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View Full Version : Heat Pump pointless? (check my math!)

hp_dude32
10-25-2006, 01:38 PM
EDIT, hold the phone, I might be comparing apples to oranges here, electricity is an hourly rate, versus physical volumes for gas and oil.

Oil is fairly close as I think our old Aero burner did 1 GPH.

But, rate should not make a difference in overall delivered heat per unit cost, right? (rate just determines how fast you spend that money!)

-------------

I gathered the -real- cost of gas, oil, and electricity in Eastern Ontario and some odd thing appears!

At first blush, a heat pump with a 2.5 COP still cannot match the BTU/cent of gas.

Keep in mind that the gas and electricity prices include substantial "delivery" costs, the actual cost of the "product" is nearly meaningless!

Here's the data:

Gas:

1 Cubic Meter = 35.32 Cubic Feet = 36,409 Btu

1 Cubic Meter = 42 cents (200 m3/month rate)

1 Cubic Foot = 1.19 cents (200 m3/month rate)

866 BTU/cent

Heat out = 94%, or 814 BTU/cent

Electricity:

1 kilowatthour of electricity = 3,412 Btu

1 kilowatthour of electricity = 13.2 cents

258 BTU/cent

Heat out: assume a 2.5 heatpump COP: (2.5x258) = 645 BTU/cent

Fuel Oil:

1 Gallon = 139,000 Btu

1 liter = 36,720 Btu

1 liter = 60 cents

612 BTU/cent

Heat out = 80%, or 489 BTU/cent

What gives? Was the heatpump a waste of time?!

Is our gas cheap, and our electricity expensive?

Ideas?

[Edited by hp_dude32 on 10-25-2006 at 03:02 PM]

pstu
10-25-2006, 02:07 PM
It could be your calculations are perfectly OK but you are asking a subtly wrong question. I would probably go with a heat pump in your situation too. Keep in mind the price points you use are for today only. What your decision really rests upon is the FUTURE price of each commodity, and of course neither you or I can know that with any certainty.

The argument for electricity rests upon the idea its price will not rise in the future as much as natural gas (NG). If I am not mistaken much of your Ontario electricity is nuclear based, and its operational cost is quite low and not likely to rise much in the future. Coal fueled electricity has much the same argument as nuclear, however I don't recall whether your region generates much using coal. Overall in North America I do believe it represents 50% of electric generation, so you might be burning lots there too.

Natural gas on the other hand, appears to have peaked in North America in terms of physical production. What supply there is, faces demand competition from certain industrial uses. I am thinking particularly of certain types of oil production, which is big in your country although not your province -- what they are doing in Alberta is capable of consuming huge amounts of NG. Where I live in Texas the price of electricity is pretty much based on NG fuel prices, and it hurts! Although we have seen the spot price of NG cut in half, there is little assurance it will stay down for the next 5-10 years. And our electric prices remain much higher than yours, and damitall we burn a lot of the stuff in summer!

LNG imports from other parts of the world (where NG still is plentiful and cheap) will relieve some of the price pressure, but LNG economics requires fairly high NG pricing or the plants won't be there to supply *any* LNG. In my opinon, better to have lots of LNG supply at a high price, than to have low pricing and short supply. But even LNG imports are a stopgap solution to the problem of dwindling North American NG production -- maybe good for a decade, who knows after that.

One major variable is the strength of the world economy, as NG consumption will track a country's GNP. I would not wish a depression on any (non-hostile) country, but if one occurs then demand will slow and pricing will be lower for those of us that have any money.

Overall my opinion is that your heat pump is a logical choice, as NG pricing has several reasons to go up in the future. I think it will. Looks like you will pay a bit more near-term but I expect you to save money long term.

Best of luck -- Pstu

[Edited by pstu on 10-25-2006 at 02:13 PM]

hp_dude32
10-25-2006, 02:24 PM
Yup, Ontario has about 33% nuclear, and 25% hydroelectric, 30% gas/oil, and the rest coal (being phased out by 2009).

I'm still trying to figure out if there's a serious flaw in my analysis...

Regardless, the new furnace will be a vast improvement over the oil furnace, particularly when you include electricity savings. (Infinity 96 uses about 200W (1.85A) -overall- on low speed heat!!)

If I'm right, I guess you simply disable the heat pump and use it as an AC unit until the prices make it practical. (as before, the opportunity cost for the heat pump was pretty small...)

Hmmm....

[Edited by hp_dude32 on 10-25-2006 at 02:27 PM]

tecman
10-25-2006, 07:26 PM
Your gas efficiency of 94% is unrealistic. 90% is possible with a condensing furnace and the right conditions. 85% is a better average output.

