WF Series 7 Desuperheater E15 HW Limit Faults

The alternative is your cool loopfield sucking the heat out of your nicely warmed buffer tank.

 

I think you are right. Will get you the discharge temps hopefully this weekend. Thanks for your help!!

 

HI,

I still have continued to have the faults, but if I don't look for them I don't even realize they have occurred. That may not be the correct answer, but maybe they are ok to have?

Regards,
Joe

 

Joe,
In the middle of the summer is your unit make all the hot water your need or is the unit coming up with E15??? My unit was just installed a few months ago and I am very happy with the HVAC side, I am disappointed in the hot water side. I wish WF would give me a reasonable answer. E15 is an error code. Why not make it a W15 (warning code that conditions are not favorable for hot water).

 

Henry,

I have not looked lately to see how many E15 faults I have but will do so soon and report. I do seem to have plenty of hot water, and if my memory serves me correctly my buffer tank stays around 95-105 degrees in the summer. I have sensors attached to my buffer tank and hot water heater. I will look back to July or August and graph out the average monthly temp of both as soon as I get a chance and post.

Regards,
Joe

 

Joe,
Thanks for your help.
Henry

 

Henry,

Wow what a surprise! Last time history was cleared was sometime in July, I can't remember the exact date. Sorry, this took so long!

One would think this would suggest an issue..........

 

Joe,
Can you email me
Thanks

 

E15 is a code. It is not a error or fault in operation. It is simply an alert for the service technician.
The translation of that code according to WaterFurnace is-

-HW over limit or logic lockout. HW pump deactivated.

Excerpts from Waterfurnace Specification Catalog-
http://www.waterfurnace.com/literature/7series/SC2700AN.pdf

- Intelligent hot water assist control - The Aurora
control determines operation of hot water assist
dependent upon system parameters to maximize
overall system efficiency. Selectable hot water set
points through the AID Tool.


-Advanced Hot Water Generator Control
(Domestic Hot Water Option)

An AID Tool selectable temperature limit and
microprocessor control of the process is featured. This will
maximize hot water generation and prevent undesirable
energy use. An alert will occur when the hot water input
temperature is at or above the set point (130°F default) for
30 continuous seconds. This alert will appear as an E15 on
the AID Tool and the hot water pump de-energizes. Hot
water pump operations resume on the next compressor
cycle or after 15 minutes of continuous compressor
operation during the current thermostat demand cycle.
Since compressor hot gas temperature is dependent on
loop temperature in cooling mode, loop temperatures may
be too low to allow proper heating of water. The control will
monitor water and refrigerant temperatures to determine if
conditions are satisfactory for heating water.

I would say from the parrisjr AID tool screen shot the Aurora control did what it was supposed to 913 times.

 

Geoxne,

I know we keep beating a dead horse and I do understand that it is working as advertised, but....... What I don't get is, I have sensors on both my entering and exiting desup water lines and I have never seen the EWT anywhere near 130 degrees. I have also verified the setpoint with the AID tool to be 130.

Just saying........

 

The AXB might assume that the loop is too cold in A/C mode, thus you would transfer heat from the tank into your loop field, thus it deactivates the DSH pump...It compares the tank temp, the refrigerant temp and and the loop temp. It might shut it off at tank temps below 100F in A/C mode.

 

Thanks doc,

Then it sounds as if there are other actions that would give this limit other than the desup EWT at 130 degrees.

I am doing a little test. I reset all my "faults/limits" today and I will wait 24 hours. At that time I will see how many E15 limits I have and will post a graph of my desup entering and leaving temps, along with my buffer tank temps for the same 24 hour period, to see if the 130 degree limit is ever reached. I am currently running in heat mode.

Just wanted to back up my claims with data.

Then I will let this dead horse rest!

Regards.......

 

So, 8 "fault/limits" in the past 24 hours. As you can see nothing near 130 degrees.

Ok, "Dead horse can rest now"!

 

Your DSH performance looks normal. What is the upper limit you have the DSH set for?

 

Sorry Doc, I meant to post this.

See pic!

 

What size is your unit?

 

Doc,

It's an NVV036 which I believe is a 3 ton unit......

 

It appears that your tech did not set up the flow at all, they are still at factory setting. You are likely wasting pumping power.
Nor the DSH temp. That I would set for 140F since you have a buffer tank now, correct?
Any idea what your delta T is for the incoming water.
How is your loop field configured? Mow much pipe, what size?

 

It appears that your tech did not set up the flow at all, they are still at factory setting. You are likely wasting pumping power.
Any suggestions? When you go into the change setting mode it gives you an extra setting. "VS pump control" of which mine is "off"! See pic.

Nor the DSH temp. That I would set for 140F since you have a buffer tank now, correct?
Yes, I now have a buffer tank and I just set temp to 140F for limit

Any idea what your delta T is for the incoming water.
Water supply to buffer tank?

How is your loop field configured? Mow much pipe, what size?
Horizontal loops (4) @ 600 feet each, buried 6 feet and I think the OD of pipe is 3/4, but I am not 100% about that.

 

Joe,
My system seems to be working great in the winter and terrible in the summer. My DSH is set for 14oF and my VS pump is set to 5 to 100% vice 50 to 100%.

Doc,
My system is a 5 ton Series 7, almost the same as Joe's. The delta T for the water temp inside the DSH is very close, right now (in heat mode) it runs 110F in and 120F outlet. But, I believe my buffer tank is not homogeneous in temp. I believe that if I can get a mixing pump in the buffer tank the hot water part of the Water Furnace would be more efficient. Especially in the Summer. Like Joe's system in the summer the unit kicks on and as soon as the water in the DSH heats up to around 102F it gives the E15 (ERROR) and the loop field is running in the low 60F.

Does anyone have the parameters for the E15 to kick on besides the upper temp limit??

Thanks,