Getting dry in the house!

[Guyerst]

We have a humidifier on the furnace, but now that we are burning the furnace rarely runs. And it's getting dry in the house!

I'd rather not deal with another humidifier (again), so I'm starting to think about seeing if I can get the humidifier on the furnace to turn on with the blower. I'm hoping it's as easy as moving the humidifier power wire from the current furnace connection to a wire tied to the blower.

Has anyone done this? Any idea if the humidifier power is taking off of a specific voltage output from the furnace? Like I said, I'm just beginning to look into this and need to dig into the wiring more... but thought I'd ask the group here to see if anyone has already done this.

Thanks!

 

[Rangerbait]

Howdy! Just give it a Google with your model of humidifier and furnace...mine calls the blower model with or without my furnace running.

 

[Gotrek]

Leave open water buckets/containers in your house. You'll be surprised how well that works

 

[moey]

Ive never done this but I do know that you need heat in order to speed up evaporation across the humidifier. No heat no moisture added to the air. You need temps 115 or so to get a standard humidifier on a furnace to work you cant just blow luke warm air across them. I would be worried about mold issues if you hooked it up running with just the blower.

Geothermal systems run with 90F air or so and they use steam humidifiers because they cant get any moisture out of a standard humidifier with 90F air. Youd be at a even lower temp.

 

[semipro]

I'd very surprised if you couldn't do what you're thinking. Having never had a humidifier I don't know how they're wired.
Moey's point on air temp is valid though.
There seem to be several types of humidifiers though so how it works may make a difference. There's bath types with rolling evaporative drums, and mist or steam humidifier systems (I believe these inject after the air handler).
Houseplants are a good option as they improve overall air quality as well as adding moisture.

 

[Easy Livin’ 3000]

Leave open water buckets/containers in your house. You'll be surprised how well that works

And if hydrophobic aliens show up, you'll be all set- Swing away, Merrill, swing away!

 

[Rangerbait]

Ive never done this but I do know that you need heat in order to speed up evaporation across the humidifier. No heat no moisture added to the air. You need temps 115 or so to get a standard humidifier on a furnace to work you cant just blow luke warm air across them. I would be worried about mold issues if you hooked it up running with just the blower.

Geothermal systems run with 90F air or so and they use steam humidifiers because they cant get any moisture out of a standard humidifier with 90F air. Youd be at a even lower temp.

Mine's installed on the return since there was no room on the supply, and plumbed with hot water...not nearly as efficient as on the supply, but it's kept us nice and comfortable so far.

 

[greg13]

Simple solution, just burn WET wood!! As it burns it gives off steam, steam cools and adds moisture to the air!
Hey it works on paper. Just ask any Engineer, (You know the people that design things that are impossible to work on).

 

[DickRussell]

I'm surprised no one else has yet commented on the fact that a house with exceedingly dry interior air is invariably a house that leaks far too much air. That dry outside air flushes out the humidity produced by normal human occupancy. But this has been discussed many times on this forum. Do a search on it. You'll find that, long term, your solution to the dry air problem lies in an aggressive air-sealing effort on the exterior shell of the house, not dumping a lot of moisture into the air. You don't want that moisture leaking out through the walls and into the attic space, where it will contact cold surfaces, condensing, and leading to mold and rot over time.

 

[Hogwildz]

You have to have some serious air leaks for the issues your describing. I run a Kenmore console humidifier, and have no issues with condensation or mold. If the attic is properly ventilated, there should be no issues with moisture or mold. as the ventilation takes care of that. A stove generally does not use enough air to exchange the house air enough to dry the house out as you describe.

 

[Guyerst]

I should have included some numbers in my original post...

I have the furnace humidifier set up to put us at 40-45% when it's running regularly.

We typically run the insert just in the evenings and over the weekend, so the furnace will run at least first thing in the morning and will keep the humidity comfortable.

The wife has been off of work the last month, so we've been running the fireplace 24/7 and the furnace has only fired a couple times. Humidity has been hovering around 25-30%.

So, not what I would call exceedingly dry. Just am more comfortable at 40% vs. 30%.

I'm hearing a lot that I'd not get much gain without the warmed air from the furnace. One guy told me he has to run the blower almost 24/7 maintain a 10% rise, and I was hoping to get that with running the blower for an hour or so. I'd rather run a console humidifier again than run the blower all the time.

Thanks for all the input!

 

[Hogwildz]

I should have included some numbers in my original post...

I have the furnace humidifier set up to put us at 40-45% when it's running regularly.

We typically run the insert just in the evenings and over the weekend, so the furnace will run at least first thing in the morning and will keep the humidity comfortable.

