Our thanks to Joe Hardin from AMI Geothermal for his honest and accurate thoughts on DX systems…
I have continued to gently (uncommon for me) voice my DX concerns but feel obliged to sum them up given recent rebirth of the topic.
Want a DX system? Ask yourself these questions:
1) Do I want a system that is not recognized by the International Code Council?
It is true, in Michigan for instance if you install a DX system the code requires a hydrostatic test of loop system......show of hands, who wants to run water in a refrigerant circuit hundreds of feet long? How do you get it all out to avoid damage to the compressor?
2) Do I want a system in my home that (often) the same code requires an industrial type machinery room for?
Also true. Though the International Mechanical and Residential Codes apparently haven't heard of Direct Exchange Heat Pumps, they do identify that once over X lbs/ft3 of X refrigerant, one must have a machinery room with ventilation, refrigerant leak alarm etc. Let's say it again, the quantity of refrigerant in your DX system if leaked, could be injurious to the occupants of your home- therefore industrial measures (and related expenses are required).
3) Do I want a system that eliminates an inexpensive circulator pump, simultaneously increasing the workload of an expensive compressor?
While seldom mentioned, don't you think adding (sometimes) 1,000 extra feet to a refrigeration circuit might tax a compressor a little more?
4) Do you want to put geo loops in the yard that very seldom corrode (if proper protocols are followed) or the ones that never do?
I grow weary of water source guys hype of loop corrosion or refrigerant leaks in the ground. A Good DX installer will mitigate the possibility to almost nothing. That said, HDPE fears only impact and sunlight.
5) Do you want a system that is 3% of the market, or 97%?
Seriously if you were buying a car- one to take you to work every day, are you going to get the one that often costs more, has a smaller dealer/tech/part network just because the salesman says you might save $90 a year in gas (based on laboratory tests not actual driving)?
6) Do you want a system where most manufacturers, license holders, etc. have not held
the product line for 10+ years?
Go ahead check some domain registrations etc. and please don't bring up the sale of FHP to Bosch, I don't think Bosch is in the same category as XYZ DX, LLC.
7) Do you want a system where most dealer/installers have spent less than 5 years with the product?
8) Do you want a system that attracts more new guys since they don't have to buy new tools?
Watersource manufacturers aren't particularly better at vetting new dealers, but extra tools and less finicky installations suggest greater financial security and less opportunity for mishap on installation.
9) Do you want a system with 5 times the refrigerant in it?
Things made by people and installed by people do fail. If you get a leak on a your system do you want the one that has less or more- like maybe $800 more to leak out?
10) Do you want the system that tears up more of your lawn?
While DX boasts of smaller foot prints, what they mean is less pipe. Sometimes this is more holes however or longer trenches etc.
11) Do you want the system with less loop field flexibility?
DX loop fields are refrigeration circuits that ave a prescribed length and pitch- coloring outside those lines may interfere with compressor's oil recovery harming the equipment. Water loops can follow the grade (saving excavation on hilly lots) or be increased where dry soil is present.
Do you have DX in your home now? Do not despair.
Systems in my AO have been up and running more than 20 years.
Efficiency while ultimately hindered by ground thermal conductivity is still quite good.
Everything that has refrigerant in your home is potentially Injurious to the occupants. That a DX system has more suggests no greater risk of leak occurrence, and injury is unlikely. Greater sales today will hopefully keep some of these guys around for parts etc.
Who sells DX?
With all this in mind why would anyone want to sell DX equipment? There are essentially 3 types of companies:
A) Tax credit band wagon guy-
Often low bank preferring system with less business start-up costs (i.e. fusion tools, flush carts etc.)
B) Marketing minded guy-
"everyone is selling those systems for X price, if I'm the only one selling this system I can charge a more premium price."
C) Old geo guy trying out new technology, perhaps thinking of a distributorship opportunity down the road.
Or it may be some combination of the 3. My decision after training in 2 different systems (kinda a combination B and C guy)? I made friends in that industry in MN that I trust and would like to support but for now I must wait and see. I have not decided not to ever sell DX. I had to ask myself "why is the biggest dealer of the biggest distributor of X brand, dropping the product in favor of water source...and why did that same distributor just take on a water source product?" Geo systems are fairly expensive; eating a few lemons can really hurt a small shop.
About your DX dealer you will have to ask yourself:
"is he ignorant of the code- following the code- subject to a different code or ignoring the code?" and "why is the aggravation of selling the least popular product worth it to him". There can be very good answers to the questions, but you won't know until you ask. Then of the manufacturer you have to ask why an organization as big as the International Code Council is not worth approaching to get the equipment recognized and maybe the refrigerant detector waived by exception or at least a reduction of measures required for compliance.
All that said, the best geo heat pump is still "whatever is sold by the best dealer in your town."
This does not rule out DX.
There are always exceptions.
I welcome rebuttal from a DX manufacturer.
I think I may contact the ICC myself to see if they have been approached and if there is something new in the pipe line.
"We Dig Comfort"
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