​appliance heat waste

[bcroe]

All the clothes driers here seem to be very energy inefficient. Typically they take the warm air in the house, heat
it more, then blow it outside into the winter. All that energy goes mostly to heat the great outdoors. Am I out of
date, or is that still the way its done?

Recirculating that air may not be a solution. How about, draw in air through one of those quite long concentric
tubes (heat exchanger) used to ventilate very tightly sealed houses? The hot outgoing air goes through the outer
tube and outside, hopefully transferring a lot of energy to the incoming air.

My central vacuum has the same issue, but I must have dust going outside. So does the gas water heater;
perhaps a bigger problem is a tendency for outside air to flow in backwards when its not running (practically
all the time). An electric water heater would cure that, if I have the KWH to spare.

From an energy (built up reserve) management perspective, options of electric or propane water and clothes
would be useful. Perhaps an electric water heater ahead of the propane would work. A second, electric element
in the propane clothes drier sounds doable, or maybe not.

Bruce Roe

[J.P.M.]

Winter/cold weather recovery of the heat contained in warm air or in some cases water is a nice idea of the "you could just" variety. As in for example: You could just vent the dryer indoors and save a bunch. (and watch the window rot from sweat and have a house full of lint) Or: you could just use our super duper heat exchanger and save a bunch (and watch it foul with lint, get moldy, smell, quickly plug up and impair clothes drying, thus increasing the use and cost, not to mention creating a safety hazard. That second one is usually some peddler with a P.O.S that is no more than a tool that uses consumer ignorance to separate fools from their money. I spent the better part of 7 or so years early in an engineering career designing industrial heat exchangers and boilers. My separate R.E./conservation activities allowed me to see that most of the stuff available for home use is a waste of money, and some of it downright unsafe. For the previous example, get a solar clothes dryer.



Air/air heat exchangers for homes are not much better. First off, most houses are energy sieves to begin with Older homes have ~~ 1-4 air changes /hr. simply due to leakage where surfaces meet ( or don't quite meet). The exchangers themselves are usually about 20-30% efficient. The better ones have claimed easy access for cleaning. that's often a dubious claim. Condensate take away/handling - an essential - is sometime entirely absent. Most folks will be much further ahead by tightening up a home, keeping it clean and using ADEQUATE ventilation in kitchens and baths for moisture removal. BTW: Don't vent to an attic or crawlspace - that's the fool's way out. The moisture laden air will quickly cool, the H2O vapor will condense and settle in the area, even if will ventilated. Take it outside and control the movement with dampers.

Motorized dampers for gas appliances seem to be effective and safe. They are mandated by some states/areas. I used them in Albuquerque on the water heater and Boiler.

Overall, caveat emptor. Shysters will use your ignorance to get in your knickers. Believe it.

[Logan5]

Prior to moving to Florida, I installed a damper and a lint canister and diverted warm moist dryer air inside to reduce waste in the winter. It worked very well. Now we have opposite problem, I upgraded our bathroom vents with humidistat's, now during a hot shower the fan is automatic and removes the damp hot air before it engages the Air conditioning. There are many ways to save, Best way is to reduce need..

[J.P.M.]

Best way is to reduce need..

Big +1 on that.

[peakbagger]

Just write the check for a heat pump dryer http://www.heatpumpdryers.com/. Far more efficient but reported to be a lot slower.

[bcroe]

I had hoped J.P.M. would come back with the complete story, thanks. Certainly
the solar powered clothes dryer gets used as weather permits. Lint seems to be
the biggest problem. When winter requires the indoor dryer, humidity is so low
that moisture probably wouldn't be a problem. At least the high efficiency propane
furnace uses outdoor air. I'm thinking the best immediate action would be use of
motorized dampers for everything. There are gravity flappers, but they may not
do a very good job.

The heat pump dryer is the sort of innovation I wanted to hear about. SOME
versions are ventless, somehow solving the moisture and lint problems. The vent
is the bigger deal to me, as it may be leaking 24/7. Recirculating the heat is also
an advantage; the use of a heat pump matter less because I'll just need to come
up with the indoor heat from my house system. Bruce Roe

[Logan5]

When I lived in the city I had a Lasko washer dryer combo. As I recall it had some sort of compressor in it. No vent, washed and dryed small loads, about 3 hours, I am sure things have improved since then.

[J.P.M.]

