Humidifier Help

I have a natural gas furnace with a Honeywell pass through style humidifier installed on the cold air return with a bypass to the hot air output.

I have it so configured so that the water flows through the humidifier when the furnace fan runs and the humidistat calls for humidity. The fan is set to run constantly.

My problem is that I can't get the humidity inside the house above about 33%. My goal is for 40%-45%.

I have 3 digital hygrometers that all show the humidity around 30%-35%.

I even got a 2nd whole house console style humidifier yesterday that I've been running in conjunction with the furnace humidifier and so far still haven't seen a difference.

The house is about 7 years old, and as far as I can tell, sealed pretty tight.

The furnace runs about 6 1/2 hours a day to maintain the temperature at about 68-70 degrees but the fan runs 24/7.

What can I do to raise the humidity to proper levels?

Thank you.

Re: Humidifier Help

The cheaper furnace humidifiers are usually connected to the hot side of the furnace. Our old furnace had one with a wheel that was the evaporator pad that spun connected to the hot air duct going to the vents in the house. We could easily get over 50 percent with that unit however when temps dropped below zero there was a ton of ice on the windows.

Re: Humidifier Help

I'm confused how does it work on the cold air return,doesn;t seem right or is it just a sensor on the cold return

Re: Humidifier Help

It confuses me too, but I've found several different manuals online for humidifiers (same as mine and other brands) and they all say it is best to install it on the return side.

Seems to me that as the humid air goes through the burner, it would dry right back out...

When the humidifier runs without the burner (just the fan), it's basically the same as a console style humidifier so I can understand a benefit there.

Re: Humidifier Help

We haven't used a humidifier for many years ... a couple houses ago. But when we did, I installed it. As I remember, it hung on the warm air side and had a wheel with a foam evaporater pad (%#@! to clean!). It had a hose like a plastic dryer vent that went from the cold air return to the humidifier. Normal air flow down the cold air return caused some of the cold air to divert through the humidifer and mix with warm air back to the house. We could easily get the house humidity WAY up with that. The only thing keeping window frost under control was that we also had a high capacity wood stove that otherwise dried the house air to be desert-like. Somehow, after playing around with it over a few months, I was able to balance the two so everything was good -- we kept the furnace fan on all the time to circulate house air, and I played with air registers, louvers, and dampers to pull some of the family room (ie wood stove heated) air through the whole house (not terribly successful but that was my goal).

It would seem to me that a humidifier on the cold-air return could be costly and dangerous. Think about it. If you're introducing moisture (humidity) before the air goes through the heat exchanger, how much additional rust will happen? And that will eventually lead to a leak in your exchanger requiring premature furnace replacement.

I'm certainly no expert, but this seems logical to me. If someone else really knows, I enjoy being educated.

Re: Humidifier Help

Another thing is typically when you are cooling a house you want the blower fans on all the time. When heating a house you do not want this because the thermostat could be at 70 and the fans will be blowing cold air which will create a windchill in the house. Blowers should stay on for a about a minute after the burners shut off and not turn on again for about 20 to 30 seconds after the burners fire.

Re: Humidifier Help

Thanks for the comments.

Eurolarva, I don't think I agree with you about running the fan only in the summer. I think running the fan year round keeps the temperature in the majority of the house more consistent. That being said, we don't spend a lot of time in the basement, so if it's cooler downstairs, and warmer upstairs, that's not such a bad thing...

I've seen those roller pad style humidifier you guys are talking about. This is a little different than that. It's a pad of material that fits inside of a bracket. Water flows in the top and flows through the pad in to a condensate drain. The back of the pad is open to the air duct and the front of the pad has warm air from the pass-thru vent pushing the warm air through the pad.

It looks a lot like the attached picture.

So, more to add on to the story - since I got that 2nd humidifier, yesterday I saw the humidity level actually get to 42%! Now, I'm not sure if that's because the outside humidity went to 50% or not but after everything was looking better, the console style one stopped working! It just won't turn on... AARRGGHH!!!

Guess I'll go exchange it tomorrow...

