Heat pump dryers: are they worth it, and can one replace gas?

A regular dryer heats air, blows it through your clothes once, and pushes it outside through a vent. A heat pump dryer keeps reusing the same warm air: it pulls moisture out of it with a cold coil, collects that moisture as water, and warms the air again. That loop is why it can use far less electricity, and why it needs no vent at all.

How much less? Estimates vary by source and model. NYSERDA, New York's energy agency, says heat pump dryers are at least 28% more efficient than conventional dryers. Hydro-Québec puts savings at 30% to 60%. The federal Building America Solution Center cites up to 70% for some units. ENERGY STAR certified models are the most efficient.

Here is what that looks like on a bill. For example, if your current electric dryer uses 60 kWh a month, a 28% cut saves about 17 kWh and a 60% cut saves about 36 kWh. At 30 cents per kWh, that is roughly $5 to $11 a month. The monthly savings are real but modest, so for many homes the bigger reasons to choose one are practical ones.

Where a heat pump dryer makes the most sense. Homes and condos with no dryer vent, or a long, awkward vent run. Small laundry closets where a stacked or combo unit fits. And homes replacing a gas dryer where there is no 240-volt dryer outlet, because many heat pump washer-dryer combos are designed to run on a standard 120-volt outlet. Standalone heat pump dryers vary, and some need a 240-volt circuit, so check the installation guide for the exact model before you buy.

The trade-offs. Hydro-Québec says loads can take about 25% longer to dry. The water the dryer removes has to go somewhere: into a drawer you empty, or through a drain line, often into the washer's drain. Lint filters need cleaning after every load, secondary lint traps about monthly, and the condenser area on the schedule your manual gives. Some models use refrigerants that are greenhouse gases, so compare the refrigerant listed on the spec sheet if that matters to you.

Installation tips from the Building America Solution Center. Step 1: Pick a spot that stays above 40°F with enough airflow; a tiny, sealed, windowless closet is a poor fit. Step 2: Leave at least a 3/8-inch gap under the dryer for air. Step 3: Plan the condensate drain before delivery day. Step 4: If you are removing a vented dryer, seal the old vent inside and out so it does not leak air.

Replacing a gas dryer adds one more job: the gas line has to be shut off and capped safely. Have a licensed plumber or contractor do it, and ask whether your city requires a permit. Some cities do; Berkeley, for example, asks for a permit with a final inspection for a capped dryer gas line under its Building Emissions Saving Ordinance (BESO).

Rebates for heat pump dryers come and go and often depend on your utility or local energy agency. Check your utility's rebate page or the Switch Is On rebate finder before you buy.

A small step for today: look at your laundry spot and note three things: the outlet type, whether there is a drain nearby, and whether there is a vent in the wall.