I live in Alaska. I have 2 Waterfurnace series 5 closed loop units heating a radiant heat floor in a newly constructed 6 star energy rated home. These two 2 ton units both heat the home taking ground source water at 28F and providing 140fF water for the floor via a heat exchanger. The units were installed in October 2015 and 2 weeks ago the compressor in the "B" unit shorted out. The compressor was replaced and now 2 weeks later the compressor has failed again. The "A" unit runs flawlessly. I have 6000 feet of in ground tubing in ten 600 foot horizontal "slinky type" coils. Each of the ten legs is about 150 feet long. To add to the puzzle I am using off peak power for 11 hours each day and to heat the house they run continuously at -20 outside air temp. I think I am freezing my field but the inlet water never goes below 28 degrees. If the field were not recovering somewhat i would expect the temp to drop during the operation cycle. It doesn't.The units are rated to 20F. Any ideas? Waterfurnace and the warranty guys are stymied and are hesitant to through another compressor at the problem without knowing why we are having failures. Thanks for your time. Mike

Before jumping to any premature conclusions more information is needed. Shorted compressor could have several meanings. Was the windings shorted to ground or were the windings shorted between the two set of winding internally inside compressor. Was the failure of original compressor the same as replacement. The first thing which needs to be verified is during compressor replacement were all driers replaced. Is there oil contamination. Was this a burn -out. Is there acid or moisture in the system. Was refrigeration circuit evacuated to 500 microns or lower. This might tell us why compressor number two failed. Also are the electrical components in the start and run winding circuitry correct. Is there a bad or wrong size run capacitor. There maybe some engineering design flaws which took out original compressor. A lot more information is needed.

Since these are sealed compressors and WF has yet to open the original unit we don't know the cause of the short. The A phase generated amperage of 267.3 and the B phase was closer to normal LRA reading 132.4. Dryer was replaced along with a new capacitor. Triple evacuation along with a nitrogen pressure test of connections.Wiring was done the same as the original as the tech took pictures to verify replacement. The acid question is a good one, I didn't smell the take out but contamination is a possibility. I will relay your questions to the refrigeration company owner that does WF warranty work. The original installer is in FL for the winter but might have the most GEO experience of anyone in the state. BTW using 20% methanol as antifreeze in the ground loop. The warranty company has been very responsive when I met with the owner for an hour and a half yesterday when the builder went to see him. The installer said the field temp of 28 is what he would expect this time of year. Frost levels are probably 3 feet at time of year and maximum of 8 feet is not uncommon by spring. We will probably see -40 for two weeks this winter as we run about 20 degrees colder than Anchorage. Thanks for the questions, I'll get back when I get answers. In the mean time I am installing a Toyo boiler to supplement the A unit that is still running.

Can you post the model number?

Why is the discharge temp 140F for radiant floor heat? Seems kind of high. Any idea how deep the field is? 28F EWT is still fine, the units can live with even less. Not unusual in Alaska. You loop is going through phase change and stabilizing right below freezing. Pictures would help too. Manifolds, flow centers, tanks, everything you got.

Sorry it has been so long since my last post, gathering information. Discharge temp was set by installer. This goes into a 120 gallon heatexchanger. Output to floor is mixed at 110. Since I use power offpeak (for 1/2 price) I have 125% of my needed storage capacity in my floor and the 120 gallon tank. This number was generated by an independent engineering firm because the power utility requires it.
Waterfurnace has told the company doing the warranty work that I need almost 6000 more feet of in ground tubing. The installer who winters in FL, says the Waterfurnace told him that the current 6000 feet is sufficient. I just installed a Toyo OM128HH boiler to heat the house as the temperatures are going down (-15 today) and the house was only 58 degrees. Will post pictures. Thanks Mike
PS Waterfurnace please PM me, thanks

Pictures attached of system

 That is ground water in the ditch. All soils in my area are sand. Ten 600 foot coils.

Two series 5 units  model NEW050A10HCSS0BN                                               Last pic in this series is heat exchanger / boost 120 gallon hot water heater (3500 watts) for radiant floor heat.

  Last pic is heat exchanger for potable water.  Gutter is to catch condensation from ground source pipes.

Incidentally at 0 degrees outside and at 70 degrees inside the house looses 31,500 BTUs /hr.
Mike

Your system should be easily keep up with your house. The issue is a design flaw.

A geo system uses much more energy the hotter it has to make the water. In a hydronic system, it is counterproductive to pay for the extra energy need to get the water up to 140 degrees, only to mix it down to 110F again. Why not having the heat pumps run at 110F which will gain you 40% higher efficiency by the heat pumps.

Although the installation is nice and clean, there are significant "red flags" on your pictures. Your system is simply designed like an old boiler system. Not like a modern geo system.

Your house is likely cold because you do not get your heat energy to your distribution system, not because of the loop field has an issue.
Lets start with the basics here:

What are the model numbers for the heat pumps and the circulation pumps for the loop field?

Why do yo have two (2) ton units instead of one 4 ton unit?

Please describe your radiant floors.