The wife has been off of work the last month, so we've been running the fireplace 24/7 and the furnace has only fired a couple times. Humidity has been hovering around 25-30%.

So, not what I would call exceedingly dry. Just am more comfortable at 40% vs. 30%.

I'm hearing a lot that I'd not get much gain without the warmed air from the furnace. One guy told me he has to run the blower almost 24/7 maintain a 10% rise, and I was hoping to get that with running the blower for an hour or so. I'd rather run a console humidifier again than run the blower all the time.

Thanks for all the input!

25-30% is not healthy. I skipped running the console last year, as we has a humid milder winter. Just replaced the filters and had to get the console running again. was at 27% and it was just too damn dry, and could feel it in the morning & breathing etc. Now at 40-45%, much better.

 

[Guyerst]

Yeah, that's pretty much the situation we have here.

I think I may still try setting up the humidifier on the furnace to run with the blower. I think 5% more would help, and 10% would be ideal. General consensus is that i won't get much without the heat, but those console humidifiers manage to get a lot of moisture into the air without heat...

Found the humidifier power wire on the furnace card, so just need to google up a schematic to find the blower + wire andput a meter to it to make sure the voltage is ok.

I'll be sure to update with my results...

 

[moey]

Keep an eye out for condensation close to the humidifier. With supply temps being low it will be hard to effectively evaporate water to get it through the entire duct system. The moisture then may just cling to the walls of the duct making a mess. Think putting your had a few inches from the humidifier it gets wet hold it further away and its fine.

 

[woodgeek]

FYI, most home humidity meters are ±10% accurate, and can drift over the years.

Most older (i.e. pre 1990) construction in cold climates is at risk of damage if RH > 35% or so.

I like humidity as much as the next guy, and have a hygrometer I trust, and can't feel a thing until RH gets below 30%. Static and furniture breaking and that stuff starts up at 20% and below.

You guys suffering at 30% RH might just have a cheap-azz meter. All the cheap ones I have owned over-read RH at the low end.

 

[Hogwildz]

I have 3, and they all are within 5 of each other. I disagree with 35%, but not going to debate it. To each their own.

 

[woodgeek]

The number IS debatable and depends on the house, but 40-45% RH is dangerous for many older houses.

The dewpoint at 30% RH is 37°F, the dewpoint at 45% is 48°F. At the first one you might get condensation and mold under the roof sheathing in a poorly airsealed and poorly ventilated attic (a common problem). Even if your attic and framing were tight, in the second case you would have water pouring off single pane windows, or off the storm windows if you had those, and rotting your sills (another common problem).

The health benefits of humidity (mostly less germ susceptibility and spreading) are there at 30-35%. More might be nice when you are sick, but go steam up the bathroom, not the whole house.

 

[stee6043]

Two years ago I installed an Aprillaire humidifier on my furnace. I too needed to use the return ductwork due to my boiler heat exchanger being in the way on the supply side. The Aprillaire (and I'm assuming other brands as well) will run the fan once every 30 minutes or so to check humidity levels and will also manually continue to run the fan to humidify even if you don't have a call for heat.

What you're looking for is exactly that functionality. You may not want to invest in an all new humidifier but the new rigs come with that capability standard. They also have external temperature sensors which allow the system to lower the house humidity when the outside temp drops. This helps avoid moisture on the windows.

I run my humidifier on the second to the highest setting. It can generally maintain mid 40% humidity on an average winter day. On weeks such as last week when highs stay in the single digits it will drop into the low 30% range.

I haven't experienced any downsides to having the unit on the return plenum. Perhaps my fan runs a little longer? Who knows. I plumbed it with hot water and change the filters each year. It's been great.

I hate static...

 

[Hogwildz]

The number IS debatable and depends on the house, but 40-45% RH is dangerous for many older houses.

The dewpoint at 30% RH is 37°F, the dewpoint at 45% is 48°F. At the first one you might get condensation and mold under the roof sheathing in a poorly airsealed and poorly ventilated attic (a common problem). Even if your attic and framing were tight, in the second case you would have water pouring off single pane windows, or off the storm windows if you had those, and rotting your sills (another common problem).

The health benefits of humidity (mostly less germ susceptibility and spreading) are there at 30-35%. More might be nice when you are sick, but go steam up the bathroom, not the whole house.

