Water Furance Envision Problems

I have a WF Envision NDV026 It was installed in Jan of this year. House was built in 1994, ducts are in the attic, house has a basement which has duct work for it downstairs. Main level and basement are heated and cooled with this unit. I was supposed to heat and cool main level and basement for less money than it took to do with the traditional heat pump which only did the main level (and have more comfort). Returns upstairs and downstairs. unit is located in the basement at one end of the house.

House is 1500 square feet main level and 1500 square feet basement, 3000 total

Ground source loop.

The unit will not keep up when the temperature hits high 80's or above outside. Currently it is 78 degrees in the house;it is 94 degrees outside.

Contractor has been back several times to adjust fan speed, and has covered/uncovered the return for the basement area.

I asked the contractor to get the factory technician involved and he did. The factory tech found the water temp coming in was too high and his recommendation was to add more length to the loop. Contractor added an additional loop. Loop was dug with a ditch witch and he said the average depth was 4 feet. The original loop was dug with a track hoe, all of the loops were in one trench (4-5 feet deep). Soil is red clay with a lot of stone (sandstone mainly).

After that we still have the same problem. this is a two stage unit, it hits stage 2 mid morning and runs all day, it will be after midnight before it stops running (gets down to 74 degree setting).

Contractor was back today and changed out the water in the loop.

I feel the unit is not working properly or is undersized. Other contractors quoted the 26 for the upstairs only.

Any thoughts on this would help me a lot. I feel the contractor may be inexperienced in these units even though he told me he was a factory trained rep.

More info:

When we turned the unit on in the winter after the install the heat was just not comfortable. This is in comparison to my original 17 year old outside unit heat pump.

Power bill is almost identical to last year.

Thanks!

 

Was a Man J compliant load calculation performed?

What is the tonnage of the heat pump this system replaced?

What is the temperature of the loop water entering and exiting the unit after it has been running all day in stage 2?

 

The original loop is 300' one direction, then the pipe comes back in the same trench (racetrack style). there are 2 loops in this section. The other recently added loop is about 400 total, the trench itself makes a loop.
This is a 2 ton unit with a dual compressor.
I do not have the load calc specifics but will request.
When I spoke with the installer today, he said the incoming temp should not be over 94 degrees. It is 104 at the incoming loop, 110 degrees upon exit.
All I know right now, I may post pictures of the trench when dug if I can find them.
Thanks for the help.

 

That's some HOT water

Which makes a huge difference in efficiency.
The heat pump is working correctly but the loop is not dissipating the heat.
How deep did they put the loop? and for clarification, you have a trench 300' long with two loops (four pipes) running in it?

My loop water hasn't been over 70 ....but I may have oversized mine a bit. But it never goes to stage 2 either (I'm sure winter will be another story)

 

You are correct, 300' trench (first one) with 2 loops (4 pipes)

4-5' deep. Code called for 4-6.

Also found out contractor figured load with EE windows, which I have in the basement but not upstairs. House was built in 1994, M and W dual pane windows upstairs.

 

I found the original load calculation sheet.

 

I agree that we are having trouble rejecting heat to the ground and that is not the heat pumps fault.
What was the nature of the soil? How did contractor handle backfill/compaction?
How wide was trench?

joe

 

Trench was approx. 2' wide, dug with Trac hoe.

Dirt was pushed back into trench, I don't think any compaction test was done.

Soil is red clay. Also hit a lot of rock which appeared to be sandstone.

 

Try watering the heck out of the loop field if economically feasible. That will both cool the tubes (briefly) but also aid in consolidation and improved heat transfer pipe-to-soil

 

Yep if we're talking clumpy gooey modeling clay then you probably don't have good compaction. Good news is it will improve with time. Extra loop will be a bonus.

Fashion a pipe on the end of a hose to stick in the ground along trench and get the clay to soften up with water. Once you get good compaction your trouble will likely cease.
j

 

Update, I talked to the contractor today. He is now saying that the soil is just too warm and will flush the water again.
This is where I need the boards help. This seems to go against what I researched on the Geo units.
I sent this info to WF as well.

 

Perhaps your installer needs a little more WF training time.
"soil is just too warm" means heat exchanger (loop field) is either too small or not adequately coupled with the ground (bad compaction).
Re-flushing the loops will change your EWT for minutes or maybe an hour but is a collosal waste of time.
Only way re-flush helps is if loops are air locked.
Tell installer not to bother til regional rep comes with and agrees that's the problem.
This guy's really lost.

j

 

The reginal rep has been out. He suggested added the additional loop a couple of weeks ago which was done, but with an average depth of only 4'

I spoke with the rep Monday and asked him to call this guy again. He was surprised that the additional loop did not make any difference.

So, he is getting direction from the reginal rep.

WF is involved, I sent them another message last night.

 

If I understand you correctly, you have in the original loop 300' out and 300' back = 600' x 2 loops = 1200'.

Then a second loop was added with 400' total. That makes 1200' + 400' = 1600'. Is all of this correct?

This would make 1600' / 2 tons = 800' of loop per ton. We have 600'/ton in our system which is plenty for us in SW VA (most installers quoted us 500'/ton.)

I wouldn't worry about the 4' average depth. We also have an average depth of 4' (pipes go out at 5' depth and back at 3' depth.) Our EWT's run about 75°-80° in cooling mode.

Your loops may be air locked.

 

Thanks for the reply.

Keep in mind with the 600' loops, both are in the same ditch.

What part of the country are you in?

 

We're in Southwest VA.

We have 5 tons total. We have three trenches with 1,000 feet of 3/4" HDPE in each trench. Our trenches are 250' long where your trenches are 300' long. Our trench was 2' wide. Sounds like your pipe layout is similar to ours (4-pipe configuration.)

 

Geocub,

Have you contacted your contractor to discuss the results of the blower door test and your options for a resolution? Also, what was the design temperature? Have you experienced excessive temperatures above that temperature?

 

He is here now and is planning to do some things to address what the test found.

He reviewed the program with me where he does the load calc. Good to see, but that is not my area of expertise. I reminded him that I had 3 quotes and the other two vendors quoted larger units. I asked was there any communication between dealers if so could he ask what they was different from his figures.

Design temperature for the AC was 70 or 72, we have consistently hit 80 degrees inside this summer.

 

Blower door test?
A 2 ton unit can't reject more than capacity (/overheat properly sized loops). If installer designed it ( it appears) for a max EWT of 94, and then added loop, there is no reason EWT should be 105F REGARDLESS of gain in the house.
There is a loop problem here.
Industry standard suggests paralell loops be equal length. Further suggesting inexperienced installer.

Geo cub,
What is the heat gain for the house?
Your heat pumps capacity diminishes with higher EWTs. You might be rightsized but poorly coupled to the earth.

Joe

 

Joe,

Thanks for the reply, exactly the type of feedback I am looking for.

Is the heat gain a number the contractor can give me?

Added loop is 250' per contractor, I walked it off for my estimate. All loops merge into two manifolds or T' ees outside the house and 2 lines enter the house.

Kerry