I have been researching geothermal heating and cooling for the last few months and one thing I am always having problems with is understanding how much of an electrical draw a heat pump will have. I find it is very difficult to find an exact amperage in the specifications sheets. Why is this not always included? What is the average electrical usage for a geo heat pump? 20A? 30A? 50A?

I have a generator sizing chart. I think it's from Waterfurnace. I will try to attach it.

With my 4 ton GSHP doing both water and air, this time of year it uses between 40-60 KWH per day.

ChrisJ

Take a look at this thread:

http://www.greenbuildingtalk.com/Forums/tabid/53/aff/13/aft/81031/afv/topic/Default.aspx

FWIW, my 3 ton system with ground loop uses about 8A at 230V.  Aux strip usage is extra the rare times it's needed (tonight may be one of those times as it's already 0 outside).

I live in Western New York it has been about 4 degrees since I woke up at 4:30 AM today. I read my meter almost every day @ 8:00 PM. I have a large house with a 4 ton Climate Master installed in 2012. I have averaged the number of KW's used per day since 2006 and I compare it with what my meter is now reading. During heating season I use about 40kWh more per day with my geothermal than I did in previous years with fuel oil and wood pellets. This comes out to about $4.50 per day. I could not purchase a bag of pellets for $4.50 and if I could it would take 3 or 4 bags per day to keep the house 70. If I was heating with fuel oil I would be using about 5 gallons per day which costs about $20.00 per day. Does that help?

Electrical circuit size would be loosely 10 amps/ton. LRA loosely 60 for a 2 ton and plus 20 for each additional ton.

Thanks for the responses.

Wasn't sure what LRA was, now I see that it is the "starting amps" for an electric motor, as opposed to the "running amps". Correct me if I'm wrong.

joe.ami, Are you saying that the overall amperage requirements for the entire system are approximately 10amps/ton + an additional 60+20 for LRA?

So 3 ton = (10+10+10) + (60+20) = 110 amps total? (and so on)

This seems very high, despite the LRA not being utilized more than 1% of the time.

I am trying to get an overall picture of what sort of electrical draw I am going to be having. I currently have 200 amp service and the largest electrical users are my stove and dryer. Stove is on a 50 amp circuit and dryer is on 30. I am also planning to switch over to electric water heater, which would probably be on a 50 amp circuit.

(Not including everything else) that puts me at 130 amps already, leaving 70 amps left, am I right? So assuming I were to look at a 3 ton system, I would be over by 40 amps, thus needing an upgrade of service?

Again just trying to get a broad perspective here.

We have a 3 ton Waterfurnace Envision NDV038 with 10 kW aux heat strip
and a desuperheater. The desuperheater preheats a 50 gallon buffer tank
connected to an 80 gallon electric finishing tank.

The house is 100% electric with 200 A service. The following is a list of all
of the higher-power circuit breakers, (i.e., everything above 20 A / 110 V):

45 A / 220 V … Waterfurnace Envision NDV038 heat pump
60 A / 220 V … Waterfurnace 10 kW Aux heat strip & ECM blower
30 A / 220 V … 80 gallon domestic hot water heater (finishing tank)
40 A / 220 V … GE Profile electric range
30 A / 220 V … GE Profile clothes dryer
20 A / 220 V … domestic water well pump

Although that comes to well over 200 A, it's not a problem. The breakers have
ample headroom -- PLUS, we retrofitted a softstart (Waterfurnace "Intellistart")
to greatly reduce the compressor starting current and eliminate any dimming
of the lights on compressor startup.

Waterfurnace's electrical specs as follows:
MCC …... 26.0 A compressor Maximum Continuous Current
RLA ……. 16.6 A compressor Running Load Amps
LRA ……. 82.0 A compressor starting current -- without Intellistart
LRA* …... 29.0 A compressor starting current -- with Intellistart
Misc …..… 9.8 A fan motor + loop pump + desuperheater pump
FLA ……. 26.4 A Full Load Amps for total unit, except aux heat
AUX …… 40.0 A 10 kW Aux Heat strip - max current @ 240 VAC

The system has been running for a little over 4 years, without the slightest
problem -- other than the slight dimming of lights on compressor startup --
and the Intellistart retrofit totally eliminated that minor annoyance. BTW,
the Intellistart is now available as a Waterfurnace factory-installed option.