adding a humidifier to a furnace

[brechmos]

Hi,

I am new at this. We bought a 70+ y.o. house here in Ontario. The summers are warm and moist and the winters are cold and dry.

The A/C was added onto the furnace, bu there is no humidifier for the winter. I opened up the ducting immediately above the furnace and the condensor for the A/C is sitting right there. As far as I can see, if I add a humidifier the only place to put the small duct carrying the moist air would go in immediately in front of the condensor. Would there be a problem with this? I am assuming as the A/C is off in the winter, the condensor is off. And with the air blowing by when the furnace is going that the moist air isn't going to sit around on the condensor.

Any advice would be appreciated.

Thanks.

[Mikepier]

On my system, the humidifier is mounted on the return duct, close to the furnace. Then there is a small 6" duct coming out of the supply duct going into the humidifier.

[brechmos]

Right, I will mount my humidifier on the return duct close to the furnace. That end of things I am all right with.

The small duct that comes out of the humidifier has to go into the supply duct (hope I have the word right, the part with the warm air) right above the furnace. Right at that point is the A/C condensor, inside the ducting. Is it all right to shoot the moist air over the condensor?

[Smarty]

My humidifier blows directly onto the A/C coil and works just fine. My prior furnace/humidifier was set up the same way and also worked fine for 20+ years. I live in a very cold climate in the Northeast U.S.

[brechmos]

Great. I'll see if I can hook it up tonight.

Thanks.

[trader4]

It's the AC evaporator, not the condenser that you are looking at. The main thing to look out for is not to damage the evaporator while you're cutting the necessary hole for the humidifier. IMO, by far the best humidifiers are the Aprilaire. And I like the self powered models, (760) that don't shunt air from the hot air plenum back to the return. I've had the 760 for 7 years now. It's very easy to service, the whole thing just lifts off. All I do is clean it once a year and replace the media once every 2 years.

[Mikepier]

I have the Aprilaire also, but it rarely turns on. I have to set my humidstat past 30% for it to turn on. Maybe my air in the house is not that dry.

[Art Todesco]

Warning, some humidifiers are designed only to mount on the hot air plenum. I have an Aprilaire mounted on the side of the AC A coil. There is plenty of room and has never caused any problems. I don't know about new Aprilaire units, but the old ones were supposed to be on the hot air plenum.

[Smarty]

I too especially like the Aprilaire self powered units, and also use / love the 760. I'm on my third Aprilaire in 34 years, the first two each lasting nearly 20 years apiece. I would imagine that a small Dremel cutting wheel or nibblers will cut the plenum skin without risk to the coil.

Smarty

[Smarty]

Aprilaire makes two types AFAIK. The ones I have always used sit in the hot air plenum immediately near the A/C evaporator coil. The other style, called a "bypass" unit sits on the return duct with a connecting pipe to the hot air side.

Smarty

[Stormin Mormon]

Sounds like you ought to call a heating guy, and get it put in right.

A humidifier won't hurt the condensor, cause that sits outdoors. The evaporator gets wet when it runs in the summer, so that's not an issue. Evaporator has a drain, right? Cause it gets wet.

There are some jobs where it takes longer (and costs more) to do it yourself. Unless you're really good with tools, this is one of thems.

[trader4]

While I agree there are some jobs that it doesn;t make sense to do, I don't think installing a humidifier is all that difficult or requires special tools or skills. Only non common tool might be a pair of tin snips. I put in my Aprilaire 760 and it was fairly easy. I'd say easier than putting in a garbage disposal.

[Mike Hartigan]

I agree. Installing a humidifier is one of those jobs that seems daunting until you actually do it ("You installed it yourself? Cool!"). With regard to hacking the furnace, all you're doing is cutting a hole in some sheet metal and covering it with a humidifier. And we've just ascertained that the location of the hole is not too critical. Nothing goes 'inside' the furnace. The difficult parts are the plumbing and the electrical hookups, and even those are pretty low on the DIY difficulty scale, IMO. While I don't give a blanket reject to the 'Hire a Pro' mantra, I think that this is one of those jobs that readily lends itself to a do-it-yourselfer.

[mm]

I know what you mean. I thought if I cut a hole in that metal, all the good heating and cooling spirits would come out and get lost. Sort of like drilling a hole in the side of my car's engine.

But it worked out ok.

The humidifier came with a template. I just had to make sure there was nothing hiding behind the hole I was going to make.