Paul

fortressofcomfort
10-25-2006, 07:36 PM
I agree with pstu; for now NG is cheap but wait 5-10 years. But really, WHO KNOWS?
In these days, energy is bought, traded, and sold daily and therefore the commodity or retail prices can change almost overnight.
That's the beauty of dual fuel, you can choose which energy source is most appropriate at that time. And times surely change.
There will surely be times when the heat pump will be worth having.
Cheers!

p.s. 25% hydro is pretty remarkable, no? I think in MD we get about 3% from hydro.

smokin68
10-25-2006, 09:10 PM
Your gas equation isn't correct, and you're figuring a heatpump at it's lowest efficiency.Your price per cu ft of gas can't be higher than the price per cu meter. If you divide your 36409 btuh/cu ft by the 119 cents/cu ft, you get 309 btuh/cent@100%.

beenthere
10-25-2006, 09:13 PM
Originally posted by hp_dude32

-------------

Here's the data:

Gas:

1 Cubic Meter = 35.32 Cubic Feet = 36,409 Btu

1 Cubic Meter = 42 cents (200 m3/month rate)

1 Cubic Foot = 1.19 cents (200 m3/month rate)

866 BTU/cent

Heat out = 94%, or 814 BTU/cent

If 1 cubic meter equals 35.32 cubic foot,then why does a cubic foot cost more then a cubic meter.

pyropaul
10-25-2006, 09:19 PM
Originally posted by fortressofcomfort

p.s. 25% hydro is pretty remarkable, no? I think in MD we get about 3% from hydro.

Here in Quebec it is over 98% and is closer to Can\$0.07 per kwh ... so heatpumps are very economical to run, especially GSHPs with their pretty much constant COP.

Paul.

gas1
10-25-2006, 09:42 PM
you need to get each fuel converted to Therms, or cost per 100,000 btu's and all heat pumps are better than Strip Heat

hp_dude32
10-25-2006, 09:55 PM
Originally posted by beenthere
If 1 cubic meter equals 35.32 cubic foot,then why does a cubic foot cost more then a cubic meter.

Huh?

Seems to be a lot of people can't read a simple decimal! "1.19" cents is a little bit more than once cent, not 119 cents!

(the cu ft. was just there for illustrative purposes anyways, it has no bearing on any of the calculations...)

Anyhoo, no matter if you use BTU, therms, GJ, or Dekatherms it'll all work out to the same proportions.

Certainly, anything above super-cold, HP's are more efficient than strip heat, but that is not the primary observation here. (gas vs. HP)

Bottom line seems to be that in the particular case of central/eastern Ontario, the cost of electricity is too high to make a heat pump viable, assuming you have gas available.

The most disconcerting part is that our Carrier rep was singing the praises of how much more cost-efficient heat pumps are, which in this region's case is simply wrong, and has been probably for at least the last 3-5 years!

I'm not unhappy that we went for the Infinity hybrid system, as with the rebates and the very competitive quote, it was a no-brainer, but it's a bit of a shock to find out that the HP operating costs are -higher- than gas!!

Hmmmm....

[Edited by hp_dude32 on 10-25-2006 at 10:03 PM]

hp_dude32
10-25-2006, 10:06 PM
Originally posted by tecman
Your gas efficiency of 94% is unrealistic. 90% is possible with a condensing furnace and the right conditions. 85% is a better average output.

Paul

Won't substantially affect the outcome, the difference is too great. The worst case would be near-parity, which is still pointless if you didn't get a really good deal on the HP, versus just an equivalent AC unit with your furnace.

Also, the Infinity 96 is rated at 94.1% AFUE by the US Government...

[Edited by hp_dude32 on 10-25-2006 at 10:17 PM]

browntigerus
10-25-2006, 10:56 PM
First 13.2 c/kWh very expansive.

Our kWh 9c (US) per 400kWh
4.9c per rest

10% discount for HP

So like I have to compare 4.5c/kWh to ( 100c/cF Ng + 26% Surcharges) * 0.8

beenthere
10-26-2006, 05:34 AM
Originally posted by hp_dude32

Originally posted by beenthere
If 1 cubic meter equals 35.32 cubic foot,then why does a cubic foot cost more then a cubic meter.

Huh?

Seems to be a lot of people can't read a simple decimal! "1.19" cents is a little bit more than once cent, not 119 cents!

LOL, missed the word "cents".

cem-bsee
10-26-2006, 07:13 AM
this is Canada -- which has HUGE gas & oil holding shale reserves!
anyone ever hear of the 125+ y/o power plant at Niagra Falls?

I believe one should first conserve = tighten the envelope.

do you know your heating costs per DegreeDay per sq ft? -- for 5y?

I am lost as to your fuel costs:
elec: \$/kwh=?
nat gas: \$/cm=?

[Edited by cem-bsee on 10-26-2006 at 07:19 AM]

hp_dude32
10-26-2006, 08:43 AM
OK...

I got the specifics for Ontario Hydro rates (Hydro One).

- 11.56 cents per kWh based on measured and derived usage

- a flat fee of \$11.55/month

Derived usage is a slight increase of your meter reading based on transmission losses.

If you use 2000 kWh per month, you're looking at 12.5 cents/kWh.

If you use more or less, the fixed cost will be amortized higher or lower, giving you a slightly higher or lower per kWh rate. (if you use 1000 kWh, it's around 13.2 cents)

About my putting the HP COP on the low-side, that's simply taken directly from the Infinity 16 HP ratings sheets, and biasing up slightly, as the "high-temp" COP is pretty much pointless, and the efficiency curve of any heat pump rises sharply as you reach the 30 degree area, thus making the high COP a bit misleading. (see any balance point worksheet...)

Regardless, even if you assume a "low" 12.5 cents/kWh and an unlikely average COP of 3.0, you are -still- above the cost/BTU of natural gas!

Gas is on the way down fast, electricity is going nowhere fast in Ontario, except up! :(

Bottom line, think of a heat pump in Ontario as a back-up heat source to gas, not some silver bullet of efficiency.