I have been looking for something that probably doesn't exist for
reasons I don't know.

I am trying to find out if there is such a thing as a heat exchanger
for a dryer that would attach like a humidifier to a furnace?

I have read MANY posts and articles about just piping the exhaust of
the dryer into the house and how bad that is with lint and moisture.

What I am looking at is something like an air-air exchanger where each
"circuit" is closed.

So the dryer would still exhaust outside but on the way it would flow
through a box that is on the cold air return of a furnace. The
furnace would suck air through the box and collect some of the heat.

Just curious if anyone has ever seen anything like this, if it is even
feasible, and what issues this would cause?

wrote in message
...
I have been looking for something that probably doesn't exist for
reasons I don't know.

I am trying to find out if there is such a thing as a heat exchanger
for a dryer that would attach like a humidifier to a furnace?

I have read MANY posts and articles about just piping the exhaust of
the dryer into the house and how bad that is with lint and moisture.

What I am looking at is something like an air-air exchanger where each
"circuit" is closed.

So the dryer would still exhaust outside but on the way it would flow
through a box that is on the cold air return of a furnace. The
furnace would suck air through the box and collect some of the heat.

Just curious if anyone has ever seen anything like this, if it is even
feasible, and what issues this would cause?

Here's a thing you can use with an electric dryer, to provide warm moist air
in the house. I wouldn't use it for other than winter months:
http://www.improvementscatalog.com/h...ryer-vent.html

wrote in message
...
I have been looking for something that probably doesn't exist for
reasons I don't know.

I am trying to find out if there is such a thing as a heat exchanger
for a dryer that would attach like a humidifier to a furnace?

I have read MANY posts and articles about just piping the exhaust of
the dryer into the house and how bad that is with lint and moisture.

What I am looking at is something like an air-air exchanger where each
"circuit" is closed.

So the dryer would still exhaust outside but on the way it would flow
through a box that is on the cold air return of a furnace. The
furnace would suck air through the box and collect some of the heat.

Just curious if anyone has ever seen anything like this, if it is even
feasible, and what issues this would cause?

For an electric dryer, all you need to do is filter the exhaust and distribute
it somehow. A high efficiency furnace filter in an appropriate enclosure would
probably do the job without createing too much back pressure.

Don't do it with a gas dryer.

On Mar 25, 12:02 pm, wrote:
I have been looking for something that probably doesn't exist for
reasons I don't know.

I am trying to find out if there is such a thing as a heat exchanger
for a dryer that would attach like a humidifier to a furnace?

I have read MANY posts and articles about just piping the exhaust of
the dryer into the house and how bad that is with lint and moisture.

What I am looking at is something like an air-air exchanger where each
"circuit" is closed.

So the dryer would still exhaust outside but on the way it would flow
through a box that is on the cold air return of a furnace. The
furnace would suck air through the box and collect some of the heat.

Just curious if anyone has ever seen anything like this, if it is even
feasible, and what issues this would cause?

As a mechanical engineer, I have thought about it for a long time

buying, if available....haven't seen one

OR

building one...haven't done it for a number of reasons

I live in SoCal so my heating demands are not all that high. the
temperature differences involved are pretty low so heat transfer won't
be great, the air stream is a little dirty (so maintenance will be an
issue), air stream contains mositure so condensation, corrosion &
freezing will (can) be issues. The heat ($'s) saved (at least for my
potential installation) won't justify the cost. My laundry room /
porch is tiny and incorporating a heat exchanger into the system would
be a lot of work.

This does

On Mar 25, 3:27*pm, BobK207 wrote:
On Mar 25, 12:02 pm, wrote:





I have been looking for something that probably doesn't exist for
reasons I don't know.

I am trying to find out if there is such a thing as a heat exchanger
for a dryer that would attach like a humidifier to a furnace?

I have read MANY posts and articles about just piping the exhaust of
the dryer into the house and how bad that is with lint and moisture.

What I am looking at is something like an air-air exchanger where each
"circuit" is closed.

So the dryer would still exhaust outside but on the way it would flow
through a box that is on the cold air return of a furnace. *The
furnace would suck air through the box and collect some of the heat.

Just curious if anyone has ever seen anything like this, if it is even
feasible, and what issues this would cause?

As a mechanical engineer, I have thought about it for a long time

buying, if available....haven't seen one

OR

*building one...haven't done it for a number of reasons

I live in SoCal so my heating demands are not all that high. *the
temperature differences involved are pretty low so heat transfer won't
be great, the air stream is a little dirty (so maintenance will be an
issue), *air stream contains mositure so condensation, corrosion &
freezing will (can) be issues. The heat ($'s) saved (at least for my
potential installation) won't justify the cost. *My laundry room /
porch is tiny and incorporating a heat exchanger into the system would
be a lot of work.

