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oil pan 4 02-28-18 02:27 AM

Home made heat pump clothes dryer.
I have a spare fully functional electric dryer tjat i dont use and a portable 1 ton A/C unit (not a window unit) that I don't really use any more also.

Probably keep it simple, plumb the A/C discharge into the side of the dryer. Add a hot air bypass if needed.
Don't know how much I will modify the dryer beyond that.
Don't think I will use electric resistance heating at all.
Plumb the cool air into the house.
Locate the whole assembly out in the garage.
Keep it simple.

Daox 02-28-18 07:49 AM

Cool project!

How do you propose to deal with the condensate / water removal?

oil pan 4 02-28-18 08:48 AM

Just blow the waste heat and humidity through the dryer discharge and out side like a normal dryer.
I'm not relying to recreate a consumer heat pump dryer.
Which acts like a wet clothes dehumidifier.
The purpose of this one is make some cold air, while drying clothes for use during warmer months. Which there are 7 or 8 of here per year.
Then during the winter I use my normal electric dryer that's just vented into the house. Which is what I'm doing now
That way I will have a winter and summer dryer, the benefit being drying the clothes will help heat or cool when needed.

Semipro 03-03-18 07:03 AM

So you're planning basically to replace the electric heating elements with the the AC condenser?

oil pan 4 03-03-18 09:02 PM


Originally Posted by Semipro (Post 58648)
So you're planning basically to replace the electric heating elements with the the AC condenser?

Yes, and direct the coold discharge into the house.

AC_Hacker 03-04-18 10:41 AM


Originally Posted by oil pan 4 (Post 58629)
I have a spare fully functional electric dryer tjat i dont use and a portable 1 ton A/C unit (not a window unit) that I don't really use any more also.

I think your idea is really good.

However, I suspect that a 1Ton HP is over-sized.

I say go with what you have, and adjust what needs adjusting.

Good luck on your project.


P.S.: a clothes dryer is essentially a de-humidifier. Maybe more good could be piping all your dryer air through a dehumidifier instead. They are already set up so that humidity in the air (clothes) will freeze on the evaporator coils, and a built-in sensor detects when sufficient frost has built up and a frost removal cycle starts, and the frost from the air (water from your clothes) drains into the little bucket. Then the de-humidifier returns to moisture removal cycle. There is even a sensor, such that when sufficient moisture has been removed from the air (AKA: "your clothes"), the machine will stop.

jeff5may 03-05-18 10:37 PM

What ac hacker said. Use your 1 ton unit to be a big dehumidifier. Retrofitting a conventional electric dryer would be simple. Use the dryer blower as is to move air. Rig the condenser upstream from the electric heating element and let it find its way to the clothes. Rig the evaporator downwind from the blower, and recirculate the exhaust air back towards the condenser. The waste heat generated by the compressor will concentrate in the air loop and aid the evaporation process.

oil pan 4 03-06-18 06:37 AM

The dryer doesn't need to reuse it's own heat since it will be used in summer only, out in the garage where it will be 80 to 100F with 15 to 50% humidity.

The heat pump discharge will produce up to 18,000btu, if the dryer only uses 2/3 of that it's still over 3kw worth of heat.
If doing it this way makes the dryer take a little longer that's fine since it will be helping to cool the house.
This design goes against conventional design by actually helping cool the house. Every other design puts off heat.

jeff5may 03-06-18 07:18 AM

Ok but you do understand that water evaporates at a nonlinear rate versus delta T right? Most all dryers cycle around 160 to 175 degF exhaust temperature so they don't take 3 hours to dry a load. You know what happens to heat pump performance at these condensing temps right? If you're doing an airside pump and dump, you may be better off just preheating your dryer suction air. Let the electric element finish the job downwind from the condenser.

oil pan 4 03-06-18 09:53 AM

I know gas and electric dryers can get that hot but it does not appear necessary on all but heavy denim.
The electric dryers converted to run 120v across the heating element don't get nearly that hot and dry light weight clothing just fine.
My flirI7 shows the discharge on my air conditioner being about 125 to 135F which is hotter than my 120v dryer. So I don't see why it wouldn't work great on all but the heaviest clothing.
I also have the advantage of very low humidity that most of the country does not have.
Probably won't work as well if the air going into the heat pump condenser coils starts off at 80 to 100%.

If I really need it I can put the heating element on a switch say for denim.
Then run the whole thing off my 30 amp garage 120v welding circuit.

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