The Homemade Heat Pump Manifesto

[AC_Hacker]

Originally Posted by jlaw

As AChacker says I do live in that 62-67 degree area. I am about 1.5 west of the ocean. Sometimes we get 1 snowfall a year. The stream never ices even on the edges. I understand, mostly, the operation and function of the heat pump I don't understand completely the design issues involved with adding a water to refrigerant exchanger. How to calculate size, exactly where to cut into the condenser line, how much pipe would be needed, the effects it would have on my current system, etc. I am capable of doing the physical work such as cutting brazing, adding refrigerant, doing electrical, etc.

based on information I previously supplied I am looking for guidance from the smarter guys than me. Have a great day.

You should start by looking into any infiltration leaks or insulation issues that need to be resolved. Money spent on these heat loss issues will have a better return for you than what you will spend on the heat pump.

Then, after you have this taken care of, you need to come up with the amount of heat you need to keep your house temperature at the level you will be comfortable (probably about 68 F).

You can do this with some kind of calculator. There is a really good one at Biild it Solar [THE LINK] For this to be useful, you need to be honest about how your house is, not how it's going to be.

Another way is that you can measure the amount of heat you are using right now. We are just about at the coldest time of the year. If you use electric heaters, you could put Kill-A-Watt to each one and see what the highest rate over an hour or two that you need.

The reason this is important is that this quantity will determine everything else. If you don't know the quantity of heat you need, you're just stabbing in the dark.

So let us know when you have these things in order, and we can get to work.

Best,

-AC

[AC_Hacker]

Originally Posted by jhwelder

...Has anyone figured out a way to switch the hx's from summer use to winter use(like Randons cross over valve) but with ball valves or something?...

Actually heat pumps usually use a solenoid actuated refrigerant reversing valve.

Above is a photo of one. Randen's heat pump is unique, because he is reversing the water flow through the HXs.

For HXs to have maximum efficiency, you want the fluids (refrigerant & water) to flow in opposite directions. Randen's design maintains the counter-flow even when the heating/cooling mode is reversed. The 'normal' reversing valves take an efficiency hit.

I suspect that most folks who are hacking together a reversible heat pump would find it much easier to use the refrigerant flow reverser. But Randen is obviously pretty skilled at what he does.

Yes, I think a water reversing setup could be achieved with off-the-shelf manual valves. It might look a bit messy, but it could be done.

If you can't figure it out with a pencil & paper, let me know, and I'll see what I can come up with.

-AC

[jhwelder]

I guess I did not explain my question very well. I actually am trying to change the flow of coolant from my air coil and gs. I think I may have figured it out though.
I am planning on having an evap hx and a condenser hx with an antifreeze mix flowing through them. From one it will flow through a big hx which will have ground water pumping through, and the other will flow through the air coil in the ductwork. I want to be able to direct heat to the house in winter and cool the house in summer. I am using mostly used parts for my set-up since it is very low budget. I am building the evap hx and the condenser hx from a large truck air tank from work that was going to the junkyard. It is a 12" +/- round x 4ft long aluminum tank that I will cut in half and make two tanks. The tanks will have an aluminum tube in the middle with the refrigerant tubing wound around it and the outer wall of the tank. Antifreeze mix will flow through from opposite ends in a reversed flow of the refrigerant. The pipe fittings for the mix will be angled to create a whirl pool affect. Should create turbulence., which I hope to be effective in heat transfer. I dont know if this all makes sense or not. It is all experimental.

Joe

[AC_Hacker]

Originally Posted by jhwelder

...I dont know if this all makes sense or not. It is all experimental...

Why don't you do a drawing of what you propose and post the drawing? It will help you get your thinking clear and also allow others to see what you are attempting and to offer their thoughts.

1 picture = 1000 words (maybe even more!).

-AC

[Thepprof]

Hi; I presume if you have enough knowledge to hack a unit you have a very good handle on basic functions of a minisplit. I am a landlord in richmond, Va. and after being screwed (pardon my French) by several local ac contractors I took to the local trade center and took the basic courses for air conditioning etc. I keep my CA Units serviced and working. Last year I installed 2 12k 13 sear Klimaire minisplits. One install went as instructed and when I checked it yesterday it was kicking a 20 degree differential at the air handler with the outside temp rising up from 19 to the current 25 degrees outside.

