GSHP Performance Monitoring
Last Post 11 Feb 2009 12:24 AM by tuffluckdriller. 20 Replies.
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roooooomieUser is Offline
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06 Feb 2009 10:22 AM

My GSHP system (horizontal closed loop) will be installed in the next couple of weeks, and I wanted to install one of the WEL systems, or even a simpler WEL type system in order to be able to monitor the overall system performance.

I don't need the ultra detail I see with some WEL installations, but what sensors at what locations are inherently necesary to be able to calculate the COP of the system as a whole at a high level average, above average or below average? 

#1) I want to be able to establish base lines, so I can tell if the system performance is degrading over time.
#2) I want to be able to tell if the loop is providing a large enough heat sink for the tonnage required
#3) I want to be able to calculate a rough estimate of COP

Im not an electrician, HVAC buff, or engineer, just a regular joe type who sees the value in putting some sort of diagnostic ability into the system which can only easily be done during initial install.  I want to be able to track if my investment in a GSHP is going to yeild an ROI equivalent to my estimation.  I want to be able to document the efficiency to help substantiate an the additional long term value added to the home. 





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06 Feb 2009 06:15 PM
Posted By roooooomie on 02/06/2009 10:22 AM

My GSHP system (horizontal closed loop) will be installed in the next couple of weeks, and I wanted to install one of the WEL systems, or even a simpler WEL type system in order to be able to monitor the overall system performance.

I don't need the ultra detail I see with some WEL installations, but what sensors at what locations are inherently necesary to be able to calculate the COP of the system as a whole at a high level average, above average or below average? 

#1) I want to be able to establish base lines, so I can tell if the system performance is degrading over time.
#2) I want to be able to tell if the loop is providing a large enough heat sink for the tonnage required
#3) I want to be able to calculate a rough estimate of COP

Im not an electrician, HVAC buff, or engineer, just a regular joe type who sees the value in putting some sort of diagnostic ability into the system which can only easily be done during initial install.  I want to be able to track if my investment in a GSHP is going to yeild an ROI equivalent to my estimation.  I want to be able to document the efficiency to help substantiate an the additional long term value added to the home. 






Take a look at these two posts, I use an already running PC, a 1-wire adapter and a bunch of 1-wire sensors.

http://greenbuildingtalk.com/Forums/tabid/53/view/topic/forumid/13/postid/48359/Default.aspx

http://greenbuildingtalk.com/Forums/tabid/53/view/topic/forumid/13/postid/48361/Default.aspx


you can get parts from http://hobby-boards.com that simply plug together to monitor temps and such. You can use the free software LogTemp to monitor them.
I probably don't have $50 invested and it does a pretty good job.


engineerUser is Offline
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06 Feb 2009 07:58 PM
Other low tech ways to do this include hourmetering the unit, measuring loop temps, outdoor temps and frequently reading electric meter.

A year of this has taught me my house baseload and unit operating hours / costs as they relate to outdoor temps.
Curt Kinder

The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill

www.greenersolutionsair.com
BrockUser is Offline
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07 Feb 2009 07:13 PM
I am very interested in WEL as well, but so far I just have cheap digital thermostat's on everything, incoming field, outgoing field, heat pump return, heat pump out, furnace in, furnace out. I did add an hour meter on the geo unit when it was installed, VERY handy, simple install, I just tapped off the circulation pump tie ins. I just read these weekly, basically looking at the low temps recorded for the field stuff and record the hour meter. I also record the utility electric meter outside weekly as well.
Green Bay, WI. - 4 ton horizontal, 16k gallon indoor pool, 1.8kw solar PV setup, 3400 sq ft
engineerUser is Offline
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08 Feb 2009 12:38 PM
I found $30 Readington digital hourmeters - LCD display down to tehts of hours, 7 year battery, decimal blinks while 'on' and work of any AC voltage from 20 to 277 - very versatile.
Curt Kinder

The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill

www.greenersolutionsair.com
tuffluckdrillerUser is Offline
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09 Feb 2009 10:10 AM
The Readington measures on time or current?
Clark Timothy (clark@pinksgeothermal.com)
Geothermal Heat Pumps: Heating and Cooling that's Dirt Cheap!
www.pinksgeothermal.com
roooooomieUser is Offline
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09 Feb 2009 11:49 AM
A follow up question..

