The Homemade Heat Pump Manifesto

[S-F]

Pachai, I certainly have no data to back this up but I imagine that immersing the evaporator and the condenser in barrels and circulating the barrel water would turn out to be much less efficient than a mini split or even a couple mini splits.

[AC_Hacker]

Originally Posted by S-F

...would turn out to be much less efficient than a mini split or even a couple mini splits...

S-F,

I agree with you, but I think the lessons pachai stands to learn are much more valuable at this point than mere efficiency.

Pachai, I think you should continue on with your idea, full speed. Don't let anyone slow you down. Take lots of photos.

...but the compressor still needs to be upright. It needs it's oil to circulate properly so it can keep running.

Full speed ahead!

-AC_Hacker

PS: I picked up another AC yesterday for $7... I think I'm gonna need a 12-step program!

[jroode32]

Hello All, I am pleased to have found this forum, I have been working on this for almost a year now due to lack of time but recently have made some great progress. I know I have a lot to learn and have many questions but I hope to be able to answer some questions too.
About 7 months ago I installed 600' of 1/2" Pex pipe, the pipe is in a slinky style configuration and is buried in 2 40' trenches (300' in each trench) at a depth of 6-1/2' (I will post pictures) the two 300' circuits are connected in series (above ground I didn't want any connections underground but I did insulate the pipe heavily all the way to 6.5') I have a small reservoir located inside in which a larger sized "pond pump" sits submersed, it pumps about 1.4 GPM through the system for a cost of 60 Watts. Here where I live on the Gulf Coast just a few minutes from the Florida line in sweet home Alabama I'm from Michigan, lol and by the way I'm on page 41 of this thread and I just want to thank everyone for putting all their knowledge up for the world to see.

JRoode32

[Xringer]

Wow, great looking slinky pic!
I'm assuming you are just looking for cooling, since the winters down there are pretty mild.
Both heating and cooling make things more complex,
and actually worth the effort, if you live where it gets cold..

You should start up your own thread, with a ton of pics please!


Best of Luck,
Rich

[AC_Hacker]

Originally Posted by jroode32

...recently have made some great progress. I know I have a lot to learn and have many questions but I hope to be able to answer some questions too...and I just want to thank everyone for putting all their knowledge up for the world to see.

jroode,

Congratulations! I see that you are in the midst of hacking an A.C. ... How's that working out for you?

Your loop field will be useful for more than heating an cooling a house... for instance, you can extract heat from the ground loop to heat domestic water.

If you need any more help, just leave a post here. I monitor this thread daily.

Keep up the good work...

Regards,

-AC_Hacker

[jroode32]

Ac Hacker, I know you can use the ground loop for domestic water heating but here where I live, solar water heating is the way to go and I have been using nothing but solar heated water since April 25th 2010 here are a couple of pics of the batch style solar water heater I built for less than $250 and regularly see temps above 140 degrees F to compensate for the shorter days in the winter I added a 3'X4' mirror to increase the collection area even on 25 degree day it will get above 120 degrees, I never did take a picture of the insulation but I insulated and sealed it very well as well as used double pain glass to trap in the heat. Air-conditioning is my biggest concern now that the old electric water heater is off the grid.

I guess my first question is what do you guys think about using r290 (propane) or mx-12a (propane and butane blend) AKA Maxi Frig? I've read about as much as I could find on the topic and I don't see much if an extra risk. What do you guys think?

[AC_Hacker]

Originally Posted by jroode32

I guess my first question is what do you guys think about using r290 (propane) or mx-12a (propane and butane blend) AKA Maxi Frig? I've read about as much as I could find on the topic and I don't see much if an extra risk. What do you guys think?

If you work with R-290, you need to know you are taking full responsibility for your own safety.

Most consumer devices that use propane have built-in safety features that we take for granted. If you defeat these safety features, you are increasing the hazard to yourself.

I first found out about R-290 from some blogs where German children were using the stuff to make extreme chillers for their video games, because they couldn't get anything else.

I have used R-290 (bar-b-que gas), and it works. There is a purity issue with it, in that the fuel grade is not 100% propane. I have tried to find info as to what the typical additional gases are, and butane is what I keep come up with.

I did see a paper written about the effect on refrigeration efficiency if there was some butane. The paper concluded that 5% to 8% butane would actually increase efficiency.

If you had a large system of several Tons capacity, and the compressor, etc. was inside the house envelope, you would be inviting very serious trouble.

