Humidifier

[alpha]

I have an electric heat pump and gas forced air furnace. The furnace has an Aprilaire humidifier installed and it is working properly. The only problem is when the outside temperature drops below about 30 degrees the humidifier does not add enough humidity. The humidity levels drop to around 20% and it really needs to be above 30%. That seems to be a fairly common problem with that type of humidifier.

In our area of the country the maximum length of time the temperature stays below 30 degrees is about 2 weeks. That's a "cold snap" for us. We usually have several "cold snaps" a season. I was thinking that a portable humidifier would help bring the humidity levels up to a more comfortable range during those short time frames.

I know the protable ones must be cleaned, disinfected, etc. Does anyone have any experience with portable ones that have better performance and they would recommend?

[pierhogunn2]

if you have CVS pharmacy in your neck of the woods, they are selling the cheap old steam humidifiers for >$17.00, I picked up 2 last night and I have run them for about 10 hours now, and can feel quite a difference in my comfort...

you may have to clean them, but they are dirt cheap, and easy to use

[cgallery]

Don't you have a humidistat connected to the central humidifier, where you can adjust the humidity based on the outside temperature?

The colder it is outside (typically), the less humidity you want INSIDE, as too much will condense on windows and other exterior wall surfaces.

[master53yoda]

the aprilair humidifier will only work when the gas furnace is operating. it requires over 120 degree discharge air temp. to add any amount of moisture to the airstream. the discharge air temp. in heat pump mode is only about 95 to 100 degree. Heat pump humidification reguuires steam injection in order to work. your best bet is what pierhogunn2 suggested. As long as the interior Humidity is between 30% and 40% you won't have static problems and should not have any condensation problems. place the steam humidifier close to a return air duct and it will provide a good air mix for the whole house.

[Kristofor]

The colder it is outside (typically), the less humidity you want INSIDE, as too much will condense on windows and other exterior wall surfaces.

Agreed, but the total amount of water that needs to be added increases significantly as the temperature goes lower. Raising -20 degree air that was dry to begin with, up to 70 degrees (in the house, 120+ in your furnance) will make it bone dry. However, that effect is much less noticable going from (a usually much more humid) +30 to +70.

Alpha, I'm wondering how you know it's working fine if the temps at which it would normally be most noticable it appears to not be working? Can you tell how much water it's dispensing per day? Using a room steam humidifier when it's cold/dry (below 0) we generally put ~3-5 gallons of water into the air per day. With warmer more humid weather with temps near 30 that might be as little as a gallon or two to keep the same relative humidity. This is on top of showers, cooking, etc. on a relatively tightly sealed (7yrs old) house, but one which does have a fresh air intake always open...

the aprilair humidifier will only work when the gas furnace is operating. it requires over 120 degree discharge air temp. to add any amount of moisture to the airstream. the discharge air temp. in heat pump mode is only about 95 to 100 degree. Heat pump humidification reguuires steam injection in order to work.

Your suggested fix of using an external steam humidifier sounds like a quick, easy, and cheap solution.

Your description of the operation of the built-in humidifier makes it sound like the system would work the best during a "cold snap" when the gas furnace was more likely to be used than the heatpump. The described behavior/symptoms are opposite of this. I am wondering how best to assess if the built-in humidifier is indeed operating correctly. I have never had one of these in a house where I have lived so I cannot offer any direct insight.

[alpha]

Don't you have a humidistat connected to the central humidifier, where you can adjust the humidity based on the outside temperature?

Yes. I have a new heat pump with a new thermostat. You can choose one of two settings; manual or automatic. Auto is based on the outside temp. while manual is supposed to be a fixed percentage. Mine is on manual and the highest setting which is 46%.

The colder it is outside (typically), the less humidity you want INSIDE, as too much will condense on windows and other exterior wall surfaces.

That's right. If you have condensation inside your windows, you have too much humidity which could actually cause a mold problem in your walls and attic.

Bob

[scmhogg]

Out here, we have the reverse. It is very dry in the summer and more humid in the winter. On extremely dry days, I put a stock pot full of water on the stove.

Steve

[alpha]

Alpha, I'm wondering how you know it's working fine if the temps at which it would normally be most noticable it appears to not be working? Can you tell how much water it's dispensing per day? Using a room steam humidifier when it's cold/dry (below 0) we generally put ~3-5 gallons of water into the air per day. With warmer more humid weather with temps near 30 that might be as little as a gallon or two to keep the same relative humidity. This is on top of showers, cooking, etc. on a relatively tightly sealed (7yrs old) house, but one which does have a fresh air intake always open...

