DX Geothermal Pond 4 ton Heat Pump

[MEMPHIS91]

Randen, yeah I have heard as large as twice as big for the VFD. If the savings are not going to out weigh the cost it would make no sense to go 3 phase. Though I do really like the slow start up.

Jeff, yeah I saw that, but again my lack of knowledge got in the way. So it in fact does look like a good deal. I should be able to find a 4 ton single phase r22 around here for cheap, with as many hvac guys as I know.

I guess I need to start designing some controls soon.

[randen]

It may just be me. I don't understand why the desire for complex controls on smaller systems. If the selection is made for the proper BTU fit, a couple relays and pressure, temp. limit switches and let the vapor-compression machine purr away.

For our DIY systems a tad oversizing of the HX would be more beneficial than over complex controls. IMHO

For my home installation the heat-pump during the windiest coldest part of the year may not stop, just purr away for 24 hrs. and may loose a little ground for heat. But that's a more desirable fit. These 3 ton HPs are single phase and just either on or off.

They are just great. Saving bags of money

Randen

[jeff5may]

If you REALLY wanted to save the mucho dinero, you could plumb the turbotec hx into your existing heat pump. If equipped with its own TXV, it could change the way the old unit performs (for the better).

Or not.

[MEMPHIS91]

Thanks guys you are right.
Pro 15:22 Without counsel plans fail, but with many advisers they succeed.

I have no argument, it will save a lot of work and money to do single phase.
Jeff, I guess I've never seen a compressor like the one you linked me too. I really don't need a crankcase heater either, BUT its pretty cheap and does look like a good fit.
What about these other two
Surplus City Liquidators
Copeland ZR45K3 PFV 135 3 3 4 Ton AC HP Scroll Compressor 208 230 60 1 R 22 | eBay
What is the difference in the one you linked and these?

Randen, I will start looking into pressure/temp switches. This project is turn out to be pretty cheap.

[jeff5may]

OK, emerson has consolidated the lineup of its latest (ZRK5) replacement scroll compressors. The 51 models it used to make (in various motor windings and whatever else custom in each model) has been trimmed down to 13 models. All of these ZRK compressors are emerson/copeland factory replacements for a bazillion proprietary part numbers made for the hordes of different brands of HVAC manufacturers.

I believe the red 3 phase pots you were looking at before are field replacements built for trane. Cuz painting them bright colors makes them completely different, inside and out. The strange numbers help too.

Here is the bulletin:
http://www.digitalscroll.com/uscampaigns/mb2010cc-4.pdf

The two ZRK3 models you linked to are single-phase brothers of the 3 phase scrolls you were looking at before. The main differences seem to be motor windings and marketing for the refrigerants that were supposed to replace r-22 during its phase-out. Obviously, the market has shifted to R-410a units (different family of relacement pots: ZPK5) and ongoing replacement of existing r-22 pots.

The CRK6 compressor I pointed out is rated for use in a circa 1980's 10 SEER unit, as that is what the pots were factory-built with way back then. If you can find an old goodman, york, trane, coleman, etc, 10 SEER air-source unit (just check on craigslist for a few days or weeks) it will have either a scroll like you found or a recip like i found in it. If you stick the turbotec hx and a txv on the old pot, then it will more than likely put out more than its nameplate btu's if you feed the hx enough warm water. Likewise, if you stick one of the newer pots (rated inside a 20 SEER factory unit) in the old 10 SEER original unit, it will most likely not put out its nameplate btu's because of the inefficient outdoor coil.

http://yaunco.com/images/ebay/compre...pfvratings.pdf

[MEMPHIS91]

Thanks jeff that makes sense, yes I would really like to stay with a scroll compressor. The indoor coil is an issue but I know of ALOT of the new N style copper coils that had a small leak from the high pressure 410a that I might be able to find and repair, if not, they are not too expensive.

If I'm going to take the time and money to build the system, I would like for it to be as efficient as sensibly possible. So upgrading the indoor coil is for sure an option, so is a more efficient compressor.

Should there be a certain compressor I should be looking for?
Are there other ideas that would make this build even more efficient? Of course ones that are worth the time/money.

[mejunkhound]

I would like for it to be as efficient as sensibly possible.

May have missed it in a previous post, but have you looked at all the ramifications and advantages of the different changes? Versus bigger this or smaller that, etc.

For instance, have you researched Mollier diagrams and plotted out(or made up a spreadsheet) of how the COP of the system will change for each small independent revision to any given system? And then fine-tuning the charge with subcool and superheat calculations?

On own old 4T Rheem air-air heat pump, when time came to replace compressor, found that downsizing the compressor to a 2T compressor and revising charging for optimal subcool (e.g letting there be some liquid sit in bottom of the now oversized condenser) gve almost 3 T heating at higher COP.

[MEMPHIS91]

mejunkhound, I have the coolpack program just still learning to use it. But you are very right that I need to plot all the info to come up with the best fit for the system. Only thing that is for sure right now is a 4 ton turbotec coaxial coil.
I can change the indoor coil, compressor, and the txvs.
I know of a hvac junk yard that I could probably get some 3-4 tons air coils out of, and make a larger inside set of coils. But not too big cause I still want to keep my temps low enough in the summer to condensed the moisture out of the air.

[jeff5may]

Now is the time to figure out how much heating and cooling you really actually need. Who knows who or how the unit you have was matched to your house? Have you done, or had done, an energy audit or heat load analysis? How well is the home sealed and insulated? Have any improvements been made since the 4 ton unit was installed? Answering these questions will. get you in a sweet spot as far as overall btus required.

You may expose issues with your home's envelope that could be dealt with to drastically reduce your heating and cooling needs. Materials like caulking, foam and rubber seals are ultra super cheap compared to the leaks they stop. Added reflective or refractive insulation is an investment that starts paying you back the day it is installed. These materials incur no running costs, next to no periodic maintenance, and have very long lifespans..It is always wiser to reduce your demand than improve your supply.

[jeff5may]

Since you are doing a water-to-air configuration, it would be in your interest to get acquainted with waterfurnace and their tech support info. They have been making units just like you are planning out for decades. They use turbotec coax coils and the same Copeland scroll compressors you are looking at in the units they produce. Even better, they post loads of charts and graphs of well-researched data for all the units they sell. They use manufacturer part numbers in the parts lists of the units they build, so you don't have to waste time trying to cross a strange part number to the original source.