Thank you, the parts ran me about $30. So not the cheapest but should make that money back after the first month of running. I hope a trend is started as well. Way to many people live in a reality that society has created that tells them that doing things on their own is stupid, dangerous and impossible. A reality that that same society seeks to gain much income and power from.

AC
I found a formula online that should give me a exact cap tube size. But I do hope the original one is at least the right diameter.

I saw in another post how you said to calculate the COP. What would be best way to measure water temperature accurately?

Yes the drill bit is homemade I made it after trying to go past 30 feet with just teeth cut into the PVC pipe the first time a ever drilled a borehole. Its just a 2 inch double female with flat bar weld at slight angles on the side and a square piece in the center. It cuts through the wood and small spots of sand stone we have here.

[NOTE: After I wrote all this, I realized that you only wanted to know about water temperature. I answered a lot more, but I'll let it stand for other readers. As to your question, I would think that if you removed the sacrificial anode rod and made measurements through that, it would work well. You are likely to have temperature stratified water, so I suppose a measure at the top and at the bottom, and averaging them would be a fair approximation.]

Calculating COP with a water heater is fairly easy.

The general idea is: COP = (energy out) / (energy in)

One BTU is the amount of energy to raise one pound of water one degree F.

You will need to know what the weight of water is in your tank. If you know what the volumetric capacity of the tank is, you can convert volume of water to the weight of water.

The density of water is about 62.4 pounds/cubic foot.

The density of water is also 8.343 pounds/gallon.

So, I will guess that your tank is 50 gallons, so 50 x 8.343 = 417.15 pounds of water.

Next, you will need to know the initial temperature is in your tank. For this, you could just stick a thermometer in, maybe through the hole in the top for the sacrificial anode rod, and take a reading. I will just guess that the starting temperature is 50 degrees F. You will want to know how many degrees the water is heated to. So you will subtract your beginning temp (50 F) from your final temp.

Next you will need to be able to measure the amount of power used. A Kill-a-Watt meter is an accurate and cheap way to do this. It can tell you how much power (kW-h) is used, and it will also keep track of time, if you plug it in at the beginning off the test.

So now, you have the initial conditions.

I'm not sure what method you are going to use to stop the heat pump when the water reaches the desired temperature. Even if you don't have this arranged yet, if you run the system for an hour and a half or so, you'll get useful information.

Now, having written down the initial temp, you start the test...

Plug it in and marvel at your creation... but don't get too carried away, because you are conducting a scientific test.

Make sure that the Kill-a-Watt doesn't get interrupted during the test, or it will 'forget' the data.

After the run time (maybe 1.5 hours), record the power power that the Kill-a-Watt indicates (kW-h). Also record the run time from the Kill-a-watt. As I recall, the Kill-a-Watt measures watt hours, but when the count goes over 999 watts-h, it goes to kW-h. So, when you do your calcs you will want to make sure that you are in watts... so 1.234 kW-h will be the same as 1234 W-h.

Just guessing here... let's just say that at the end of the test, your water temp is 85 degrees. This may be a bit tricky because you will have stratification with hotter water on top and colder water on the bottom. So do an average of top and bottom temps.

POWER OUT (power produced by your heat pump)

Your power-out will be (1042.9 pounds) * (85-50 degree F)

... so power-out = 1042.9 * 35 = 14600.25 BTU

Converting this to the electrical energy equivalent you divide by 3.412

elec power = 14600.25 / 3.421 = 4279.1 watts.

POWER IN (power consumed by your heat pump)

Read the kW-h from the Kill-a-Watt.

let's just say that you read: .9 kW-h

This would be the same thing as 900 W-h

then you multiply by time (1.5 hour) to get watts

Watts = (900 W-h) * (1.5 h) = 1350 watts

CALCULATE COP

COP = (power-out) / (power-in)

COP = (4279.1 watts) / (1350 watts)

cop = 3.2

I think that your efficiency will be better.

Best,

-AC

Gotcha, sorry I was thinking I would be measuring this under pressure, but that makes more sense. Just fill it to the top and pull the anode out. Perfect because I have a kill-a-watt meter and aquarium thermometer.
Thanks for all the useful info. I just copied that into a word document and printed it for save keeping.

