Main advantage is in new construction, you don’t have to accomodate a vent pipe or a 30A circuit/gas conduit so you have much more flexibility on where to place your laundry room. Cost savings on construction alone can pay for the appliances. Much less of a compelling option for retrofitting into an existing space.
I like this video from a custom home builder (Matt Risinger) focused on high efficiency homes on his personal experiences installing a HP dryer into his personal, newly built home:
My house was built in 1960 and the laundry room has a 220 outlet that has probably never been used. When I bought the house it had a gas dryer from 1980 give or take a couple years. I replaced it with a gas dryer in 2010 or so. I left the plug there when I remodeled because it’s nice to have options.
One thing people who have heat pump dryers mention is that the clothes that come out of them aren’t actually wet. We just are fooled into thinking they’re wet because they come out cold(er than a normal dryer) and we associate cold with wet. Once they are out for a couple of minutes, they’re now the temperature we expect them to be and thus they now feel dry. It’s a weird psychological quirk that a lot of people never get used to and that affects people’s subjective evaluation but they objectively perform well at drying clothes.
New construction of a single family home shouldn’t have a problem accommodating a dryer vent. In apartments, condos, townhouses, etc. there could be such concerns, and existing structures might have issues. The efficiency of heat pumps should be the selling point for those dryers.
Depends. if you have a house with great 360 views, you might want to run all your plumbing through the middle and have the bathrooms/laundry room in the center of the house. Or you might want to stick a combo washer/dryer in a kitchen island next to the dishwasher. Or you might want to put it inside a closet on the landing of staircase.
I’ve seen all 3 versions of that in different houses I’ve been in where the flexibility of not requiring a dryer vent allowed for much better laid out houses.
There is value in such flexibility. However, conventional dryer vents would not add appreciable cost in new construction. Dryer vents can be run through walls and joists between floors and vent under eaves. Refitting an existing structure could add significant costs to achieve the same results.
I would still consider a heat pump dryer based on the savings in electricity and no need for exterior venting would be a bonus. But I would still consider venting for a conventional dryer in the design for possible future considerations such as a larger conventional dryer. Any home design must also consider vents for kitchens and bathrooms. If those have to be centrally located to avoid blocking the fantastic view then a dryer vent could be added as well.
Again, none of these are reasons not to get heat pump dryer.
Is it advisable to have a long run for a dryer vent considering potential lint build up?
Regardless, I am definitely getting a heat pump dryer when my current one gives up the ghost.
Dryer manufacturers specify maximum run lengths, local codes may apply, and any vent needs some kind of accessibility for practical purposes. A central location in a home doesn’t make that impossible, and usually not even difficult.
However, it makes sense to me to design around a heat pump dryer that doesn’t require venting to save on operating costs. I don’t know what gas dryers cost to operate because I don’t have a gas line. I know electric dryers cost a lot to operate around here since our electricity is produced at a money burning plant. The next time we need to buy a dryer I’ll be looking closely at a heat pump model.
Another consideration for venting is summertime use in in an air conditioned house. If you don’t have an exterior vent for the dryer you’re paying to cool the exhaust. It’s apparently less heat than traditional electric dryers produce, and it’s produced efficiently from the heat pump, but an exterior vent would keep the operating costs down. Hopefully you could switch to interior venting in cold weather.
I do not know if all heat pump dryers are the same but mine requires no venting whatsoever. There is no discernible heat leaking from the dryer at all when it is operating (beyond the door getting slightly warm). Everything stays in the dryer. As such it has no effect on my interior temperatures.
The video @Shalmanese linked earlier suggested that a normal vented dryer may be moving as much as 9,000 cubic feet of air out of the home. That air needs to be replaced which means outside air coming in which, in summer and winter, is not ideal since you will pay to “fix” the temp of the new air coming in. Another added cost but it is difficult to nail down just how much money that is.
Being a closed loop system that repeatedly cools and heats the same air there is much less heat produced in the process that will transfer to the dryer and the clothes. The conventional dryer was exhausting large volumes of hot air in order to dry clothes. I’m surprised the operating cost advantage for the heat pump isn’t greater than the 28% figure I’ve seen. However, they don’t simply heat air as the conventional dryer does, it also has to cool that air again to remove water. So they have to find the best balance between costs of exhausting hot air or cooling it to remove water.