What are the data points I need to measure to calculate COP. Outside temperature, kwh, inside temperaure?

Whats the best way to get KWH? If I have a split system, how does that change this process?
Bill NeukranzUser is Offline
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09 Feb 2009 02:52 PM

Posted By roooooomie on 02/09/2009 11:49 AM
... What are the data points I need to measure to calculate COP. Outside temperature, kwh, inside temperaure?

Whats the best way to get KWH?

If I have a split system, how does that change this process?


Data points needed: KW (not KWH), EWT, LWT, GPM.

Need to exclude pump power in KW measurement.

A way to get KWH is to use a WattNode.  While highly accurate, it's not your least expensive alternative. (WattNode also produces highly accurate KW measurement, which is what you need.  COP is an instantaneous metric, not an accumulated metric.)

You'll need to think about how you're going to get KW measurement for a split system, to include compressor and air handler, and not include pumps.

Best regards,

Bill
Energy reduction & monitoring
American Energy Efficiencies, Inc - Dallas, TX (www.americaneei.com)
Example monitoring system: www.welserver.com/WEL0043
engineerUser is Offline
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09 Feb 2009 09:21 PM
Readingtons just measure on time.
Curt Kinder

The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill

www.greenersolutionsair.com
tuffluckdrillerUser is Offline
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09 Feb 2009 11:10 PM
COP is kW out/kW in.

This is easier measured as BTUh.

BTUh out = system cfm / (1.08 x delta T)
delta T is the temp. difference measured from the return air to the supply air.

BTUh in = (Compressor Amps + blower amps + pump amps) x 29.3 x measured voltage
Not sure if you need to adjust this for power factor, though. That's been discussed in other threads...

Note: to be accurate, the cfm must be accurately measured. With electric heat, this can be somewhat easily done. Disconnect Y (compressor control wire) and run the blower and the electric heat strip. If it is a 10 kW strip heat, then the BTUh output of it = 10,000 x 3.413. Probably to be more accurate, measure the strip heater's amps, and times by the measured voltage to get the kW output.

Using the same equation as before, but rearranging it, cfm = BTUh x 1.08 x delta T.

Make sure the delta T is measure from a point where the sensor does not "see" the strip heat so as to minimize/eliminate any effect of radiant heat from the strip heater.

Now you'd reconnect the Y (compressor control wire) and disconnect the strip heat control wire. Now run the test using the heat pump to measure the delta T, etc........

Another way to get the cfm, somewhat accurate (need to remember elevation), is to measure the static pressure drop across the blower/coil, and look up the blower data.

The readington unit seems like it could be very useful.
Clark Timothy (clark@pinksgeothermal.com)
Geothermal Heat Pumps: Heating and Cooling that's Dirt Cheap!
www.pinksgeothermal.com
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10 Feb 2009 09:24 AM
hey bill, why not include pumping power in your cop calc, arent we looking for performance of the sytem(not just the heat pump)
tuffluckdrillerUser is Offline
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10 Feb 2009 09:29 AM
Yeah, why not include pump power? That would be completely misleading as to "in the field" COP.
Clark Timothy (clark@pinksgeothermal.com)
Geothermal Heat Pumps: Heating and Cooling that's Dirt Cheap!
www.pinksgeothermal.com
Bill NeukranzUser is Offline
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10 Feb 2009 09:48 AM

I believe the major GSHP manufacturers measure COP on the water side (and measure EER on the air side), do not include pump power, and include heat from the compressor in the calculation.  I know this is how WaterFurnace, for example, computes COP.

Thus, if an owner's purpose of measuring COP is to verify that the unit is performing to manufacturer's stated specs, (i.e., 'did I get my money's worth') then I would think COP needs to be measured as I note above.

But, certainly, deciding that COP is more accurate if pump power is included and compressor heat is not included (as many commonly do), and deciding to measure KBTU/hr on the air side versus the water side (which may be easier to do) is simply a matter of what one wants to accomplish with the COP measurement.

