There's a product out there that you can put inline on your dryer
exhaust vent. It's a simple device that let's you divert air flow into
your home through a vent instead of it going outside the house. I
thought this would be a good way to cut down on heating costs this
winter but I've heard it sometimes creates too much dust and moisture
inside the home. In winter, I don't have humidity problems, but I
don't want a lot of dust.
Is this kind of product good and safe to use? What are the pros and
Thanks for you advice.
Haven't any experience with this, but it sounds, on the surface, like a free
lunch. My gut says adding this much moisture and fine dust to the inside of
a house sounds like a mold/mildew nightmare waiting to happen.
"Haven't any experience with this, but it sounds, on the surface, like
lunch. My gut says adding this much moisture and fine dust to the
a house sounds like a mold/mildew nightmare waiting to happen. "
Hard to imagine that occasional use of the typical home dryer is going
to lead to mold and mildew problems. The average load of wash doesn't
have a huge amount of water in it. Certainly not much compared to the
amount that a furnace mounted humidifier or even a regular humidifier
can generate. If those don't cause problems, surely a dryer won't.
Dust might be an issue.
Two other questions. Is this safe with a gas dryer, or only electric?
I would think a gas dryer needs to be vented outside. The other
question would be if any codes address this.
It has a fair bit, and in many households the dryer is run at least every other
around 45 minutes at a time.
The furnace-mounted humidifier will TURN OFF when humidity levels are where you
to be - that's what a humidistat is for. A dryer re-direct vent will keep
moisture into a small area of the house, regardless of how high the humidity
No fee lunch.
I has a similar device years ago. My oil burner service man showed me why
it was not a good idea when he pulled out all the accumulated lint in the
intake. The burner was running rich and wasting oil.
"It has a fair bit, and in many households the dryer is run at least
every other day, for
around 45 minutes at a time. "
If it's run every other day for a load of wash, that's not very much
water at all.
"The furnace-mounted humidifier will TURN OFF when humidity levels are
where you want them
to be - that's what a humidistat is for. A dryer re-direct vent will
moisture into a small area of the house, regardless of how high the
humidity might be. "
Yeah, we know that. But the amount of water from a dryer every few
days isn't going to amount to much in a typical home in winter. My
furnace mount one runs frequently during the winter. The diverter
gizmo he's talking about can be switched. If it starts to get too
humid, all you have to do is set it to go outside instead. I don't see
the humidity thing being a real problem. He could certainly try it and
see what happens.
You may be right, but not necessarily. People who buy high end dryers
may not care about saving money on gas or electricity. They want
convience and performance. Afterall there are a lot of high end
automobiles that don't pay close attention to gas mileage.
That said, you might be right about the moisture/mildew and that isn't
something I'd want to gamble.
Will help direct heat into the room, can be used on electric dryers
only! Will also add lint, water vapour and any chemicals left from the
soap and fabric softners used.
Appliance Repair Aid
I usually run a humidifier in my home 24/7 during the winter anyway, so
I don't think the moisture will be that critical, but it's something to
keep an eye on.
I'm wearing the clothes that hold the chemicals from the sap and fabric
softeners so I'm not sure how much worse off I'll be if they are in the
That kind of heat I expect will heat more than just the room. It's a
shame there isn't a way to take advantage of all this extra heat which
is literally being thrown out the window. We do a lot of laundry here
and with heating costs going up this could have a huge impact on our
On the link provided there were too products. Maybe if I used them
both in conjunction. There must be some way to properly filter the
vent and use that heat!
(thanks for your post)
Wearing something and breathing it are different threats, and
most of the dryer vent/bypass rigs I've seen just have a shutter
and a screen, so dust is a noticable problem. If you could
find a filtering system that would take out the dust, and still
handle the airflow, that would be helpful.
But an air-to-air heat exchanger will do nearly as well,
and not have the contaminant issue.
I remember as a kid I read an article in Popular Mechanics (Or maybe it was
Popular Science) magazine about building your own dryer vent kit to blow the
hot air into the house for heating. I built it. It was nothing more than a
wooden box with a four inch duct collar on it and a fiberglass furnace
It slowed the drying time down considerably because of the air restriction
and the floor was wet from the dampness. It didn't stay connected to the
dryer too long.
If you want to utilize the lost heat you will need to get a heat exchanger.
It will allow the air to pass freely to the outside and at the same time
absorb the heat. I don't know where you can get one, but you might want to
try a supply house that caters to the HVAC trade.
My personal experience has shown that keeping the dryer vent pipe clean
reduces the drying time. I have my dryer vent duct insulated to prevent
condensation as my duct passes through the attic.
With a 16 X 20 furnace filter, I don't have much air restriction, if
any. I vacuum the filter weekly and replace it when lint impregnation
begins (~monthly). I've never had wetness on floor or condensating
My main forced air return duct is in the utility room (basement) with
the dryer. I added a closable vent to the duct to draw the
heated/humidified air into the forced air system during the winter
months when the furnace runs and the dryer is vented to the filter box.
I check the furnace filter often and have found no extra lint build up
due to the dryer.
you can not use the exhaust from a gas dryer.
you can use the exhaust from an electric dryer.
also, here's a better vent closing device:
One house I lived in had the washer and dryer in the garage with no
vent for the dryer. I never had any humidity problems as far as it
didn't create mold or anything but you could tell it was more humid
when it was running. It didn't make any dust clouds in the air but
dust bunnies built up behind the dryer and workbench after a while.
Basic physics at work here.... Medium to lukewarm exhaust air with
lots of humidity and particulate pollution (dust) is a waste product.
You want to get rid of it. There is a bit of heat value available
for recovery but the quantity is low and un-economical to extract.
In most cases, a dryer only runs for 1 - 1 1/2 hours each day (if that
much) and by the time you add the inefficiencies of an air-to-air heat
exchanger, there is just not that much energy to extract.
The humidity that is potentially worth something is offset by the
expense of maintaining a filtration system that can clog very easily
with all the dust. (Look at your dryer filter... You are supposed to
manually clean this before every load). Dusty, moist air is not very
healthy in a sealed house.
When all is said and done, the most economical solution is to vent the
dryer exhaust to the outside, and this is why its been done that way
I tried it a few years ago. I had a problem with condensate on water pipes,
so I quit.
Keeping the filter clean (IIRC I used pantyhose) was bothersome also, though
I would have continued doing it except for the condensation.
We have one of these "Extra Heat" dryer vent diverters and they do work,
however, despite the screen included, we do get a fine dust from the lint,
settling all over the basement. But the BTUs of heat brought in is
significant. For the $10 we spent on it, I'd say it's worth it.
Mark & Mary Ann Weiss
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