I have a ClimateMaster TEV 38, closed loop 3 ton system; one year old. The thermostat provides lots of info, and I'm wondering what numbers I should expect when in state 1, stage 2, etc? I live in eastern PA. How do I know the system is working efficiently? I noticed with sub-20F temps and wind, the AUX heat comes on sometimes. I guess that' to be expected. My house is about 2000 SF and I'm using about 100kW of electricity for entire house, including heating.

Dr.Rock,
Just for comparison, I have a 4 ton closed loop system, about 2100 sq foot house, I would say "medium" insulated (the bottom half is 1959 cinderblock and plaster, the top is 2012 addition 6" studs and fiberglass insulation), Eastern PA here, too (Bucks County). With temps around 15F, the system runs in stage 1 and often stage 2, but it runs constantly. With the current cold spell and wind, the aux heat is going on occasionally, maybe an hour total for the day. I keep my thermostats at 67 or 68F. I have a desuperheater to preheat the hot water for the house, too.

I don't know the KWh used, but my January electric bill was $280. I know $100 is just the house appliances, computers, lamps, cooking, etc. I can attribute the other $180 to the geo for heating. It sounds like a lot, but Jan is my typically hugest bill, April/May and Sept/Oct, I don't use any heating/cooling, and the summer the geo contributes $30-$40 per month. The yearly average for heat/cool is $60/month.

I know my house isn't the tightest, nor is my ductwork, but I used to have oil, and even with the declining price of oil, my heating cost is 1/2 what it used to be. Back was oil was $4/gal, my heating cost was 1/3 to 1/4 of what it was with oil. I'm very happy.

Here's my WEL site, if you're interested in some numbers and runtimes -  www.welsever.com/WEL0487

Thanks for the answer to my question. My house sounds similar to yours w/only some insulation in the catheral ceiling roof and walls (built when oil was 0.25/gal. My system is running in stage 2 as I write this and the temps outside are 10F. AUX is on alot of the time b/c it seems the system can't keep up with the temps outside. I have a desuperheater for water, which is wonderful. I only use about 4 kW/day to heat all the hot water we need. My January electric bill was $333 for total house plus hot water. I also have an air heat pump for the Master suite that was added onto the house (not heated by geothermal. Yesterday to today I used about 120 kW for 24 hrs of heating and all electric use in the house (cooking, dishwasher, lights, etc.). I calculated, based on my PECO records that since I installed my geothermal last Feb, I used about $2300 in TOTAL electricity for house, heating, pool; everything, and of course, no OIL! Oil has costed me in the past $3000, so I $300 less than now. I'm just curious b/c I read that geothermal should provide all the heat you need w/o the AUX, but that's not my experience. Without AUX we'd be cold. Thanks again.

What's a WEL site?

What's a Welserver and how is it used?

WEL is a data logger that allows you to monitor many different facets of geothermal and other system types. The site (welserver.com) has plenty of information on its features.

Speaking for myself and my house, the previous owners had oil bills of 300 per month year round, so my average of $60 per month for heating and cooling is amazing.

Most geo systems are designed to work when the temp outside is above a certain point. Most have aux heat to make up the difference when it gets extremely cold and the house is losing more than the geo can supply. For example, my house geo was designed for a balance point of 15f. So at 15f outside, my geo could take care of the heat in stage 2, running 100% of the time. Below 15, like right now it's 2f outside, the aux has to supplement.

But even if the aux was on for an hour total today, it would only add about $1.50 to my bill.

There are some geo systems that people have that can supply the heat no matter what the temp is outside without aux, but often these systems have super efficient loops, long loops, perfect duct work, and a well-insulated house.

Last winter, it never got much below 15f ever, so my aux never switched on. This year, it's on when it needs it.

"There are some geo systems that people have that can supply the heat no matter what the temp is outside without aux, but often these systems have super efficient loops, long loops, perfect duct work, and a well-insulated house. "
Those systems are often grossly oversized and may cost more to run than a right sized system with a little auxiliary.

Nothing wrong with perfect ductwork and a well insulated house, but grossly oversizing the heatpump is a rookie mistake in terms of longlivity, efficiency and upfront costs.

Posted By dr_rock on 15 Feb 2015 02:50 PM
I have a ClimateMaster TEV 38, closed loop 3 ton system; one year old. The thermostat provides lots of info, and I'm wondering what numbers I should expect when in state 1, stage 2, etc? I live in eastern PA. How do I know the system is working efficiently? I noticed with sub-20F temps and wind, the AUX heat comes on sometimes. I guess that' to be expected. My house is about 2000 SF and I'm using about 100kW of electricity for entire house, including heating.

4 ways:

1. (No expense)  Watch your aux heat and get a sense for how often it's on.  If it's not used for many of the average days, and if it's mostly used just for the coldest days, than that's a pretty good empirical measurement.

2. (About $700) Get yourself a WEL unit, a WattNode and a couple of Current Transformers.  Measure kWh/day as a function of Heating Degree Days (you can look up HDD for your location).  This is a common measurement.  Compare this to standard forms of heating to see if indeed you're getting the deal you think you got.  Many people I know think the $700 investment is worth it to confirm they got what they paid for.

3. (About $900) Add a couple of temp sensors to the setup in the second option, measure water flow delta Temp across the coaxial coil.  Meanwhile use a pressure gage to measure delta Pressure flow across the coax coil, and look up in a chart what the water flow is.  Now use the WEL to compute and report COP.  Compare to advertised COP claim.

4. (About $1500) Add a flow sensor to option 3 above.  Eliminates the pressure gage readings and assuming that flow is constant.  Still compute COP, just more accurately.  Still compare to advertised COP claim.

I did option 3 above.  Confirmed my units are running close to manufacturer claims.  That was how I answered 'How do I know the system is working efficiently?'

You can see implementation of my WEL unit, WattNode, Current Transformers, and water loop temp sensers at
http://www.welserver.com/WEL0043 .

Best regards,

Bill