Just trying to ascertain if my geo systems are using a "reasonable" amount of electricity.  I see there is a checklist of questions to be used, but thought I'd post this while I complete my homework!  I live in a northern BC community and have a house that is 2,400 sq ft. on the main with large vaults, 2,400 in the basement, 1,300 upstairs and a 800 sq ft garage all of which is heated via forced air or hydronically (two seperate geo units).  Over the last five days our temperatures have averaged in the -15C to -20c ranges.  On each day I've used between 150KW to 175KW.  Normal 2x6 construction, lots of windows.  I realize the amount of information required to fully qualify an answer, but looing for a reasonability check.  Is there any place where owners can enter their rough stats and see how other peoples systems are functioning?

A few other questions not specific to geothermal, but if yo have nay knowledge would appreciate your insight.

1)  Also have a honeywell humidifier with their fancy thermostat.  Do these typically sraw a lot of power when running?  We are very dry here so I think it runs often.  Also, think it forces the fan on when it wants to run, should this be set to only run when the house is heating?

2)  Are water to water units more efficient then forced air units?  I have a 10 degree differential on my water unit, should this be increased to mpromote longer run times?

Trying to learn as much as possible, but I've never dealt with anything ike this before, so I'm pretty green.

he reason I ask is that he Geothermal company I bought from Nextenergy has a calcualtor that estimates I will only use $1,200 per year based on my house size and location.  This seems ridiculously low, but makes me wonder if my system is performing well given I'll use that in the four months of winter!


Cheers from the North!

You can collect the data to approximate the btu output and get a COP value to check the geo systems - but it's not trivial. You can also take the btu value and the outdoor temps and compare to other's figures for btu/degree day/sq foot. This tells you how the house is performing.

So if your are heating a 4500sqf of conditioned space plus 2400 sqf unconditioned basement in BC for $1200 for the heating season, don't worry about anything ! Water units are as efficient, they are just rated differently.

Doc,

I think the OP is asking whether 150-175 kwh / day is reasonable consumption for the described house, system and present weather. The $1200 per year is an estimate provided to the OP, and he/she fears it might be low based on observed consumption.

Schadwick - two questions:

1) Do you know what your approximate daily consumption has been during times of little or no heating or cooling? That's crucial info to tease out the system's use vs rest of house

2) What is your electricity rate (cost per kwh)

If you have a Honeywell True Steam humidifier, the electric coil is rated around 10 amps and yes some can be wired to run the heat pump blower independant of heating cycles.
J

Ah - I learn something new every day - I hadn't considered heavy electricity use of a humidifer. Boiling water with electric resistance to increase humidity is fairly pricey.

Posted By engineer on 21 Nov 2010 10:52 AM
Ah - I learn something new every day - I hadn't considered heavy electricity use of a humidifer. Boiling water with electric resistance to increase humidity is fairly pricey.

Lesser of evils and a comfort issue. Not a fan of drum humidifiers and flow through models don't deliver much with 95* bypass air soyou are literally pumping money down the drain......resistance coils remain.
j

Thanks for all those taking time to provide feedback.

1) Electricity is about .08 KW.h
2) Used between 50 to 60 KW each day over summer, did have some moderate ac on.

The $1,200 estimate is off of the nextenergy site.

So, if humidifier is using 10 amps plus whatever the fan draws this would account for a reasonable amount of energy use.  Also, on the coldest days I noticed my pre heat tank for hot water is still getting lots of heat.  I don't have auxiliary heat installed at the moment.

I think I'll drain my garage lines as the slab only has a 1/2" insulation under it and we have three doors which I'm sure are not good insulators.

I live in Ontario. My total cost per Kwh last month was (Kwh consumed divided by TOTAL cost of bill)= $ 0.16/Kwh. This includes - Delivery Charges; - Regulatory Charges; - Debt Retirement Charges; What is your TOTAL Cost per Kwh ?/

The most trouble free and energy efficient humidifier I've owned is a misting/spray type one fed by reverse osmosis water (which was there for drinking water already). It has a thermostat so that it only runs when there is warm duct flow.

Total cost is .1143 kw.h but the difference is all taxes.

Posted By engineer on 21 Nov 2010 09:21 AM
Doc,

I think the OP is asking whether 150-175 kwh / day is reasonable consumption for the described house, system and present weather. The $1200 per year is an estimate provided to the OP, and he/she fears it might be low based on observed consumption.

