DIY heat pump??

[Xringer]

Per the pdf..

1.Adding heat to the accumulator during the winter heating
season will retard frost accumulation on the outdoor coil.
The frost-less concept worked as expected.However,when
the ambient temperature drops below32F,adding a
moderate amount of heat will not prevent frost accumulation
on the outdoor coil and,thus,the heat input to the accumulator
should be stopped. Heat should be added to the
accumulator only when the ambient temperature is between
41ºF and32F, where frost is most likely to accumulate on the coil.


That seems like a lot of stuff to precisely control to allow you to get down
to 32 deg.

If I could get heat out of 40 deg air & higher I could be happy with that.
When it was really cold, I still have oil & wood or coal..

Last night it got down to 36 at one point, but there has been a lot of time
during the last 24 hours when it's been above 40..
And during some of that time, I could have used some space heat..

These guys have a way to pump heat out of really cold air..
Hallowell International: Products

[NiHaoMike]

There's a heat pump out there that has a wire running through the outdoor coils but electrically insulated from the actual coil. The wire connects to a circuit that generates high voltage, very high frequency AC (about 800v at 915MHz). When power is applied, the frost in the gap acts as a very lossy dielectric, heating up very fast and vaporizing almost instantly. The resulting shock wave blows the rest of the frost out of the coils.

[Xringer]

That's a great idea. Explode the ice out of the coils!

Just a guess, but I'll bet that generating Zapping power at 915 mHz is not something that the typical DIYer would even think about.

Funny, I was just thinking about the ice problem the other day.
How to apply heat real fast and efficient.?. Answer, RF!
I immediately started thinking about the fancy soldering iron on my desk at work. It uses RF power (coax cable to the tip) and it warms up almost instantly. It's the best soldering iron I've ever used..

It never entered my mind to light off the whole outdoor coil with RF..

HAHA! I can just picture that thing getting turned on in the summer
and working as a giant Bug Zapper..

[Mara]

Instead of building your own heat pump you can buy portable AC units with this feature. I have Amcor 12000BTU portable unit (ALD12000EH) that we use wintertime to heat up our bedroom. (So other part of the house isn't heated much while sleeping.) This did reduce our combined gas and electric bill significantly. The only downside is that the unit is rather noisy... but you get used to it.

[Xringer]

I looked at the specs on that one a while back..
http://www.sylvane.com/images/produc...e-h-manual.pdf
The heat works down to 41 degrees. That's okay for Texas, but it use would be limited up here.
I would be able to use it on days like today! But next month, it's going to stay below 40 a lot of the time.



I can't even see how it would work in heat or AC mode with only a single hose to the outside.
Some of the other heat+cool models I've seen have two hoses. One for in and the other for out.


I can almost see how a single hose could work, blowing out cold air when it's heating and blowing out warm air when it's cooling.

But, if it's blowing air out of your house, what's the source of the air??
Once my house has vacuum inside it, it will suck in air from the outdoors.
(Vents from the kitchen & bathroom)..
If it's sucking in ice cold air, it doesn't really help me much.
If the house was really tight, it wouldn't work at all.

[NiHaoMike]

They make window heat pumps as well.

[Xringer]

I've been reading about those window/wall units. They cost almost double the price of a regular AC unit. And are pretty dang efficient.
But, when the temps get down under 40 degrees, they start loosing efficiency due to defrosting requirements or, they just frost up and stop working.


If I had the voltage wired in, and warm-air duct work, and the money for a Hallowell system, that would be my choice..

Hallowell International: Acadia Heat Pump

They work pretty well at very cold temps..
http://www.gotohallowell.com/assets/...hrenheitLR.pdf

Maybe next summer I'll see about installing their hotwater HP, if it's ready to ship by then..

[Mara]

Concerning the single hose portable AC, those work well as long as outside temperature is not too cold or too hot. As you figured out they cause vacuum to your house and replacement air is coming from the leaks of the house. I do not use these if outside temp is below freezing, or above 100F... In those conditions the efficiency becomes miserable.

[theCase]

I wonder how a reverse AC unit would work if you had it facing the south, then enclosed the area along the house with a clear plastic lean-to with the ends open. It could raise the ambient temp on a sunny day and provide a bit more efficiency. Maybe?

[Xringer]

Originally Posted by theCase

I wonder how a reverse AC unit would work if you had it facing the south, then enclosed the area along the house with a clear plastic lean-to with the ends open. It could raise the ambient temp on a sunny day and provide a bit more efficiency. Maybe?

I've been thinking about that too. Add-on green houses or 'sun rooms' are
pretty nice heat sources when south-facing.

If you installed one using some good thermo-pane windows, and had the whole air-space well insulated, you could just pump the warm air into your home using a simple fan.

But, if you went with plain glass or plastic, you would need to get the air space up around 50 to get good results with the reverse AC unit..
The larger the air space, the better!