Posted By ColdInNY on 20 Dec 2011 10:28 AM
...
Thinking about investing in welserver software so I will have data incase I need it. What are others thoughts?

In a recent thread (above), ColdInNY asked if using the Web Energy Logger (WEL) is helpful to diagnose possibly being short of water loop pipe length.  Rather than respond to that thread directly and possibly take it off course, I thought I’d start a new thread here to address how the WEL is ideally suited to monitoring the ‘health’ of a geothermal Ground Source Heat Pump (GSHP) system.

 

Entering Water Temperature (EWT) is a very easy measurement to record over time to show how well the water loop is performing.  For example, here’s a 13 month chart showing the ‘health’ of my vertical closed-loop system:

 

Here we see that my water loop gets to about 85° (F) max in the summer, and to about 61° in the winter.  Keep in mind my GSHP system is in Dallas, a very warm season climate.  Thus loop design is focused on keeping the summer EWT as cool as possible, versus in a cold season climate where keeping the winter EWT as warm as possible is the goal.

 

Watching this chart every once in a while provides reassurance that the loop is performing properly.  If my loop was not designed properly, it would be easy to see, as summertime EWTs would be much higher than shown (and at the expense of significant A/C SEER degradation).

 

Another concern is long term, over many years change in the soil temperature where the loop is, making the loop eventually no longer able to perform.  In a warm season climate this would be loop field heating – in a cool season climate this would be loop field cooling.

 

Here’s an example of EWT for the past 3 years:

 

Here we see that the maximum EWT has risen at about a 1° per year rate – 82° in 2009, 83° in 2010, and 84° this year (2011).  More time (years) will be needed to determine if this is due simply to warmer summers for the past 2 years, or if indeed loop field heating is occurring to the point where in 10 plus years significant SEER degradation occurs during summer A/C.

 

A second temperature measurement that is excellent at monitoring the health of GSHP equipment is maximum daily compressor discharge refrigerant temperature.  Here’s a 13 month example:

This is the temperature of the copper pipe near the GSHP’s compressor that contains the refrigerant coming out of the compressor.  This is the maximum daily temperature, something that’s easy for the WEL to produce.

 

Here we see it well behaved and normal.  In the summer compressor discharge refrigerant temp rises and falls slowly in line with EWT.  The same behavior occurs in the winter although it’s a little harder to see.

 

The key value to this chart is that over time it can tell you when a problem’s coming.  This gives you time to react in a controlled manner, avoiding unnecessary emergency expenses.

 

For example, twice I got alerted by the above chart that something was wrong with my 3 ton GSHP unit well in advance of an equipment lock out condition.  We can see these two situations summarized with the same chart over a 3 year period:

In both cases circled, a refrigerant leak had developed in the evaporator coil.

 

As refrigerant slowly leaked out, compressor discharge refrigerant pressure slowly dropped and its temperature comparably increased.  Left unfixed, at some point the GSHP’s low pressure monitor would have enabled, turning off the unit hopefully before compressor damage occured.

Here the chart showed well in advance that something was wrong, and that at some point the compressor was going to overload and lock out.  Seeing the problem developing slowly, it was possible to initiate repair (evaporator coil replacement) at a time when it didn't have to be done as an emergency action.

The cost for doing this monitoring with a WEL unit, including the provided WEL web site and lifetime data collection, both with no monthly fees, and with no required s/w installation on anything, is about $410 for the WEL unit, and about $15 for each of the two temp sensors (EWT and compressor discharge).  The monitoring scenario above is probably one of the easiest to implement with a WEL: nail the WEL to the wall, plug in its transformer power supply, make a LAN connection, string a CAT5 cable to where EWT and compressor discharge can be measured, connect up a couple of temp sensors to the cable, and you’re basically done.

 

The expense here is certainly more than simply measuring occasionally, manually with a thermometer, EWT, or compressor discharge temp.  But if you want something that’s no fuss / no mess and runs continuously forever, giving you an exceptionally reliable and  very good picture of the ‘health’ of your GSHP unit, I know of no other better ‘bang for the buck’ capability.

 

I’m at WEL0043 – please feel free to ask me any questions that I can be helpful with.

 

Hope this is helpful.

 

Best regards,

 

Bill

Impressive data.

I'm working on a proposal for 3 units totaling 15 tons of geo to replace aging air source equipment at a local "nature center" Every third grader in Jacksonville, FL visits the center once annually. The client and I both want a real time monitoring system as an exhibit.

I normally use TED for power monitoring but it is too limited at just 4 channels for this system, and it can't handle 3 phase. I'm looking into Wel as an option for both public display and system monitoring.

I do not agree with your interpretation of temperature data as it relates to a refrigerant leak. Refrigerant pressure and temperature track each other only when and where liquid and vapor coexist - saturated conditions ; typically in the middle of air handler coil and waterside coax.

Refrigerant enters the compressor as a low pressure superheated vapor. Enroute to compression it contacts compressor motor armature and stator coil wires, cooling them and therby picking up even more superheat. The action of compression adds yet more superheat. If charge is low owing to a refrigerant leak, refrigerant mass flow through the compressor drops and compressor discharge superheat rises. Discharge pressure drops, rather than rises, although discharge temperature rises since compressor heat is exchanged with a smaller refrigerant mass flow rate.