Re: Humidifier Help

i have that same style as in the picture..i think its humidaire...my fan only come on when theres a call for heat..and i dont have any accurate way to check the humidity in the house..but when i first moved in it did not seem to work at all...i soon found out that the valve for the water was off..i 've been told by a hvac guy that the valve should only be on a little bit...after i turned the valve on it dtill did'nt seem to turn on and i have a test setting on the humidistat..i wired a 24 volt transformer to the valve and tried it like that for a bit...it worked but it was always on...its now hooked up properly and turns on for about a minute when the furnace first fires up...i know theres some humidity in the air cause the storm door fogs up almost immediatly now...ok i dont think any of this was helpful but good luck!
rob

Re: Humidifier Help

I would think it should be wired so it's on only when the furnace fan is on.

This kind is much better than the rolling pad I had a dozen years ago, but it also wastes more water.

Like I said before, I'd be very concerned about increased corrosion in the cold air return below it, the fan and fan motor, and the heat exchanger. Those aren't designed to have high humidity. Be sure to inspect and lubricate them faithfully. Does the humidifier manufacturer provide any warning or warranty for consequential damages?

A house we owned 30 years ago had this kind of humidifier (that was an April Aire) and it had no problem keeping the humidity so high every window was always almost completely frosted (I was so ignorant back then).

Thanks for the photo. Something's not right if you have such a problem getting humnidity up. Do you have a major air leak somewhere letting in much drier outside air? The only other thing is the question that do you *really* want your humidity level that high? Most homeowner magazines and expert web sites all say the optimum is much lower (depending on outside temperature).

Re: Humidifier Help

Thanks, Arboldt.

The humidifier does only run when the fan is running.

The humidity level seem to stay around 30% all the time, while that's not horrible, I'd like to have it closer to 40%. My wife complains constantly about dry skin so anything I can do to to raise the humidity helps.

I'm not aware of any sources of major air leaks, and really don't think there are any because over the past few days we've been getting snow. The outside humidity has been about 40% but the inside humidity stays at 30%. If there was a leak, I'd think the inside humidity would match the outside.

Is there a better way to check for air leaks other than the obvious sunlight around doors and feeling drafts?

I appreciate everyone's comments.

Re: Humidifier Help

as i said i know my humidifier is working but the wife still complained it was to dry..i got a small one to put next to the bed...look for air leaks with smoke..a cigarette works well...maybe incense...i doubt u have a major leak though u would have noticed that...or so i'd think...

Re: Humidifier Help

After discussing with 'our' heating guy here, he feels that the reason your humidity level is still low, is because you're running your fan all the time. It never gets a chance to catch up, because as soon as the burner shuts down, the humidifier does too. I've never heard of anyone running the fan all winter long -- other than ceiling fans. Mine never shut-off except for cleaning, and to change direction for winter/summer.

With your furnace fan running constantly, it's definately drying out your air more than a ceiling fan would. My ceiling fans (set to low) move just enough air to keep the area temp steady. But a furnace fan blows HARD... HARD for heat, or HARD for just the fan setting. It's designed to move a lot of air, in a hurry. Keeping in mind, it also moves a lot of air next to a cold wall, or windows, thus drawing the cooler air off of the windows or doors too. Keeps moisture down on the sills, but it doesn't sound like that's a problem.

Just for fun, try turning the fan to auto, instead of on only. If you have a ceiling fan, turn it way down, and let it run. (mine make a full rotation about every 2 or 3 seconds, to give you an idea.) Let the humidifier run as you normally do, and wait a couple of days, and check your humidity level.

With your in-plenum humidifier, does it give you any issues? I've heard water quality can determine how well they work/don't work. At one time, I did have hard water, but then installed a softener, and I am considering installing an April-aire....

Re: Humidifier Help

All of those in furnace humidifiers are bad for the furnace, and everything else. Shut it off and buy one of those "cabinet style" ones like I have. There cheap, reliable, and your house humidity will be just fine. If you have a two story house you may need one on each level.

Re: Humidifier Help

40% humidity is too high for the winter. Asking for a mildew problem above 35%

Do you have a HRV? no way to humidify a home more than about 30% with one of those going.

Where's the humidistat?
A lot of lazy furnace installers put them on the furnace. It should be in the living room or hallway to the bedrooms.

