AC Hacks a Heat Pump
 

Thanks to a tip from stalwart EcoRenovator Geo NR Gee, I got lucky and found this magnificent piece for $35. (Outside unit only, no inside unit.)


My purpose in buying it is to convert it from Air-In-Air-Out to Air-In-Water-Out so that I can use it to heat hydronic floors.

I wanted a unit that used R22 because of the higher hacking potential (check), and also I wanted a unit that was NOT inverter technology (check). In all honesty, an inverter tech unit would be much more efficient, but the technical barriers involved in hacking one have not yet been breached, that I know of.

So, either I have a brand new unit that is in great shape or I have inherited a total lemon.

The unit has Model Number: AS0RD12AA0G1

I have searched for technical information, such as service information and schematics, but have been unable to locate anything other than owners manual, and sales literature.

Actually owning an indoor unit would be only marginally useful to me, but having schematics would be very useful.

I anticipate that the fan has maybe three speeds, while the compressor has but one.

There will likely be some communication issues involved in realizing the potential of this unit.

Any help or ideas would be most appreciated.

SOME PICS:



Best,

-AC_Hacker

Sounds like a fun new project AC Hacker. However, does this mean a nail in the coffin for the GSHP project?

No, not at all, the GSHP supplies good heat... not as much as I had hoped (bigger, deeper loop field needed). But luckily, as it is, it is able to supply heat when the really foul weather is upon me and the temperature severely drops.

So, what I'm going for is a hybrid of GSHP and ASHP and use each when appropriate. Here's a link to a study of a much larger installation... but the principle is the same. Check out the installation costs...

When I was doing my winter testing, I realized that we can have unseasonal, balmy winter days and sometimes a whole week when the air temperature significantly exceeds the ground temperature. An ASHP would work best in those conditions. I can leave the heat in the ground for when I really need it.

So that's the grand plan... and I'll probably be using your differential Arduino project to switch between the two.

Best,

-AC

Heat Pump Test #1...
 

So I noticed that the heat pump had six chopped off wires coming out of it...


...and it looks pretty much like the setup for my Sanyo, which is an inverter technology unit... I assume that this one is not.


After meditating on the wiring diagram for an appropriate time to calm my mind, I decide that I should hook up power to this unit and see what happens.

I savaged a computer power cord (much too light for normal operation, but OK for testing).

I hook:
Green to Green
White to White
Black to Black

... seems like a safe way to proceed.


Then I make sure that there is no noise in my shop so I can hear if anything goes haywire, and I connect power.

No heartbreaking sizzle of frying Chinese components, no arcing to be seen or heard, no wafts of smoke rising from the unit. Just blissful silence.

So I look down closely at the circuit board...


...and I see a small green LED (green circle) blinking quietly, benevolently. We have power and all is peaceful.

I look closer, and I see a tiny button that is labeled "TEST KEY" (blue circle), which I suppose is the Chinese term that means "PUSH ME". So, I push it...

Nothing happens, and I regret ever going the 150 miles to get this unit, or ever getting involved in refrigeration and... AND IT STARTS RUNNING!

Oh yeah, the built in time-delay that all HVAC devices have to prevent damage. I must have told fifty people about that, not counting the forum postings... many thousands of people if I do count the forum.

So, as I quickly lunge to pull the plug, I notice that the fan is running and the compressor is making appropriate sounds.

I'm good to go, the unit has passed test #1!!!

NEXT STEP is to try to get some info on those control wires, and then to find an appropriate refrigerant-to-water HX.

I imagine that there is some kind of three-step signal that controls the fan, that might also be useful to use to control a water pump.

Best,

-AC

Great news that it works! Some questions. When the electronic controller (audrino) senses its too cold out for the ashp to operate efficiently, the gshp valve turns on?

Is the unit for heating and cooling? Since you were just intending on using it for the hydronic floor heating, could you then switch in the summer to cool the house with another valve and run line inside for cooling?

That's the idea at this point. I'm sure that there will be some data logging and tweaking to find the best cross-over point.

Well, you've seen my house and it's pretty small, and doesn't take much to cool it (or heat it). I usually need A/C about 7 days a year. My little factory-made 3/4 Ton AC/heat pump puts out more than enough cool air to do the job.

But regarding summer cooling, using the little GSHP would be the better way to go. Because when the temperature starts heading into the high 80's the loop field is maybe 57 F or 58 F, and has a very large capacity to absorb heat. That's a much more efficient heat dump than 85 to 100 degree air.

I tell you Geo, I'm really looking forward to getting some radiant floor action going on here in my house. My living room isn't critically tight, but it's pretty tight, and this evening, even though I've had the temperature set at about 70, when I'm sitting in a chair or lounging about on the couch, I am not comfortably warm.

Right now, the heat pump has been off for about 15 minutes, as it heads into night mode, and the temperature at floor level is 55 F, but the temp at ceiling level is 65 F, and my feet are cold.

I get grumpy when my feet are cold.

Hope all is well with you & yours...

Best,

-AC

Here's your users manual as a start.

http://products.geappliances.com/Mar...=981130016.PDF

That PCB looks like it is just a switch mode power supply and some logic. The board has a pair of opto-isolators on it. Follow the wires from the 4 terminals that connect to the indoor unit and see if two of them connect to the optos (IC9 & IC10) at the bottom left of the board.

My theory is two of those wires supply power to the indoor unit, and the other two signal back. I'd expect something dumb like (A)Compressor & (B) Reversing valve.
I'd have thought the indoor unit has no requirement for any fancy comms to the outdoor unit. The outdoor unit may have some thermistors and other control gadgetry that assist in managing defrost & condenser fan speed.

Have you got access to high resolution scanner? Some scans, or even high res photos of the back of the board, and some labelling to tell us which wires go to what devices from the plugs on the front might help us figure it out.

Most units seem to have those in one form or another. They are useful for firing the compressor up from outside while you pump it down.

Have you been *really* lucky and got a unit with its factory gas charge still in it?

I guess I'll just have to crack a valve a wee bit to see...

-AC

This just in from Acuario...
 

This just in from Acuario:

Hummmm....

Sobering thought from someone with plenty of electronic skill and test tools, and who has spent lots of time trying to crack the code on an inverter machine.

I was thinking, when I bought the unit, that I might have to do something like that...

-AC