In the UK they solve this problem by locating the R-290 containing parts in a separate envelope, removed a safe distance from from the house.

Working with R-290 will involve risk. I would not recommend working with it in an enclosed area, and I would advise face shield and protective clothing.

R-290 does not require as high a pressure as R-22, R-12, R 134a, or R410a.

It is compatible with mineral oil as found in R-12 and R-22 systems.

It also has a Pressure-Temperature curve that is really close to R-22, so cap tubes meant for R-22 will work pretty well.

I actually tried to braze a system that had R-290 and had leaked down... I ended up with a flame-thrower. I was lucky, and didn't get hurt... don't do anything stupid.

If you work with R-290, you will be assuming full responsibility for you own safety.

-AC_Hacker

[jroode32]

AC_Hacker,

Thank you for your input on R-290, on second thought I think I can get my hands on a jug of R-22 its not worth adding the extra risk to save a few bucks.

I do plan on keeping the compressor inside (as of now) and insulating it well to ensure all of it's heat goes into the ground as well. Just out of curiosity how far could I split the low side from the system without any significant efficiency losses?

At this point I still need to purchase a set of AC manifold gauges as well as a vacuum pump (I found what looks like a decent 3 CFM pump at Harbor Freight but I'm a little skeptical about their gauges what do you think? have you seen them?) I am very new to HVAC, but for the past 2 months I have searched relentlessly reading anything and watching anything informative on the subject and have learned a lot but I still have some questions to be answered before I feel totally confindent.

About Me: I hold a bachelors in electronic engineering from ITT Technical Institute I play with test equipment on a regular basis my career is in the field of "going green" and I have sold and installed numerous solar water heating systems, I sell high quality L.E.D. lighting and have converted 28 high rise condos stairwell lighting (mandatory 24 hour operation) from 2 4' fluorescent tubes that with the ballast uses 75 watts to 1 4' L.E.D. no ballast that uses only 15 Watts, so my point is I love the science and I love to learn, so thank you all very much for answering my "stupid questions" I am grateful...

There are a few things I don't quite understand...

1. where exactly would I measure temperature on the system to find my sub-cooling and super-heat?
2. When pulling a vacuum on a system, what in the world is 28-29-30 inches of Mercury and what do inches and mercury have to do with any of this?
3. When charging a newly Hacked AC, from what I've read I would want to do it from the low side? When do you turn on the compressor?

Thanks
JRoode

[AC_Hacker]

Originally Posted by jroode32

...I do plan on keeping the compressor inside (as of now) and insulating it well to ensure all of it's heat goes into the ground as well.

If you had the compressor outside the building envelope, you'd have less noise, and if heat was lost, it would be to un-conditioned space, so not such a problem.

Originally Posted by jroode32

Just out of curiosity how far could I split the low side from the system without any significant efficiency losses?

Too many unknowns for me to be able to give you a good answer... however I have seen mini-splits with runs as long as 35 feet. I have seen some amazing tubing insulation meant for HVAC, tiny space for tube's inside diameter & thick walls.

Originally Posted by jroode32

At this point I still need to purchase a set of AC manifold gauges as well as a vacuum pump (I found what looks like a decent 3 CFM pump at Harbor Freight but I'm a little skeptical about their gauges what do you think? have you seen them?

Yes, HF gauges, that's what I'm using. Gauges meant for R-410a have to be built for 400 to 500 psi, and won't be so accurate for lower pressure gases like R-22 & R-134a, especially so for R-290.

I'm using the HF 2-stage vac pump. I think it's a real dandy for hobby/experimental stuff. If I were a real HVAC guy, using a vac pump on a daily basis, I'd get something better, but for around $150 I think it's a darn good value. I tested my vac pump and it went down to 60 microns (manifold gauges will not measure down that low) that's certainly enough for what I do.

Keep in mind that when you do a pump-down, use new oil. The oil has the ability to grab moisture out of the gas (or air, once it is opened) so it assists the vac pump.

Originally Posted by jroode32

I am very new to HVAC, but for the past 2 months I have searched relentlessly reading anything and watching anything informative on the subject and have learned a lot but I still have some questions to be answered before I feel totally confindent.

Quite all right... we all have to start somewhere. Some of this info is much more difficult to come by than it should be. There are some good HVAC blogs, but they don't like to help DIY guys... still good info to read there.

