5 Ton GSHP Build
 

I made an error infusing my ground loop with Propylene Glycol. The infusing part went well but the purging air completely out of the loop didn't. The circulation pump ingested that illusive bubble, cavitated and my evaporator began to freeze as the water/glycol hadn't had enough time to mix.
I know what your thinking, where was I.? I had watched that 3.5 ton for an hour. It was 6:00 o'clock and I decided to go home and come back to see how warm the shop got.
When I returned, the shop was getting chilly and there was a huge block of ice were my HX should be.:eek:

Long and short I wasn't carefull enough to ensure the air had left and my homemade 3.5 Ton GSHP suffered a terrible fate.

It made me grumpy. I didn't really want to do a rebuild when outside temps were dropping to -15 Deg C. I re-installed my old GSHP the 2.0 Ton. My first GSHP attempt. It keeps the shop +12 Deg C min.

The unit was ripped out and torn apart to rebuild the HX.

Well since its apart maybe we should think of improving the Heat Pump (put in TIM ALLEN'S "lets rewire that bad boy")

As BradC had been thinking of the advantages of a 3 phase compressor I had as well. So on the bench as I write there is a 5 Ton 3 phase 208 V scroll compressor (new surplus) (insert Tim Allen "Grunt") Taking the place of the old 3.5 Ton recip. The 5T is smaller dia but 2 in. taller

The 3 phase scroll is more efficient than the recip and can be controlled with a varible frequency drive. This will allow the heat/cooling output to be modulated with speed control. With this the compressor can be started with a ramping to speed and programmed to ramp in the early morn. hrs. and after my work is completed slow to keep the shop warm. There are a lot of possibilities. The VFD has relay out-puts to run the circ. pumps. The VFD should be here this coming week. But as we have 3 phase in the shop we can run it without the VFD.

This weekend a little more brazing and should be running in place early next-week:thumbup:

Randen

What a great looking compressor.

Looks like you're off to a great start!

Best,

-AC

5 Ton GSHP Build
 

Most of the components have arrived and are being assembled. A few alterations have been nessisary. The height of the new compressor is about an inch taller and its having a bit of a snowball effect with now the case not being tall enough and the reversing valve position. In true Ecorenovator fashion the new build is also sporting a suction tube heat exchanger. Mikesolar and Jeff have done some work showing some efficiency gain but we'll have to see what happens
The varible frequency drive VFD is taking its time arriving. But until the final strokes are completed on the 5 Ton the little 2 Ton will keep the shop almost warm.

Up grades to the 5 Ton:
scroll type compressor
VFD
Liquid sight glass
new filter/dryer
Suction line HX.

Randen

randen,

Great pix on an awesome project. I attended a solar installer's training conference some years back, and they strongly recommended a different type of pipe insulation for solar installations. Seems the type that is least expensive and most available (the type you have) does not handle the temperature cycling that solar installations are subject to. Their life is short and they become brittle and crumbly after a few years.

The type that was recommended was a black, closed cell, sponge rubber type of insulation. And their primo choice was the rigid fiberglass stuff that is so difficult to install.

I don't know if your application will have the large range of temperature cycling that a solar system would have, but you might keep it in mind. Shouldn't be too hard to change out, if required.

Also, on your suction tube heat exchanger, did you do any kind of quantitative sizing, or was it more of an inventor's intuition?

Lastly, what dimensions (lengths, diameters, etc) did you use on your tubes-in-tube HX?

By the way, I think your copper-in-plastic HX is just brilliant!

(* in pic #2, I see a panel with many buttons... that explains a lot! *)

Best,

-AC

AC Hacker
You are correct That is the cheap foam insulation. For the temps involved it should be just fine. But for exterior applications (solar) it would not do the suns exposure turns it to dust and it could melt. The foam for the GSHP will tolerate the -20 Deg C to 60 Deg C enclosed away from light. I did use the rubber foam for the 2 ton unit.

The suction tube HX is just a guess. I wasn't going to put one in. Thought I would give it a little try.

The lengths of tube are about 26 ft three pcs of 3/8 copper tube twisted for turbulance inside 1.5" dia outer tube.

