Help With WaterFurnace Envision 5 Ton Locking Out on Low Pressure / Comp
Last Post 28 Jul 2014 12:23 PM by a0128958. 20 Replies.
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Bill NeukranzUser is Offline
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21 Jul 2014 06:09 PM
I could use some help on an observed problem today with my WaterFurnace Envision 2 stage variable speed 5 ton air-to-water unit.  It only runs for a few minutes and then shuts down with the Low Pressure / Comp red light flashing.

A diagram of my system is at http://www.welserver.com/WEL0043/ .  The model is NDV064A111CTL.  It was installed in 2007 - this is the first trouble I've encountered with it.


It last ran fine today at 11:30 AM.  Performance numbers from my WEL monitoring unit include:

Running on 1st stage (Y1)

EAT = 75 degrees
LAT = 60
Delta = 16

EWT = 74 degrees
LWT = 79
Delta = 5
Flow = 21 gpm
(2) Grundfos 1/6 hp 385 W pumps in push-pull configuration; sounds like they're running fine; not leaking; not too hot to touch 

Power (including blower fan) = 2934 W
EER = 15

Inside cabinet temp = 89 degrees

Compressor refrigerant discharge line temp = 116 degrees



The next time it came on it only ran for 2 minutes, triggering on the blinking red light Low Pressure / Compressor.  This was at 12:05 today:

Running on 1st stage (Y1)

EAT = 80 degrees
LAT = 66
Delta = 14

EWT = 76 degrees
LWT = 80
Delta = 5
Flow = 21 gpm

Power (including blower fan) = 2941 W

Inside cabinet temp = 93 degrees

Compressor refrigerant discharge line temp = 107



I thought I had my WEL set up to give me advance warning before a unit lockout can occur.  Obviously not, as I don't see anything wrong with the above numbers.

Is there anyone here that can give to me a tutorial on what causes the Low Pressure / Compressor lock out situation?  It would be much appreciated!

Many thanks!  Best regards,

Bill
Energy reduction & monitoring</br>
American Energy Efficiencies, Inc - Dallas, TX <A
href="http://www.americaneei.com">
(www.americaneei.com)</A></br>
Example monitoring system: <A href="http://www.welserver.com/WEL0043"> www.welserver.com/WEL0043</A>
engineerUser is Offline
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21 Jul 2014 11:30 PM
Bill,

I'd guess it is any of loss of charge via an air coil refrigerant leak or a wonky TXV starving the air coil / compressor suction to the point where it trips on low refrigerant pressure, or a wonky low side temperature sensor

While standard advice is not to put a set of refrigerant manifold guages on a geo system until heat of rejection (HR) is calculated, I think you might need refrigerant pressures and temps to sort this out.

You don't mention whether the system is in Y1 or y2 when the lockout occurs. That would be good to know. The compressor dischg temp of 116* suggests system is in Y1, not Y2, but it would be preferable to confirm that hypothesis.

HR for 21 GPM at 5 DT is 52,500 Btuh; backing out 3kW input power yields net cooling effect of about 42 kBtuh...seems about right for a 5T in low gear. Airside delta T seems light, but can't be sure without humidity / wet bulb figures.

Check the temp sensor that triggers the fault...I think it is a 10k thermistor, so the typical resistance vs temperature for one of those applies.

Hope this helps
Curt Kinder <br><br>

The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
Bill NeukranzUser is Offline
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22 Jul 2014 01:18 AM
Curt, very helpful.  Thanks!

In my controls work with the WEL I learned a while back that while the WEL handles pressure sensor readings incredibly well, the pressure sensor fittings themselves are tough to keep properly connected / not leaking.  So I decided back when my personal WaterFurnace Envision units were installed that I would not monitor pressures.  Hence, no pressure readings to report here

But I've got everything else.  Thanks for reminding me I forgot to state what stage  - I fixed it - it's 1st stage as you correctly guessed.