Re: Humidifier Help

My last house was forced hot air w/central AC. I installed both the AC and an AprilAire humidifier. The humidifier was a water pass through design so no standing water to develop lime scale. The humidifier was installed on the hot side for a couple of reasons. 1. and most importantly, the hot air aides greatly in evaporation. B. Less to no condensate accumulation on the cold side where mold growth can become an issue.

Using this approach, you could set the humidistat to just about any relative humidity and maintain it. However, you want to control relative humidity based on outside temps to reduce window condensation.

The humidifier fan is only strong enough to cause the main airflow to go through the pad. It can't work by itself. It runs when the furnace blower is running, if the humidistat calls for moisture.

Re: Humidifier Help

newbie4life said:

After discussing with 'our' heating guy here, he feels that the reason your humidity level is still low, is because you're running your fan all the time. It never gets a chance to catch up, because as soon as the burner shuts down, the humidifier does too. I've never heard of anyone running the fan all winter long -- other than ceiling fans. Mine never shut-off except for cleaning, and to change direction for winter/summer.

With your furnace fan running constantly, it's definately drying out your air more than a ceiling fan would. My ceiling fans (set to low) move just enough air to keep the area temp steady. But a furnace fan blows HARD... HARD for heat, or HARD for just the fan setting. It's designed to move a lot of air, in a hurry. Keeping in mind, it also moves a lot of air next to a cold wall, or windows, thus drawing the cooler air off of the windows or doors too. Keeps moisture down on the sills, but it doesn't sound like that's a problem.

Just for fun, try turning the fan to auto, instead of on only. If you have a ceiling fan, turn it way down, and let it run. (mine make a full rotation about every 2 or 3 seconds, to give you an idea.) Let the humidifier run as you normally do, and wait a couple of days, and check your humidity level.

With your in-plenum humidifier, does it give you any issues? I've heard water quality can determine how well they work/don't work. At one time, I did have hard water, but then installed a softener, and I am considering installing an April-aire....

Click to expand...

Thanks - Some good ideas here.

Originally, the humidifier would only run when the burner was on... I "fixed" that. The humidifier now runs whenever the furnace fan runs and the humidistat calls for humidity.

I'll try setting the furnace fan to auto and put the ceiling fans on low.

I won't know for a few days though because it's been raining so the humidity inside is at a good level now...

Re: Humidifier Help

Caveman Charlie said:

All of those in furnace humidifiers are bad for the furnace, and everything else. Shut it off and buy one of those "cabinet style" ones like I have. There cheap, reliable, and your house humidity will be just fine. If you have a two story house you may need one on each level.

Click to expand...

I tried a Honeywell unit for several days (like the one in the picture)... it may have made a small difference (2-3%), but then it broke... I may try to make a trip to the hardware store tomorrow to replace it.

It's kind of a pain having to fill it up once or twice a day though and from what I hear, these things can grow a lot of mold really fast.

Re: Humidifier Help

whywhyzed said:

40% humidity is too high for the winter. Asking for a mildew problem above 35%

Do you have a HRV? no way to humidify a home more than about 30% with one of those going.

Where's the humidistat?
A lot of lazy furnace installers put them on the furnace. It should be in the living room or hallway to the bedrooms.

Click to expand...

I don't exactly know what an HRV is (Heat Recovery Vent?). If it helps, I do have a vent outside that goes through an insulated duct into the air return that goes to the furnace.

The humidistat is in the finished basement area not on the furnace.

You might be on to something - thanks!

Re: Humidifier Help

I think Whywhyzed might be on to something.

I have a fresh air duct that goes in to the return air plenum.

I was chatting with the HVAC guy at work today about that and he suggested that I should block that off when the heat is running. The fresh air duct doesn't have a damper in it, so I'm planning on installing one.

Am I going to do any harm by closing off the outside air duct into the return air plenum in the winter?

Re: Humidifier Help

Running the fan all the time will not dry the air out unless the heat is on with it. I use a General 1040 bypass Humidifier hooked up to the plenum and I can get 50% if I want it. I also run the blower year round so that the temperature level is more consistant and the humidifier is hooked up to run when the blower runs if the humidistat is calling for more humidity. I also use an electronic air filter which can only work when the blower is running. I do all this because having 27 years as a HVAC tech has taught me a few things...