Both units were running

Both units were running

Both units were running

Both units were running

Sorry. Phone ran away with the enter key

You have 12.1 gpm on the source (loop) side, and 12.4 gpm on the load (radiant) side. So your flow is good, the only problem is that it takes (2) circulation pumps per heatpump what should be the task of (1) circulation pump each. Lets say they have 2500 hours run time, and you pay 17cents/kwh, and each pump uses 230 watts when running, it does cost you a bit. Now the question is if the additional operational costs are worth digging through your new porch.

Just an update for those interested. The WF rep (territory mgr Pacific NW) who visited my home today said that the field size is too small for the coiled design. Further up in the thread are pictures of the installation. They rough calculated that I need 10-12k feet. I gave him the heat loss calculations to further refine the field size. Last month I lowered my unit temp to 105* instead of the 140* set by the installer. When the system now comes on, the aquastat turns off the toyo boiler and one unit can maintain the 105* by running only periodically. Inlet temp still 28.5 with one unit running. WF will be replacing the second unit (again) but I will not run it until the field size is increased or other information solves the problem. I really appreciate the input and time that you all have invested in my situation. I wish that I could have availed myself of your services for the initial installation. WF rep said my units shut down when source temp hits 15*. I wonder if the units were pulling too much heat from the ground, why didn't the unit protect itself? Also the first failed compressor just gets shipped by WF to Copeland. I doubt that any determination of failure is ever done. I asked what the analysis of the compressor oil was and he said WF didn't know.Thanks again. Mike

No offense to your WF rep, but the units he sells have an operating range between 20 and 120F entering from the loop field temperature according to his spec book. No idea why he makes the comment that your loop is too small when you EWT is stable at 28.5F. The purpose of the loop is to get the EWT within the operating range of the heatpump.

28.5F sounds very good to me, especially in Alaska. It does not matter what they calculate, when the measurement suggests that your loop field size is fine. And yes, the units lock down when the loop is going below the operating range of the heat pump. But that appears to never being the case.

Thought I would give an update on my ground-source situation. To keep my present double 4 ton units, WF required the installer to put in another 6000 feet of independent field tubing along with separate connections to the other 4 ton unit. Since the installer is back in AK, we met and my wife balked at tearing up her new terraced lawn and flower bed. The compromise was to remove the one running 4 ton unit, the one broken 4 ton unit and install a single (brand new) 504W11 six ton unit. If after the next winter the field is an issue (to be determined by WF), the installer will increase the current field size. He is also plumbing the system to remove my potable water heat exchanger due to the fact that during normal waking hours (I use off peak power at night) it actually lowered my hot water recirculation temperature by a measured 10* which meant that I was heating the heat exchanger with my electric hot water heater since the recirc return line went into the heat exchanger not the electric hot water heater. I installed a separate tempering tank to preheat my hot water using the waste heat generated in the "furnace room'. He is also removing the mixing valve for the in floor heat.
My delta T is 6.5 psi @ 32* so according to the installation manual the flow center pumps may have to be changed to get the required 19 gpm. According to "the book" with a low field temp (unavoidable), the other two values of entering load temp and field flow must be normal. My lines to the field are 2" not the 1 1/4" as I was told by the contractor.
IMO WF really stepped up to get this straightened out. Any comments or corrections to my logic would be appreciated as this process is happening now. Thanks
Mike

So they are replacing (2) 4 ton units with a single 5 ton unit? The largest 504W11 (066) has a rated 11,500 BTU/h higher capacity then the 050 unit.

Since your loop field temps were ok, your load of your house was low, indicating that both 4 ton units were not running more than 50%, not sure what the compromise will do here.
In other words, the heating energy of your house does not change. Thus, the heat extracted from the loop field does not change, wether you do this with (2) 4 ton units running only partially, or a single 5 ton unit. The amount of energy extracted from your loop field is the same, and remains the same. Why one solution would require 6000 feet more field tubing than the other one is mystery to me. Did this come directly from Waterfurnace, since they by company policy, usually stay out of making design recommendations, nor do they get involved into any design requirements. Thus the BS meter is blinking wildly! Did your installer tell you all that?