The COP calculation that I'm using, that I have on the first page of my system summary ( http://welserver.com/WEL0043/ ), is

COP = (HE + Pwr) / Pwr

Where HE is Heat of Extraction, and Pwr does not include pump energy.

Best regards,

Bill

Energy reduction & monitoring
American Energy Efficiencies, Inc - Dallas, TX (www.americaneei.com)
Example monitoring system: www.welserver.com/WEL0043
MasoudUser is Offline
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10 Feb 2009 10:04 AM
Clark,

Could you explain why -

BTUh in = (Compressor Amps + blower amps + pump amps) x 29.3 x measured voltage?

I don't get 29.3.

Regards, Masoud
Bill NeukranzUser is Offline
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10 Feb 2009 10:34 AM

Here's an example of measuring COP for the purpose of comparing to manufacturer spec (i.e., no pump power, compressor heat included, measured at water side of heat pump):

Highest frequency of COP measurement is at 4.8.  This compares to a manufacturer's (WaterFurnace in this case) spec of 5.1.  So I'm well within 10% of manufacturer claim.

Best regards,

Bill

Energy reduction & monitoring
American Energy Efficiencies, Inc - Dallas, TX (www.americaneei.com)
Example monitoring system: www.welserver.com/WEL0043
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10 Feb 2009 11:26 AM
Posted By Masoud on 02/10/2009 10:04 AM
Clark,

Could you explain why -

BTUh in = (Compressor Amps + blower amps + pump amps) x 29.3 x measured voltage?

I don't get 29.3.

Regards, Masoud

29.3 seems to be the conversion of watts into BTU. 1kW = 3413 BTU ... though I suspect there's a scaling issue here. 1/3413 = 0.000293 - but at least we can see where 293 came from.

As for COP the only fair measure is total heat delivered / total power in  - this is especially true for open loop systems where the pumping power can be considerable which really affects the effective COP.

Paul.
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10 Feb 2009 03:21 PM
Thank you Paul.

Regards, Masoud
tuffluckdrillerUser is Offline
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10 Feb 2009 05:10 PM
Masoud,

It takes 29.3 kW to get 100,000 BTU with electric resistance heat. Basically in the calculation, it's just a constant.

The purpose to me of measuring actual COP is to prove who's unit has the actual highest efficiencies. WF and CM, among many other water based systems, don't account for all of the energy required to make the system work, but they sure do market those artificially higher COPs and EERs.
Clark Timothy (clark@pinksgeothermal.com)
Geothermal Heat Pumps: Heating and Cooling that's Dirt Cheap!
www.pinksgeothermal.com
MasoudUser is Offline
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10 Feb 2009 07:17 PM
Clark,

Thank you.

Regards, Masoud
engineerUser is Offline
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10 Feb 2009 10:09 PM
Reading the notes in WF's ARI ratings I see allowances are made for both pumping and blower power. These notes also take into account recent 'metrification' of ARI rating calculations - essentially rounding to whole centigrade temps.

Clark - check it out...

"Pump Power Correction Calculation
Within each model, only one water flow rate is specified for all three groups and pumping Watts are calculated using the
following formula. This additional power is added onto the existing power consumption.
• Pump power correction = (gpm x 0.0631) x (Press Drop x 2990) / 300
Where ‘gpm’ is waterflow in gpm and ‘Press Drop’ is the pressure drop through the unit heat exchanger at rated water
flow in feet of head.
Fan Power Correction Calculation
Fan power is corrected to zero external static pressure using the following equation. The nominal airflow is rated at a
specific external static pressure. This effectively reduces the power consumption of the unit and increases cooling capacity
but decreases heating capacity. These Watts are significant enough in most cases to increase EER and COPs fairly
dramatically over ARI 320, 325, and 330 ratings.
• Fan Power Correction = (cfm x 0.472) x (esp x 249) / 300
Where ‘cfm’ is airflow in cfm and ‘esp’ is the external static pressure at rated airflow in inches of water gauge.


So it is fair to observe that actual system conditions probably won't match ARI conditions and so EER and COP will vary, but I don't think it is fair to label those ratings as "artificially high" owing to neglect of pump power
Curt Kinder

The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill

www.greenersolutionsair.com
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