Humidifier addition to a gas furnace
I want to add a humidifier to my gas furnace.
Any recommendations will be helpful.
If you have had good or bad results from a humidifier please post details.
I want to add a humidifier to my gas furnace.
Any recommendations will be helpful.
If you have had good or bad results from a humidifier please post details.
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Replies
FLo-tech type.. Install on plenum.
If it's a standard forced-air upward-blowing furnace, this is one of the most straight-forward installs for a humidifier.
The important thing is to evaluate beforehand how much space you have for the unit. The typical humidifier is about 16x16 inches, and you need that much space available on either the cold air duct entering the furnace, or (preferred) the hot air duct leaving the furnace.
There are two basic types of humidifiers: One type contains a built-in fan to run the air through the "medium", and needs only be connected to one duct.. The other type uses the pressure differential between the cold and hot air ducts to move the air through the "medium" and employs a small (maybe 3" diameter) duct between the two air ducts.
All humidifiers, of course, need a water supply, and most more modern units need a drain connection as well, since they intentionally "spill" water to reduce lime buildup in the unit. If you don't have an available drain nearby, however, you can rig a "condensate pump" to pump the drain water up and over to the nearest drain.
So evaluate where (hot or cold duct) you have space for the unit, and how close the required water and drain connections are, then begin to choose a unit. Which style of unit you use depends a fair amount on the constraints imposed by the ductwork, etc.
It don't matter if its an up, down ,in ,out, or whatever type of unit ,as long as it has an air movement to the registers.
If the water vapor from the humidifier comes in contact with the air that is being delivered (impregnated) then it will most certainly be humidified, and carried along the ductwork and into areas of the house.
A downdraft unit will generally have the hot air plenum under the floor, not a convenient place to mount the unit. Not all units can be mounted (and work effectively) on the cold air plenum.
The Jenair's can be mounted on either, but you still have to run the "bypass" to the supply plenum.Having looked inside hundreds of the "tray of water & fan type," I'll never install another one. They are almost always somewhere between mildly and completely disgusting, unless rigorously maintained and cleaned.I don't know about yours, but my church isn't a hotel for the holy, it's a hospital for sinners
Sojourners: Christians for Justice and Peace
Yeah, like I said, there are several types of humidifiers. The bypass type generally lets you put the unit on either duct. But again, with a downdraft unit, the output duct is basically below the floor, so running the bypass may be a problem.The tray style units are fairly rare any more. Units like the non-bypass Aprilaire 700 use a continuous flow medium just like the bypass units. They just add a fan to provide the airflow without the need for the bypass.
>>non-bypass Aprilaire 700 use a continuous flow Ahhh. I don't think I've seen any of those. I'll have to take a look so I don't embarrass myself when I do run across one: "This doesn't look right to me -- all of the AAs I see have the bypass."Thanks!I don't know about yours, but my church isn't a hotel for the holy, it's a hospital for sinners
Sojourners: Christians for Justice and Peace
As long as moisture is introduced into the air stream, it makes no difference whether its installed on the supply or return.
For a bypass unit it can be mounted on either hot or cold duct, since hot air will always pass through. For a fan-type unit, if it's mounted on the cold duct it won't evaporate as much water. (I'm guessing effectiveness is cut in half.) Aprilaire allows their fan unit to be fed hot water in this case, but other brands aren't rated for hot water.
They don't necessarily have to be mounted on the plenum. There are many types that can be mounted on the Main trunk line (supply or return.
Most units need to be mounted on a vertical surface. You are correct that this need not be the main plenum, or even the main trunk, for that matter.Requirements are sufficient surface area for mounting (around 16x16 for most), availability of water (possibly hot, depending), availability of a drain or facilities for a condensate pump, and, for bypass units, a suitable way to route the bypass duct between supply and return ducts. It's also a good idea to have the unit in a "leakage OK" area, especially if on a condensate pump.[Forgot to mention]Also, most units need some sort of power, though for bypass units this can usually be tapped off the furnace transformer. A fan current relay is also probably needed in the case of a fan-based unit. This can lead to some complex wiring.
Edited 11/29/2004 9:56 am ET by DanH
16"x 16" ? space for a humidifier. ?? I don't think so.
You can put 2 or 3 of them in that space.
16 x 16. geeez.... lol.
>>16"x 16" ? space for a humidifier. ?? I don't think so.
>>you can put 2 or 3 of them in that space.Not the one's I mostly see - 16" x 16" is about right.I don't know about yours, but my church isn't a hotel for the holy, it's a hospital for sinners
Sojourners: Christians for Justice and Peace
I installed a Honeywell unit at my last house. Was the type that had a duct that fed from the cold air return into the unit and then the unit was mounted on the hot side plenum - I think
One thing I was told when looking at that time was to get one that had a probe that read the outside temp - then some how adjusted the humidity accordingly.
Sorry - memory is a bit foggy, but, that is what I remeber now.
was not too difficult to hook up and definitly helped in the Minnesota winters
How old is the house?
Contrary to popular opinion, furnaces do not dry out the air in a house.
Living in a house adds moisture: cooking, cleaning, even breathing.
The warmer the air, the more moisture it will hold, and, as it leaks out of the house, cold air comes in to replace it. (Called air exchange.)
All the furnace does is convert the incoming dry cold air into warm dry air.
So, if your house is getting too dry, the first thing to do is to improve the weatherization - cut down on the air exchange rate and the moisture will stay in the house longer and you'll save on your heating bill.
If you really do need a humidifier, get an evaporative-drip type, like the Aprilaire:
http://www.aprilaire.com/category.asp?id=F16F78145781484A8A7C756B87F43AB3
and see http://www.aprilaire.com/pdfs/10005406.pdf
Mount the unit on the cold air return and use 6" duct for the "bypass" to the hot air supply plenum.
If you get a cheap evaporative type with the tray of water, be prepared to clean it often. They can get pretty rude with that water just sitting around.
I don't know about yours, but my church isn't a hotel for the holy, it's a hospital for sinners
Sojourners: Christians for Justice and Peace
"All the furnace does is convert the incoming dry cold air into warm dry air."Often that cold air is fairly humid before being warmed up.If I remember correctly the average winter RH in Kansas City is higher than the average summer RH.
The problem is, when you heat air, the RELATIVE humidity drops, even though the absolute amount of moisture in the air remains constant.
Arrow,
My experience has been that it is a waste of time unless you want to run the furnace fan continually. I tried two different types and finally went with a Sears 12 gal console type. My house is fairly well insulated and the furnace really does not run that often, even in the coldest weather we get here in the Washington DC area. I also do not like the house burning up, 65 degrees is fine with me. I will tell you that you can tell when the humidifier is empty, it feels a lot cooler in the house. If your furnace fan is running all the time, the furnace mount humidifier might work ok, if not, I dont know if its worth it.
Just my experience,
Bill Koustenis
Advanced Automotive Machine
Waldorf Md
My furnace fan runs constantly winter and summer so it keeps the air in the house mixed and helps prevent hot heads and cold feet.
Also I don't like to hear it coming on and off all night and the motor likes to run.
I can understand why the humidifier would'nt work well without the blower running.
My wife has sinus problems and thinks one will help so I will get one and see.
Thanks all for the replies. I'm still looking.
I rigged ours with hot water, and set it up so the humidistat turns on the furnace fan. Eliminates that "awkward" time in spring and fall when the furnace doesn't run often enough to keep the humidity up.
Arrow,
The humidifier will definitely help with the sinus problems. We can tell when ours is empty without even looking at it :) It makes a huge difference in the comfort level of the house.Bill Koustenis
Advanced Automotive Machine
Waldorf Md