Advice on installing a clothes drying cabinet in a passive house
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Tad Everhart
Jun 22, 2013, 8:10:12 PM6/22/13
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I've wanted a passive house clothes drying cabinet/closet since an acquaintance showed me a photo of one in our PHIUS training in May, 2008. The idea seemed an elegantly simple ways to enjoy the two-fer of drying clothes with the airflow from mechanical ventilation.
When we installed the piping for our ventilation system, we installed a return above the location where our clothes dryer used to sit (next to the clothes washer) so that we could install a clothes drying cabinet or closet. We moved the dryer out to the garage, and we throw away a lot of heat and CO2 using it all winter. I've had the duct we installed stoppered for 4 years, but I haven't stopped hoping for the drying cabinet/closet.
A few years ago when I looked for a cabinet, I could not find one sold for the US market, and I considered having a cabinet maker build one for me.
Picking up the trail again a few days ago, I was delighted to find we now have multiple options. Two seem especially promising.
Asko sells its model in the US, and there are at least two different distributors in Portland. The local wholesaler has staff who enjoys Asko's cabinet in her house.
And an American company, Staber, based in a small town South of Columbus, Ohio makes one for sale at a slightly lower price. Staber's cabinet is similar to Asko's, and the outside dimensions are nearly identical. Even the controls are similar. I think it's interesting that Staber started this product line with commercial grade clothes drying cabinets for firehouses (so firefighters could hang their jackets to dry). The domestic model (cabinet) is an off-shoot from its core product line.
Unfortunately, neither company appears to have printed advice on piping its 4" exhaust to a ventilation system return duct and operating the cabinet within a ventilation system.
The Asko installation manual suggests venting to outside or simply venting into the laundry room (which might be a nice source of moisture in a nordic country like Sweden where the Asko is made). I don't want that moisture in my house.
My plan was always to connect it to the return side of the HRV ventilation system to use the "free" ventilation.
The Asko has a fan (powered by a 35-watt motor) which the operating manual predicts will move 45 m3 of moist air per hour (26.5 cfm) under normal operating conditions through the cabinet. You can operate it either with or without heat from the built-in 1,200-watt electric resistance heating element. Asko estimates a cabinet full of clothes dries in 1 hour with heat or 8 hours without heat.
If any of you have (or know anyone who has) installed such a cabinet, I'd appreciate your advice.
I believe that the 26.5 cfm from the cabinet is a fairly good match for our Zehnder CA350 HRV's level 1 airflow (65-72 cfm). We have a "Y" in our return system so that 1/2 of the volume can come from bathrooms and the balance (25-35 cfm) could come from the cabinet side of the return system. The cabinet would be installed on the side of the "Y" that picks up only two returns. One of those is the kitchen. The cabinet would tend to short-circuit the kitchen exhaust. Thus, we'd plan to damper off the cabinet when it's not in use (and not use it when we want more exhaust from the kitchen.
I might be tempted to disable the fan built into the cabinet, but 35 watts is far less electricity than our dryer motor uses, and I'd rather error on the side of extra ventilation. Perhaps we could eventually substitute a lower-volume fan.
Our plan would be to load the cabinet in the morning, open the damper in the return duct connected to the exhaust from the cabinet, and turn it on to run while we're all out of the house (usually 6 hours). We'd probably experiment with the various heat settings (there are 5 levels). I expect that in winter, we use at least some heat. In summer, I expect the system would provide some cooling, but I'd rather line dry. Other than the additional fan electricity, there should be little waste as the HRV will recover around 90% of the heat in the exhaust air. We'd simply be substituting heat supplied by the cabinet for heat produced by the electric resistance in-duct heater.
I'd appreciate your advice and experience.
Thanks,
Tad
When we installed the piping for our ventilation system, we installed a return above the location where our clothes dryer used to sit (next to the clothes washer) so that we could install a clothes drying cabinet or closet. We moved the dryer out to the garage, and we throw away a lot of heat and CO2 using it all winter. I've had the duct we installed stoppered for 4 years, but I haven't stopped hoping for the drying cabinet/closet.
A few years ago when I looked for a cabinet, I could not find one sold for the US market, and I considered having a cabinet maker build one for me.