I had a thought for a tube in tube HX if anyone would like to try. It should be easy with ABS drain tube for the outer shell and 1/2 copper for the refrigerant. All the fittings you require can be purchased at the hardware store. You could fasten these to wall or up in the floor joists any length you want for minimal dollars.

The buttons belong to the CNC lathe. I've been operating machine tools for 35 yrs. Although the learning curve is steep and long for these things. I don't touch the manual stuff anymore. The new machines with their on screen programming are fabulous.

Randen

A little clarification on pipe insulation:

The less expensive type sold at the big-box stores (frost king O/E) is polyethylene plastic foam. This stuff is ok for insulating water pipes. At higher temps than about 140 degF, it tends to shrink (up to 25%, quickly), then melt at higher temps. Since dhw rarely gets above 140 degF, it is by far the most widely used in homes. It isn't used much in commercial applications, due to the lack of industrial ratings. When exposed to the elements, it lasts up to 10 years.

The more expensive type sold at the same stores is (armaflex AP) is rubber foam. This stuff is the go-to material in industry for insulating anything where moisture is a factor. It is rated to 220 degF (105 degC), and has very minimal shrinkage properties. Long-tem durability is 15 years or more. At high temps or when exposed to the elements, it tends to harden. However, it costs about twice as much as the plastic equvalent.

Both types have close to the same r-value (about r-4 per inch thickness), so the main considerations when deciding which type to use are temperature range and exposure to the elements.

For insulating solar and steam heating systems, contractors use armaflex HT or an equivalent. It is rated for temps up to 150 degC and has UV protection built in. It is not readily available at your local home improvement warehouse. It also costs 3X as much as polyethylene.

Lots of DIY'ers stick a rubber layer inside a poly layer when superinsulating solar or boiler lines. The armaflex takes the heat, the frost king provides added r-value for less money.

Here's an article comparing the two common types:
http://www.enviro-tec.com/pdf/catalo...ns-FromNIA.pdf

Randen,

The new rig looks and sounds as if it should perform much better than your previous setup. I anxiously await your progress. That unit is much more massive than anything I would ever need. But with heat pump tech, bigger is definitely better.

The variable-speed compressor is the icing on the cake with your rig. It should be able to allow you to do whatever you want to with the new unit. At start-up, you can save power. Then you can ramp up to whatever capacity you need, then slow down to maintain a high COP near your target temp. It should save you a lot of energy and pay itself off quickly.

All true, but randen now has a compressor that is capable of extracting heat more rapidly from his loop field than it is able to provide.

As long as he runs the compressor below that limit, no problem... but if he goes above it, there would be problems.

randen, I think it would be advisable to regularly monitor your incoming loop temp, especially at the point where the water leaves your HX. That's the critical point. Maybe with some kind of alarm.


It's as if you now have a very large engine under the hood of your car, and you need to be more cautious when you drive.

Best,

-AC

5 Ton GSHP Build
 

AC Hacker Wrote:

I think it would be advisable to regularly monitor your incoming loop temp, especially at the point where the water leaves your HX. That's the critical point. Maybe with some kind of alarm.

In deed the installed ground loop is only 4 ton but this is a continuous demand rate. The 5 ton GSHP will only require 5 Ton worth of heat on occation. Weekends and after hours temps are set back and not always do we experience -20 Deg C. temps. With the propylene glycol in the ground loop we can theoretically go <0 Deg C. But Extremly bad idea. However as we approach 0 Deg C. there is a lot of latent heat there. But I promise I'm not going there. Not to mention what could happen to our COP.

The whole idea here is to save money hacking your own heat-pump. To-date this is my third build and a lot of time invested. Hopefully now I will be able to keep the shop warm and save enough to have made it all worth-while. I have learned alot. Maybe with the money I will save I can invest in more insulation.

With the VFD I can control how much heat is being pumped. At 6:00 am I can ramp up for the 5 ton for a couple hrs till I get into the shop then drop back to 3 ton while I'm there working and then cruise through the night at 2 Ton.

AC Hacker you are right just because you have 600 HP under the hood you don't need it all the time. Periodically if you want to put the peddle down to pass or pullout its nice to have it on tap. Otherwise to cruise to work on 50 HP it still gets you from where you are to where you want to be.