This does- Hide quoted text -

- Show quoted text -

Living in ND and having 4 kids I think our dryer is on all the time!
So if this would work I could reclaim a lot of heat.

Yeah I have tried to think of those issues too (plugging and
condensation).
I was thinking of some kind of filter where the exhaust goes in and a
drip pan like thing for condensation. Kind of like an AC coil some
how collects condensation.

One thing that would be nice with my design (if it would work at all)
would be that it would work on a gas dryer too.
I was planning on no mixing of air flows. Like an engine radiator,
the antifreeze is separate from the air.

The amount of surface area needed would probably be immense and would
that slow the exhaust air flow down too much?
Not sure.

On Tue, 25 Mar 2008 12:02:17 -0700 (PDT),
wrote:

I have been looking for something that probably doesn't exist for
reasons I don't know.

I am trying to find out if there is such a thing as a heat exchanger
for a dryer that would attach like a humidifier to a furnace?
-snip-

I know I've seen this setup for stovepipe over a wood stove- and I
*Think* I've seen the same setup for dryer vents. It is a box-
say 14" on each side- with ? 1" ? pipes through it, open on each end.
Perpendicular to them is the inlet and outlet. . . . . . .

Here's the stovepipe one-
http://www.transoceanltd.com/applian...oves/magic.htm

The ball in the center is attached to a scraper that you clean the
pipes with occasionally.

Jim

On Mar 25, 3:02 pm, wrote:
I have been looking for something that probably doesn't exist for
reasons I don't know.

I am trying to find out if there is such a thing as a heat exchanger
for a dryer that would attach like a humidifier to a furnace?


I've always wanted to build a heatless clothes dryer. It would just
be a large air tight container you fill with clothes, seal up, and
then evacuate all the air. Under a vacuum, the water would boil right
out of the clothes with no more than ambient heat. It wouldn't need
any moving parts other than the pump.

Might wrinkle the clothes a bit.

On Tue, 25 Mar 2008 15:57:08 -0400, RBM wrote:

wrote in message
...
I have been looking for something that probably doesn't exist for
reasons I don't know.

I am trying to find out if there is such a thing as a heat exchanger
for a dryer that would attach like a humidifier to a furnace?

I have read MANY posts and articles about just piping the exhaust of
the dryer into the house and how bad that is with lint and moisture.

What I am looking at is something like an air-air exchanger where each
"circuit" is closed.

So the dryer would still exhaust outside but on the way it would flow
through a box that is on the cold air return of a furnace. The
furnace would suck air through the box and collect some of the heat.

Just curious if anyone has ever seen anything like this, if it is even
feasible, and what issues this would cause?

Here's a thing you can use with an electric dryer, to provide warm moist air
in the house. I wouldn't use it for other than winter months:
http://www.improvementscatalog.com/h...ryer-vent.html


They suck. They invariably fill the room with dryer lint.

On Tue, 25 Mar 2008 13:26:43 -0700, Bob F wrote:

wrote in message
...
I have been looking for something that probably doesn't exist for
reasons I don't know.

I am trying to find out if there is such a thing as a heat exchanger
for a dryer that would attach like a humidifier to a furnace?

I have read MANY posts and articles about just piping the exhaust of
the dryer into the house and how bad that is with lint and moisture.

What I am looking at is something like an air-air exchanger where each
"circuit" is closed.

So the dryer would still exhaust outside but on the way it would flow
through a box that is on the cold air return of a furnace. The
furnace would suck air through the box and collect some of the heat.

Just curious if anyone has ever seen anything like this, if it is even
feasible, and what issues this would cause?

For an electric dryer, all you need to do is filter the exhaust and distribute
it somehow. A high efficiency furnace filter in an appropriate enclosure would
probably do the job without createing too much back pressure.

What it'll do is clog up within a few hours and then damage your dryer.

The Reverend Natural Light wrote:
On Mar 25, 3:02 pm, wrote:
I have been looking for something that probably doesn't exist for
reasons I don't know.

I am trying to find out if there is such a thing as a heat exchanger
for a dryer that would attach like a humidifier to a furnace?


I've always wanted to build a heatless clothes dryer. It would just
be a large air tight container you fill with clothes, seal up, and
then evacuate all the air. Under a vacuum, the water would boil right
out of the clothes with no more than ambient heat. It wouldn't need
any moving parts other than the pump.

Might wrinkle the clothes a bit.

It's called freeze drying.

a

"AZ Nomad" wrote in message
...
On Tue, 25 Mar 2008 13:26:43 -0700, Bob F wrote:

wrote in message
...
I have been looking for something that probably doesn't exist for
reasons I don't know.