MEMPHIS91 & AC.

These are the most fantastic machines. All of use hot water every day and while the hot water tanks are just sitting, they are losing heat energy every minute. So from a DIY - energy efficient upgrade wow this is the one.!!

Yes the COP is a cool thing but remember that this heat-pump is going to be maintaining a temperature at the top of its heating capacity envelope.

The amount of energy required to heat the water from 50 Deg F to 90 Deg F its a walk in the park. But that stretch from 90 F. to 110 F. its going to need a longer run time to reach that temp.

With this you will see your COP may start out at 4.0 but ultimately in a domestic supply condition you may be somewhere 2.5 to 2.0 But even 2.0 is amazing!!

Imagine if you could Eco-renovate your Chevy for a few bucks and get 42 MPG instead of the 21 MPG

This particular build with the ground DX will be a star. AC just imagine MEMPHIS91 is doing this without circ. pumps, external heat exchangers and or fan motors. ONLY that little compressor (275 watts!!!!!). Heat sequestered directly from the source (ground) pumped directly to the Tank.!!!

OK I want to build one now!!!

WE SHOULD ALL BUILD ONE

Randen

Yeah, you're right. The COP will start high and gradually fall off as the delta-T decreases. And under normal working conditions, the 'start' cycle to 'stop' command will be working at the low delta-T end of the scale.

But, "You never outgrow your need for insulation", to paraphrase the milk ad.

And don't forget that he is in MS, and the yearly environmental temp is such that standing losses from the tank will be smaller, PLUS the ground temp in MS is about 24 F warmer than yours, so his little compressor will not have a very heavy lift.


I think MEMPHIS91 will have ample bragging rights!

-AC

AC-Hacker

Right on all accounts. And don't forget his water supply temp. will be a lot higher than we experience in the great white north. During winter the water supply temp can be a teeth rattling 45 Deg F. infact in the depths of winter I must temper the cold with the addition of hot to rinse after brushing. BURRR.

But KOODOS to MEMPHIS91. Keep us informed.
I would like to report summer like conditions have arrived here in southwestern Ontario and for our domestic hot water is now heated with solar (DIY). The collection is via a 80 watt circ. pump from about 10:00 to 4:00pm. 120 gal of 140 Deg F. water for nearly FREE!!

Randen

Yeah COP is something I understand just seems to vary a lot under different conditions. 42 MPG does sound nice.
AC
I wish I could take credit for all this, sure it was my idea to put it all together but I'm just pulling from hundreds of other peoples good ideas.

So today was BOREHOLE DAY.
Here is the 2 inch drill adapter I made. It has a compression tee, the 2 inch side is for the drill pipe, the 3/4 inch side is a valve to help the pump prime, also makes for a nice handle. Two 90 degree turns into a 2 inch female that connects directly to the output of the mud pump. http://ecorenovator.org/forum/attach...1&d=1432863292

Here is the 2 inch pump line and drill pipe connected.
http://ecorenovator.org/forum/attach...1&d=1432863292

This is the mud pump that is pulling water from the near by pond and sending it about 75 feet away to the drill location. Water flows right back into the pond.
http://ecorenovator.org/forum/attach...1&d=1432863292

This is just a cool picture of the water flow coming through the drill head. I am rethinking a better drill idea. But this works fine for now.
http://ecorenovator.org/forum/attach...1&d=1432863292

The first 10 feet is SO easy, I stated at 3:30pm and the first 10 feet was done at 3:50pm.
http://ecorenovator.org/forum/attach...1&d=1432863292

Then comes the hard part. As you can see its solid clay. The idea is to slam the drill head into the bottom of the hole and then twist the clay loose and plunge it down again. The plunging action shoots the heavier solids up and out of the hole.
http://ecorenovator.org/forum/attach...1&d=1432863292

Then just keep adding pipe with glue on couplings. This is my second bore hole so I reused the first pipe, hence the 2 joints back to back. This is not a fast job, it takes time and TONS of energy.
http://ecorenovator.org/forum/attach...1&d=1432863292

I stopped at 6:45pm to have dinner with the parents and brother before he heads back to DC. I got to 28 feet and hit coal. I CAN get through it, but it will just take some time. It could be 3 inches or 30 inches thick. I'll probably give it one more run tomorrow just to try to get to 30 feet. But as you can see it really is very easy. 3 hours 15 minutes, plus I repainted a wood heater while waiting for glue to dry.