They do need a drain for the water though. Shouldn’t be a problem when they are located near a washing machine as most dryers are.
As for the heat pump it is basically like a window air conditioner. If you have ever been around one of those you’ll note hot air exhausts outside and cool air exhausts inside. Heat pump dryers are basically that. There is no special cooling unit and heating unit. It is the nature of an air conditioner to have a hot and cold side and this just makes use of that in a constant circle of air cooling and heating all in the same circulation. It’s pretty neat and a wonder they were not used earlier (while they may have refined the cycle there is nothing particularly new about the tech).
It actually is possible for them to dump water into a catch (I think…if you need that you’d have to ask) which is good for two cycles before needing to be dumped. A drain would be much simpler, of course and, since it needs water hookups, chances are there is a drain nearby.
Oops…I conflated the washer with the dryer. The dryer can dump extracted water into a catch if necessary. Of course, the washer needs a drain. Since both are usually next to each other it shouldn’t be a problem but, if you really wanted to, you could put the dryer in the middle of your living room and operate it there.
I’m lucky, I guess, in that our washer and dryer are in the garage, which gets fresh air from vents in the garage door, and which stays at whatever temperature that air is. This is reasonably practical in this climate.
Maybe that’s just for the appliance itself rather than the appliance plus conditioning all the makeup air? For a heat pump dryer the electrical usage of the dryer itself is the only one that matters. For conventional gas/electric dryers you also have to consider heating/cooling all the air being sucked into the house to make up for what’s being exhausted. In cold dry climates you can vent the exhaust into the home. You do want to filter it of course (a woman’s stocking works surprisingly well for that), and make sure you want the extra moisture.
A tricky thing with gas appliances is that they usually only report the gas usage, not gas + electric. Motors and pumps use non-trivial amounts of electricity, but you need to dig into the specs of your gas dryer, gas furnace, or gas boiler to find the power draw of the drum motor, blower motor(s), and circulator pump(s) respectively, along with any other controls. The latter ones are also going to be running an awful lot longer than a clothes dryer, oven, or microwave. So a high-draw over a short time adds up to a lot less total power usage than medium or even low-draw equipment running 8-12 hours a day.
I don’t know how they measure it. It’s not just the energy required to heat the air, the air also has to be cooled to remove water. It’s a closed loop cycle but each phase consumes energy.
For a heat pump dryer it’s easy, since it’s all electric they just measure the wattage at the plug. The heat pump itself is basically just a dehumidifier, so the heating/cooling is all happening through one system. Then there’s the electricity used by the drum motor. It all goes through the same plug so it’s easy to measure.
For a conventional gas dryer the power is also all going through the same plug. However since the air is exhausted outside, it puts additional load on your heating/air conditioning system just like running an exhaust fan. That additional energy use is not shown in the energy guide sticker or any other documentation.
For a gas dryer, they have the same issue with venting and load on your heating/air conditioning as a conventional electric dryer. They also have the issue of only reporting the gas usage on the energy guide sticker, excluding the electrical usage for the drum motor and blower. So in a place with cheap natural gas it can look like a big win at first, but that’s because not all sources of energy use are accounted for, whereas they mostly are with a heat pump dryer.
I hadn’t thought of that but in a tightly insulated house, a heat pump dryer might be preferable for the reduction in conditioned air lost to the vent.
Seems weird that there aren’t dryers with two vents that utilize outside air as an input. In certain hot, dry climates, you might be able to get away with drying your clothes decently with just the fan and tumbler running. Instead, we take a bunch of expensively cooled air, then expensively heat it up again and use it once before dumping it outside.
Most dryers have a No Heat mode and Laundry rooms can usually be isolated from air conditioned space so they could operate on environmental air for maximum efficiency. I assume clotheslines are more common in climates like that for even higher efficiency drying.
I live in a place where people don’t need air conditioning. I have a gas furnace for heating but the laundry room doesn’t have a vent for heating and it’s closed off from the rest of the house. Even if people have air conditioning, most washer and dryers I’ve seen are in the garage in a separate room that’s not heated or cooled.