I am trying to find out if there is such a thing as a heat exchanger
for a dryer that would attach like a humidifier to a furnace?

I have read MANY posts and articles about just piping the exhaust of
the dryer into the house and how bad that is with lint and moisture.

What I am looking at is something like an air-air exchanger where each
"circuit" is closed.

So the dryer would still exhaust outside but on the way it would flow
through a box that is on the cold air return of a furnace. The
furnace would suck air through the box and collect some of the heat.

Just curious if anyone has ever seen anything like this, if it is even
feasible, and what issues this would cause?

For an electric dryer, all you need to do is filter the exhaust and distribute
it somehow. A high efficiency furnace filter in an appropriate enclosure would
probably do the job without createing too much back pressure.

What it'll do is clog up within a few hours and then damage your dryer.

A furnace filter? There are many square feet of element there. I don't think so.

wrote in message
...
On Mar 25, 3:27 pm, BobK207 wrote:
On Mar 25, 12:02 pm, wrote:





I have been looking for something that probably doesn't exist for
reasons I don't know.

I am trying to find out if there is such a thing as a heat exchanger
for a dryer that would attach like a humidifier to a furnace?

I have read MANY posts and articles about just piping the exhaust of
the dryer into the house and how bad that is with lint and moisture.

What I am looking at is something like an air-air exchanger where each
"circuit" is closed.

So the dryer would still exhaust outside but on the way it would flow
through a box that is on the cold air return of a furnace. The
furnace would suck air through the box and collect some of the heat.

Just curious if anyone has ever seen anything like this, if it is even
feasible, and what issues this would cause?

As a mechanical engineer, I have thought about it for a long time

buying, if available....haven't seen one

OR

building one...haven't done it for a number of reasons

I live in SoCal so my heating demands are not all that high. the
temperature differences involved are pretty low so heat transfer won't
be great, the air stream is a little dirty (so maintenance will be an
issue), air stream contains mositure so condensation, corrosion &
freezing will (can) be issues. The heat ($'s) saved (at least for my
potential installation) won't justify the cost. My laundry room /
porch is tiny and incorporating a heat exchanger into the system would
be a lot of work.

This does- Hide quoted text -

- Show quoted text -

Living in ND and having 4 kids I think our dryer is on all the time!
So if this would work I could reclaim a lot of heat.

Yeah I have tried to think of those issues too (plugging and
condensation).
I was thinking of some kind of filter where the exhaust goes in and a
drip pan like thing for condensation. Kind of like an AC coil some
how collects condensation.

One thing that would be nice with my design (if it would work at all)
would be that it would work on a gas dryer too.
I was planning on no mixing of air flows. Like an engine radiator,
the antifreeze is separate from the air.

The amount of surface area needed would probably be immense and would
that slow the exhaust air flow down too much?
Not sure.

*************************************

Without a lot of pre-filtering, any small sized heat exchanger that could do
this would quickly plug up. Condensation in the exchanger would produce an ideal
environment for bacteria growth, which would need to be dealt with.

One could run the exhaust through a very large area filter and into a large
duct, say 6" with very well sealed joints so condensation cannot leak through
the joints. It could run across the basement in the joist space from one side of
the basement to the other, sloped so the water would run down to the far end and
out of the house. Around this duct, would be another, say 8" in diameter, with a
blower blowing room air from the far end to the dryer end between the two ducts,
forming a counterflow heat exchanger.

By using an oversized duct, the extra length should not cause dryer problems. I
suppose that the filter could be eliminated if the inner duct were frequently
cleaned. Without cleaning, the pipe walls would gradually become insulated with
link, and lose effectiveness. Cleaning could be accomplished with a 6" plastic
chimney brush, run in from the outside while the dryer runs on an air cycle to
blow the loosened lint out. Lengths of 1/2" PVC pipe with male/female threaded
fittings on opposite ends make an excellent, cheap chimney brush handle, by the
way.

"Jim Elbrecht" wrote in message
...
On Tue, 25 Mar 2008 12:02:17 -0700 (PDT),
wrote:

I have been looking for something that probably doesn't exist for
reasons I don't know.

I am trying to find out if there is such a thing as a heat exchanger
for a dryer that would attach like a humidifier to a furnace?
-snip-

I know I've seen this setup for stovepipe over a wood stove- and I
*Think* I've seen the same setup for dryer vents. It is a box-
say 14" on each side- with ? 1" ? pipes through it, open on each end.
Perpendicular to them is the inlet and outlet. . . . . . .

Here's the stovepipe one-
http://www.transoceanltd.com/applian...oves/magic.htm

The ball in the center is attached to a scraper that you clean the
pipes with occasionally.