Well that was almost too easy. 28 feet in an afternoon. Wow. In my area, I would just call a drill truck. The whole area is on top of Mammoth Cave. Rocks the size if basketballs in clay or limestone. Good for you, bad for me.

Did you decide what size compressor to rob from its home? If you are not going to push your COP with a critical charge and high evap temp or use an expansion valve, I might just call it quits at 28 feet.

Propane is sort of the opposite property wise compared to r22. Low molecular weight, high heat capacity, less viscous. More will flow through the same cap tube vs r22, and the engineers say run a shorter cap tube. I never have, and everything worked out ok for me.

Jeff
Basketball rock don't sound fun. The compressor is out of a 5,000 btu window unit. It was running R22 and says LRA 23.00.

AC you asked a long time ago about temperature control mechanism. I plan to just wire it off the existing bottom element thermostat.

I went ahead and chipped my way 12 inches through the coal (I know its coal because when it dries you can light it on fire), and so we are at 30 feet deep!
http://ecorenovator.org/forum/attach...1&d=1432928711
Bad place to drop something valuable. Water level was at 6 feet.
http://ecorenovator.org/forum/attach...1&d=1432928711
So on to coil making. I made 3 of these up the pipe as per the suggestion by Jeff5may.
http://ecorenovator.org/forum/attach...1&d=1432928711
This is a shot of the entire drill pipe out of the hole.
http://ecorenovator.org/forum/attach...1&d=1432928711
This is the coil in the hole. It went in much easier than I thought it would. I also ran in a permanent temperature probe. It will be interesting to see the change as I run the unit, and winter vs summer.
http://ecorenovator.org/forum/attach...1&d=1432928711
This is the 3 part mixture of peagravel, lime stone and powder lime. (1.75"x1.75")x3.14159x360" gave me the amount of material needed to fill up the hole. And it work out perfect. I love when math works, or should I say I like when I make math work right.
http://ecorenovator.org/forum/attach...1&d=1432928711
And this is the insulated lines running under the patio where the compressor will be.
http://ecorenovator.org/forum/attach...1&d=1432928711

I'm ready to start the compressor or work. Main 2 points to figure out are the oil, how much and what kind. And the cap tube, how long and what size. I do have one on the window unit right now that I can use but should I shorten it some? My current one is 33 inches long and measures at .11 inches OD.

Update:
I got the service ports brazed on, compressor mounted, return line wrap around top of compress and brazed in. I talked with a HVAC tech today. His numbers said 31 inches would be about right for the cap tube. And I'm using mineral oil, not sure how much yet. Temperatures at bottom of borehole holding steady at 66.2-66.5F all day.
http://ecorenovator.org/forum/attach...1&d=1433117216

This was quite the productive weekend for you. Great updates.

MEMPHIS91,

I think that this is, in reality, the only way civilization progresses.

-AC

I wonder if you will even need an anode? I have a hunch that electric heater elements induce a small voltage into the water in the tank, which accelerates galvanic erosion. Since you are not going to use electric elements, you may not need that anode.

Maybe a better use for the anode hole would be a couple of temperature sensors, permanently mounted. One placed high and one placed low, for future data logging, or performance monitoring.

-AC

Really great job!

You have done a good job of utilizing the conditions and assets that are immediately available to you:

• soft ground
• a pond
• low-tech drilling method
• sloping ground to drain water overflow back into the pond
• using the mud pump as a really big muscle

Just great! I hope that more of your Southern Neighbors, who are also blessed with easily-drilled soil take advantage of your example.

The only improvement that I can think of is that you can get glue-on male & female screw-together connectors for your drilling pipe, which might make assembly & disassembly, and storage and transport easier.

Awesome!

