WF Series 7 Desuperheater E15 HW Limit Faults

DSH capacity in heating is 2 or 3 times DSH capacity in cooling at typical loop field temperatures. DSH capacity in cooling does not approach DSH capacity in heating until ground loop temperatures are around 100F.

 

Setting the VS to 5% is too low. For the 9 gpm the 3 ton 7 series needs we usually set it for 25-30% minimum, and 65-70% maximum. But I don't know your loop field pressure drop. I meant delta T on the source, in and out from the loop field.
You can force the unit in various stages in manual mode, and then check the flow and the delta T. I usually use stage 2, 6 and 12, and try to be at 5-6 degrees delta T at 2nd stage, and 5 and 9-10 gpm at stage 6 and 12.

 

Doc,

Before I start trying to dial in the settings above, I should tell you that I have a Envision 5 system on the same loop field. I would assume the settings you described above should be done when the Envision is not running. I just want to make sure that the Envision being on the same loop field does not call for different settings from above.

I did a quick look and with my VS settings @ 25% min and 80% max and at stage 6 with only the Series 7 running my outputs are:
Stage 6
EWT 55.4F
LWT49.9F
8.3 gpm

Regards

 

Looks good at stage 1.
What size for the Envision? All on a single loop field, 4x600ft 3/4" loops? Is that correct?
What is it at Stage 1 and 12?

 

Doc,

Envision is a 2 ton and yes all on the same loop field [4 @ 600ft 3/4"]

I let each test run about 5 minutes each today so it could settle out. All readings taken with only the series 7 running.
VS settings still @ 25% min and 80% max

Stage 1
EWT 57.6
LWT 54.9
6.4 gpm

Stage 6
EWT 56.7
LWT 50.9
7.4 gpm
EAT 70.2
LAT 90.7

Stage 12
EWT 57.3
LWT 49.6
9.0 gpm

 

OK......Are both heat pumps ever come on at the same time?

 

Yes most certainly.....
Here are the runtimes for the past 24 hours. Compressor 1 is the Series 7 and Compressor 2 is the Envision.

 

Then this is pretty ugly. The 2 ton can use about 6 gpm, and the 3 ton 7 series about 9-10 gpm, about 15 total, which gives you a pretty ugly pressure drop numbers if 15 gpm are pushed through a 4 x 3/4" loop field. Turn both pumps on and measure your delta T again, and you will see how 1 pump steal flow from the other. Was this designed by your installer?
Your loop temps still look pretty good, any idea where they are at the end of the heating season?

 

HI Doc,

Yes this was designed by my installer. I have not had a chance to get you the additional data today, but I will and I will post it here.

I went back to March 1st 2015 and pulled my loop temps for a 24 hour period along with outside temperature. See attached picture.

*EWT 1 and LWT 1 is for Series 7
*EWT 2 and LWT 2 is for Envision

*These sensors are all on metal pipe right next to each unit and insulated from basement ambient temperature.

I have attached a picture of my setup, and I am sure you are going to hate it. At this point I don't know that I have any choices other than to live with it and make the most of it....

Go easy.......lol

 

The sensors will be off by a couple degrees, but overall your temps look OK. I remember you posted that picture before. The way the pumping and the flow center is set up is very inefficient. Yes, indeed I hate it.

How is this set up. Is the water being pumped through both heat pumps all the time, whether they are on or not? Is the variable speed pump coming on when the 7 series turns on, and the 26-99 constant speed comes on when the 2 ton turns on? Do you have motorized valves on the pipes prior to going in the heat pumps?

I also remember the red valves with their high flow restrictions.

 

Doc,

The setup is: I assume water will circulate through both pumps as there are NO automatic vales installed, only the red ball valves for flow control ( I assume)

The Envision is connected through some control wire that goes to the Series 7 pump control board, so both loop field pumps are controlled from the Series 7 system even for the Envision. Even when the Envision system comes on by itself the loop pumps are controlled from the Series 7.

Regards,

 

Extremely inefficient, wasting all the pumping.

First, the 7 series runs forever, it should only have 1 variable speed pump, which throttles down. The constant speed pump comes on first, total waste
Second, your are pumping through 2 heat pumps when only one is running, big waste.
Third, there should not be a red ball valve as a flow restoration on the source side of any geo system. Why pay for more pumping?

You should seriously consider having them moved and the ball valves cut out. One variable speed on the 7 series, one constant speed 26-99 on the 2 ton unit. Simple and efficient.