When I installed the other unit something went wrong and when tested in the apartment it seemed to be locked up. There was no gas remaining in the system. I pulled the unit brought it home and put it in the shop. the plan was to pull the usable parts to use as repairs for the remaining unit and a replacement unit that I was going to purchase. I read on this site that propane could be used a a substitute for R410 I decided to put the system back together and see what would happen. I tested the compressor by bypassing all of the compute stuff and it ran. I reassembled the unit in the shop and assuming that it was still junk I purged and vacummed the unit and started adding propane. Since I had all of the covers off of the unit I could use my IR thermometer and measure the areas of the compressor coil that the heat was being radiated out of. As I added more propane the coil eventually was passing heat from the entire coil. Initially it was coming from the lower third of the coil I kept playing and the unit eventually was showing a 20 degree air handler delta. I ran it several times over several days and decided to reinstall the unit in the apartment. I purged the unit, pulled a vacuum and now decided to service it with R410A. I do not have scales and so guessed at the first shot and as before with the propane kept adding liquid until the entire coil on the compressor was radiating heat. I pumped the unit down to 0. reinstalled the unit and it has been working fine every since. I went over yesterday and after I checked the previously mentioned unit I checked this unit and it was kicking a 30 degree Air Handler Delta.
I got the idea regarding sensing coil temperature from the basic Frig course that said that the coil needed to be saturated and that indicated to me that the heat would be radiating out of the entire coil. Since the only way currently to service these minisplits is by evacuation and weighing in the correct amount of gas does my system of reading the temp of the evap coil not make sense?

[AC_Hacker]

Originally Posted by Thepprof

...does my system of reading the temp of the evap coil not make sense?

Wow! Yes, it makes great sense. This is an approach I had never thought of.

I'm really curious what some of our other folks will think about your approach.

So what was your Basic Frig Course?

Best,

-AC

[Geo NR Gee]

Originally Posted by Thepprof

As I added more propane the coil eventually was passing heat from the entire coil. Initially it was coming from the lower third of the coil I kept playing and the unit eventually was showing a 20 degree air handler delta.

Thepprof, How long did you have to wait when adding the refrigerant to see the results on the IR thermometer?

[Thepprof]

The last 3 HVAC fellows I have trusted cost me big. This is what prompted me to learn about HVAC. The first one sold me a air handler for $3000 when all that was wrong was a hole in the compressor coil caused by a residents lawnmower. The second one overloaded the system and destroyed the compressor (I think on this one) and the third one after servicing a unit that I had serviced for the last 5 years with no trouble did something that caused all of the oil to leak out of the system hence another $3000.00 system..

The Ac course is a 1 year thing based on The 4th edition of Refrigeration and Air conditioning An introduction to HVAC. This is the main course taught in this area prior to taking the test go get your AC card. I never took the test just wanted to understand HVAC. I've been servicing my regular central air systems for years now. installed 1 total new system and had a buddy do the vacuum and charge thing as this was my first unit. The minisplit threw me a curve ball since I was just getting the hang of super and sub heat.

I've done a lot of side reading. The idea to check the heat dispersal as a indicator was quite by accident when I was playing with the unit in the shop using Propane to see if the unit would actually work. I did not want to test using R410A since it costs so much and the pressures so extreme. I could not find any local ac fellows that understood much about these Mini-splits. The one buddy I had that had a masters degree in HVAC and was equally smart on the common sense end of things has left town... I did not have scales and just gave the unit like a 30 second shot and monitored what was going on. The first shot indicated the unit was working but not very good (like a delta T of 4 degrees and I noticed that the heat was coming out of the lower portion of the compressor coil . I added another 30 second shot and Delta t came up as did the portion of the coil emitting heat. It was simple after that. Funny you are the first HVAC fellow that understood and agreed.

I II have to thank the Klimaire technician as he seemed to understand and gave me some hints along the way since I did not have scales. I guess I've bent your ear enough for now... Owen

[AC_Hacker]

Originally Posted by Thepprof

... I guess I've bent your ear enough for now... Owen

Not a problem at all.

Hope you stick around to help answer some of the questions that come rolling in.

-AC

[AC_Hacker]

The 'Manifesto' just broke 400,000 hits!

Some time in the last day or so, the 'Manifesto' sailed past 400,000 hits.

When I started this thread, I hoped that there would be some interest, but I must say that I am extremely pleased, beyond my highest expectation.

Even better than a mere hit count, is that it has attracted some very interesting folks who already have, and are gaining more expertise in heat pump hacking. This is really different from professional HVAC installation and maintenance. It's also different from full-on HVAC engineering, although it borrows from both.

I think that we are creating a new space that didn't really exist before.

Of course, I want to thank Daox and all the others that work behind the scenes to keep this whole thing moving forward by supporting the forum and deflecting the swarm of spam posting, that land on this site like pesky mosquitoes.

Also, to thank are my fellow hackers who have fired up their brazing torches and waded in to make something work for them... something that didn't exist before. And left a trail of useful photos & postings that we can all learn from, on the various threads that are continually appearing.

It's all great fun, and I find myself struggling to keep up with the progress and collective expertise that is emerging here.

It's pretty miraculous that people with a curious interest in this particular technology, from all over the world, can easily exchange very useful information.

Sometimes I wish we could all gather around a real campfire somewhere and actually meet and swap stories... Maybe when we sail past 1,000,000 hits!

Thanks to every one!

Best,

-AC_Hacker