Whole House Humidifier Installation in Denver: Cost and Which Type to Get

Plan on about $1,000 for the AprilAire 720 when we add it to a new furnace or heat pump. That's what we put in most Denver homes. A bypass unit is about $700, and a steam unit runs $1,900 to $2,800 or more.

We only install humidifiers alongside a new furnace or heat pump, not as a separate job on an existing system. Adding it during the install is also when it's cheapest: the ducts are already open and the controls are being wired.

Powered, for most homes. The AprilAire 720 has its own fan, so it adds moisture even when the heat isn't running hard. It puts out up to 18 gallons a day, enough for most homes up to about 4,200 sq ft, and the only upkeep is a water panel once a year.

Bypass, if budget comes first. It uses the furnace blower to push air through the pad, so it only works while the blower runs. On mild days and in tight, well-insulated homes, that isn't often enough.

Steam, for big or unusual houses. The AprilAire 800 boils water and injects it into the ducts. It puts out the most moisture regardless of airflow, which matters in homes over about 4,500 sq ft, rooms with 16-foot ceilings, or houses where the heat rarely cycles. It costs more to run and needs descaling.

All three use a digital humidistat that lowers the target as it gets colder outside, so your windows don't sweat.

A whole house humidifier works with a heat pump air handler the same way it works with a furnace. The difference is that a heat pump sends out cooler air than a gas burner, and evaporative pads put out a bit less moisture in cooler air. The AprilAire 720 still keeps up in most homes. We size it when we design the system.

Indoor humidity in a heated Denver house regularly falls to 10 to 20% in winter. The EPA recommends 30 to 50%. Below 30% you get static shocks, dry skin and sinuses, and gaps opening in wood floors and trim.

Dry air also feels colder at the same thermostat setting, so many people turn the heat up a degree or two to feel comfortable.

A portable unit covers one room, roughly 300 to 500 sq ft, and needs refilling every day. You'd need six to eight of them for a 2,500 sq ft house. A whole house unit is plumbed in, covers every room on the ducts, and runs quietly next to the furnace.

Portable units still make sense for a nursery or a sick room. For the whole house, a furnace-mounted unit is the practical answer.

It adds about 2 to 3 hours to a furnace or heat pump install, 3 to 4 hours for steam.

1. Mount it. We cut the opening in the supply or return duct, mount the unit and seal it. Bypass units also get a short duct back to the return.
2. Water and drain. We run a 1/4-inch line from the nearest cold water pipe, with a shut-off, and a drain line.
3. Controls. We wire it to the system's 24V controls and install the humidistat.
4. Set it. We test water flow and set the target, usually 35 to 40%. You'll feel the difference within a day or two.

• Bypass and powered: one water panel a year (about $30, 10 minutes). Water runs $1 to $2 a month at Denver Water rates; a powered unit adds about $2 a month in electricity.
• Steam: descaling once or twice a year ($85 to $150) and a new canister every 3 to 5 years ($100 to $200). Electricity runs about $15 to $25 a month in winter.
• Lifespan: 15 to 20 years for bypass and powered, 10 to 15 for steam.

Turn the water off for summer. The humidistat handles the rest. If you're also looking at filtration, see whether a more expensive HVAC filter is better.