I'm pretty familiar with WaterFurnace's evaporator refrigerant leak problems.  My 3 ton unit went through this cycle of bad evap coil.  My 5 ton unit is virgin, never worked on - perhaps the leaking evap coil problem has caught up to this unit too.

My plan:
1. Replace air filter
2. Inspect evap coil for refrigerant leakage (I learned how to do this a lot with all of my 3 ton unit's problems)
3. Check thermistor for proper resistance.
3. Call repairman.

Thanks!

Best regards,

Bill
Energy reduction & monitoring</br>
American Energy Efficiencies, Inc - Dallas, TX <A
href="http://www.americaneei.com">
(www.americaneei.com)</A></br>
Example monitoring system: <A href="http://www.welserver.com/WEL0043"> www.welserver.com/WEL0043</A>
Bill NeukranzUser is Offline
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22 Jul 2014 02:07 AM
Well, I'm learning.  From the instruction manual:

"When the Comfort Alert senses a fault that the Premier2 board will act upon (lockout), the Envision Low Press/Comp LED will flash.  This LED is shared by both the unit Low Pressure Switch and the CA.  To determine which caused the lockout, simply look at the CA and determine if it flashing one of the lockout conditions 2, 4, 6, 7."

Indeed I've got CA Yellow Flash Code 6: Open Start Circuit  - 'Y' tstat demand signal with no current in the start circuit.  Perhaps my Run capacitor has failed.

Thanks.  Bill
Energy reduction & monitoring</br>
American Energy Efficiencies, Inc - Dallas, TX <A
href="http://www.americaneei.com">
(www.americaneei.com)</A></br>
Example monitoring system: <A href="http://www.welserver.com/WEL0043"> www.welserver.com/WEL0043</A>
engineerUser is Offline
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22 Jul 2014 06:28 AM
Ah...the rest of the story!

Run cap is a candidate. Any HVAC tech able to fog a mirror should be equipped to test the cap. A minor irritation of the cap mounting location is that it is too narrow to accept my favorite US-mad brand of retrofit capacitors - AmRad.
Curt Kinder <br><br>

The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
BergyUser is Offline
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22 Jul 2014 08:28 AM
21 GPM through a 5 ton is excessive flow. Try to get your flow back down to 15 GPM, in 2nd stage.

Bergy
joe.amiUser is Offline
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22 Jul 2014 10:53 AM
A failed cap often has a convex top (we liken it to Jiffy Pop). Odd to start the compressor or get 2 minutes of run though.
Joe Hardin
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Bill NeukranzUser is Offline
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22 Jul 2014 03:00 PM
Posted By joe.ami on 22 Jul 2014 10:53 AM
A failed cap often has a convex top (we liken it to Jiffy Pop). Odd to start the compressor or get 2 minutes of run though.
Thanks Joe.

In a WF Envision unit, it's a pretty big aluminum outside material capacitor, mounted a few inches away from the Premier2 control board.

I looked for a Start capacitor and associated relay, but, it's not there.  Looks like the Envision only has one capacitor, a 'Run' capacitor, in series with the Start winding.

My thinking is this Run capacitor has failed, and that there's current only in the run winding.

I think I understand why the compressor runs for a couple of minutes:

1. When the compressor first turns on, the Comfort Alert module immediately signals 6 flashes (current only in Run circuit).
2. CA module waits 30 seconds, makes the test again, again measures no current in the start circuit
3. CA module waits 30 seconds, does 3rd test, again measures no current.
4. CA module waits 30 seconds, does 4th (and final) test, again measures no current.
5. After the CA tries 4 times, it signals to the Premiere2 board to do a shutdown.
6. Permier2 board does the shutdown.
7. Premier2 board turns on the Low Press/Comp diagnostic LED on outside of unit.

So, interesting learning.  I think I've now rationalized every observation to what could be an open Run capacitor.

Except for maybe why the compressor is able to initial start up in the first place.

