OK, here's the deal. In 2007 I built a new house in upstate New York. The house is a 2400 square foot ranch. The walls are insulated with R21 plus I used a insulated vinyl siding (additional R4), the ceiling has a full layer of R38 and 75% of the ceiling has an additional R21 on top of the R38. I did the insulation myself, so I can vouch for all seams being taped. All of my windows are double pain, argon filled, low e windows. I had a Geothermal contractor with 35 years experience install a WaterFurnace Versatec 3.5 ton unit with a 10 kw electric supplemental heat. The house has 4 zones, 2 Jackson System Central Processing Units, Robertshaw 9560 thermostats. So far no problem! Here's the problem my electric usage ranges from 1200 kw per month Spring and Fall to as high as 5200 kw per month in the winter. This past month with temperatures not very cold (highs 35-55, lows 19-35) we used 3400 kw. My well pump is a 2hp pump, so I know this is using some of the electric. My well is 350 deep with the water level 18 feet from the top it's providing 8GPM to the open loop system returned to the well. I have a Mono XT Drive on the pump to prevent start up spikes, etc. Here's the family makeup: 3 adults that work during the day, and one 17 y/o who's in school during the day. Nothing is left on during the day. 80% of the lights in the house are CFL. No lights are left on in unoccupied rooms. One to two tvs on 3-4 hours per day (6 on the weekends). All appliances are energy star most 3-7 yrs old (most 3). No pools, hot tubs, or other electric hogs. We keep the heat set at 68 and AC set at 75. Electric furnace is turned off at the breaker. The geothermal furnace runs a lot (between 40 and 50 minutes an hour) and it's not that cold yet. The last two winters our we've been over 5000 kw for the months of Jan and Feb. I've asked my contractor numerous times why I'm using 4000 kw a month to heat, and he has not helped. He wants to charge me 4 hours of travel time plus his time on site to take another look at it. I'm not looking forward to another winter of $700 electric bills. My last house I built in 1999 and live in for 7 years never had utility bills over $300, and we kept the heat much higher in the winter (natural gas system). I know this was long I apologize. Any ideas?
Bill associated with geo You can find the kwh of your heat pump and multiply it by cost per kwh of your utility. You seem to know the run time so then multiply by the hours per month to see what your bill associated with geo is. Then you can look at troubleshooting the geo. Do you have an ecm blower on the versatec? Hopefully with 4 zones. Scaling on heat exchanger with open loop would lead to deficiencies. Need some temperature measurements. You said electric furnace is off. You mean the supplemental strip heat?
A 2 hp pump even with a mono drive is a lot of electric usage. Did I understand correctly that your discharge water from the geo goes back into the supply? efficency and performance is all based on entering and leaving water temps. Also a common thermostat eror seems to be that the resistance heat is wired to come on everytime the unit runs. Lastly you need to look at your house in terms of heating load to insure that the unit is sized properly, a blower door test would tell you alot. Hope this helps Eric
Thanks for the responses. I'm not sure if I have a ECM blower or not. From what the electrician told me last week. My geothermal system is drawing 12 amps (2640 watts) times 20 hours 52 kWh. My pump is using 5-7 amps (1200-1700 watts) times 10 hours approx. 15 kWh. My well pump runs approximately 50% of the time the geo system is running. Yes my water is returned to my supply. I have another geothermal contractor (not the installer) coming out on Thursday. I'm trying to get some ideas ahead of time. I have another contractor coming to conduct a energy audit (which includes a blower door test). I've spent close to $20,000 on the system already, and I don't want one of these contractors to tell me I need to spend more money on something that's not going to work. That's why I'm taping into the wealth of knowledge on this forum. By the way the past 24hrs the temperature range was 18-35 degrees. Thermostat set at 68 woke up this morning house was down to 63.5. KWs used in the past 24 hrs 174 (ouch). By the way Yes the electric back up heat is off.
Although your unit is larger my 2 ton unit running 24/7 for 30 days in 2nd stage would draw around 1440 Kwh. I would be looking at the well pump or heat strips as others have indicated.