-AC

P.S.: I just wanted to say, that at the beginning of your thread, you said that you wanted to "give back". Well, MEMPHIS91, your ideas, great descriptions and photos have done just that. If I may be so bold, on behalf of everyone who has shown interest in what you are doing, I'd like to send out a big thank you!

And you're not even done yet!

MEMPHIS91

I think you have impressed the big gun, AC Hacker. You have checked all the boxes on how efficient one can heat water. Plus you have done it with your own two hands. Many talk the talk but we have seen that you actually are flying along with a super project. I like many are on the edge of our seats to see what the final numbers will be.

Randen

With the rig at hand, the galvanized pipe union would serve as the anode if the factory anode is removed. The zinc plating would dissolve first, then the cast iron. As long as this fact is known and understood that the union should be swapped out before it eventually fails as prevention, then removing the anode rod would be ok. Otherwise, I would find another way to run sensors. The only common metal less noble than zinc is magnesium.

If ultimate precision is not paramount, the thermometers need not be in intimate contact with the waters. Most manufacturers place their sensors in the heating element fittings or on the outside wall of the tank. A very few have custom, threaded fittings or are inside a well of some sort. It seems that on the wall, somewhere under the insulation envelope would be pretty close.

WOW! Thanks for all the comments guys.
Daox, it was in fact a good weekend, its pretty easy to work hard when a project is coming together so well.

AC, Thanks man! The true life of a hacker, to use what he has around him, cause he is to cheap or to broke to buy it. lol JK

Concerning the anode, I have 8 grains per gallon of hard water, so I would like to keep it in.

Randen, Thanks man, trust me I'm on the edge of my set as well.

Jeff, yeah that is what I was thinking to. Good data is awesome, but I think it can be close enough from the outside of the tank.

UPDATE! SHE IS ALIVE!
http://ecorenovator.org/forum/attach...1&d=1433209592

I got everything wired in, tank filled with water, and I pulled a crazy low long vacuum, made sure it held and started to fill. Low side came on up to 15 psi. Pulling 2.3 amps. With a high side temp of 136F. Then the low came up to 17 psi (on its own, nothing added) and temp was 145. All of a sudden it jumps to 25 psi with a temp of 162F pulling 2.5 amps!! That was only running for 20 minutes. I got scared and unplugged it. The tubing going into the ground was frosted from half way down the evap tube all the way into the ground.
Is this ok? It felt like the evap tube was surging some, not a constant flow. I mean 163F is HOT. I just don't want to burn up the compressor.
Thoughts? Once I get it running right, I'll start running test.

Thanks again guys for following along with me on this project.

EDIT: I'm thinking i might have put to much oil/ or wrong size cap tube. I guess it could be to short cause the evap to flood.

MEMPHIS91

Sounds like you have a great machine. I think the pressures and temps are good. Maybe a tad over-charged but I would let it run. You did charge your system according to the manual supplied with your system, right.??? HeHe. I found that my sweet spot was 18 psi but my evaporator is a different temp than yours. You could very-well be in the sweet spot for your DX evaporator. Wire in your tank temp switch (lower) turn it to a lower temp setting 110-120 and enjoy the moment.

You're a little concerned about the life of your compressor but it is used??? recycled from the scrap pile?? If the compressor motor stalls or overheats you have two safeties your circuit breakers and a thermal overload. Don't forget your now operating at lower pressures than with the R22 refrigerant. It should be just fine.

You may want to concentrate the extra copper turns to the top portion of the compressor were the bulk of the heat is generated with the compressing of the refrigerant in the scroll to a lessor degree with the motor windings.

2.5 Amps!! 300watts!!! vs a 3000watt resistant element?? You deserve some bragging rights!!!

What is the cost of electricity in you area?? We're at $0.22/Kwh all in.

Randen

All good from what I see.

You may already know this, but when you are charging, it takes a bit of time for the system to adjust to the change in charge... like maybe 20 to 30 minutes for each change. So don't be in too much of a hurry.

I'd be interested to know a few more details about your oil. How much did you add? Did you completely drain the oil and the re-fill with fresh oil?