Picking up the trail again a few days ago, I was delighted to find we now have multiple options. Two seem especially promising.
Asko sells its model in the US, and there are at least two different distributors in Portland. The local wholesaler has staff who enjoys Asko's cabinet in her house.
And an American company, Staber, based in a small town South of Columbus, Ohio makes one for sale at a slightly lower price. Staber's cabinet is similar to Asko's, and the outside dimensions are nearly identical. Even the controls are similar. I think it's interesting that Staber started this product line with commercial grade clothes drying cabinets for firehouses (so firefighters could hang their jackets to dry). The domestic model (cabinet) is an off-shoot from its core product line.
Unfortunately, neither company appears to have printed advice on piping its 4" exhaust to a ventilation system return duct and operating the cabinet within a ventilation system.
The Asko installation manual suggests venting to outside or simply venting into the laundry room (which might be a nice source of moisture in a nordic country like Sweden where the Asko is made). I don't want that moisture in my house.
My plan was always to connect it to the return side of the HRV ventilation system to use the "free" ventilation.
The Asko has a fan (powered by a 35-watt motor) which the operating manual predicts will move 45 m3 of moist air per hour (26.5 cfm) under normal operating conditions through the cabinet. You can operate it either with or without heat from the built-in 1,200-watt electric resistance heating element. Asko estimates a cabinet full of clothes dries in 1 hour with heat or 8 hours without heat.
If any of you have (or know anyone who has) installed such a cabinet, I'd appreciate your advice.
I believe that the 26.5 cfm from the cabinet is a fairly good match for our Zehnder CA350 HRV's level 1 airflow (65-72 cfm). We have a "Y" in our return system so that 1/2 of the volume can come from bathrooms and the balance (25-35 cfm) could come from the cabinet side of the return system. The cabinet would be installed on the side of the "Y" that picks up only two returns. One of those is the kitchen. The cabinet would tend to short-circuit the kitchen exhaust. Thus, we'd plan to damper off the cabinet when it's not in use (and not use it when we want more exhaust from the kitchen.
I might be tempted to disable the fan built into the cabinet, but 35 watts is far less electricity than our dryer motor uses, and I'd rather error on the side of extra ventilation. Perhaps we could eventually substitute a lower-volume fan.
Our plan would be to load the cabinet in the morning, open the damper in the return duct connected to the exhaust from the cabinet, and turn it on to run while we're all out of the house (usually 6 hours). We'd probably experiment with the various heat settings (there are 5 levels). I expect that in winter, we use at least some heat. In summer, I expect the system would provide some cooling, but I'd rather line dry. Other than the additional fan electricity, there should be little waste as the HRV will recover around 90% of the heat in the exhaust air. We'd simply be substituting heat supplied by the cabinet for heat produced by the electric resistance in-duct heater.
I'd appreciate your advice and experience.
Thanks,
Tad
GnormanTheGnome
Jun 23, 2013, 7:01:26 PM6/23/13
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Hi Tad,
--
"It's not what you look at that matters, it's what you see." Henry David Thoreau
Consider adding a spin dryer to your plan and deal with less moisture in your ventilation system. A friend of mine is using one of these and then hanging the clothes outside. He says they dry faster than without the spin dryer:
There are other models out there, but the concept is great. Use a few minutes of energy to centrifuge most of the water out of your laundry after the washer. Then you can put them in your drying closet without the need for additional heat and with much less moisture to deal with. You could also get a washer wringer if you want a bit of a workout in lieu of using electricity!
Linda
Tad
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Tad Everhart
Jun 25, 2013, 5:49:05 PM6/25/13
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Linda,
Thanks. That is helpful. Our front-loader's max spin speed is 900-1,200 rpm. The Spin Dryer is 3,200 rpm. Perhaps it would remove a significant amount of water given 3 times the speed. And I was pleasantly surprised by the cost. Rare that any appliance comes with an unexpectedly low price tag ($145).
Tad
Thanks. That is helpful. Our front-loader's max spin speed is 900-1,200 rpm. The Spin Dryer is 3,200 rpm. Perhaps it would remove a significant amount of water given 3 times the speed. And I was pleasantly surprised by the cost. Rare that any appliance comes with an unexpectedly low price tag ($145).
Tad
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