Cost of Heating Fuel

13 years ago

I am having a Hybrid system installed next week. (Oil Furnace & Heat Pump.)

Can someone point me to a method to calculate heating costs using the oil furnace versus using the Heat Pump given I know the cost per Kw-Hr of electricity and the cost of heating oil per gallon.

It would seem that these two values some measure or amount used per unit time could be incorporated into a thermostat control.

Not having ever had a Heat Pump, I don't yet know when the heating task is taken from the heat pump and assigned to the oil furnace. Outside air temp?

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Comments (10)

User
Original Author
13 years ago
Ooops.... I found this discussion of the relative costs of heating by furnace and heating by Heat Pump.

http://ths.gardenweb.com/forums/load/hvac/msg110023096458.html
weedmeister
13 years ago
This switchover point depends on several things: the heating efficiency of the HP, the insulation and 'tightness' of the house and probably other things I can't remember. A thermostat determines when to 'switch over' (to auxilliary heat) when it sees that the HP can no longer raise the temperature of the living area in a fixed amount of time.

Some thermostats allow the sensing of outside temperature. They then can be set to switch to auxilliary heat when the outside temperature is below a predetermined (and adjustable) value. This value would (I suspect) be determined by both room comfort and wallet comfort.
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creek_side
13 years ago
"Not having ever had a Heat Pump, I don't yet know when the heating task is taken from the heat pump and assigned to the oil furnace. Outside air temp?"

Depends on the thermostat. Do you know what make and model will be installed. Set up wrong, there is the potential for running the backup heat when it really isn't needed.

If the thermostat is sophisticated enough, you can set it up to maximize comfort, or you can set it up to minimize heating expenses. The installers should discuss it with you in detail. From my experience and from reading numerous posts, they seldom bother.
User
Original Author
13 years ago
The equipment will be:

Carrier Performance 80 Series - 80% variable speed oil furnace model #58VMR105-1-12.
Input 105,000 BTU and Output 85,000 BTU.

Carrier Performance Series 16 SEER Heat Pump model #25HPA636A.

Matching Carrier evaporator coil model #CNPVP4821.

New Carrier programmable thermostat model #TP-PRH-A with outdoor temperature sensor.
tigerdunes
13 years ago
saltidawg

I would analyze your fuel costs and comparison very carefully. oil is a wonderful heating fuel but if operating costs are important to you, I would chuck the oil altogether. there is no doubt oil will go back up and exceed its record highs.

any chance of nat gas availability?

IMO
User
Original Author
13 years ago
tigerdunes,

My heating costs are VERY low. I keep the temperature right around 60 degrees during the day and in the wee hours. We keep the house at around 64-65 from 5:00 PM to 10:00PM.

I currently have a 37 year-old Bryant furnace that has been well maintained, but I suspect was oversized when installed.

My wife insists that I insist on having oil heat so that I occasionally can get a whiff of the smell of diesel fuel. (I am a retired Navy Submariner and that odor brings back memories of years past. :-)

Gas is not an option at my location and electricity is very high here. If I've done the math correctly, at 28 degrees outside, my furnace burning $3.30 a gallon heating oil and my heat pump using $0.19 a Kw-Hr electricity are about even as far as cost.
tigerdunes
13 years ago
salti

I respect your reasons. I would just be certain that you are sized correctly especially on the oil furnace.

IMO
User
Original Author
13 years ago
Thanks tigerdunes.

I had an interesting change to my heating situation last winter. I have a two-story, 4 Br colonial home. Built in 1973.

18 months ago I had blown insulation added to the attic floor at an R-38 value. The rest of the home is original - single pane glass windows, likely air leaks all over, etc, etc.

With the additional insulation, now when the furnace runs the upstairs has less heat loss due to the added insulation and the temperature upstairs rises quickly. The thermostat is upstairs and sensing the rapid temperature rise, shuts down the furnace. The result is that it is now too cool downstairs and toasty (64 degrees) upstairs.

My solution last winter was to run the furnace fan continuously for a few hours. This worked fine.

I did try shutting down on the heat registers upstairs as opposed to running the fan continuously, but the fan solution seemed more comfortable.

There are numerous homes in my development with my floor plan and each and everyone of them suffer from an inability to adequately cool the second floor. It is my belief that the 1973 duct design and fabrication leaves much to be desired. I'm hoping the variable speed fan will help this situation out - coupled with that extra attic insulation. As far as I know, no one with my floor plan has installed a heat pump. I am eager to see if it works out.

My solution to the 2nd floor A/C lack has to install a window unit in the 2nd floor MBR. As we are empty nesters, that works out fine for us.

I really am grateful for the help I've received here in the last week or so. Great service for we homeowners.
tigerdunes
13 years ago
saltidawg

it is my experience that added insulation is more cost effective as far as comfort and reducing the load whether heating or cooling than new dbl pane windows.

If I was in your shoes, I would ask dealer to take a look at adding dampers to the supply lines to the upstairs/downstairs to better balance the floors. usually it it is not too expensive. of course, zoning controls would be even better but that comes with a price.

BTW, was a load calculation performed especially on heating?

Good luck on your new system.

IMO
User
Original Author
13 years ago
tigerdunes,

Yes, a heat load calculation was performed.

I understand the insulation and window replacement point you make. I paid $1000 for the blown in R-38 attic insulation in my 1,000 Sq Ft attic.

I have no plans to replace windows at this time. (Next project will be a re-do of the master bath.

In five years or so would love to sell and move closer to my grandchildren. (Either CT or IN.)

I've been fully retired for 15 years. I have the "perfect" wife. (That's a wife that has a job AND loves it.)

Cost of Heating Fuel

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