Best regards,
Energy reduction & monitoring</br>
American Energy Efficiencies, Inc - Dallas, TX <A
href="http://www.americaneei.com">
(www.americaneei.com)</A></br>
Example monitoring system: <A href="http://www.welserver.com/WEL0043"> www.welserver.com/WEL0043</A>
Bill NeukranzUser is Offline
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22 Jul 2014 03:08 PM
I called the repairman, telling him I've got a CA module indicating 6 yellow flashes.

He immediately said over the phone the first thing he'll check is the Run capacitor.  He has a capacitor checker.  Particularly noting that my air and water temps, and deltas, are reasonably 'in the ballpark.'

In the Dallas area right now it's Christmas time for HVAC maintenance.  'Waiting lines' are long.

Noting that we have two units for the house (the remaining operable unit for me covers the bedrooms), and that there are many customers right now in Dallas who don't, I told the repair person 'at your convenience!'  Could thus be a while!         

I'll report back once the problems been diagnosed and fixed.

Interesting learning.

Best regards,

Bill

Energy reduction & monitoring</br>
American Energy Efficiencies, Inc - Dallas, TX <A
href="http://www.americaneei.com">
(www.americaneei.com)</A></br>
Example monitoring system: <A href="http://www.welserver.com/WEL0043"> www.welserver.com/WEL0043</A>
joe.amiUser is Offline
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23 Jul 2014 07:20 AM
You could get a capacitor and replace it yourself if you like. They are not expensive and if it doesn't fix the problem you'll have a spare.
Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
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Bill NeukranzUser is Offline
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23 Jul 2014 10:19 AM
Posted By joe.ami on 23 Jul 2014 07:20 AM
You could get a capacitor and replace it yourself if you like. They are not expensive and if it doesn't fix the problem you'll have a spare.


Joe, much appreciate the prompting on this.  Since I said 'at your convenience' it could be a while. 


WF documentation says the Run Capacitor for a 208-230/60/1 compressor installed into a Dual Capacity Vertical NDV064 (5 ton) unit is part number 16P002-24.

Internet Search of 16P002-24 doesn't yield any results.  But there's plenty of 16P002D24 results: 80 mf, 370 V.

Internet Search of 16P002D24 shows out of stock and/or obsolete.  Replace with 16P002D41: 80 mf, 440 V, $48 mail order.

I'll see what I can find here locally.  I have a commercial account, for example, with Grainger.


Many thanks!

Best regards,

Bill




Energy reduction & monitoring</br>
American Energy Efficiencies, Inc - Dallas, TX <A
href="http://www.americaneei.com">
(www.americaneei.com)</A></br>
Example monitoring system: <A href="http://www.welserver.com/WEL0043"> www.welserver.com/WEL0043</A>
joe.amiUser is Offline
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24 Jul 2014 07:29 AM
I'll bet Grainger has one
Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort!
Bill NeukranzUser is Offline
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24 Jul 2014 01:41 PM
Grainger didn't have it.  I ordered it, $48 including postage, mail order.  Bill
Energy reduction & monitoring</br>
American Energy Efficiencies, Inc - Dallas, TX <A
href="http://www.americaneei.com">
(www.americaneei.com)</A></br>
Example monitoring system: <A href="http://www.welserver.com/WEL0043"> www.welserver.com/WEL0043</A>
Bill NeukranzUser is Offline
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25 Jul 2014 11:16 PM
OK, we now have A/C again! Received part today. Without testing existing run capacitor (don't have a capacitor tester), I just went ahead and replaced it.

All works fine. installed it tonight after waiting for attic to get down below 120°F.

Compressor start winding appears to run at about 10.3 A - I measured it.

Notes learned on WF Envision units:

1. They were originally manufactured for a 440 VAC run capacitor, but, at assembly time a retrofit of a 370 VAC was installed. Perhaps there was a real shortage of the 440 VAC 'flavor' at the time of manufacture (my unit was installed in July '07 . Now I'm back to 440 VAC, with the new capacitor in the originally sized hole.

