Jun 10, 2024 6:44 pm

Re: Humidifier for ducted heat pump?

Post by Legoman666 »

Also, all heaters "dry" the air the same amount. The only caveat would be a ventless gas heater, but alas, CO poisoning.
Time2Decumulate
Posts: 48
Joined: Tue Jan 29, 2019 1:41 pm

Re: Humidifier for ducted heat pump?

Post by Time2Decumulate »

Another vote for Aprilaire 800. Works great with our Misubishi hyper-heat heat pump air handlers.

We've had our Aprilaire for 12+ years and maintenance has been easy.
MCST
Posts: 278
Joined: Mon Aug 21, 2023 7:03 pm

Re: Humidifier for ducted heat pump?

Post by MCST »

Legoman666 wrote: Tue Oct 29, 2024 9:56 pm I have a Mitsubishi heat pump and an Aprilaire 800.

Steam costs the same to run as an evaporative humidifier. Think about it. There's no free lunch. You want to turn water in to vapor. Heating the water directly costs x. Evaporating the same amount of water will cool the air down, which will cause you have to heat the air back up. Still costs x to achieve the same humidity.

Evaporative humidifiers suck. The filter gets clogged and nasty, they are slow.
Did you have the same company install the humidifier that did the heat pump? There are only a few local companies that do Mitsu heat pumps around me, and I'm not sure any of them install Aprilaire.

Does the steam put less strain on the HP to keep the temp at the set point since it's already heating the water to make it evaporate?
mgensler
Posts: 409
Joined: Sun Aug 20, 2017 9:17 pm

Re: Humidifier for ducted heat pump?

Post by mgensler »

We're in the Midwest and had gas furnaces with humidifiers before installing our ducted heat pumps three years ago. We always struggled to maintain acceptable humidity in the house during the winter even though we had two bypass humidifiers. When planning our energy upgrades, we learned that humidity escapes in the winter due to holes in the building envelope. We had a blower door test with thermal imaging done to identify the holes. We then spent some time air sealing. Result is we have consistent humidity in the winter without having to install humidifiers. Even on the coldest days it's great and no longer have to worry about water collecting on the glass.
Legoman666
Posts: 24
Joined: Mon Jun 10, 2024 6:44 pm

Re: Humidifier for ducted heat pump?

Post by Legoman666 »

MCST wrote: Wed Oct 30, 2024 5:45 am
Legoman666 wrote: Tue Oct 29, 2024 9:56 pm I have a Mitsubishi heat pump and an Aprilaire 800.

Steam costs the same to run as an evaporative humidifier. Think about it. There's no free lunch. You want to turn water in to vapor. Heating the water directly costs x. Evaporating the same amount of water will cool the air down, which will cause you have to heat the air back up. Still costs x to achieve the same humidity.

Evaporative humidifiers suck. The filter gets clogged and nasty, they are slow.
Did you have the same company install the humidifier that did the heat pump? There are only a few local companies that do Mitsu heat pumps around me, and I'm not sure any of them install Aprilaire.

Does the steam put less strain on the HP to keep the temp at the set point since it's already heating the water to make it evaporate?
Yes, same company. Very small shop, just one guy and a helper.
Technically, yes although I wouldn't call it strain. It's doing what it's designed for.
MCST
Posts: 278
Joined: Mon Aug 21, 2023 7:03 pm

Re: Humidifier for ducted heat pump?

Post by MCST »

Our company recommended the fan powered Aprilaire 700. Anyone have experience with those? It's evaporative, not steam.
User avatar
firebirdparts
Posts: 4763
Joined: Thu Jun 13, 2019 4:21 pm
Location: Southern Appalachia

Re: Humidifier for ducted heat pump?

Post by firebirdparts »

MCST wrote: Wed Oct 30, 2024 5:45 am
Did you have the same company install the humidifier that did the heat pump? There are only a few local companies that do Mitsu heat pumps around me, and I'm not sure any of them install Aprilaire.

Does the steam put less strain on the HP to keep the temp at the set point since it's already heating the water to make it evaporate?
No and yes.

HOWEVER: You do have a decision to make. You can either use the humidifier to command the fan on, or you can limit the humidifier to only operate when the fan is already on. the first one is may require modifying the heat pump a little bit in my experience (if you try to use the control wiring as-is, you'll backfeed the compressor contactor). That might not happen with some thermostats, I don't know. For 100 years, furnaces all had similar controls, but at some point it's worrisome to break into that system on a heat pump you don't sell.
This time is the same
Saving$
Posts: 2573
Joined: Sat Nov 05, 2011 8:33 pm

Re: Humidifier for ducted heat pump?

Post by Saving$ »

mgensler wrote: Wed Oct 30, 2024 6:11 am We're in the Midwest and had gas furnaces with humidifiers before installing our ducted heat pumps three years ago. We always struggled to maintain acceptable humidity in the house during the winter even though we had two bypass humidifiers. When planning our energy upgrades, we learned that humidity escapes in the winter due to holes in the building envelope. We had a blower door test with thermal imaging done to identify the holes. We then spent some time air sealing. Result is we have consistent humidity in the winter without having to install humidifiers. Even on the coldest days it's great and no longer have to worry about water collecting on the glass.
This is correct.

Colder air has lower relative humidity, so when the building envelope is leaky it not only puts greater load on the HVAC system, it dries the air out more.
Post Reply