I would like to monitor my loop temperature long term (armed only with a meat thermometer) to get a better feel for what is normal with our loop, and to possibly alert me if a problem occurs.

How often should the loop temperature be checked and recorded?  Is there any other relevant information that should be recorded at the same time, (like heating or cooling degree days for the period)?

In general terms, at what loop temperature (high and low) should a person be concerned with a closed horizontal loop?  Also, is there a certain amount of loop delta T withing a certain period of time that would indicate a problem (assuming normal thermostat settings)?

Ideal vertical loop operates within +/- 20 F of deep ground temp. Horizontals probably need to allow for a bit more swing. Your system should have intended design max and min EWTs. I would expect those to be somewhat exceeded during periods of severe weather (such as is underway now in much of the US).

I would spot check it mornings during very cold weather, evenings during hot weather.

You might also read your electric meter between bills. Eventually you'll get a sense of what your house uses under various conditions. Mild, no HVAC days are useful for learning baseline 'balance of house' consumption. Eventually you'll learn to attribute readings with activities and conditions such as doing several loads of laundry or roasting a Turkey.

My basic monitoring is a cheap indoor / outdoor thermostat with a probe. I attached the probe to the returning field line and then once a week I record and rest the max low temp. I now have about 18 months of temps and I can see this year I am about 3 degrees warmer than last year at this same time. Again it is basic but a place to start.

I agree that monitoring the loop temperature can be very educational toward peace of mind that your system is working fine.  In fact, I do exactly this for this very reason - see chart below for a 'picture' of my loop temperature over the past year that I look at from time to time to affirm all is well with the loop/system.  (I also do this for outgoing compressor refrigerant temperature to provide early warning of a compressor problem if it develops.)

In case you want to 'jump off the deep end,' to accomplish this perpetually with no continuous measuring effort, without needing a meat thermometer, with just a couple hours of installation investment, and you're willing to invest $525, you should consider using what I'm using ( Web Energy Logger ).  It's really incredibly simple, if you think the time savings, and the freedom from ever having to do manual measurements, is worth the financial investment noted.

Best regards,

Bill

Thanks Bill. Are you sure you want me to get this? Do you have any idea how many questions I would ask you about installation and interpreting the results?   Seriously though, I'm sure I will get one at some point.

Can one unit record 2 compressors and split the results into different charts? I assume it would take longer to hook up to our split system since the air handler is in the attic...

Actually, the biggest fear people have is that they'll need to ask a lot of questions.  Then they find out that 'coming down the learning curve' is easier than expected, and they end up with less questions than anticipated.  Plus, the WEL business owner excels at providing support via email, phone, and a forum like this.

Take a look at http://welserver.com/WEL0043/ , the location for my real time charts.  You'll see a few examples of my 2 GSHP systems combined onto a single chart for a single variable, like the EWT chart I illustrated earlier (showing EWT for each of my 2 units - black line for my 5T unit, blue line for the 3T unit).  And you'll see opposite examples where some subjects are presented across 2 charts, one for each GSHP unit.  I.e. my supply and return air temp values for each unit are presented on 2 separate charts.  It's really as simple as deciding what measurement values (up to 8) you want on any given chart, and deciding what frequency of update you want (my charts range from 1 measurement per minute (24 hr charts) up to 3 measurements per day (one year charts).

I initially thought the cost was a lot.  Then I started realizing how much I appreciated not having to remember to go take measurements at the same time every day/week/month.  The real clincher was when one of my charts showed me a developing compressor problem (last year about this time) that I was able to get fixed before any permanent damage occured.  The avoided repair costs simply by having advance visibility to a problem more than paid for my WEL unit.

The capacity of the WEL unit is such that if you really want to 'jump off the deep end,' you've got room to monitor more than just GSHP units.  In my case, I recently added in monitoring for my solar PV system just recently installed.

Best regards,

Bill

I can tell you that most problems can be linked back to water flow. Loop temperatures problems often can be traced back to waterflow. The fluid in your pipes has to be flowing in a turbulent manner, which means the fluid is "bouncing" from one side of the pipe to another giving you good heat transfer. If you have been measuring temps for a while and they suddenly drastically change on you I would look into waterflow. Waterflow rates are derived by checking pressures on your P/T ports. You then take the change in pressure or Delta P and go to your install manual if you have one. This manual will give you a range of flow rates that are acceptable for your unit(s).

I would expect water in a closed loop to either flow normally or quit entirely, which you'd figure out pretty fast. I suppose if one pump out of two died the system would markedly degrade without quitting entirely, and temperature monitoring would annunciate that condition

geo14, thanks for the info. I was wondering how water flow is calculated.

engineer, our flow center is conveniently located on the wall at the bottom of our basement stairs. In a low tech way, I often check to make sure both pumps are operating by placing my hand on the pumps to feel if they are operating.

Vibration can be transmitted from one pump to the next. I think I'd trust warmth over vibration in a multi-pump center

Bill, how does the WEL monitor power consumption?

The WEL has a number of input connection types to accommodate a wide variety of measurement values: a 1-wire network connection to read 1-wire technology connected device produced numbers, 4-20 ma analog input connections for devices that produce a variable current/voltage proportionate to what's being measured, and pulse counting input connections for devices that produce a variable pulse stream proportionate to what's being measured.

Devices that measure flow (electricity, gas, water) typically produce measurements via providing a proportional variable pulse output, or a proportionate analog voltage/current output.  These are purchased, external-to-the-WEL devices, much like the 1-wire temp sensors.

The most common AC power flow measuring devices I'm aware of are of the pulse output style.  (For DC flows, many times these measuring devices produce variable currents.)

The WEL does the rest of the work.  In the case of pulse inputs, it's a very sophisticated variable frequency pulse counter.  The WEL contains internal arithmetic capabilities to translate the counting of pulses to watts / kWh (electricity), gpm (water) and CCF (gas), depending on the measuring device.

For power consumption, there are a number of products to choose from that produce a proportionate pulse stream compatible with the WEL's pulse counter inputs.  Probably the most popular, and the unit the WEL's pulse counter inputs were originally designed to, is the WattNode from Continental Control Systems.  This item is a very accurate true RMS AC watt-hour transducer.  This is what I'm using.

Many examples of how WEL users are measuring things are here: http://welserver.com/ww/ .

Hope this helps.

Best regards,

Bill

I can second the praise of the WEL system. I just got it and it is amazingly well designed, and almost a must for everyone trying to monitor the performance of his/her system. It is cheap for what it does, do yourself a favor and get it! You never look back! http://welserver.com/WEL0267/