HVAC swap or not?

jchuOctober 10, 2011

I have a 23 YO two story home in SE PA, about 4000 sq ft. Currently serviced by two 3 Ton carrier heat pumps. I am new to the home (and the area), so I have no idea how it performed last winter.

The upper unit (in the attic) uses strip heaters for second stage heat. The lower unit (in the basement) uses fuel oil for second stage heat. The lower unit works great (heat and cool). The upper unit, not so much, but I'll address that in a separate thread.

The chimney sweep has indicated that my chimney (for the fuel oil) is not in good shape and needs to be lined, to the tune of about $1500. I've also discovered that fuel oil is about $3.50, while propane (which I require for other appliances) is about $2.50. I know propane has less energy than fuel oil, but that the furnaces may be more efficient, and require less maintenance.

So I'm considering replacing the lower system from HP + fuel oil to HP + propane with direct vent. I figure this gives me a $1500 "advance" on a new system, by NOT spending it to line the flue, which I won't need with a direct vent unit.

The outside unit (a 697CN036) is about 12 years old. The inside unit appears to be original (though I did not check the coil). While it all works fine, it's not exactly new.

So... I am NUTS for wanting to convert from fuel oil to propane?

They gave me several options -

#1 25HBC536A + CNPVP3621A + 58MVC080-14 + Infinity Stat = 10K

#2 25HCB636A + CNPVP3621A + 58MVC080-14 + Infinity Stat = 12K

#3 25HNB636A + CNPVP6321A + 58MVC080-14 + Infinity Stat = 11K (after rebates)

He also mentioned combination #1 with a 58MCB080-12 for 7500 or #1 with a 58MEC080-12 for 9300 when I asked how often the propane would even be running with the HP.

I don't want to drop to the 80% furnace, because I don't believe they are direct vent, and them I'm back to the same flue problem.

Do I need a variable speed fan? Do I need a 2-speed heat pump? Should I just fix the dang flue and live with it for now?

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You are certain your oil and propane prices are correct?

Normally propane/gal tracks oil more closer.

I like the idea of getting rid of the oil furnace.

I assume you are against an all electric system for downstairs. Correct?

Post back.


    Bookmark   October 10, 2011 at 1:31PM
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Yes, I'm pretty sure on the fuel prices. I know historically they track closer. I'm not sure if the current gap is a trend or an anomoly.

I would be concerned about all electric in the NE. Not so worried upstairs, since it's mainly bedrooms (and heat rises anyway).

    Bookmark   October 10, 2011 at 2:00PM
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You might want to find some work sheets on line for calculating heating costs. The US DOE has some. You plug in current energy and equipment costs to help figure out if the heat pump, oil or propane is the best heat source. Then you get a crystal ball to predict fuel prices and you will be all set.

    Bookmark   October 10, 2011 at 2:17PM
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Is the oil furnace the only combustion source using the chimney? How do you heat your hot water?

A two-stage AC/heat pump is nice to have in the summer if your area has high humidity. The Infinity system does a great job controlling humidity.

You need to calculate the heat pump costs with your current electric rates vs. the 95% furnace using propane. This will give an idea at what temperature the heat pump is more econonical to run compared to the furnace.

    Bookmark   October 10, 2011 at 2:38PM
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You have the right idea. I would prefer propane over oil since you can get 95% efficient and forget about the chimney liner. The main key is to have good high-efficiency single stage heatpumps for the majority of the heating. Oil is always going to be expensive from now on.

    Bookmark   October 10, 2011 at 3:22PM
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I should have clarified. The system I have today is a heat pump, the fuel oil is second stage heating. I intend to retain the heat pump, but change second stage to propane rather than fuel oil.

    Bookmark   October 11, 2011 at 8:28AM
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