A friend of mine is interested in replacing an LP with GSHP. He went to a 3 hour course at the local College and left pretty discouraged.  He was led to believe that he would need to replace his existing submersible pump with a variable speed pump if he wanted to do an open system, which would be very expensive.  I thought he may be able to use his existing well and pump as long as there was sufficient volume, and it didn't short cycle.  Even change pressure tank to a larger one to prevent that.  Any info???

Also, why is desuperheater used rather than HOT WATER GENERATOR???   

A desuperheater takes advantage of excess heat to generate domestic hot water. If the GSHP is running in the cooling mode the generation of hot water is free. If the GSHP is in the heating mode the generation of hot water reduces total heating capacity by about 10%. The unit does not run just to generate hot water, it will only generate hot water when the unit is running.

Bergy

Sorry I worded it wrong. Where did the word desuperheater come from rather than Hot Water Generator?

they both mean the same thing.

Desuperheater refers to the fact that the temperature of the refrigerant exiting the compressor is significantly higher than the saturation temperature associated with its pressure.

That excess temperature is referred to as 'superheat' and can be stripped off and used to heat water to domestically useful temperatures even when saturation temperature is fairly low. That process is "desuperheating" and the gizmo that does it is so named.

HTH

I'm surprised no one commented on coolmccool's first question about a friend using his current well pump vs a variable speed pump for open loop geo.

All open loop owners I know, have used their domestic water wells and single speed pumps with larger pressure tanks for their geothermal systems, all several years old. Higher energy efficiency of variable speed pumps is desirable, but economic feasibility rules. I think Joe may expand on this.

In addition to adequate water supply and disposal means, the quality of water has to be checked. These requirements are generally available from geo heat pump manufacturers' websites.


Prefix "de" in desuperheater means undo (as in deglaze a pan or defrost a freezer), the technical stuff has been well explained.

Regards, Masoud

In the late 1040's and early '50's nobody had staged or variable speed well pumps yet most everybody had open loop systems. So tell your friend it will work fine. The downsides are noisey operation (due to excess pressure that has to be reduced by a flow rater), higher pumping expense, less regular pressures in the rest of the house, and more frequent well pump replacement.
There is an old addage that a running motor lasts longer (the starts and stops are what gets them). While I don't have data on the longevity of variable speed pumps, it does make sense to me that they should last longer by providing only enough for demand versus the old design which is more akin to racing your car to the next stop sign only to slam on the brakes.
I would suggest to your friend that he throws the money his GSHP saves him into a cookie jar (or some other high yield savings vehicle:) and when his old well pump croaks (6 to 8 years) he takes that money and invests it into a variable speed model.
By the way De-super heater is to Hot Water Generator what facial tissue is to Kleenex. They are all de-superheaters but not every manufacturer calls theirs a "hot water generator."
A note regarding titles of threads......I can't speak for everybody, but I don't read every thread. Some topics are less interesting to me than others. As most of my systems are closed loop, I don't do much with well pumps and only peaked into this thread today as a customer had pump questions Friday. My point (not criticism) is that folks may want to get the gist of their question into the subject line for the best chance of getting an answer.
Good Luck,
Joe

I agree with Joe 100% about saving some cash from the operating expense of the lp only I would buy the variable speed unit the first year I realised savings and sell the old water pump to my neihbor as a spare.

By adding storage to limit cycling in a geo application you are still cycling the pump, you have just increased the interval. Storage costs money, so do not buy it. Install the system, stash some money, and upgrade the whole way, not just in part.

Variable speed pumping equipment is to geothermal what a pump start relay is to a automatic lawn irrigation system "fewer parts and a greatly extended service life"

I have an open loop with a normal submersible pump. I use a CSV (Cycle stop valve) to maintain a constant house pressure, while at the same time remove pump cycling during extended use. It is not the most efficient, but it's simple. No problems, and my electrical cost increased by $600 and reduced my propane costs by >$4500 for the heating season. So a one year heating savings of >$3900

my previous system was open loop system, i also used a CSV to reduce short cycling the pump. another note on open loops is you should consider a cupronickel coil, this will allow you to do repeated acid flush's which may be required depending on your water quality. i did them once a year. open loop system are generally cheaper, my system was very affordable as all the plumbing was already in place to supply and dispose of the water. my total installed cost was $6400 and thats with a desuperheater and the cupronickel coil!! this increased my power bill about $500 but saved me $2500 a year in propane so the payback was quick. another benifet of the open loop was water quality. the best thing for a well is to pump lots of water out of it, or water quality increased incredibaly, before the geo system we needed charcoal/carbon filters to reduce the taste in our water, after a few weeks of heating with geo we were able to remove the filter elements and enjoy perfect water.