Two series 5 units  model NEW050A10HCSS0BN  Looking at the nomenclature I think I have two 5 ton units  (050). Attached are the pictures of the geo pumps. I have two systems because that is what the expert installed. We lost our home and 6 outbuildings to a forest fire in 2015. All we saved were the pets and 2 expired passports (another story). I had to have a knee replacement about the same time so all decisions except the general design of the house were left to the general and subcontractors. The general broke his hip and had to leave the state for a complicated replacement.
 At this point I am ready to scrap the entire system and just use the toyo boiler. Limited labor warranty from WF makes a compressor change out $1024, I just got the bill.
 And I have another dead compressor that lasted 2 weeks before failure. I'm sure finger pointing will start soon between some of the parties involved. I have about $35k into the geo portion.  I really appreciate any help. WF is supposed to come to AK sometime this spring and look at this system along with some other installs that have problems.


  Type UP-26-99U  Part Number  97941989



















p1

Forgot to describe the radiant floor breakdown. Basically I have 4 master zones. Garage, Basement, East side of the house with a subpanel with 3 subzones and finally a zone with the living room, master bedroom and master bath subzones. The tubing is in gypcrete and I can post pics if that is helpful.. Thanks again.
Mike

So, 120 gallon BTU thermal energy store...ok, what is the capacity there? 8.34 * 120 * can we assume a 30 degree delta T? 8.34*120*30 is about 30,000 btu. Enough to heat your house for an hour, not enough to carry over the off peak period.

You might check wiring ground...with frost heaving, MEA had the Nuetral disconnect from my OPTS, creating a situation where the heat pump had no nuetral. There was some crazy arcing going on in the mechanical room that day my friend.

Its cold today, isn't it, neighbor! - Fellow Willowbilly - Brian

Thanks Brian, ground is good. The a unit runs perfectly but I can only get 92 degrees out of one unit in my allotted time. Thank God for the Toyo carrying the load. If weatherman is to be believed we could go to -30 by Monday. It will be -40 on the River, I have a 6 hour run planned with the pups.

Posted By willowbilly on 12 Jan 2017 02:02 PM
Two series 5 units  model NEW050A10HCSS0BN  Looking at the nomenclature I think I have two 5 ton units  (050).

That would be a 4 ton unit.  The 050 is the unit capacity in BTU.

1) You have mixing valves installed in your radiant. Water to water heat pumps efficiency depends the load temperature whereas the higher temps are detrimental for efficiency. With your design, you are paying now for having your water heated up and going to the zones, only to have the temperature mixed down again. In addition, the return water is piped through the buffer tank as well, mixing with and cooling down the supply water even before it goes out to the zones. This design alone costs you at least 50-60% efficiency.

2) Zones pumps on each circuit, which now has a long runtime (due to the colder and mixed down supply temperature), increasing the electrical consumption.

3) You should benefit from an outdoor reset controller reducing your supply temperature on warmer days.

4) Given that your floor heating is in gypcrete, you should easily get by with 95F supply temperatures, not 140F.

5) WF builds boxes and supplies the installers with them, they are not responsible for the above mentioned design issues. Although their direct to dealer sales model sometimes implies that they are more involved in dealer endorsement than others.

6) pumping efficiency is not very high with 2-pump flow centers on 4 ton units, but that is a minor point right now.

The equipment you have is excellent, and the install is clean, but the design of the system causes the above issues.

In summary, your design causes causes your heatpump to run much less efficient than it can or should be, and puts significantly more stress on the compressor. While they are designed to be delivering 140F or even 150F water temp, it does not mean you should always run them at the max temperature.
It is designed like an old boiler system, without much appreciation that the lift between source temperature and load temperature defines heat pump efficiency.

Hope this helps.
While I recognize that there are many different ways to design a geo system, the design applied in your case causes inefficiencies which significantly vary from the projected operational costs, for the above reasons, and makes the equipment prone to early failure.

Thanks for your input, WF is replacing the second compressor but I will leave the system dormant until an onsite opinion by WF next month. What I have obviously doesn't work and I appreciate all the comments from the forum. I hope that I can locate a company that can engineer a proper system here in AK. My hopes on that are dim. It seems like I have yet to find a geo company that doesn't think "old school". Minus 40 here today, toyo has the house at set temperature of 68.

The engineering part is easy.

But you need a open mind installer who is willing to listen.

The NEW W-W Optiheat units from waterfurnace run pretty much trouble free for us, as well as other installers, so I understand that they like to understand why they are failing. Your load side will need to be repiped, your equipment can be salvaged, but you would need a few different pumps and valves. How do you make your domestic hot water? Let me know if you need help with anything.

Heat exchanger (Well-McLain), and hot water heater (electric). I also have a desuperheater but that just is plumbed to the output to the house. Thanks for the offer, I have so much money into this system I just want to stop the bleeding. Looking at $1024 for the next compressor replacement due to a limited labor warranty. It costs $266 just to move the technician from his shop and back. 2 hours @ $133/hr Minus 43 here today.