Again, the fact that there was a mixing valve installed by the installer tells me that your installer does not understand heat pump systems. Why would you spend all that energy to bring the water up to temperature only to cool it down again (mixing valves) before you send it out to your radiant system?

An no, you do not necessarily need upgraded flow center pumps. Run your load discharge temperature a bit lower (which you hopefully intend to do anyway without the mixing valves) and your heat pump will be happy. 19 gpm is not necessarily required for a 066 model, specifically with 28.5F incoming water temperature from the loop field. Thus the slightly lower flow rate or the slightly less than 30F EWT does not put this unit under stress, but the high discharge temp of above 140F chosen by your installer, which he then mixed down anyway via mixing valves.

"When any of the factors are at the
minimum or maximum levels, the other two factors must be at
the normal level for proper and reliable unit operation. Consult
the Capacity Tables for each model to determine allowable
normal operating conditions."

Here is the link to the capacity tables.
http://www.waterfurnace.com/literature/5series/SC2508WN.pdf

Yes, the waterfurnace rep required the field extension and to be copied with a letter of agreement. I know the the 066 is a 5.5 ton unit. Last year it was labeled as a 5 ton unit. Now it is labeled a 6 ton unit on the book I got with the unit although 66000 btus equal 5.5. Delt P on the field flow now gives me 19 gpm after extensive running of the flush cart removed all the air.
The original installer removed the mixing valve and replumbed the the supply and return from 3/4" to 1". He also installed an outdoor temperature sensor to control the unit. I think the problem was trying to get the unit to run at 149* output (as measured at the output of the unit with my 10,000 point data logger) when set to 140* on the sensor of the hydrozone control at the bottom of the buffer tank when the field temp was 27*. Refrigerant pressure differential too great for continuous operation (9 hrs at a time) might be the culprit. I agree that if the field temp had been too low, the unit would have saved itself. BTW WF told me that if the installer didn't fix the problem to my or their satisfaction, they would pay for the field repair as a last resort. He said this in front of the other company's owner that replaced the seized 4 ton unit. All the work was done at no cost to me. I do realize that I've spent more money than I should have for just a single 066 in the first place, but the unit is now plumbed like the drawing I was sent and I do thank you for that. I may have gotten more involvement and total operational commitment from WF than most, but I hope not. Thanks, Mike

Optiheat 066 has a rated heating capacity of 54,500 bt/h at 32F entering water temperature, and a cooling capacity of 54,000 BTUs/h at 77F EWT. Not sure where the 6 ton, or even 5.5 ton labeling comes from.
Page 7 of the specification manual:

http://www.waterfurnace.com/literature/5series/SC2508WN.pdf

Not sure if WF knows about the rep getting involved in the design issues. Yes, the temp sensor in the tank are always indicating a bit lesser temperature, but that was not the issue. Nor was the 27.5F loop field temperature. The biggest issue putting unneeded stress on the compressor was the continuous setting at 149F leaving water temperature, when then mixing down the water temp again with mixing valves. Also a 3/4" line is unheard of with previous 4 ton units. WF has to have a serious talk to your installer, I am sure they had one.

Good for you that WF offered to pay for a larger loop field (that is a first I heard), don't let that hear any WF executives, but it would not change the EWT much in an Alaska setting. Again, WF builds great machines, and sells those to installers, but does not get involved in how installers or customers use them.

IMO, WF also needs to have a serious talk with their technical staff about the system not shutting itself down under conditions that are damaging to the compressor.

    Thanks for the correction.  Marketing best case under optimum conditions using a ground water system 5.8 tons @ 68* EWT. Water loop 6.9 tons @ 68*. My installation revision is 08/15  The specification PDF document link is 08/14 and has the unit range listed from 3 to 5 tons.    http://www.waterfurnace.com/products.aspx?prd=504W11     has it at 6 tons.     I also noted a discrepancy between installation manuals on the website and my document.

Not sure why that spin is made by WF. The 066 units have not changed technically. They have 11500 BTU/h more heating capacity than your previous 050 units, which are still considered 4 tons.
Plus the nomenclature usually is for cooling capacity, which is traditionally higher then heating capacity. It is a rating game...