Randen

One quick note on my build. Most items I source online and have no problems but you need to be patient. I didn't receive my filter drier and I wanted to braze it together this weekend. I called a wholesaler for a drier. NO I CAN'T SELL IT TO YOU. I wasn't asking for Freon. Had to call a HVAC guy!!!!

Good news VFD arrived this morning. Just shy of $300.00 a 4kw unit. Won't be long now.

Randen

OK, I just want to caution you, and this is a BIG CAUTION... but your 4 Ton loop is, as you said a rate. And your compressor capacity is a rate.

So, this is my theory:

When you draw heat from your loop, you have many, many feet of pipe that go through the earth, but the earth only oozes heat, it releases it slowly. The water in your pipes can release it's heat very fast to your HX. If you try to draw heat 20% faster from your loop field than it can produce, you will quickly exhaust the heat in the water, well before you exhaust the heat in your field.

If you are actually going to do this, please be sure that you are sitting in front of your system, close to the OFF SWITCH and be sure that you are continuously monitoring...

Because, if I am right, things will change quite suddenly.

I experienced this myself on a very small scale, It was a hot day in August, I has a tiny 450 watt compressor drawing heat out of a 12 foot deep hole, and the loop froze in a matter of minutes (a very few minutes).

randen, you're my hero, I want you to stay that way.

Best,

-AC

AC_Hacker I will approach this with some caution. The ground loop now is a mixture of propylene glycol and water protecting from freezing down to -15 Deg C. But if my loop approaches 2 Deg C I'm going to stop the system I don't what to freeze the ground around the loop tubes. I've heard some stories about making permafrost. And airconditioning in the summmer is not the cure.

Randen

Randon, I would not be too concerned about the 2C mark. Since the glycol is good to -15C, you will not harm the system going down farther than 2C. Also, you will have a VFD so you can run it at 80% if you like just to keep it closer to the original design. Keep the pumps running regardless.

Randon, how did you filter the propane? I was thinking that there might be non condensables that are keeping your performance down.

Vlad had the definitive cure for that. Just pull it out of the bottle as a liquid. If they can't condense, they can't leave.

Yes, but you can get water with your liquid propane and there is varying amounts depending on supplier. Am I missing something here?

Well we have another GSHP running. The Varible Frequency Drive (VFD) is sooo smooth with the way the motor ramps on start-up. Of coarse you can control the presure with the speed. The scroll compressor is soo quiet. It is just running on the bench with no heat exchanging fluids so temps and pressures went crazy after 1 min.
I had programmed in a ramp to 3450 RPM in 5 sec and a ramp down to 0 RPM in 10 sec. If the motor becomes overloaded it will shut down. As the motor is starting you can watch the LED read-out with the current voltage RPM as they change. You can set a fault to wait on re-start. There are so many great capibilities with the VFD. It has low voltage input for the thermostat control. I may have to wait till the weekend to install the GSHP with the loop connections.

Randen

No, you're not. I am. I forget you guys get really dirty gas. Ours is about as clean as clean.

Having said that, pulling liquid and then feeding it through a couple of filter/driers would take care of that. The molecular sieves used in those will grab the water pronto.

I hope there is a high pressure switch in the loop somewhere set for maybe 325psi (as well as low pressure that can double for loss of refrigerant). You don't want to rely on the the pot for high limits.

I don't think ours is that much dirtier than yours but the mixture is different. Warmer countries have more butane than we would. We all have some moisture in propane or there would be no use for condensing boilers.

Congratulations!!

Is there some kind of computer control interface to the VFD?

-AC

Yes
It has some sort of connection. but first we'll get some heat then message the programms

Randy

The moisture exploited in condensing boilers comes from combustion. Burning propane = 3 CO2 + 4 H2O. Unless the propane is contaminated, it contains 25 ppm or less of moisture. More than this amount freezes up the valves in the pipeline and filling stations.

5.0 Ton build
 

The new homemade GSHP is being tested for leaks both refrigerant and the water side for the heat exchangers. Everything looks good. The varible frequency drive is programmed for basic function. For this application this particular VFD wouldn't let me power the 3 ph compressor with supplying single phase only. In the basic circuit design of the VFD the line power 240 VAC 60Hz is applied to a bridge rectifier to 360VDC approx. on the DC buss and from there the munipulation of the Voltage, Current and Frequency. The manufacturers must want to confirm with this model they have the 3 legs for the 3 phase. VFD's can be purchased that will operate from single to 3 ph.

