Pennsylvania E5 - Frze Detect FP1 errors with Waterfurnace Series 7 and Ground Loop

I looked at that as well. However, 4 x 1" lines have an acceptable pressure drop for 13.5 gpm , and are "ok" balanced as described. Just to be clear, all the boreholes for each loop are in series, correct? You should be able to have enough velocity in the loops to purge all the air out, with a normal purge cart (1.5-2.0 HP).
Do you have a reducing header? Other question is what the length of the header pipe from the house to the loop field, and what is the diaper of the pipe going out to the loop field?

 

docjenser, thanks for the thorough response. With the tech visit this week, the min and max is now 30% and 100% (was 60% max) with max flow rate observed at 13.5gpm. I'm not certain about min but believe it is 6.5 pm at 30%. The brine ratio was adjusted last year and tested again this week and is not perfect, but close. All the boreholes in a loop are in series and each loop is in parallel to the header. The header is about 25 ft from the house and then another 20ft run inside the house. The header to Geo unit is using 1.25"tubing. Additionally, the slightly varying total depth of each loop (within +/-5%) seem to be within design standards based on my research.

ChrisJ, geokne, thank you both as well. You are certainly picking up on something that is a big concern for me. I asked the installer techs the same question about how you would know if fluid is moving through all 4 loops - no good answer on this. I do know that the installer is not happy about the decision the loop sub-contractor made to do this unusual setup. Last year when the brine ratio was adjusted, I'm convinced air was injected into the system. Within hours of the tech leaving, I was getting multiple E5 daily. The system could not run on ~speeds 10, 11, 12 without going into E5 so it appeared as though we lost 1/4 capacity of the system. The installer finally had to bring in a much larger flush cart than they typically use and they did "super purge" the system as mentioned. The tech appeared to have success on this last year as he showed me the water level in the cart dropped pretty significantly (fluid replacing air) and he showed me that the liquid level in the cart did not drop when he shutoff the pump. However, temps rose in the days after this repair attempt and never dropped down low enough to cause issue until this past week so I was not sure if the change in brine ratio (antifreeze t coolant) and subsequent super purge actually resolved anything.

Earlier this week, a tech adjusted the max flow as I mentioned and it does appear to be making a difference. The EWTs and LWTs seem to be higher at any given out door temp, but it is a little early to tell and somewhat subjective based on my memory of prior observations (the techs may have log access, I do not). We are expecting temps in the teens this evening so I will be watching EWTs and LWTs closely.

All - I'm still not clear on how the auxiliary heat is supposed to work. If it does get really cold tonight, what is that would cause the aux heat to kick on? Does it only come on if the system (running at max speed) cannot satisfy the thermostat? i.e. the thermostats call for aux heat vs. the Geo system itself?

 

Yes, unit cannot hold temperature, or the temp is dropping 2.5F below set point, usually turn on supplement heat. If you did not have enough flow, and the E5 was occurring in the higher compressor stages, is all a simple result of the circulation pump not going to higher percentage.

If you don't have any air in it anymore, and the fluid level in the flow center not changing much when the loop get deadlocked is a sign of lack of air in the loops, then the loops balance themselves. You might have 3.1 gpm in one loop circuit, and 2.9 gpm in an other one, but you don't have one circuit completely locked, unless you have a lot of air in it.
Chances are it all comes down to your incorrect pump setting.

Check the lowest flow, at stage 1 (gpm).

If your EWT is around 30-32F, and you have 13.5 gpm max, your loop is absolutely fine.

 

For the Series 7, if you have a single thermostat aux heat is energized when room temperature drops below set point by 1.5F at factory settings. The differentials can be adjusted in Installer Settings on the thermostat.

If you have the IntelliZone 2 system, it gets more complicated. Differentials can be adjusted in Installer Settings but the IZ2 has in addition staging options that will turn on aux heat more aggressively depending on the weighted % of zones calling.

In any case, as you have observed, aux heat will energize when the unit has locked out. Your system as described will maintain set point without aux heat until it locks out. It is not considered economical to encourage aux heat use to "save" the loop field.

 

I have a pump that can do a super purge.

I also have both digital and analogue ohm meters and would test the sensors against a known quality digital thermister.

I am not sure why the idea of learning or seeing what is going on with this system is a joking matter. I am not learning a new language to type here.

 

That is a great improvement. Sometimes the obvious solution is overlooked when chasing down the rabbit hole. Factory settings for VS Pump are Min 50%, Max 100%. Someone adjusted settings along the way without verifying proper flow. The shame is it took over a year to correct.