I was going to suggest that the oil may have been perfectly OK, if the compressor had not been sitting open for any appreciable amount of time. But you finished the system before I could say anything.

At any rate, I'm very interested to know what your COP tests look like.

Best,

-AC

With a cap tube metered system, you charge by superheat. At the muffler intake, you should always have 10 degF or more to ensure you are not flooding your evaporator. The other thing to watch is discharge pressure. As your hot water tank rises in temp, the discharge pressure will follow. Normally, it will go up around or above 200 psig. For your rig, 250 psig will give you a 125 degF condensation temp; above that level of pressure, your efficiency will pay dearly.

It all depends on how hot you want or need your hot water to be, as well as your consumption habits.

Randen, Yes I am very pleased so far.

Thats a good idea, i'll pulling the loops in tighter and higher.

AC, I added about 1 teaspoon of refrigeration mineral oil. And yes I was giving it a while to settle out. Probably only 15 minutes or so though.

Jeff, Can you explain that alittle better. "at least 10F" You mean the suction line before the muffle should be at least 10F?

I'm bout to fire her back up and see what happens.

Update. 50 gallon tank. Its been running for 2 hours, has jumped from 72 to 78F water and used .5 Kwh. More details on that later.

http://ecorenovator.org/forum/attach...1&d=1433282974

CRAZY! It spiked at 194F!!
But i think I found out why, just because my compressor was at 235F I decided to put a small fan on the compressor, and instantly my temperature on the high side drop to 150F at 10 psi. I think I need better cooling on the compressor. Maybe more wraps of copper tubing? The ones I have wrapped now are not very tight, only part of it is touching.

Hmm

Compressor is running hot. And 2 hrs and only 6 Deg. F gain Something is not right. Did you happen to check your DX and tank HX tubes to be clear of kinks.

I can't see the gage very well but is the low side only 12 psi. I believe you need to in-crease your charge. I found anything less than 18 psi didn't move any heat.

Let the compressor cool and add some charge and try again.

Randen

When I get back to around 18 psi the cap tube sounds like something is squirting into it and it is back is surge. My psi drops and raises 2-3 psi with the sound as well. I for sure probably put to much oil. I unhooked my high side gauge and my hand was instantly covered in oil. But my water number look much better.
So best way to get the oil out?

The things you are describing sure not out of the ordinary for an r290 system. For one, the mineral oil and propane dissolve in each other like carbonated soft drink. The oil will follow a leak. The cap tuBe doesn't care if it passes liquid, gas or oil. The compressor cares. It wants a little oil and lots of gas, no liquid refrigerant.

The thing that concerns me is your gauge readings. With 60 degrees or better ground temp, you should be having no frost leading to or from your borehole. If there is frost going from the cap tube into the hole, either you are low on charge or the cap tube is plugged up. If there is frost coming from the hole into the compressor suction side, the obstruction is in the borehole close to the exit.

Since you have low suction pressure and high discharge temperature, I suspect your charge is low. The compressor is trying to move gas, but the high compression ratio and low flow rate is making it work hard without much cooling. The 20 psi gas in the suction side has a boiling point below freezing, thus the frost. Going through the borehole, it is coming out with 40 degrees of superheat.

All this talk of superheat begs some explanations. Superheat is simply the difference in temperature between the saturated suction temperature ( read the r22 scale on your gage) and the actual refrigerant temperature. When the propane passes through the cap tube as a liquid, it has a boiling point that is high due to the discharge pressure.

As it leaves the cap tube, it encounters a sudden and drastic pressure drop. As a result, the boiling point drops suddenly and the liquid evaporates and boils. When the refrigerant changes phases, it assumes the saturated suction temperature until it all boils off.

That picture shows 12psi low and 145 psi high.

The numbers I am getting now that randen said to add some is 25 psi low and 165 psi high. With MUCH better heat transfer. I drained the system and turn the compressor of its side with the service port valve removed, oil PORED out. So I think that will help some.

The compressor is not getting liquid. The suction line wraps around the pump 3 times. I bet it picks up 25+F. Pretty sure that is how I am those higher than normal 170-185F high side temps. And that is being measured at the tank itself.

