Acuario & Jeff5may

Thanks for the heads up on the length of the HX tube. As we know longer is better. Already installing that lenth of heat exchanger tubing proved problematic. Using the baseline that the A7 install by Xringer I had modeled the HX lenth. The tubing I used is 5/16 od so a little more surface area by a 1/3 and about the same length. The proof will be in the end trial. Xringers A7 was 7Kbtu mine is a little smaller at 5Kbtu.


Xringer wrote: "I unrolled the HX loop and I think it was just under 15 long. So, less than 30 feet round-trip. The OD is just under 0.22" (5.6mm)."

Randen

Well I must admit it was pure chance/luck. The place where I buy it from sells rolls of un insulated 1/4" tube in lengths of 5 metres.

We need to keep in mind the operational parameters here.

As I recall, Acuario, you are using compressors that are in the 12,000 BTU range or larger, am I correct? Also, you are working to achieve an output temp of maybe, 80 degrees F, am I correct? So your compressors are larger and your lift is lower.

Randen's compressor is less than half that size, but at the same time the maximum temperature is going to be maybe 110F-ish. So his compressor is smaller, but his lift is higher.

Jeff5may, if you are right regarding the 'magic number', it's probably because of the lucky combination of smaller compressor and higher lift.

-AC

SHHHH...don't spoil the magic. It doesn't work if you explain it!

Hi guys,
Randen, I made the same fittings you made except for the end return. I suspect that you took a wall stub for roughing in sink and cut the end off for the spun end. It looks nice but I am a bit concerned about its pressure rating for refrigerant. I guess we will see. Also i would make sure the anode is really good or you will loose your refrigerant within a short time. Another option would be to coat the copper in an epoxy paint. Effectiveness may be SLIGHTLY lessened but it may prolong the life quite a bit.

I was making the HX for small solar systems and the problem I had was spinning the big coil into the tank so I made a union type fitting instead which was easy to make a water seal on.

About machining, landlord is selling the building so I got the boot. 600V, 3700lb lathe and mill has to go and I am looking for really nice smaller ones that can run on 240V and fit in the (5000ft down to 600ft) new, perhaps temp, space.

another hot water tank heat pump
 

The assembly of the copper HX coil into the HWT didn't work out so well. I had pre-twisted the coil counterCW and piled the copper tube into the tank like the A7 HX installation, but trying to turn the adaptor in caused the tube to kink. I'm going to try to cork-screw a different orientation of coil in and try to turn the adaptor in like the original electric element.

The length of the HX has been subject to some controversy. The length of copper is 22ft. of 5/16 and if what Xringer had indicated was in his A7 for a heat exchanger this coil may have more surface area with a smaller compressor. I say lets giver a try.:thumbup:

Randen

http://ecorenovator.org/forum/attach...p-sam_2417-jpg

http://ecorenovator.org/forum/attach...p-sam_2418-jpg

When I saw your fitting, I wondered about twisting it into the tank..

http://i46.photobucket.com/albums/f1...W/P1000706.jpg

The A7 comes with a two piece fitting, the only part that turns is the retaining/collar nut.
http://i46.photobucket.com/albums/f1...W/P1000707.jpg


And it will leak a little, if you don't crank it down tight.. (Easy does it)..
http://i46.photobucket.com/albums/f1...W/P1000710.jpg

PS: That little nut with the small tube for the heat sensor blub also leaked.. Had to be tightened a little.

What refrigerant is the compressor designed for and what are you going to use?

If it's a R22 compressor, R290 (or more accurately, R433b, a R290 based mix designed to replace R22) will be nearly a drop in replacement, but expect about 125F maximum hot water temperature. It would work very well for showering, but dishwashing effectiveness might be less than you like.

If it's a R410a compressor, you'll get about 2/3 the capacity after giving it the Davuluri Treatment, but 140F should be easy to attain. Note that you'll need to watch your discharge temperature if you do that. Counterintuitively, that's more likely to be a problem with lower evaporating temperatures.

In either case, you'll want a TXV since a cap tube would not be very well suited for such a wide range of conditions. You'll also want some sort of remote control to allow the temperature to be set as low as 105F in order to get more efficiency under more normal conditions, but allow it to be boosted for dishwashing. You might also want to look into replacing the rather inefficient PSC fan with a Delta with Cindy Wu technology. You'll be surprised just how inefficient smaller PSC fans are.

Randen,

Thank you for posting the details & photos of this attempt, even though it was not a success.

This provides a lot of information for all of us.


BTW, in the thread posted by Hv23t, The tubing was 1/4"... The diameter you're using is 5/16". It's possible that the slightly smaller tubing that Hv23t used was just enough more compliant to make the turn.

His fitting was almost identical to the one you made...


And his procedure was very nearly the same as yours:

Pretty similar...

Best,

-AC

I think the main difference is that the soldered joint turns the tube as it's being tightened, while the compression fittings do not. Use plenty of sealant (or Teflon tape) on the compression fittings since they tend to leak. That's especially problematic on the discharge line due to thermal cycling.