[HaroldCrump]

I'm planning to install a central humidifer (the kind that plugs into the central heating system).
What features to look for when shopping for such humidifiers?
Any recommended brands?
Anything to watch out for?

 

[brad]

Do you really need to humidify your entire house, or just certain rooms?

We've found that the best ways to keep our house (and the rooms that we occupy most) in winter are:

1. Make pasta frequently. If you leave your hood exhaust fan off (not normally a good idea, especially if you cook with gas), the steam will raise humidity throughout much of your house.

2. Instead of using the dryer, leave your washed clothes to dry on racks. I also do this to humidify the closet where I keep my uilleann pipes (Irish bagpipes, whose reeds are very sensitive to dryness) -- I just hang a pair of wet corduroys in there and the humidity climbs to 50% or higher in no time.

We also have a couple of humidifiers that we use in individual rooms when the humidity gets too low. The best (but expensive) is the Venta, which is what we use: no filters to clean, very simple but effective system. They're available in Ontario from several dealers. The higher purchase price is offset by the lack of need to buy filters, although you do need to buy some special cleaning fluid (which works incredible well) and an additive to the water if your water is hard. I've been using mine for 8 years now and it's fantastic. I only run it when we're in a long cold snap and the house humidity drops below 35%. Normally the humidity level in our house, even in the depths of winter, is around 40% but that's because we keep it cool...16 at night and no more than 19 or 20 during the day. I work at home, and sometimes jack the heat in my office up to 21, but that's it.

 

[Dana]

We have a Honeywell humidifier attached to our furnace. We had the same type of humidifier in our last house as well. If you have dry skin this appliance can be a life saver. If you keep it set too high, though, condensation will start to form on the inside of your windows. Also, the humidifer only benefits you if the furnace fan is blowing so if you like to keep your house cool and your furnace isn't on very often you may have to turn the fan on to increase the humidity.

Our humidifier has a cylindrical-sponge-thing (not the technical term) that rotates around and around soaking up water. This sponge thing needs to be changed every couple of years and costs about $5.99.

 

[high octane]

Isn't it easier to heat dry air? I've always thought you want a dehumidifier in the winer, as my windows always have condensation. Maybe its just where I've lived

When I rented from an old lady in SK she would disconnect the dryer vent to keep all that humidity inside.

I thought she was crazy but if you want humidity, your dryer is dumping it outside so why pay

 

[HaroldCrump]

Thanks brad, Dana and high octane.
brad, to your point - yes, I feel we do need a central humidifier because of several reasons - dry skin, newly installed hardwood floors, etc.
We have managed using the room humidifiers for over 5 winters now and I think it's time to put in a more permanent solution.
The RH inside the house stays below 40% most of the winter and during Jan - Feb often falls below 30%. I feel this is too low.
I would like to keep it between 35% - 45%.
We put in new hardwood this summer and humidity below 30% is not going to be good for it.

 

[raisacombs]

I need some humidifiers for my apartment, because it is very dry. I wanted to know what the difference was between the two, and which one is best for this type of issue. Thank you!

 

[OhGreatGuru]

You might be better in the long run to test your house for air leakage, and seal it better. Outside air in the winter is very dry, so if you are drawing in more fresh air than you need this lowers indoor relative humidity. A leaky house also wastes energy. Those furnace add-on humidifiers used to be common, but are becoming rarer as our houses have become more air-tight.

 

[Dr_V]

You might be better in the long run to test your house for air leakage, and seal it better. Outside air in the winter is very dry, so if you are drawing in more fresh air than you need this lowers indoor relative humidity. A leaky house also wastes energy. Those furnace add-on humidifiers used to be common, but are becoming rarer as our houses have become more air-tight.

This is exactly what I was thinking about (with respect to this thread), but had held back from posting.

As OGG pointed out, if your humidity is low, rather than spending money on a humidifier, I think that you should consider asking yourself where your building envelope is allowing the humidity to escape. Likely culprits include:

- doors
- fireplace(s)
- electrical outlets
- windows
- attic insulation
- vents (furnace, drier, bathrooms)

The insulation of many of these items can be dramatically improved without much cost and without too much handyman knowledge.