A standard well pump will work but  since it is pumping to a pressure much higher than needed, it will use more power than necessary.  A large pressure tank will reduce cycling.

IMO, best is to size the well pump to deliver the volume at the low pressure needed by the GSHP (with no restrictions) and then add a booster pump to get the high pressure needed for domestic water.  No variable speed pump and no cycling of the well pump.

One fine point - if you do use the high pressure water and need to restrict it, restrict it after the GSHP, not before.   You get more deposits after it is depressurized.

as a coincidence my installer uses Grundfos SQ submersible well pumps for his loops. i believe mine is a 1/2HP and it pumps about 16GPM

Our experience 22 years wells and pumps indicates bite the bullet and install vsp . Make sure well has adequate capacity and decent water quality. Saving your friend headaches I would only install Grundfos SQE vsp.

If every installer is going to suggest vari pumps, closed loops are gonna be a no brainer.
j

Note that a variable speed pump does not address the issue of pumping to a far higher pressure (ie, wastes energy) than needed for geothermal.

If you have a dedicated well for geothermal and a single heat pump, then variable speed is a waste because the flow rate never varies.

The number one factor limiting geothermal growth is initial cost.   So ways to reduce that cost are important.

That's the constant enigma of this site. While I agree that my customers deserve the most bang for their buck(s). I constantly find myself defending use of aux. coils, closed loop systems that operate under 32*, ~95% requirement targets, use of single stage equipment where indicated.......
I also am opposed to zone systems in principle (most people have gravitated to them due to a lack of talent in duct design for so long) or multiple appliances where one will do.
To quote a builder buddy of mine "people are funny critters."
One house we bid on had a 100K kitchen cabinet package but a 35K heating budget.
A recent homeowner set a buget for the system that I indicated we could come close too but many features would be lost. After considering our budget option, H/O decided the features lost were more important than the arbitrary number.
The thing is geo is cheap when you consider all that's involved (heating, plumbing,excavation, electrical, scores of man hours), on top of that, the combination of higher and lower education of the shoppers is adding many hours to the estimation process which has to be paid for as well. Payback, however, is a lot better than any high dollar kitchen cupboard or marble countertop I've ever seen.
Coolmccool,
The best thing to tell your friend is to get into geo however he can afford it and tweek the system from there. If he has a Chevette budget, then we shouldn't be talking Cadillacs. If he has simply set an arbitrary budget, then he may want to consider the cost vs benefit of some of the features he's not getting.
J

What do you mean very expensive? I did a seach online and I was hard pressed to find a multistage pump that cost more the a thousand dollars, even with installation, I can't imagine it costing more than 2 or 3 grand. While not cheap, when you compare this price to the cost of a new geo system, it's really not that much in the grand scheme of things. 

As for needing to change the pump, my pump is pushing 20 years old and works fine for my open loop system. I will have to admit the pump only handles the Geothermal system, the rest of the house is on city water. 
 

The geothermal system is that funny looking thing in the basement that cost a lot and the installers were terrible - they dug up my yard!  It has more parts to fail than my old furnace and it won't heat the house from 60 to 72F in 15 min like my old system did.  I had friends over and they were completely unimpressed.  Should have bought a new kitchen.


The push for more value will never end.   Anyone who resists will  face the same problems as the auto industry.

Isn't that the truth Jon. I'll talk to Climatemaster about putting more oak trim or maybe some cupholders on their heat pumps. That oughta help sell these things.

Hell I'd be happy with a couple of gauges where the needles move back and forth to let me know it's doing something and a small LED for error codes. On my Water Furnace I have 4 lights that have decoded with the manual to know what's going on. For what I paid for the system I could have gotten a new GM car with Onstar, it be nice to have more bells and whistles on it. 

"The is Onstar, we detected a issue with your Geothermal system, we have notified your service technician, Help is one the way."