Gonna pull a long deep vacuum and let it hold over night.
Thanks for all your replies!

Memphis91

A teaspoon of oil is not enough to be concerned about. And yes if you remove your gage you do get a mist of oil all good.

I believe your system is starving for refrigerant. It is possible that some funny stuff is occurring with some droplets of oil messing about in your cap tube. But once your system gets all the tubing coated and you have a healthy charge dissolving the oil I believe what you are seeing with the surging will subside.

Oh I just seen your post. Yes 25-35 psi is still healthy and when I had started my HPWH this is the pressures I started with. I believe you were just circulating hot gas from the friction in the compressor scroll and not moving any refrigerant to take advantage of the vapor compression cycle.

You are on the right track. These are the things that a true DIYer must push through to revel in true success.

Memphis91

I only now understand your previous post. When you put more charge 18 psi you seen a better water number or water temp in the tank is rising more quickly. Try starting with 30-35 psi and reduce slowly as you test for temp. rise in your tank. This may take a few days as you let it run and check the temp. vs temp rise. Install the Kwh meter and tune your system.

Randen

As per the manifesto in post 462, the pt chart for propane is here (or there, thanks ac_hacker):

http://www.glacierbay.com/ptchartpropane.asp

For your evaporator to operate above freezing, the suction pressure would need to exceed 54 psig. Every 15 psi is an atmosphere or bar of pressure, so at 55 psig(auge), you would have almost 4 bars of suction pressure, and almost 70 psi from absolute vacuum. Compared to 15 psi of gauge pressure, this equates to 7/3 as much suction gas available for the compressor to circulate, as well as 40 psi less difference across the compressor ports. The result: a few more compressor watts, a lot more mass flow, a lot lot more heat transfer. Less run time for the same heat into the water.

Glad to see it working. Just a little bit of tuning to do, then you should be good to go.

Compressors are either cooled by fan or cooled by suction gas.
Cooled by fan is obvious. You need a constant airflow over the shell. Cooled by suction gas requires a minimum mass flow and a minimum suction return temperature.

Your in-ground evaporator is going to be _very_ effective at superheating the returning vapor, and unless you are properly charged you will get inadequate compressor cooling from that. In fact, I'd hazard a guess that at your mass flow you won't get sufficient cooling unless you are spitting back liquid into the compressor shell (which you don't want to do). So the fan is the go.

jeff5may is spot on with his assessment of charge and mass flow. You need more gas. You will as a consequence draw more power, but you'll greatly increase your overall mass flow and COP. If you can get it to where your suction line to the compressor is "sweating" (ie it is cold enough to get atmospheric moisture to condense on it) then you will probably not need fan cooling either.

Get the spec sheet for your compressor, and look at the specs for evaporating temperature vs power draw. That is about where you want to be aiming.

Got some numbers for you. I charged up to 35 and let it run for 2 hours. With in 20 running at full charge my high side was right back at 185-190F. Coming back from the ground loop the line did start to condense which I think is a good sign but any cooling effect it has for the compressor is lost because its back warm again after making the wraps around the compressor.

Time (in minutes)- Power(in KWH)- Average water temp - bore hole temp
00 - 00 - 85.5F - 66F
30 - .25 - 89.8 - 65.7
60 - .33 - 91.6 - 65.5
90 - .51 - 94.4 - 64.4
120 -.69 - 99 - 64
150 - .88 - 102.2 - 62.7

I still think something isn't quite right. But much better than last night.

To be honest, unless the coil surrounding the compressor is pretty much bonded to the shell it's doing almost nothing for you. Radiant heat from the shell will superheat the gas in the pipe which will admittedly slightly cool the air between the shell and the pipe, You'd be so much better off just removing the pipe coil as the cool gas will do far more effective cooling of the compressor being piped straight into the shell (which is how the compressor is designed to work).

Now, your photo appears to be a rotary unit, so the suction gas does not get dumped into the shell but passes the compressor first. Cooler intake will still result in a cooler discharge.

Yeah your very right. I had not thought about cooling needs until after the build. 190F for a discharge temp is pretty high. So tomorrow The coil will come off.