The VFD has so many cool features from timers to relays to many operation profiles as well as Analog input for speed control. The VFD even has a counter for time operating and # of cycles. Can hardly wait to play with it but will have wait until its installed with loopwater running through the HX's

The compressor is rated 240 V 3ph 17A running load. Thats 5 Ton 60 KBtu if .you check a single phase compressor of the same capacity you will see they almost double the amount of run current. I'm expecting it should be no more expensive to operate than the 3.5 Ton single phase that I removed.

I wish I had thought about this when we had the geothermal units installed in my home. We did talk about that option because we are nearing the capacity of our 100A service to the house. We thought about changing the service to the house to 3 phase and installing a small step down transformer. With this we could have installed 3 phase heat-pumps that operate for near half the cost. Our service line to the house is quite long so we do experience a little line loss.

In my 5.0 Ton build I included a suction line heat exchanger. This is something that Jeff and Mikesolar have been doing some work on. I had the bits and pieces it took a little extra time but now its included. I just worked with the space and pieces I had and its 1.125 dia x 7" lg. around the 7/8" suction tube. Hopefully we will gather a little more efficiency.

In the photo's you will notice a nice trick to stop tubes from vibration. Using a tie-wrap and a section of rubber tube you can lash the tubes together with the rubber tube between simple & effective. In the top veiw you will see the modified TXV with the old gate valve handle as well as the sight glass. The sight glass is really a must have. With it you can confirm the condensor is full of liquid refrigerant. It is suprising how sensitive the TXV's are. Just a 1/8 of a turn can alter the pressure alot. The cheapy foam pipe wrap is more for the prevention of condensation than heat loss. Without this the floor around the GSHP gets wet with condensation. The wrap also helps with noise reduction. The other copper tubes will have the insulation slipped on when the GSHP has finished operating for the probationary period.

Randen

Cool, I'm quite lazy compared to you guys...:D

Randen,

Man, I just can't get over that expansion valve mod! It just looks cool... like the red button on the car the men in black drive. In an industrial setting, it would have a big yellow tag on it, or a lock or something. It would read "SUPERINTENDENT USE ONLY" or "DO NOT ADJUST BY PENALTY OF LAW". Just awesome.

I'm not so sure about the suction liquid exchanger, though. From what I can see in the pic, it doesn't look like there's much space between the two pipes. It could become restrictive at higher flow rates and cause a pressure drop. I'm no expert; the piece may work just fine. But I would keep an eye on it just in case.

It is about the same as the westinghouse one that I copied so it remains to be seen how it works.

Thanks guys

I have the unit inplace. It was alot of work, took the hole day. As I loaded the compressor up it got noisey. Damm liquidation junk. It would seem to produce a lot of heat. Jeff the suction line HX has a delta T of 4.6 Deg C. This should have some effect on efficiency. Don't worry I made sure there is ample flow.

The pressures are 60 suction and 230psi liquid. I had played with the TXV up to 375psi and it got noisier than the recips. I had.

The VFD is really nice. I'm going to phone the liquidator to see if he has another compressor. I'm worried being its really heavy that the courier dropped it bending something on the inside that you would only notice after you put some presure on the system. I get a really good head presure and it seams to draw the right current but judging from my commercial scroll units I have at home, its quite noisey. If something is interferring and it starts to make metal it will all be junk. How would you wash out all the metal to not cause an early death to the next compressor.

I did check to make sure it had oil before I brazed it together. It looks like I may be putting together number 4 GSHP I really didn't want to go into mass production.

Looks like I'll be reinstalling the little 2 Ton

Randen

What did you pay for the pot? What was your discharge temp and head temp at 375psi?

Mike I paid $150 for it. And getting it here was $200. But the work assembling and installing wow. I'm trying to gather the courage to Rebuild again. I know that deep grating noise with-in that compressor is going to result in metal shavings and sudden death.

