Furnace Mounted Humidifier........

Scotty370 · Dec 27, 2010

I'm about to buy a replacement for an old plentium mounted humdifier. The old one, a 'Kenmore', had all kinds of "moving stuff"! A fan, a gear driven media wheel, and bottom tank, and floats, and valves, etc, etc, etc,,,,,,,,they all got lime coated, and besides the servicing, the deposits ultimately 'did it in'! I'm looking at an Aprilaire 700 Auto, as a replacement, but have a question.

Anyone know what the water consumption is like on these? It's a much simpler system. A 'drip' system over a media that the hot air is blown through. But, It needs a drain line to carry off the unevaporated water. I'm on metered water, and don't what to be spending $, on water down the drain. Any experiances out there? TIA ~Scotty

jdonovan · Dec 27, 2010

I've got one of a similar design. The water consumption is highly dependent on your homes need for humidity.

I put a valve inline so I can adjust how much over flow water there is. When the HVAC guys installed it, it would have a substantial overflow and I just kept seeing money down the drain.

Now with the flow valve installed I've got it adjusted so I get a slow trickle down the drain. That flow also helps carry away mineral deposits, so you don't want zero out flow.

Right now we are hearing the unit run nearly 24/7 so I would guess we are putting 10-15 gallons a day into the air. I won't know for certain until the next water bill comes in.

However even at 10Gal/day, 300 gal per month, thats only about $1.50 at my towns water rate.

The house is MUCH more comfortable, and I've been able to reduce the thermostat by 1-2 degrees, so net-net I'm probably saving quite a bit more money in heating costs than I'm spending in water.

zzvyb6 · Dec 27, 2010

Beam me up, Scotty! To the Southside (end of McKinley Pkwy and Dorrance) is where I grew up. The quick answer is that little water is wasted because you can set the humidity control so that NO water gets to the drain line. It ALL evaporates. In other words: the hot air will evaporate all the water that you supply. This may not jive with the humidity level that's comfortable, but its adjustable. For my furnace with the nearly identical system, there is just a small drip of water when it's running wide open. The amount is a lot less that what the A/C drain line produces. You can control it with the water valve opening setting, too. Dial it back until no water gets drained. I have a 110v outlet that's relayed to my gas valve control. So, the humidifier water valve gets opened only when the gas is on, not all the time, and not controlled by the blower relay. That means that the blower continues to run after the gas/water shuts down until the plenum heat drops. This maximizes the evaporation of water.

Be sure to watch for signs of overhumidification. Attic insulation getting damp wastes a lot of heat. Don't trust the humidity control setting. Get a real hygrometer to measure it in the living space.

dragon7 · Dec 27, 2010

My overflow drain tube would not fill a 2 gallon bucket all winter.

homedad · Dec 27, 2010

I'll bet mine fills the 2 gals in 2 hours. It seems to be a huge water waster, but I'm on a well. I guess I should adjust it.

jdonovan · Dec 27, 2010

homedad said:
I'll bet mine fills the 2 gals in 2 hours. It seems to be a huge water waster, but I'm on a well. I guess I should adjust it.

Mine was probably that way too.

But mine was hooked up via a 1/4" line "T" into the 1/2 water line, not the normal pin valve like for an ice maker, which is how many humidifiers get setup. So I think my setup had quite a bit more GPM possible.