So that is about 87C. Most compressor data sheets I've checked seem to think that over 100 is worth worrying about (212F). It's hot, but it's not out of the ballpark for a refrigeration system.

This links suggests 225F is the limit A Look At Compressor Discharge Temperatures

This discussion has some good info and similar temps.
High Discharge Temperature

I kicked it up to 40 psi last night before calling it a night. I was pulling 3.3 amps with the discharge at 275 psi. I'm thinking once I remove the coil going around the pump, the try even higher suction pressure. This build might need a larger compressor, or the cap tube more fine tuned.

Look, the reality is that a refrigeration system is a balance. A properly designed system will have a defined heat load on the evaporator, a condenser to suit and a compressor and cap tube to suit the required mass flow. Start with the heat load and work back.

Yours is kinda arse about, where you have an undefined evaporator load, an undefined condenser size and you are working with a fixed compressor size. The only variables at your disposal are cap tube and charge, but the reality is you don't want to be optimising the evaporator characteristics. You just want to optimise the COP.

We can get all scientific with looking at heat transfer coefficients, tube sizes and lengths and spend hours running numbers to allow you to buy the right compressor and size the cap tube right. Or you can just tweak the cap tube and charge to get it pretty good. Personally I'd do the latter, and I'd only start thinking about the cap tube if you just can't get it where it should be by charge.

It sounds like you are already well on the way. The two critical variables are :
A) Discharge temperature
B) Compressor power draw

As long as you keep both of those below the maximums on the compressor data sheet, then you can tweak to your hearts content. Do understand though that there is the old law of diminishing returns. Once you get it going "pretty right" with numbers you are happy with, further tuning will begin to consume more and more time for less and less gain.

Can you find a copy of the compressor data sheet and link it here for us to look at?

<edit> I've edited this because I forgot to give you a massive whack on the back and say "well done". You've already gone far past where your average beginner gets to and made a hell of an introduction. We just want to help you get it as good as you can so that your second attempt is even better.

Yes, the engineers will tell you this can't work, without all new everything. I tend to disagree. It all depends on how far you want to push your envelope.

A 5000 BTU compressor will move more than its rated capacity under some conditions. It will move less and less as the compression ratio increases. With your rig, you will probably not be able to fully work your borehole because it moves lots of heat. You can try to, though.

The condensing section in your rig will also be a superconducting heat well. Water absorbs lots of heat fast. The condensing pressure should closely follow the water temperature if the circuit isn't overcharged. The discharge temperature will be higher than normal because of the high superheat of the suction gas. Like brad said, set the charge at your max tank temperature to avoid cooking your oil or change metering devices.

To eliminate the metering device conundrum, install a txv. You can find them at surplus city liquidators or on eBay for under 20 bucks. Then set your discharge temp at max tank temp.

Awesome info. Thanks Jeff and Brad.
So looks like I have some options all of which include taking out the coil wrapped around the compressor.
Option 1: Leave the current compressor and play with the cap tubes of different length and size.
Option 2: Put in a larger compressor (that I already have, the whole unit is rated at 880 watts.) and play with cap tube sizing.
Option 3: Leave current compressor and install TXV (that I picked up today)
Option 4: Put in larger compressor and TXV.

I'm really thinking option 3 or 4, but what are ya'lls thoughts?

Data I found on current compressor.
http://ecorenovator.org/forum/attach...1&d=1433452771

The TXV I got from one of my AC friends in town.
http://ecorenovator.org/forum/attach...1&d=1433452771

Memphis 91

I've used the same size compressor 5000 BTU with a cap tube. Its working extremely well. I would go with option 3 A larger compressor will just cost more for operation. I think take a few days and with the Kill-o-watt meter and pencil slowly drop the charge and see what you get for energy in and energy out. Don't get too hasty. You may be adding some variables that could cause further complications. I would do some additional tests before adding the TXV valve.



Randen

I think you should stick with this compressor, and work with it until you get it to work as well as possible for you.

A smaller compressor, correctly set up will just take longer to heat the water. It's COP can be just as good, maybe better than a bigger compressor.

Don't be so quick to start throwing hardware at the problem.

-AC