How to Install a Whole-House Humidifier | Ask This Old House

so this is the heating system up here

all right let's see what you got so you

have an air handler that has a blower

fan inside of it's going to push the air

up into this duct you can see there's

flexible supplies on each end right here

and those go down into the second floor

now all the air that has to come back to

be reheated or riku is going to come

back through these flexible returns

right here to the bottom and the cycle

repeats now this is not a gas furnace or

an oil furnace it's actually a heat pump

and for that use these refrigerant line

sets that are connected to a condenser

outside to either heat the air or cool

the air now today we're going to

introduce a humidifier there's a couple

things we need we need water now I can

see right here you've got a water heater

up here that's great we need electricity

it looks like you got plenty right here

and we need to drain okay and I can see

there's a drain already in place right

here that's the good news but the

manufacturer of this steam you mid afire

wants to be sure we introduce steam in

the right place when I look at this duct

imagine what happens when that fan is on

the air pushes up here and it hits the

back here and against the air very

turbulent very confused if I put steam

right here there's a good chance that

all that condensation could fall right

back into this and we don't want that

that's excellent well actually it is but

we're going to have to do is to change

this ductwork and modify it so it goes

over to one side so we can introduce the

steam and all the air goes by in a nice

organized way great

this is a pretty big job so I asked

technician Ryan Gunton to lend a hand

we'll start by detaching flexible


then we'll disconnect and remove the old

sheetmetal trunk and build a new

this drive fleet will hold these two

pieces of strung together tight that's

why they call it ten knocking so we have

a series of flexible supplies that we

have to connect into our main trunk and

for each one that I'm going to use one

of these this is a take off it has a

balancing damper inside of it right here

and it has a sealant or adhesive right

here it'll make a nice tight seal to the

duct I want to cut a perfect four inch

hole and for that they have a special

hole cutter you can see it's a pivot

point right here and there's a special

drill bit right here that cuts on the

side now I put it down inside

all right how's this fit Ryan what's

good over here

good so this elbow has these louvers in

them they're called turning vanes

that'll help that air leave the air

handler and really smooth out in our new

trunk right here

we'll attach these 12-inch takeoffs just

like the smaller ones using an adhesive

strip and self tapping all right soon

you've made a lot of progress up here

remember your duct work you stick them

off the top and went both ways now we

come off come in one direction here a

nice solid trunk you can see the

flexible connections are made and this

is your new whole house humidifier right

here great let me just pull the cover

and the way it works is there's a

reservoir right here and that is half

filled with water right there and

there's an electrical element inside of

it now that element will get the water

so hot that'll turn it from water to

steam and leave out through this

insulated hose okay

this will automatically refill itself oh

okay so is there anything I need to do

to maintain it

not really the only thing is if you had

high minerals or hard water over time

that electrical element might get burned

out like a coffee machine does but that

element is replaceable okay so now here

is the wand right here now the steam is

going to come up through that hose and

these little holes will be sitting right

in the air stream and the air will go

across it and absorb every bit of that

steam into the air okay so we have to

think about the right location I want to

be down a couple of feet we'd like to be

up about a third of the way and I could

go right here but where I'm going to put

is actually on the backside right here

because the great location for the

emitter fire is right here that'll

minimize the amount of run for this hose

once I get it mounted we can run the

water great we've cut in on the cold

water feed to the water heater with a

separate shutoff and a quarter inch

copper feed to our new humidifier so

Ryan this units got a drain right it

does which is very important because

this unit will sense the amount of

minerals that build up in the cylinder

and if he gets to be too high it will

flush the cylinder that's great so it'll

help keep it clean they will all right

so we'll connect that drain down into

one of these drain connections here

that's correct perfect all right sandy

we've made our final connections here's

cold water into the humidifier here's

the drain

leaving the humidifier

got this insulated hose with steam going

to the wand we also brought a licensed

electrician and he had a separate

circuit right here and that gives us 220

volts from this panel over to the unit

and we've also got a couple of control

wires into the back oh ok so how do we

control it well there's a couple of

safety devices that are up in places you

don't to worry about one is an air

proving switch we want to make sure that

you mid afire doesn't come on unless the

fan is on ok and the other is a high

limit we want to make sure they're not

too much humidity is up in this Doug

Murray but those are hidden away you

don't need to worry about the control

you do need to think about is down the

first floor so Cindy down here is a

device that everybody knows it's a

thermoset since its temperature right

above it is the new device called


in a sense the humidity in the building

so you'll set it to the right level and

we'll bring on the emit of fire and it

actually bring on the fan as well ok so

what level did it keep it at I like to

see 35 to 40 percent I agree with that

okay but you'll get to know the right

level I also want to cost you though you

don't want to set it too high because in

a nice tight insulated house you can

have actually mold if you put too much

of it in there no okay you know what

that No well thank you guys so much we

really appreciate it and I know we'll be

more comfortable if we can get rid of

the portable humidifier yes you can