Schadwick - two questions:

1) Do you know what your approximate daily consumption has been during times of little or no heating or cooling? That's crucial info to tease out the system's use vs rest of house

2) What is your electricity rate (cost per kwh)

Well, the info we have so far is that the house is about 4500sqf of conditioned space, has two heatpumps, and is currently exposed to -15C to -20C outside temperatures, but appears to be well heated. 175 KW/day is about 7KW/hour. Subtract a baseload of maybe 2KW/hour for the appliances. Leaves 5 KW as a load for the 2 heatpumps, or 22.4 Amps at 230V. A 6 ton CM heatpump is rated at a total unit FLA of 38 Amps, including Fan and circulation pumps. Probably drawing a bit less right now with higher EWT than rated at, but pretty damned good for -20C degrees outside. I would say a very efficient house, and the heatpumps running very efficient. More info on houseload, the kind of heatpumps and their size would be very helpful to be more specific. You can meassure your temperature delta for the source pipes coming in from the ground. Then you can measure your flow, multiply it with Delta T and multiply this with 485. That get you the amount of heat extracted. (HE (BTU/H)=DeltaT(F) x Flow(GPM) x 485 (assuming antifreeze in the loops)). You then must measure the amps each unit draws when running, know the exact voltage and calculate the Wattage (W=V x A) the heatpump draws, and convert this wattage into BTU by multiplying it by 3412. Then you can calculate your rough COP assuming all the heat from the pumps is converted into heat. You take the HE, add the BTUs from the heatpump running (HP BTU), and divide it by the BTUs from the heatpump running, and you have your COP. ((HE + HP BTU)/HP BTU). With a 70 degree delta between outside and inside and a well insulated house at 4500 sqf, I would expect at least 70,000 BTU of heatload right now. Running this on 22 amps of heatpump consumption is pretty damned good. Probably your house is very well insulated, and your HP performance is very good due to still relatively high EWT from the summer.

Make sure you don't just multiply average amps by volts - power factor will make the number wrong.

Ok...I forgot the power factor. I believe it is around 0.85 for the scroll compressors used in the average heatpump. Multiply VA by 0.85 and you should get a close wattage. Good catch.

Unfortunately, my new location in question only has propane available. Ngas is very economicly and very clean burning. Canada is the largest producer of Ngas. I spend many hrs., educating myself about "Residential Geothermal" for the last 12 months. I will entertain at least 3 to 4 quotes from local Geothermal Installers. I will also demand a Escrow with CD$ 5.000.00. ( A financial instrument held by a third party on behalf of the other parties in a transaction. The funds are held by Escrow.com until it receives the appropriate written instructions or until obligations by by the seller have been fulfilled.) A well informed costumer is a good costumer. Our TOTAL PRICE per kwh including delivery and additional charges to my door in Ontario is CA$0.16. As promoted of up to 70% in savings means nothing. GET IT IN WRITING.(Total Bill deveided by kwh consumed.)

Posted By In the know on 21 Nov 2010 08:18 PM
.... I will also demand a Escrow with CD$ 5.000.00. ....

Good luck with that.    I will give my potential customers a list of references which they can call.   If they don't trust me to the job after that, then we won't be doing business together.

Ditto that.

Posted By In the know on 21 Nov 2010 08:18 PM
Unfortunately, my new location in question only has propane available. Ngas is very economicly and very clean burning. Canada is the largest producer of Ngas. I spend many hrs., educating myself about "Residential Geothermal" for the last 12 months. I will entertain at least 3 to 4 quotes from local Geothermal Installers. I will also demand a Escrow with CD$ 5.000.00. ( A financial instrument held by a third party on behalf of the other parties in a transaction. The funds are held by Escrow.com until it receives the appropriate written instructions or until obligations by by the seller have been fulfilled.) A well informed costumer is a good costumer. Our TOTAL PRICE per kwh including delivery and additional charges to my door in Ontario is CA$0.16. As promoted of up to 70% in savings means nothing. GET IT IN WRITING.(Total Bill deveided by kwh consumed.)

The tone of your demand/suggestion would shy me away as your contractor. While we give a performance guarantee (70 degree inside temperature when 0 degrees outside) and do our best to be right on the numbers with the correct Manual J heat loss, we cannot control the heating patterns of our customers. Especially in older houses on propane, people usually tend to heat them to the lower 60s F, and do not heat the whole house. After switching to geo they tend to turn the thermostat up further since the financial pain with geo is not as much as with propane. In addition, while the energy savings are pretty much a given, a customer paying 16 cents/kwh (like you) will have much lesser $$$ savings than a customer paying 8 cents/kwh. We go the extra mile for our customers in order to build them the best system possible, treat them with courtesy and respect, and have any person interested in geo talk to any of our previous customers and visit any of our previous installs, which are all happy campers. If that is not enough, I will never be able to make that person happy. No reason then to design and build a geo system for him. So while you may spend many hours educating yourself about residential geosystems, you might want to educated yourself a little bit more in courtesy and kindness towards each one of those 3 or 4 guys coming out to you and doing their best to design and build the most efficient system for you. Thanks for filling us in what an escrow is, but here is no such thing as a very clean gas burning. But if that is your notion, may be a very clean propane furnace is the perfect match for you.

If I had a propane furnace it might be where I'd put escrow agreements someone sent me to sign.

In the know,
Geo is intidating for many because of the up front cost. We get it.
Thing is on some of the smaller jobs even though you might be spending 5 figures, the profit margin on the job may not come close to $5,000. So why tie the money up at all.
Contractors have to trust as well. I do not demand that my customers escrow the installments that are due at intervals....
If you were using this as a sounding board for your escrow idea, I think you can consider it a unanimous thumbs down from the contractor's here.

We have also covered before, the contractor aversion to requests off the beaten path (whether reasonable or not). Most contractors shie away from folks with them, assuming where there is smoke there is fire.....
joe