I learned most of what I know from the blogs documenting early attempts by kids to do extreme cooling of their CPUs. There are remnants to be found here and there, but you will probably have to make good use of archive.org to get the whole story... well worth the effort. Good stuff, how to braze, all about gases, pumping down, etc... There were even some very knowledgeable American HVAC guys helping them along the way.

I have tried to bring much of that lore forward and to make it available here in this thread.

Originally Posted by jroode32

About Me: I hold a bachelors in electronic engineering from ITT Technical Institute I play with test equipment on a regular basis my career is in the field of "going green" and I have sold and installed numerous solar water heating systems, I sell high quality L.E.D. lighting and have converted 28 high rise condos stairwell lighting (mandatory 24 hour operation) from 2 4' fluorescent tubes that with the ballast uses 75 watts to 1 4' L.E.D. no ballast that uses only 15 Watts, so my point is I love the science and I love to learn, so thank you all very much for answering my "stupid questions" I am grateful...

I don't believe that there are stupid questions... but there are lazy questions, I have been guilty of that myself.

Originally Posted by jroode32

1. where exactly would I measure temperature on the system to find my sub-cooling and super-heat?

I'm pretty sure that if you search this thread for those terms, you'll find what you are looking for.

Originally Posted by jroode32

2. When pulling a vacuum on a system, what in the world is 28-29-30 inches of Mercury and what do inches and mercury have to do with any of this?

This is terminology from the days when a mercury column manometer was the only accurate vacuum/pressure measurement device available. There are tables available to convert to psi.

One thing to keep in mind, when you pull a vacuum, one of the important benefits is that the vacuum should be deep enough to cause any moisture to instantly boil into vapor, so it can be vacuumed out. Water in the system can freeze up, and block orifice tubes and causes inefficiencies, it can also combine with impurities and create acids that will shorten the life of your system. The evidence that you actually are at the very deep vacuum that you need, is not to be seen on a manifold gauge set. Their accuracy falls off at the low end of the scale. There are gauges called micron gauges that use a very interesting phenomenon to measure at this very low end. If you are using a new vac pump and new oil for each pump down, you might be able to get away with no micron gauge. I bought mine for as much as my vac pump... but it came later.

Originally Posted by jroode32

3. When charging a newly Hacked AC, from what I've read I would want to do it from the low side? When do you turn on the compressor?

Assuming that you have brazed on Schrader valves on the high-side and low-side, you then hook up your manifold set high-side gauge hose to the high-side Schrader valve, and the low-side gauge hose to the low-side Schrader valve. The middle hose can be hooked to your vacuum pump for pumping down.

BTW, when you braze on schrader valves, be sure to remove the core before you braze, & don't put the core back in until the valve is cool to the touch.

I have ball-valves on the ends of my center hose(s) and it makes thing simpler:

If you have a T-adapter on your center hose, you can have a hose dedicated to vacuum pump and a hose dedicated to gas bottle, with a ball valve at the end of each one.

So you close the gas ball valve and pump down.

Then you close the vacuum-pump ball valve.

Open the gas ball valve, and the high-side valve on the gauge set, just a bit of a shot to get the high-side gauge to just barely move to admit a bit of gas into the compressor.

Then turn the high-side manifold knob off and let gas in from the low side with the compressor running.

So, you let some gas in until the low-side gauge starts climbing, and stop the gas, but let the compressor continue to run... you'll see the low-side pressure start to drop some, as the gas and oil intermingle and everything comes up to temperature.

Keep an eye on the cap tube near the point where the liquid gas flashes into vapor. when you get close to the correct pressure, you should see frost forming on the outside of the cap tube and the part of the heat exchanger nearest to the cap tube.

For R-290, this will happen somewhere near 70 psi for R-22, this will happen about 150 psi.

You'll find that you'll have to give the system several charges and then let it run for several minutes until the charge level stabilizes near the correct point.

Some of the old-time HVAC guys just go by the frost forming. Those in the know adjust for optimum sub-cooling and super-heat.

Did that help?

-AC_Hacker

[RickHeid]

I just love reading the stuff on this forum and this is my first post. I have been kicking around an idea and just wanted to see what you guys thought. I have a well that is 6" in diamater and down 180'. The water level is always at the 45' level and the pump is 10' from the bottom of the well. I was thinking of pulling the pump back up and putting a copper coil in the 10' at the bottom with a plastic pipe feed and return to my heat pump. Then put the pump back down the well. We don't use a lot of water from the well however it seems to me this would work even better than a 180 ft hole filled with grout, as every time I use water, cold water will come into the shaft. Oh and I live in central TN.