K.

 

[HaroldCrump]

While the above facts about air-leakage and lack of insulation are true, the single biggest cause of lower RH during the winter months is central heating.
Heated air is very dry and sucks the humidity out of indoor air.
It is a delicate balance between humidifying your house during winter months and risking too much condensation.
If the humidity increases beyond a certain level (different for every house), you will get condensation on external facing glass surfaces, esp. early mornings.

Air leakage is also like looking for perfection - how do you know when to stop and how much money to spend air-tighting your house before you stop.
Can you completely eliminate air leakage?

Anyhow, for now I'm using my warm mist room humidifier - just haven't had the chance to look into built in humidifiers during the holidays.

 

[Berubeland]

While the above facts about air-leakage and lack of insulation are true, the single biggest cause of lower RH during the winter months is central heating.
Heated air is very dry and sucks the humidity out of indoor air.

True but a lot of things add moisture to the air, showers, cooking, and even your breathing adds about one litre per person per day to the air

It is a delicate balance between humidifying your house during winter months and risking too much condensation.

Indoor Air humidity around 45 to 50% starts growing mold

If the humidity increases beyond a certain level (different for every house), you will get condensation on external facing glass surfaces, esp. early mornings.

Not only on glass but wall surfaces and closet surfaces etc.


Air leakage is also like looking for perfection - how do you know when to stop and how much money to spend air-tighting your house before you stop.
Can you completely eliminate air leakage?

Yes many new homes were so airtight people started getting sick building syndrome because of the poor air quality. New homes that are very airtight are now equipped with an air exchanger. New gas furnaces and hot water tanks also tend to take their air from outside now.

Recommendations from Government and Health Agencies are for 6 complete air exchanges per day for a home occupied by a family of four. In older homes we really don't need to worry about changing the air but maintaining the balance between leakage and energy efficiency and obviously humidity.

Now my husband and son had a cold and a cough that lasted for a while and the Dr recommended extra humidity but... once we bought two with humidistats they don't even cycle.

 

[HaroldCrump]

Indoor Air humidity around 45 to 50% starts growing mold

Are you sure about that?
I thought it needed more than that to cause mold - perhaps in the 65% + range.
Indoor RH around 50% is normal during summer months anyway.

Yes many new homes were so airtight people started getting sick building syndrome because of the poor air quality. New homes that are very airtight are now equipped with an air exchanger.

I don't think our home is equipped with such a device - it's a 7 year old home, not sure if it qualifies as "new".
Do you know if it's possible to install an air-exchanger into an existing HVAC system?
What are such systems called and can you recommend any specific brands or types?

Recommendations from Government and Health Agencies are for 6 complete air exchanges per day for a home occupied by a family of four.

Are installing those "air-exchangers" the only way?
I confess I sometimes open one of the windows during milder afternoons to bring in some fresh air.

 

[Berubeland]

Yeah I am sure of it. Recently I had to purchase those air humidifiers because my hubby and baby had a cold I had to know what the "proper" humidity level was to keep it at and that was one of the warnings. Humidity over 50% can cause mold in fact in my bedroom when the thing is going at 50% my window gets full of condensation.

7 years old is a new home. The problems started when they were building the new R-2000 homes. I'm not sure how airtight your home is but being 7 years old it'll be a lot more airtight than my house built in the 60's. What they found was that the VOC's from furniture and carpet and radon and other stuff was building up in the air making people sick.

Yeah I'm pretty sure you can install an air exchanger and they probably even have some that humidify the air or remove humidity if you need that. I don't know any brands that might be better honestly almost everything I learned about it I learned from This Old House lol They did have an excellent program on it 4-5 years ago.

Opening the window changes the air in your house as does opening the door the benefit to these air exchangers is that they remove the heat/cold from the outgoing air and transfer it to the incoming air saving energy.

I think how much you spend depends on how severe the problems are and how much it bothers you.