Verifying freeze protection down to 15F would be the next order of business to put this to bed.

 

Yes, meant "now" 13.5gpm - thanks. I monitored EWT/LWT over the weekend and have yet to see LWT below 30 deg f. This seems to be an improvement especially on 24 Jan. where the low temperature hit 10 deg f in the area. However, it is hard to declare success because it was only in the midst of the brutal winter last year that the errors started on 23 Jan. 2015. i.e. weeks into a period of sub freezing temperatures with frequent lows in the teens and single digits.

 

Your EWT indicates the state your loop field. Your LWT indicates how well you are pumping and extracting heat.

 

Yes, there is success if your LWT has not dropped below 30F, that means that your EWT is a few degrees higher. While lower outside temps mean that more BTUs are sucked out of the ground, it usually has little affect on the loop field. Once a well designed loop reaches 30-32F, it will not move much more wether you have an outside cold span or not.

http://welserver.com/WEL0834/

Similar system, 5 ton 7 series, one year old. Second from the bottom graph shows you EWT over the season. It was down to 30F last year (fresh loop), it is down to 32F. It might drop down to 31F, maybe 30.5F, who knows, who cares. Neither a 20F nor a 30F degree loop throws an FP1 error.
A wrong dip switch setting, the incorrect antifreeze, or having not enough flow, does.

 

docjenser - it's been a year so hope you're still around. Had another lockout today with same freeze detect FP1 error so I reread everything here and I see your comment about dip switch settings. Using the AID Tool in Aurora Web link, I can see DIP switch settings as follows:

FP1 Off - 15°F
FP2 On - 30°F

Do you know if these settings are correct? I don't understand why I'm getting FP1 errors with EWTs hovering around 32.5F and LWT around 30.5F. Flow is 13.5 gpm and I'm fairly confident that got the brine ratio correct given the focus on this working directly with WF as well.

 

ABC DIP Switch (SW2)

SW2-1
FP1 Selection – Low water coil temperature limit setting for freeze detection. On = 30°F; Off = 15°F.

SW2-2
FP2 Selection – Low air coil temperature limit setting for freeze detection. On = 30°F; Off = Not Used

Yes, your settings should be correct.
Check the actual settings on the board. If you have access to the cataloguer, check the time when the fault occurred. Then check flow, sensor reading, etc. Could be a faulty sensor...

 

If I look at the Sensor Inputs in the Diagnostics menu of the AID Tool , I've never seen FP1 below 28°F and FP2 is typically around 78°F. Am I correct to think that this FP1 input corresponds to the Fp1 set-point which is currently set to 15°F?

I just checked and the confirmed that the physical DIP settings on the ABC board match what I reported from the AID Tool. i.e. from 1-8, Off, On, On, Off, On, Off, On, On.

As a consumer, I'm not aware of how I can get access to the history of these values as it seems this is a feature of the Aurora Web solution reserved for the dealer. So, while I know the exact time the faults are occurring based on the notifications, I cannot see the value of the inputs at the time the event occurred. I may try to setup a Web scraper tool to capture/log these values.

 

WF had issues with the FP1 sensor, you might want to call your installer to replace it under warranty

 

Installer was out on Friday. Showed me the trends including FP1. You can see the change in FP1 over time until it hits 15 deg f. So, it does not behave like you would expect a faulty sensor. In consultation with WF, they bumped up the loop pressure to just under 40 PSI (the max my well could produce), set the max flower rate on the loop at 80%, down from 100%, lowered fan speed on Aux heat from 11 to 10, and lowered the air flow for compressor from 10 to 9, and low speed from 5 to 3.

UPDATE: Just had another night of extreme cold with lows around 10 deg f overnight. The most problematic time for my system has always been early morning as you might expect so I watched the system in early morning (7am) and noticed a couple differences. First, the EWT and LWT see both about 2 deg f higher than what I would have expected. I.e. 34.9 and 32.9 deg f respectively. Second, leaving air temps are noticeably higher. Typically, I saw the range from 91 deg f to 94 deg f and now it's cranking out 103 deg f. I assumed the latter is the result of lowering those fan speeds. Finally, I see an error I don't recall seeing before: 15 - Hot Water Limit

 

Sure, if you FP1 hits 15 F it will trigger the fault, the questions is wether the temperature really is 15F. Not sure what those measures they implemented actually did in regards to the FP1.... If your refrigerant circuit is nominal, a 2 degree delta T on the source side indicates that you are over pumping, and an EWT of 34.9 F (and leaving 32.9F) should then never trigger an FP1 fault if the dip switch is set at the 15F limit.