We are looking to get a humidifier for the house: 5 year old house, forced air (propane) heating, 4200sqft (plus 900sqft finished attic), two sets of furnaces/ductwork (one in basement for ground floor, one in unfinished (insulated but unheated) attic space for second floor and finished part of attic).



Most professional sounding HVAC guy we have talked to is recommending an Aprilaire model 800 steam humidifier installed in the basement system (attic could freeze up if we have a power outage even though we have a whole house generator). Cost estimate is $4500 installed.



Does this sound right? and are there any gotchas I should be looking out for?



Thanks in advance for any feedback

the big down side to a duct mounted humidifier is the potential for mold in the duct.  its a dark place and your adding moisture.  having said that the steam ones are more expensive but much better than any one using a wet rotating filter.

Look at aprilaire 700 series humidifiers, if you can use sheet metal cutting tools you can do this yourself for a few hundred bucks. these are fan powered no rotating drums.

I just recently put on an Aprilaire 700.  Works great.  Not hard at all to do and the humidity in Colorado is so low I don't have to worry much about mold.  I will just check it when I replace filters, to be sure.  I got the one with the digital humidistat and it keeps the humidity nicely with the temperature.  

Honeywell trusteam on both units

basement unit will mount directly to the furnace

attic unit will mount in a closet and use a hose to pipe the steam up to the plenum so no worry of freezing

btw, if $4500 is just for the humidifier it's way too much

Humidifiers about 400ish each depending on the size

My only issue with the steam humidifiers is that it will add approx. 50-75 dollars a month to your electric bill.  Pass through is likely to add about $5 to your water bill.

You are right on the money depending on how much the heat runs

The main problem with other units is they only add humidity when the furnace is running

In my home that was never enough