.

tscat007 Posted:30 May 2017 10:49 PM Subject: RE: Multiple compressor failures

I agree you got duped by bad engineering. WF is caught in the crossfire. That unit is capable of producing 140 degree temps but that doesn't mean it should. That is where the engineer went south. You were pushing those units to the extreme daily. The issue is on the refrigerant side. If you did replace the compressor you need to check the following. Entering Water Temps, Leaving Water Temps, (on your loop) Water flow through the loop, Once that data is known look up those numbers on the charts found 2/3 of the way through the install manual which can also be found on their website. You haven't collected much data, just assumptions. If the pressures are high, fluctuating, low, out of recommended operating range then you will know what your next steps are. So far I have only seen guessing associated with frustration. This is science and the diagnosis should be scientific. The tech support guys at WF will also ask for this information when you call.


Thanks, since I have a science background, one of the first things I did after the replacement compressor failed was to purchase the necessary instrumentation. I have one minute profiles on field temps (10,000 points) both source and discharge, unit temperature logging at the same detail for input and output along with a certified pressure gauge to check all measurable pete points. I have the unit set to meet the "normal" standards for flow and input temperatures to the unit. The only variable that will be low but not critically low will be the field temp during the winter. Last winter the remaining running unit had an EWT of 27* at the lowest measured temperature. Following the advice I received on this forum, I reset the output temp to 105*. As noted above, the unit is now controlled by an outdoor sensor. I have the highest possible output temp set to the lowest possible measure at the lowest sensor reading adjustment of 0*. Since I have a keen interest in the unit running many years without trouble, monitoring will be continuous as my data logger probes connect wirelessly to my computer.That was the reason I oped for a new "unstressed" unit even though it is slightly larger than the single remaining unit that ran and smaller capacity than the 8 tons I had. I found it interesting that neither of the companies that worked on the unit have the instrumentation that I now possess. Their gauges aren't liquid filled and their ranges too broad. My current living is driven by temperature monitoring since my catch brings an additional $.30/lb if chilled below 39*. The help I received on this forum was/is of immense value since ground source is new to me. I've incorporated many of the suggestions I've been offered and I thank you for your input as well.
Mike

Hi Experts, Has this issue been addressed?:

What is the affect on Willowbilly's compressors as caused by the Off Peak Thermal-Energy Store ( OPTS ) where his electricity to the GSHP is cut off after 9 hours of continuous running, while his circulator pumps are not on Off peak and do run.

The circulators may not have an affect, but shutting the GSHP down when it is iced up, then five hours later, asked to restart and run for another three hours. Has the compressor defrosted enough to start well?

The OPTS program supplies energy for a thermal store scheme and energy is supplied for nine hours with a break for five, then an additional three, break for five, supply for nine, repeat.

Field pumps shut down with compressor

Posted By nooboo on 12 Jun 2017 05:09 PM
Hi Experts, Has this issue been addressed?:

What is the affect on Willowbilly's compressors as caused by the Off Peak Thermal-Energy Store ( OPTS ) where his electricity to the GSHP is cut off after 9 hours of continuous running, while his circulator pumps are not on Off peak and do run.

The circulators may not have an affect, but shutting the GSHP down when it is iced up, then five hours later, asked to restart and run for another three hours. Has the compressor defrosted enough to start well?

The OPTS program supplies energy for a thermal store scheme and energy is supplied for nine hours with a break for five, then an additional three, break for five, supply for nine, repeat.

I don't think the heat pumps ever showed any evidence of being "iced up". Why would they? Nor would any compressor actually ever need to be defrosted. Compressors are the warmest part of the system. Optiheat is a single stage on/off, and circulators are on a relay, actuated a few seconds before the compressor starts, and shut off a few seconds or a minute after the compressor shuts down, to remove any residual coldness from the heat exchanger. It is difficult to bridge 5 and 3 hours of interruption in a cold climate like AK, and more difficult to store thermal energy. I would get a couple TESLA batteries to bridge that time, and run the system at part load, bringing the house up in temp and cooling it down again would be too much un-comfort for me.