1) I believe it is no longer legal to manufacture R-22 equipment

Difference in COP between EWT in 30s vs 50s isn't all that much, and chances are that a loop able to provide EWT in the 50s is in a climate of low to moderate cooling loads.

I agree that technology hasn't evolved to the point where a single unit reliably makes domestic hotwater on demand along with HVAC.

Adding a dedicated unit for hot water may not make economic sense in all but the largest families. The desuper can provide half or more of domestic hot water, cheaply in winter and nearly free in summer. A water to water geo dedicated to hot water is probably the cheapest source of hot water, but the upfront cost is likely such that payback would be measured in decades, not years.

Quoting engineer: “Difference in COP between EWT in 30s vs 50s isn't all that much,...” Here is some surprising data from Climatemaster’s “All Product Technical Guide: 2008” for Tranquility 27, 038.

1st Stage:

EWT Heat Cap (1000 Btuh) COP
30˚ 20.6 3.85

50˚ 26.8 4.89

2nd Stage:

30˚ 30.4 3.94

50˚ 39.3 4.68

A 20˚ increase in EWT results in a 27% better COP for low stage and a 19% COP increase for high stage. The 2nd Stage capacity increase of 29% due to a better EWT can potentially save additional $ by avoiding expensive aux use.
Another surprise (to me) @ 30˚ EWT, 2nd stage COP > 1st stage COP!

Sorry, spacing in above table did not post as intended.

Regards,

Masoud

A COP of 4 vs 5 isn't actually that significant in terms of operating costs - both numbers are highly desirable (and rarely attained)

The COPS you publish are theoretical, kinda like EPA mileage estimates - YMMV

The difference in loop costs to increase EWT by a full 20 degrees in winter (or decrease it by 20 in summer) range from astronomical to infinite. I wonder also if these COPs take into account the increase in pumping power needed to drive loop fluid through the greatly elongated loop field necessary to provide more favorable EWT.

I mentioned before that a H/O who had an older heat pump and wanted to go closed loop due to well problems discovered his heat pump was only good to 45*. Sizing software suggested that would require 26,000 additional feet of loop in the ground. The new heat pump was much cheaper.

Masoud, If someone filled out the op cost calc from CM when you bought your system, you will notice average COP in the 3's. No real world application offers consistant 4 or 5 COP in heating dominated climates with closed loop.
J

Joe and engineer,

I was not promoting the idea of expecting 50˚ EWT. I’m familiar with the concepts of diminishing returns and increasing marginal costs, as they relate to loop design, installation, and target min/max EWT’s.

I posted EWT’s vs COP’s as a means, generally accepted by the industry, of providing data, which were missing in “Difference in COP between EWT in 30s vs 50s isn’t all that much...” - emphasizing THAT MUCH. That’s all.

Of course I prefer 50˚ to 30˚ any time, even in summer. But it’s not economically or perhaps physically feasible in my backyard. My well water temp is below 50˚, now.

Regards,

Masoud

I have install nearly 100 Hydro heat units, I can tell you that we have had more trouble with this model than any other. But having said that, any time you try and heat water above 105 degrees with a compressor you are going to damage and eventually destroy the unit. the high water temperatures causes maximum head pressure for extended lengths of time. To make this work you have to have a buffer tank between the domestic and or boiler. The geo unit can heat the water in the storage/buffer tank to 105 or less and then the secondary tank can heat it to design temperatures. You could use one buffer tank for each and alternate between the two. The other problem with this is that the unit would run 24 hours a day most of the winter and great deal of the time in the other seasons. You could expect to replace the compressor at least once every five years. We have had better luck with different compressors than what the manufactures use. It sounds like the contractor has  done a lot to try and solve this problem he may not know the things I told you because the manufacturer keeps telling him that it should work. As for the loop field I have seen loop fields fail but never take out the unit. Poor duct systems can cause the house to never heat up but don't cause the unit to fail. the only other external cause Ive seen is pump failure or I guess extreme power surge.

Actually, you can get Legally R-22 equipment for replacement. it has to be shipped dry. Also the desuperheater does not work at all in the summer unless you have a buffer tank, circulating 120 degree hot water thru the Geo unit will damage the compressor.

"any time you try and heat water above 105 degrees with a compressor you are going to damage and eventually destroy the unit. the high water temperatures causes maximum head pressure for extended lengths of time"

Balderdash!

1) Heat pump water heaters easily heat water to 130+. In fact, the DOE EF (Energy Factor) rating is based on energy required to heat water to 135*F.

2) Air source heat pumps and ACs routinely work in 115+ degre temperatures in the desert southwest.

3) The heat transferred from hot gas at compressor discharge to domestic water is SUPERheat, hence the term "deSUPERheater". Stated another way, the temperature of the gas does not correspond with the pressure of the gas such as one might read on a manifold guage.

I'm perplexed by the premise that one could have installed 100+ water source heat pumps and make such an ill-considered statement.

Finally, it is poor form to resurrect a thread on the second anniversary of its demise.

Climatemaster Tranquility Install manual:


"The temperature set point of the HWG is fi eld selectable
to 125°F or 150°F . The 150°F set point allows more heat
storage from the HWG. For example, consider the amount
of heat that can be generated by the HWG when using the
125°F set point, versus the amount of heat that can be
generated by the HWG when using the 150°F set point."


Even with W-W units, some manufacturers recommend not to go over 125F over an extended period of time, while some are rate the unit up to 130F. We have many running under those condition for an extended period of time.
Are you sure you put in 100+ units?

I think it is documented that compressors can heat water over 105F, I think it is also documented that higher pressures can cause more wear on equipment.

The point about more operating hours is valid. As a servicer of the old Amana HTMs I saw the folly of using the often most expensive appliance (furnace) in the house to do the job of what is usually one of the cheapest (water heater). With any appliance more operating hours especially at capacity (high temp conditions) will eat up the life of the equipment in less calender years.
I think it is also noteworty that Hydro started their ambitous hybrid pre scroll compressor. They also suffered maladies on the management side as well as design. I had high hopes when RP bought them, but have not yet heard any thing compelling.

I have seen 15 and 20 year old Hydros but they either never or had long since stopped making hot water. The one I replaced most recently had the DHW circuit plumbed through the drain on the water heater- through the boiler drain! So while the genius who installed it took the time and expense to go most of the way in 1" copper, he then stuffed the flow through a 3/8" opening. There is a good deal of documentation that installer error caused many problems.

The question I have for dirtsquirt is why 100 hydros if you see compressor failure every 5 years and more trouble than other models? I would have jumped ship long since.

I had the same question, just forgot to ask it.