Just got a message from the geothermal contractor that was coming out Thursday. Due to a job running over they rescheduled me for next Thursday. One more week paying through the nose with no answers. I'm regretting this geo system (at least regretting using a contractor that's 2 hours away, and wants to bill me 4 hours before stepping a foot in my door). If the last 2 days electric usage is any indication of the next 30 day bill I'm looking at over $700 (5300 kWh).
Good advice I'll add - do a HE with EWT/LWT and pressures this will tell if unit is running to spec. Versatec is single speed unit with PSC blower so any zone calling brings on full capacity - not ideal with 4 zones.
Update Ok here's an update! If this sounds right please let me know. Any suggestions are always welcome. Last week I had a contractor in to do the flex coil cleaning as suggested by WaterFurnace. Unfortunately we didn't see any change, even with the electric emergency heat on the system was barely able to maintain the house temp at 66 degrees, and on colder night (low teens) it was falling to 59 degrees. My installer was at my house yesterday. The water pressure coming into and out of the system was normal 20 psi, but the water temp. was only 41 degrees (cold even for NY water), and going out around 34 degrees. It appears the installer mistakenly installed my system thinking that my well was 450' deep with the water 18' from the surface when in fact it's 400' feet deep 18' from the surface. This explains why my water column is cooling off. For a temporary fix we have 1 gallon per minute draining off of the system into a drain in an attempt to introduce fresh (warmer) water into the well. After 16 hours the water coming in has increased to 44.8 degrees. My concern here is I have a very low producing well, so this is only a very temporary fix. Emails going back and forth as well as the signed proposal clearly state the well has 350' column of water producing 8 gpm that are returned to the well with zero draw down. Long story short now after paying through the nose for the past 3 winters it looks like I'm going to be paying to have my well drilled down an additional 50-70'. I think the installer should help with the cost of re-drilling, but I don't see this happening.
Something very wrong here. If your system can't hold 60°F while running 24/7 with both geo and a 10 kW electric resistance strip, it seems extremely unlikely that an additional 50-70 feet of well depth will solve the problem. I didn't notice any loop flow rate (GPM) measurements, but your source-side water temp and delta-T seem perfectly reasonable. 41°F EWT and 34°F LWT are well within WF's design envelope. If GPM is anywhere near spec, your WF Versatec 042 is working "as designed" and producing about 30k BTU/hr -- plus another 34k BTU/hr from the 10kW heater strip. .
Looby My system is drawing 8 gpm. Last night was warm (22 degrees), so system was able to keep the house at 68 degrees. Colder nights (single digits and teens) the house will lose 5-10 degrees over night. So if it's not the water column being to cold, do you have any ideas?
A delta-T of 7°F at 8 GPM works out to 28k BTU/hr extracted from the well water -- plus another 9.2k BTU/hr from Versatec's 2.7 kW operating draw. That's a total of 37.2k BTU/hr from the heat pump, which comfortably exceeds WF's 33k spec under those conditions. According to WF's tables, raising EWT to 50°F (even if possible) would yield only about a 15% increase in heat output. In order to turn off the heat strip, it looks like you need about 100% increase in BTU output -- or a 50% reduction in heating load.
My 2 cents worth I use an open well system. (slang: pump & dump) The first year I let my return water go back to within 60 feet of the submerged source outlet. I was not able to return my water through the original surface well piping. To tidy things up, I dug up the outlet line and added 3 1/2" ball valve controlled outlets (under 2 ton capacity) at 3 evenly spaced intervals which fed 3 buried 5 gallon buckets, complete with lid, drilled through like swiss cheeze. This put distance between water out and the source, (this is called Delta "T") and guarantees 100% water return to my water table. SEPARATE NOTE TO THE OBTUSE: To the 2% of people out there that think I am lowering the water table, and stealing water from my neighbors, how do you think rain gets to the water table?
The 2% may point out that you could be returning water to a different (the topmost) aquifer with your poor-mans injection well, thus still stealing from the source aquifer if it is at a lower level. The layered aquifers are common in some areas, and this setup would likely be prohibited there.