 

[OhGreatGuru]

I thought it needed more than that to cause mold - perhaps in the 65% + range.

No, in our climate (outside of Lower Fraser Delta area), indoor humidity in winter should be less than 50%, and in colder regions as low as 30%. The trouble is the temperature at the wall, at the window, and inside the walls is less than room temperature. So in those locations the relative humidity goes up, until it reaches the dew point, at which time condensation forms. (The ability of air to hold water vapour is inversely proportional to temperature.) See NRCAn publication at http://www.oee.nrcan.gc.ca/residential/personal/moisture-problems.cfm for a good discussion on this topic.

Do you know if it's possible to install an air-exchanger into an existing HVAC system?
What are such systems called and can you recommend any specific brands or types?

Generally yes, and they are called Heat Recovery Ventilators (HRVs)
See NRCan guide on HRVs at http://www.oee.nrcan.gc.ca/Publications/infosource/Pub/hrv/ You can also download it in PDF.

 

[OhGreatGuru]

While the above facts about air-leakage and lack of insulation are true, the single biggest cause of lower RH during the winter months is central heating.
Heated air is very dry and sucks the humidity out of indoor air.

Not quite true, although people often think of it that way. Heating, in and of itself, does not take any moisture out of the air. But the relative humidity goes down, because the warmer air is capable of holding more water vapour. The biggest cause of low humidity is winter air plus excessive air exchange. The outdoor air in winter is naturally "dry" compared to summer air, and when warmed up to room temperature it has a very low relative humidity. If you had no air exchange in a house though, the humidity would gradually buildup up from cooking, bathing, breathing, etc. In a tightly sealed house in our climate you actually need to add ventilation to control excess humidity (and also to control air quality). But we tend to associate low humidity with central heating because, before the advent of sealed combustion furnaces, the central heating system was forcibly introducing more air exchange in our houses than was really necessary.

 

[HaroldCrump]

I thought it needed more than that to cause mold - perhaps in the 65% + range.

No, in our climate (outside of Lower Fraser Delta area), indoor humidity in winter should be less than 50%, and in colder regions as low as 30%.

Even with a room humidifier, I have trouble maintaining indoor RH at 40%.
With the humidifier running pretty much 24x7, it still stays in the 35% range.
If I don't use the humidifier, RH often dips to 28% during the two months of Jan - Feb.
Based on your comments, should I just leave it as is and not bother about humidifiers at all?
For some reason, I always believed (maybe wrongly) that RH below 40% is bad for wood furniture, hardwood flooring (which I have), our breathing and skin.

 

[OhGreatGuru]

Based on your comments, should I just leave it as is and not bother about humidifiers at all?
For some reason, I always believed (maybe wrongly) that RH below 40% is bad for wood furniture, hardwood flooring (which I have), our breathing and skin.

You are correct that low RH is hard on skin, wood furniture, etc. (I hadn't heard it was a particular problem with flooring though.) But it is an unavoidable consequence of heating our homes in our winter climate. People who crank up the humidity because they don't like the dryness don't realize what they are doing to the structure of their home until it is too late. Read the NRCan and CMHC guides on the subject.

 

[brad]

FYI, here is a link to the CMHC article:

http://www.cmhc-schl.gc.ca/en/corp/nero/retousar/2009/2009-08-14.cfm

They do say it should drop to around 30% in winter. Personally, I find anything below that starts to be a problem in terms of dry skin, cracking furniture and beams, and especially in terms of damage to musical instruments. Our house is running around 35-40 percent right now with no humidifier running, but we keep it relatively cool here, never higher than 20 and down to 16 or 17 at night.

On the other hand, our basement has the typical problem of too much humidity in summer (it's fine in winter). Nobody ever ran a dehumidifier down there before we bought the house, and the result is that the beams are full of dry rot; you can plant a screwdriver deep into any of the beams with little effort. It's going to cost us a lot of money to replace the beams and sills; they've been reinforced but we're starting to see a few cracks in the walls from settling.