Been running setting at 45 for 11 years now, was in the attic space last year, no mold, not rot, looked the same as the day the decking was installed. Old homes tend to leak more, bringing in more drier air in the winter so they say. So not sure how they would be worse. If anything, they are going to ventilate more and dry more air than a tight home.
The only way you get rot on the underside of roof decking, is if you have a vented roof system, that is not venting enough. Most causes of roof rot is insulation being run right up to the bottom of the roof decking, soffit vents being blocked by insulation, insufficient ridge ventilation, or lack of adequate venting to start within a ventilated roof system. If you have good venting, you ain't going to get any roof deck condensation or rot, regardless of how much humidity you have. Now if the ceiling has enough air leaks, and not enough insulation, you may get some condensation there, but that would also be noticeable in fairly short time in many cases. You have to have warm air hitting a cold surface, and a properly ventilated roof ain't going to support that.

 

[woodgeek]

Exactly. Attic floor air leaks (unintentional) bring the water vapor in, and attic ventilation (intentional) let's it get out. If the latter is bigger than the former, no problemo. If the former is bigger than the latter, problem.

In my case, my leak in from the house was 15 sq ft, my ventilation area was 5 sq ft. It was that way from 1960 to 2010, and I had dripping wet sheathing and mold over the entire area when the house was no more than 30% RH (the house was so leaky I couldn't get it any higher, despite many gallons of water per day). I think the same happened to BB when he ran a humidifier.

Now my attic floor air leak is prob <2 sq ft, and my attic vent area is probably 15 sq ft, and all is well.

Ice dams went away too.

 

[Rangerbait]

Two years ago I installed an Aprillaire humidifier on my furnace. I too needed to use the return ductwork due to my boiler heat exchanger being in the way on the supply side. The Aprillaire (and I'm assuming other brands as well) will run the fan once every 30 minutes or so to check humidity levels and will also manually continue to run the fan to humidify even if you don't have a call for heat.

What you're looking for is exactly that functionality. You may not want to invest in an all new humidifier but the new rigs come with that capability standard. They also have external temperature sensors which allow the system to lower the house humidity when the outside temp drops. This helps avoid moisture on the windows.

I run my humidifier on the second to the highest setting. It can generally maintain mid 40% humidity on an average winter day. On weeks such as last week when highs stay in the single digits it will drop into the low 30% range.

I haven't experienced any downsides to having the unit on the return plenum. Perhaps my fan runs a little longer? Who knows. I plumbed it with hot water and change the filters each year. It's been great.

I hate static...

I have the same unit and it's been great, also installed on the return due to lack of access to the supply plenum.

At first I was worried that it would draw a lot of power since it calls the blower frequently, my Eyedro power meter shows that the blower only draws about 300 watts...that's a drop in the bucket compared to what the electric heat pump draws on a cold day...had a 380kWh day on Sunday when it stayed in the teens all day and everyone was home :-O. I can't wait to get my wood stove in!

 

[woodgeek]

....that's a drop in the bucket compared to what the electric heat pump draws on a cold day...had a 380kWh day on Sunday when it stayed in the teens all day and everyone was home :-O. I can't wait to get my wood stove in!

On really cold days I can break 200 kWh with my HP and some backup heat (for single digit days). Your number is more likely to be backup strips, no? Have you used the meter to break it out? Perhaps your tstat or defrost setting is calling more backup than needed at low temps.

 

[Rangerbait]

On really cold days I can break 200 kWh with my HP and some backup heat (for single digit days). Your number is more likely to be backup strips, no? Have you used the meter to break it out? Perhaps your tstat or defrost setting is calling more backup than needed at low temps.

I think it's probably more that I have a mass produced 5,000 sq ft house with crappy builder-grade windows and two heat pumps.

 

[woodgeek]

I think it's probably more that I have a mass produced 5,000 sq ft house with crappy builder-grade windows and two heat pumps.

Makes sense, but in cold weather each running flat out is 3 kW, so 2units x3 kW x24 hours = 144 kWh/day. The rest is most likely backup strip heat spiking the demand.

 

[lml999]

The only way you get rot on the underside of roof decking, is if you have a vented roof system, that is not venting enough. Most causes of roof rot is insulation being run right up to the bottom of the roof decking, soffit vents being blocked by insulation, insufficient ridge ventilation, or lack of adequate venting to start within a ventilated roof system.

My house is 22 years old, roof is 3. Full length ridge and drip edge vents. Inspector looked at the house when we bought it last June, saying "you've got great ventilation."

Yea, mostly...except when it snows a lot. Last week we got 14 inches and all the vents were covered. A couple of days ago, as it was warming up, I heard rain in the attic. The inside roof surface on the north side of the house was soaked, and the pattern clearly showed condensation rather than a leak... On the south side, we have full solar coverage, which kept the snow off the roof and some airflow on the shingles. Might also have kept the drip edge vents clear. South side roof surface was dry.

So...I will probably have to add soffit vents in the spring.

Sigh...