I had hoped J.P.M. would come back with the complete story, thanks. Certainly
the solar powered clothes dryer gets used as weather permits. Lint seems to be
the biggest problem. When winter requires the indoor dryer, humidity is so low
that moisture probably wouldn't be a problem. At least the high efficiency propane
furnace uses outdoor air. I'm thinking the best immediate action would be use of
motorized dampers for everything. There are gravity flappers, but they may not
do a very good job.

The heat pump dryer is the sort of innovation I wanted to hear about. SOME
versions are ventless, somehow solving the moisture and lint problems. The vent
is the bigger deal to me, as it may be leaking 24/7. Recirculating the heat is also
an advantage; the use of a heat pump matter less because I'll just need to come
up with the indoor heat from my house system. Bruce Roe

You're most welcome, but it's not near the whole story. A scratch/sniff maybe. Some folks in cold climates where I came from (Buffalo, NY) vented electric clothes dryers to the dwelling with a stocking over the outlet, usually in the basement, and simply turned the stocking inside out, tossed the lint for the next use and got on with it. Besides the lint that escaped the stocking - -probably ~ 50 % or so, in the days of cheap energy, before houses were tightened up, with something like 3-4 air changes/hr., that scheme did add some moisture to the dwelling, perhaps replacing some of the use of humidifiers but in a mostly uncontrolled fashion. Flash forward to now : If you do, say, 1 dryer load/day in a dwelling with, say, 1.5 air changes/hr. you'll be on you way to a moisture problem as well as a lint problem.

Once upon a time I ran some numbers involving humidity ratios, air infiltration rates and how a dryer load of evaporated water would humidify a house given some outside air conditions like temp. & dewpoint. That was before I quit drinking. I lost the details, but the above seems a reasonable recollection. It was more back of the envelope stuff than rigorous.

BTW: NEVER vent a gas dryer inside. All your canaries will fail.

As a general statement, home heat recovery uses all of the same principles and methods of calculation, including the process economics parts as when doing it on an industrial scale. It's , just that a lot of the residential scale usually winds up with half assed and inferior products and a lot of stuff that's a sham, unless it's connected to a device that's designed to a recognized code - like flue dampers on a boiler, etc. Caveat emptor.

[Sunking]

There is a good reason building codes do not allow you to exhaust dryer air into your home. There have been many devices sold to do exactly that. All of the companies are bankrupt from lawsuits from damages and injury caused by venting dryer exhaust indoors. Not only is it an extreme source moisture moisture, but also an extreme air pollutant filled with lint and air particulants Lint makes for a real nice bomb and source of fuel for fire. Not to mention breathing all that lint in does lungs wonders.

But let me save you a lot of money. You can make a better dryer exhaust filter than you can buy and cost almost NOTHING except some skin off your wife's butt. Take an old pair of panty hose and strap it onto the exhaust hose and vent inside. It comes with my World Famous Guarantee. I guarantee it will destroy your home, or double your money back.

[DanKegel]

The heat pump dryer is the sort of innovation I wanted to hear about. SOME
versions are ventless, somehow solving the moisture and lint problems. The vent
is the bigger deal to me, as it may be leaking 24/7. Recirculating the heat is also
an advantage; the use of a heat pump matter less because I'll just need to come
up with the indoor heat from my house system. Bruce Roe

The heat pump in a heat pump clothes dryer pulls heat out of the hot
exhaust, it doesn't really pull it from the ambient air, I think.

I'll probably get one of those when my current washer/dryer pair give up the ghost.
(The light in the dryer burnt out recently, does that count?
That's the kind of excuse I used to get rid of my gasoline-fired car
and replace it with a used EV. The poor honda never knew what hit it. )

[J.P.M.]

There is a good reason building codes do not allow you to exhaust dryer air into your home. There have been many devices sold to do exactly that. All of the companies are bankrupt from lawsuits from damages and injury caused by venting dryer exhaust indoors. Not only is it an extreme source moisture moisture, but also an extreme air pollutant filled with lint and air particulants Lint makes for a real nice bomb and source of fuel for fire. Not to mention breathing all that lint in does lungs wonders.

But let me save you a lot of money. You can make a better dryer exhaust filter than you can buy and cost almost NOTHING except some skin off your wife's butt. Take an old pair of panty hose and strap it onto the exhaust hose and vent inside. It comes with my World Famous Guarantee. I guarantee it will destroy your home, or double your money back.