Dryer exhaust would not be nearly hot enough for one on those to do much.

On Tue, 25 Mar 2008 12:02:17 -0700 (PDT),
wrote:

I have been looking for something that probably doesn't exist for
reasons I don't know.

I am trying to find out if there is such a thing as a heat exchanger
for a dryer that would attach like a humidifier to a furnace?

I have read MANY posts and articles about just piping the exhaust of
the dryer into the house and how bad that is with lint and moisture.

The things are between 5 and 10 dollars. Why not buy one and see if
you have the problems that others report, or if everything goes well,
like for me.

I've read those warnings too. My diverter box or whatever its called
has a lint filter, a 5x5" piece of something like window screen, and I
never see any lint coming out or lying beneath the outlet. I've been
using it for 24 years with no problems. I clean the filter about
every 30 loads, or when I see that it is partly clogged. It doesn't
clog very fast becaue there is already a lint filter in the dryer.
They sell such things at HD but they can be hard to find.

As to moisture, you need more moisture in the winter. That's why they
put humidifiers on furnaces.

Maybe if I had babies and did 3 loads of wash a day, I would have
problems, but a) I doubt it, and b) then I could switch the diverter
some of the time to send the air outside.

Trying to understand the other posters' claims of lint, maybe they dry
more lint-bearing laundry than I do. I don't actually know what
fabrics generate lint and what don't, but I do use a variety of
fabrics. The lint filter in the dryer whistles when it gets full.


What I am looking at is something like an air-air exchanger where each
"circuit" is closed.

So the dryer would still exhaust outside but on the way it would flow
through a box that is on the cold air return of a furnace. The
furnace would suck air through the box and collect some of the heat.

Just curious if anyone has ever seen anything like this, if it is even
feasible, and what issues this would cause?

wrote in news:14df1c20-ea2d-4218-a51e-
:

I have been looking for something that probably doesn't exist for
reasons I don't know.

I am trying to find out if there is such a thing as a heat exchanger
for a dryer that would attach like a humidifier to a furnace?


One thing that would recover the heat is too duct the dryer exhaust to an
HRV - Heat Recovery Ventilator. There would be a few problems to solve
the main one being that HRV's use very narrow spaces for air flow and
lint would plug them in no time at all. So you would first have to design
a way to clean all lint from the air - screens and filters. HRV's have
filters in them but they couldn't handle dryer lint without plugging
right away.

HRV's accomplish the heat exchange by running in and out air through
narrow spaces, alternating warm and cold spaces so the incoming air
channels have an out going air channel on both sides, etc. The spaces are
about 1/16 th inch wide by 12" by 12".

Another major issue would be balancing the airflow into house with
airflow out - HRV's have 2 fans, one blowing in and one blowing out and
they should be balanced fairly closely or you compromise overall house
ventilation with all of the attendant problems.

Up here, in Canada, HRV's cost around $800 plus installation.

I once thought I could design an HRV myself but there are way too many
issues to deal with, especially up here where winters are -20 to -30 C
for 6 months. I have a 2 heat exchanger geothermal heating system with 2
HRV's and they work great - house humidity is way too low in the winter
if I run them too much. MY HRV's come with defrost settings if the
incoming -30 air tends to freeze the units, drains for condensate, timers
built into switches and the dehumidistat, insulated ducting, etc. Fairly
complicated. They are claimed to be about 80% efficient.

You could look for a commercial HRV - maybe there is such a thing - there
must be an application requiring wider slots. The slots are in the heat
excahnger which is removable for cleaning. Mine are plastic so I clean
them with a pressure washer. If you had enough screens and filters maybe
the lint problem would be reduced so cleaniong the exchanger every once
in a while would be feasible. On mine the slots are so narrow and long
that I couldn't blast clumps of lint out.

On Mar 25, 3:02*pm, wrote:
I have been looking for something that probably doesn't exist for
reasons I don't know.

I am trying to find out if there is such a thing as a heat exchanger
for a dryer that would attach like a humidifier to a furnace?

I have read MANY posts and articles about just piping the exhaust of
the dryer into the house and how bad that is with lint and moisture.

What I am looking at is something like an air-air exchanger where each
"circuit" is closed.

So the dryer would still exhaust outside but on the way it would flow
through a box that is on the cold air return of a furnace. *The
furnace would suck air through the box and collect some of the heat.

Just curious if anyone has ever seen anything like this, if it is even
feasible, and what issues this would cause?

off the top of my head, two design issues; you couldn't go to a bunch
of little tubes with a lot of surface area the way you'd like to,
because you have to provide for the lint to blow through; and you
can't squeeze as much heat out of it as you'd like to or the humidity
will condense.

that doesn't mean somebody doesn't make one, though.