I called the guy that installed the heat pump and he changed a setting on the thermostat so the water would run as long as the fan is running and the actual humidity is below the setting (46%). The fan is running constantly, not on automatic. Most of the time humidifiers come on with the blower. The water drains outside the house and it is constant. I replaced the water panel inside the humidifier and it is wet, so it is working correctly. When the air heats from the furnace it circulates through the humidifier and goes back into the air intake again through the system. It is adding plenty of humidity except during a "cold snap." I think ideal humidity is between 35-45%. When it gets down to 20%, it is too dry. That's why I was hoping to find a good portable humidifier to use occasionally during the winter.

Your description of the operation of the built-in humidifier makes it sound like the system would work the best during a "cold snap" when the gas furnace was more likely to be used than the heatpump. The described behavior/symptoms are opposite of this.

I know it is counter intuitive, but the colder it is outside the less humidity the humidifier puts out.

[Shep]

We've got a nice filterless humidifier that we use when the air gets a little too dry. The brand name escapes me but it does a great job. It basicly turns the water into a rich steam, which can handle a mid size room without problems. We also have a filter type humidifier that we use in our daughters room. I really hate the filters. You have to keep them clean or replace them often.

[cgallery]

We've got a nice filterless humidifier that we use when the air gets a little too dry. The brand name escapes me but it does a great job. It basicly turns the water into a rich steam, which can handle a mid size room without problems. We also have a filter type humidifier that we use in our daughters room. I really hate the filters. You have to keep them clean or replace them often.

So, the filter-less humidifier, there is nothing you need to do with it (ever) except add water?

This has been an enlightening discussion.

[master53yoda]

A pad type humidifier is designed to operate above 120 degrees because it takes that high a temperature to get evaporation. the only way that that type of humidifier will work on a heat pump is if it is connected to a hot water line putting 120 or higher degree water on the pad. If you then run the water at all times the fan is running it will increase the humidity but your are paying more because you are wasting hot water from the water heater. If the water line going to the humidifier is hot then what the contractor did will increase the humidity but raise the energy usage by how many gallons it dumps outside. If it is cold it wont do anything. the small humidifier that i suggested placing by the return is 100% energy efficient because the energy that doesn't go into vaporizing the water goes into the air stream. On my own heat pump systems I re-pipe the coil to run the hot refrigerant discharge line through the humidifier pan which increases the water temp to about 150.

the filterless humidifiers have heaters in them that vaporize the water and discharge saturated steam. commercial AC humidifiers like what are used in electronics rooms have electric heaters in the pans.

[Shep]

Yep not much cleanup. Or at least there doesn't appear to be, and I've read the manual. The setup just has a water reserve that channels into the basin. Once it enters the basin it heats it up and turns to steam. When you're out of water, you're out of steam. The only cleanup I do when I put it away for the summer is to turn it upside down (to let any remaining water drip out) and air dry. You should probably also clean the heating element. I think our unit cost around $45-50.

Here is what mine looks like; however, I think it's been replaced with this model.

[Woodshark]

I'm a big fan of the cool mist ultrasonic humidifiers. We have two that run full time during the winter. The mist is cool so there is no danger of a steam burn, plus they don't heat the water so there is a energy savings there.

Our first was the type that used a wicking filter membrane. Yuck. It became moldy and gunked up within a month.

With this type there is no maintainance and no replacement filters to buy, just fill up the tank about every 12 hours.

Ours are much older but this model looks like a good representation of the type.

http://www.amazon.com/Kaz-5520B-Pers...995720&sr=8-34

[phi1l]

... they don't heat the water so there is a energy savings there.

ummmm .. I hate to break it to you, but there is no energy savings. the energy is going into generating sonic waves instead of heat., There is no free lunch there, the First Law of Thermodynamics has not been repealed.

[Kristofor]

Agreed, on the thermodynamics.

I don't have one of these models but if they are simply forming small droplets which then evaporate when put into the air this may well require less energy, from the humidifier.

However, humidifiers are generally used during the heating season around here. If you're trying to hold the room temp above some set point then the energy of vaporization needs to come from somewhere else if it's not provided by the humidifier. The energy "saved" in that case simply comes from the furnace instead.

If you're not trying to keep the temp up, then I guess it's just a fancy, small, indoor swamp cooler