2. The Low Pressure diagnostic light doesn't always mean low pressure. It's also meant to indicate when to go look at the Comfort Alert.

3. I have enough knowledge of electronics to know that capacitors wear out. I'm going to order another one to have 'on the shelf.' And I'm going to figure out what size capacitor goes in to my 3 ton unit and order one for it too.

Have appreciated the help from here. Thanks! Hope some of what I've contributed back has been helpful.

Best regards,

Bill
Energy reduction & monitoring</br>
American Energy Efficiencies, Inc - Dallas, TX <A
href="http://www.americaneei.com">
(www.americaneei.com)</A></br>
Example monitoring system: <A href="http://www.welserver.com/WEL0043"> www.welserver.com/WEL0043</A>
joe.amiUser is Offline
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26 Jul 2014 11:28 AM
Often capacitors are visibly damaged by the bubble top. We lose a lot of them around here in thunderstorms.
Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort!
Bill NeukranzUser is Offline
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26 Jul 2014 04:37 PM
Interesting.  Guess you guys carry plenty of them in your trucks all the time just to avoid a trip back to the office to get it.  Heck, my guess is for you professionals, when you tell the customer to go look at what diagnostic light is on, when the customer says 'Low Pressure' red, when you say that means check CA too and tell customer to go look at it and count how many yellow flashes, and the customer says 6, you just assume it's a capacitor failure, get right out there, change it out, and charge the trip and hourly charges as appropriate.  And if it's WF warranty, hopefully WF pays enough of the part plus install time to where you can please the customer and say 'its NC because it's under the 10 year warranty.'

And, I guess for guys like me who are at least capable of diagnosing and changing a bad capacitor, it's a good idea to keep one 'on the shelf.'  That's at least my plan.

I'm also thinking this would be a good idea for the 2.5 mf capacitors in each of my three Grundfos UP26-116 pumps.  My attic is pretty unforgiving on providing temp extremes every year to the heat pump units, pumps, zone controller and thermostat interface.

Thanks again for the help.

Best regards,

Bill
Energy reduction & monitoring</br>
American Energy Efficiencies, Inc - Dallas, TX <A
href="http://www.americaneei.com">
(www.americaneei.com)</A></br>
Example monitoring system: <A href="http://www.welserver.com/WEL0043"> www.welserver.com/WEL0043</A>
BergyUser is Offline
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27 Jul 2014 09:46 AM
Bill,

Why not take some pressure off the equipment, and yourself, build a climate controlled room around it.

Bergy
joe.amiUser is Offline
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27 Jul 2014 11:38 AM
I'm with Bergy, just a few studs and some pink panther with a duct opening in there......not like you have to drywall it.
Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort!
Bill NeukranzUser is Offline
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27 Jul 2014 12:24 PM
Oh my!!!  What a fantastic suggestion!  Thanks Bergy & Joe!

I feel embarrassed to have not thought of it sooner!

Already looking at pictures now to think about how to do this in a very economic manner.  As you comment, it doesn't have to have any finished appearance.

Here's a wide angle image of the 5 ton unit: http://www.pbase.com/neukranz/image/84286047 .

Vertical WF unit, suspended from the roof, steel pipe duct, very attic high roof height (35'?), pumps located 10' away from unit.

Setup for my 3 ton unit is similar: http://www.pbase.com/neukranz/image/84286063 .

I'm going to have to think about this.

Many thanks!

Best regards,

Bill
Energy reduction & monitoring</br>
American Energy Efficiencies, Inc - Dallas, TX <A
href="http://www.americaneei.com">
(www.americaneei.com)</A></br>
Example monitoring system: <A href="http://www.welserver.com/WEL0043"> www.welserver.com/WEL0043</A>
joe.amiUser is Offline
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28 Jul 2014 09:16 AM
One suggestion would be to respect service-ability of the equipment. Any removable panel that's not blocked now should not be blocked (permanently) when you are done. If studs are attached with screws and batts of insulation are held in by friction or removable straps, then you can't goof.
Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort!
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