Today is Sunday might as well be a day to switch it out with the 2 Ton

Randen

Rebuilding the 5 Ton
 

Fellow Eco-renovators

Look at the crate that showed up. Three nice sized new Brazed plate heat exchangers. Two will be to rebuild the 5 Ton heat-pump. I had found the tube and shell HX that I built was marginal in capacity so purchased some more appropriate BPHX. The HX were built to order with the proper brazed connections on the refrigerant side. and pipe thread on the loop side.

The third BPHX is going to be used for the house solar hot water. I'll post the activities on this install in another post

Looking forward To having the 3ph control for the compressor. And hopefully some really good COP.

Randen

Do the HX have distributors on the vapour outlets? Quite important. Also, once you have checked them out for quality, please let us know who to order from. Alpha Laval is a bit pricy

5 Ton GSHP Build
 

Picked up some free insulation board and had the table saw set-up. An item that will be nessisary for the 5 Ton rebuild an insulation box for the heat exchangers. I fab'ed up some boxes that will slip over after the BPHX are soldered inplace.

Recovered the R290 BBQ gas refrigerant while on the other-side of the shop soldering up some more risers for the shop solar hot water system.


Randen



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Great progress!

There's a buddy of mine named Howard that has a CNC shop, just down the road from me.

His Architect-Wife insisted on a high-end custom refrigerator for $7000 (not a misprint) to go with her Architect Kitchen Dream. After a few fitful years, it crapped out and she's hankering to go buy another one exactly the same, so it will go with her kitchen design. So Howard now figures he has $7000 to do a total re-design and rebuild of the refrigerant system on their old unit.

He had decided that for his first voyage into the tumultuous HVAC seas, he is going to go with a three-phase compressor and a variable speed drive and an Electronic Expansion Valve, all controlled by A Raspberry Pi microcomputer.

Pretty ambitious for a 78 year old guy!

Personally, I think that there is some chemical in CNC machine lubricants that make a man just plain crazy...

What do you think?

-AC

Pretty sure you could just swap the condensing unit (if that's what failed) on one of those commercial refrigerators for "cheap".

AC_Hacker

Personally, I think that there is some chemical in CNC machine lubricants that make a man just plain crazy...

What do you think?

AC_Hacker I think your on to something there. I believe it's something like my boy's Spiderman movie. CNC is like radio-active Spider Venom. With CNC you can now make things better and stronger that will last for decades.

"With great power comes great responsibilities." Now you look at everything. I Can make that a whole lot better. Toilet paper holder, Fancy Stainless wine rack, LED light fixture. The list grows. And the more you do the more you find.

Like Spiderman you find yourself fighting crime of poorly manufactured goods in the shop.

What a life.

Randen

5 Ton GSHP Build
 

Or maybe a more appropriate tittle 5 Ton rebuild again. The compressor was liberated from the housing as its too small for the new brazed plate heat exchangers. The chore for the day is to fit up the copper tubing. A bit more fitting is left to be done.
The little 2 ton kept the shop tolerable for most of this cold winter. I didn't want to change it out in the depth of winter just in-case the 5 ton didn't work-out. The nice thing is it kept it tolerable quite inexpensively.

I want to change it out with the 5 ton soon as the nights can still be quite cold and I can get a good idea on its performance.

Randen

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The discharge should enter at the top and the liquid exit at the bottom.

Randen,

I think he might be right... gravity is your friend.

Just to make sure, you might consult a couple of Brazed Plate HX manufacturer's manuals.

I believe that it is most important for the condenser side, and I have seen recommendations both ways for the evaporator side.

Beautiful tubing work, BTW.

From the pix, I can't tell if you've brazed your tubing to the fittings on the BPHXs.

Best,

-AC

Hmmm

Yes hot liquid or gas entering the top and cooling (condensing) and falling exiting the bottom so only liquid enters the TXV.

I was thinking the condenser must fill with the liquid and purge all the gas through as the liquid rises in the BPHX. This would mean the BPHX must be full of liquid but in some conditions this may not happen.

Nothing is brazed or soldered at this point. Just a rough fitting. Today hopefully the mounting for the BPHX and compressor. We will have to see what's in the stainless scrap bin.

Randen

Yup, switch the ports. Your liquid line filter won't work that well either. What are you using for SS to copper brazing?