View Full Version : HVAC guys - Humidifier install Qs.


jmd
11-27-2010, 08:54 PM
The super low humidity here is impacting our < 1yo son. We never bothered with a humidifier before but just got one (hot steam type) that gets filled regularly and I run it at night w/ the HVAC fan on only so it circulates in the house.

Now, I've done HVAC work but for fairly short time periods so I know a little but it's been 5yrs+ since I last installed an on-ducting-humidifier. Our house has an on-roof gas-pack. The return opening is in the hall and the ducting is laterally over the hallway in the middle of the house. I'm seeing humid. units that pull from the return and feed to the vent ducting.

The only access to the ducting is via the attic and I'd have to crawl up through the garage and at least 30 feet. Do-able but can I avoid that yearly service crawl? There's the water heater closet in the hallway. I'm guessing I could grab the hot water from there; run a drain down a wall and under a sink but the big question is are there humidifiers that can feed the ducting without being located right at the point where the ducting and the return are next to each other?

janaka
11-27-2010, 09:53 PM
The Honeywell TrueSteam humidifier has a relocation kit available which allows you to located the actual humidifier anywhere and run tubing to the plenum of the furnace etc.
Might be worth looking into.

Silverback
11-28-2010, 08:05 PM
Aprilair makes a unit that has a fan in it instead of running a bypass line from the return to the plenum, you just have to cut a hole in the plenum and install, it sucks air in through the outside edges, through a filter that is covered with water and out through the middle, the whole thing takes only about a 2x2x1' space on the side of one of the hot side ducts.

Alternatively, though I don't believe these are as good (I believe that they can cause water condensing out on the ducts), you can get a misting style that just mounts a nossle in the side of the plenum. Many of these use a switch with a vane that mounts in the return to tell when you have airflow, but you can avoid that by wiring it straight to the furnace control board.

No matter which type you should wire it so it can _only_ run with the heat running, and probably delay some so the ducts can get warm before it starts.

janaka
11-29-2010, 09:56 AM
Aprilair makes a unit that has a fan in it instead of running a bypass line from the return to the plenum, you just have to cut a hole in the plenum and install, it sucks air in through the outside edges, through a filter that is covered with water and out through the middle, the whole thing takes only about a 2x2x1' space on the side of one of the hot side ducts.

Alternatively, though I don't believe these are as good (I believe that they can cause water condensing out on the ducts), you can get a misting style that just mounts a nossle in the side of the plenum. Many of these use a switch with a vane that mounts in the return to tell when you have airflow, but you can avoid that by wiring it straight to the furnace control board.

No matter which type you should wire it so it can _only_ run with the heat running, and probably delay some so the ducts can get warm before it starts.

I have this april aire unit on my furnace, they are called "power humidifier's" instead of bypass. Its the April Aire 700.

At the bottom of this page you will see all of april aire's models.
http://www.aprilaire.com/index.php?znfAction=ProductsCat&category=humid

Silverback
11-29-2010, 04:06 PM
Yep, that's it. I have one also, but mine is from before they came with digital controls.

FWIW, I _really_ like the external sensor setup. You set up a temperature sensor in a shaded area outside that measures outside temp, which lets you set the humidity as high possible and it automatically adjusts it downward slightly as it gets colder so that you don't get condensation (and the resultant mold/rot) on your windows.

The only thing I don't like about it is that like any other that works by saturating an element, it flushes some extra water through it that goes down the drain. Traditionally, this would just be dumped in your sump or a drain line, which I don't have in the basement, so I had to run it in to the AC condensate pump, and then run the condensate line to a drain upstairs (if I left it running outside it would freeze in the winter). The problem is that the condensate pump gets plugged up faster that way so I have to check it and flush it about once per year.