That said, the fact that the Wel clued you into a problem well ahead of system failure is useful.

Posted By engineer on 24 Dec 2011 10:04 PM

I normally use TED for power monitoring but it is too limited at just 4 channels for this system, and it can't handle 3 phase. I'm looking into Wel as an option for both public display and system monitoring.

I've been looking at what Brultech has to offer compared to Ted.  More channels and a little more reasonably priced.  I'm waiting for their new Greeneye Monitor to come out.  Looks like it might be what I'm looking for to monitor my electrical usage, geo electrical usage, and has some one wire temp sensor inputs to boot.

http://www.brultech.com/community/viewtopic.php?f=12&t=384&sid=b489982c01111067ad167fb2e5099649

You can't beat the Wel set ups I've seen posted on these forums, though.

Posted By engineer on 24 Dec 2011 10:04 PM 
Impressive data. 

I'm working on a proposal for 3 units totaling 15 tons of geo to replace aging air source equipment at a local "nature center" Every third grader in Jacksonville, FL visits the center once annually. The client and I both want a real time monitoring system as an exhibit.

I normally use TED for power monitoring but it is too limited at just 4 channels for this system, and it can't handle 3 phase. I'm looking into Wel as an option for both public display and system monitoring.

I do not agree with your interpretation of temperature data as it relates to a refrigerant leak. Refrigerant pressure and temperature track each other only when and where liquid and vapor coexist - saturated conditions ; typically in the middle of air handler coil and waterside coax.

Refrigerant enters the compressor as a low pressure superheated vapor. Enroute to compression it contacts compressor motor armature and stator coil wires, cooling them and therby picking up even more superheat. The action of compression adds yet more superheat. If charge is low owing to a refrigerant leak, refrigerant mass flow through the compressor drops and compressor discharge superheat rises. Discharge pressure drops, rather than rises, although discharge temperature rises since compressor heat is exchanged with a smaller refrigerant mass flow rate.

That said, the fact that the Wel clued you into a problem well ahead of system failure is useful.

Curt, I fixed my description to match up to your comments regarding the science of what's exactly happening when refrigerant is slowly leaking from a system.  Thanks very much for the education!

I'm sure you're aware that using the WEL to display and record EWT and compressor refrigerant discharge temp daily highs are just 2 of many examples.  I chose these 2 to illustrate because I think they provide the most amount of 'warning time' that a problem's developing, and that each is pretty good as a single temperature monitor to indicate overall 'health' of the water loop and the refrigerant loop.

In my case I'm using a WEL to measure all meaningful system indicators.  I measure total heat of extraction (HE-KBTU/hr) and rejection (HR-KBTU/hr) from/to the earth, air heating capacity (HC-KBTU/hr), and sensible cooling capacity (SC-KBTU/hr).  I don't have a means of measuring total cooling capacity (TC-tons) because I can't measure latent cooling capacity (LC-KBUT/hr).

Using power transducers (WattNodes from Continental Controls) I also measure Coefficient of Performance (COP) and Energy Efficiency Ratio (EER-BTU/Watt-hr).

I'm working on a similar commercial project as you are where the client wants to highlight to customers energy consumption.  It's an about to be constructed casual dining restaurant that wants to implement features such as GSHPs, solar panels, high efficiency lighting, Energy Star cooking equipment, electric vehicle charging stations, etc.  The client wants to have a major display display showing energy monitoring.  Electric wiring would be implemented in such a manner to measure energy needed for major components (i.e., heating/cooling, lighting, hot water, etc.), and natural gas and water flow submeters would be put in to get these measurements.

As one example of many dashboards, see bottom of page at http://www.agilewaves.com/ .  For the restaurant project I'll be using the WEL for the display since it's accessible via a Web page.

Here are a couple of examples of commercial WEL implementations that have dashboards intended for public viewing, that may interest you:
Northwest Park - Libby Taylor Education Hall: WEL0395
WECMRD Field House: WEL0242
14 unit apartment building: WEL0522
Public civic center pool: WEL0523

In addition to industry standard pulse output power measuring transducers, such as WattNodes from Continental Controls, or OmniMeters from EKM, the WEL does interface quite nicely with TEDS and eGauge power measuring devices.  In my case I have standardized with WattNodes because it's just one source that I can get both single and three phase transducers from one vendor.  Plus, WattNodes are the only transducers I can get with high resultion (I use 300 Hz versions).

Here's an example of 3 phase power measurement using the WEL and OmniMeters for a project I did at Cal Expo: WEL0515.  This is a 60 ton Roof Top Unit with 2 refrigerant circuits and 4 compressors.  Soon I'll have an example using the WEL and WattNodes for 3 phase power measurement for a commercial office building with 7 RTUs, each approximately 100 tons - it will be at WEL0591.

If you're looking for material on energy monitoring implementation and benefits, here's some material that I've prepared that you're more than welcome to use for any helpful purpose:

http://ecm1240.plotit.com