FWIW, and mostly agreeing with what I suppose is S.K's sarcasm - to the point of offering to underwrite half his guarantee - my very limited personal experience and experimentation with indoor venting using panty hose (or panty ho if using only one leg on a dryer vent) as a filtering element was that, from a SWAG experiment, one "ho" grabbed about half of the lint input to it (I used 2 layers of ho in series (with the conversion factor 2 ho == 1 hose in the J.P.M. unit system) with the 2d layer looking like it snagged about half as much as the 1st layer. Back in the day/neighborhood, some few neighbors vented inside - with those who did mostly with electric dryers - NOMB. I did not, primarily because, while it was easy to do, it's a stupid idea, and if a gas dryer, on top of stupid, dangerous.

Besides the danger, the stupid part: I'm pretty sure the ho filter scheme might be rather self defeating due to user ignorance about the need for frequent cleaning which, if not done, will quickly inhibit air flow and slow down the drying process. Other effects, such as on the lungs, might be anecdotally estimated by comparison of lung disease incidence among textile workers, or simply by a look at the level of dust/lint added to surfaces, particularly the horizontal ones in a dwelling and using one's imagination.

As you may guess, I had no way or desire to estimate dust/lint concentration levels for a SWAG at approach to lower explosive limits, but I don't seem to recall many dust explosions in the neighborhood. There was one explosion a few years after I left, but the neighborhood was declining and I suspect that explosion was due to a meth cooker lighting up.

While I may take a somewhat lighter tone here, inside venting is, overall, and at best, and for a lot of reasons, a dumb idea - and very likely, dangerous. Don't do it.

[Sunking]

FWIW, and mostly agreeing with what I suppose is S.K's sarcasm - to the point of offering to underwrite half his guarantee

Well I do believe in giving Stupid People an Attitude Adjustment upside the head with a 2 x 4. If that fails, open a fresh can of WhoopAss and feed it to them.

Fair to say JPM we agree, don't be stupid and try this. We just deliver the message differently. Both are effective. As for the Ho method, the real danger as you say is the Lint clogging it up. That makes the dryer over heat and fire to follow if the safety devices fail to operate if they even have any.

[J.P.M.]

Well I do believe in giving Stupid People an Attitude Adjustment upside the head with a 2 x 4. If that fails, open a fresh can of WhoopAss and feed it to them.

Fair to say JPM we agree, don't be stupid and try this. We just deliver the message differently. Both are effective. As for the Ho method, the real danger as you say is the Lint clogging it up. That makes the dryer over heat and fire to follow if the safety devices fail to operate if they even have any.

Not knocking your method at all. Different strokes. Been known to use it myself when in responsible charge, Engineer of Record, or C.O., etc.

[Sunking]

Well there is a extremely good, I take that back, excellent and very inexpensive clothes dryer. So good it evens kills germs, fungus, mold, creepy crawlies, and bacteria modern washers and dryers cannot kill and completely solar powered. Leaves cloths and linens smelling great and feeling crisp. Does not work in all location year round, but even works in cold weather if sunny and windy. Got any ideas yet?










I am willing to bet there are a lot of folks under the age of 50 have never seen one before, or know how good they work. All we had when I was a kid, and stil use one.

[bcroe]

We would use ours all the time, if we could. But its a fair weather device. Bruce Roe

[inetdog]

If you want soft laundry, you just have to use rinse conditioner instead of dryer sheets.

[J.P.M.]

Well there is a extremely good, I take that back, excellent and very inexpensive clothes dryer. So good it evens kills germs, fungus, mold, creepy crawlies, and bacteria modern washers and dryers cannot kill and completely solar powered. Leaves cloths and linens smelling great and feeling crisp. Does not work in all location year round, but even works in cold weather if sunny and windy. Got any ideas yet?










I am willing to bet there are a lot of folks under the age of 50 have never seen one before, or know how good they work. All we had when I was a kid, and stil use one.

Check the last sentence of my 1st paragraph to this thread.

Used one until moving to CA.

FWIW, most HOA's forbade them until about a year ago when CA law disallowed HOA's from outlawing them.

Solar clothes dryers will also work at below freezing temps via sublimation, but the drying process will take longer, and the fabrics may be damaged by the freezing process. So, as both you & Bruce write, mostly a warm and I'd add also not raining weather scheme, but sure the way to go when/where possible. More FWIW, I always felt something therapeutic and relaxing about hanging and removing stuff from a clothes line.