Replace 23 year old oil furnace?

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ctviggen

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We have an oil furnace for heat and hot water and two AC units for cooling. We are about to have the two AC units replaced with Mitsubishi "hyper heat" heat pumps, which will do heating down to near zero and cooling. (We have solar panels to offset some of the higher cost of the electricity.)

The same installer recommended we replace the oil furnace with propane (95% efficient), which will also do hot water. The propane furnace will handle heating the house at near or below zero temps. He would install an indirect 40 gallon hot water tank, only because we're in a house with an in-law apartment and could have multiple people showering at the same time. (1 grandma, a family of four with two teen girls.)

My wife and I are in a conversation: replace the 23 year old oil furnace, or try to wait another X amount of years? I just replaced (myself) the blower motor and much else external to the furnace, to get rid of an odd sound that occurred only after the heat ran for a while. This has fixed that issue, and the furnace seems to be operating well.

Everything I read says I should replace, both due to age and efficiency. 20+ year old oil furnaces apparently aren't efficient (I see numbers of 50% - Yikes! - to 70+%).

The quote for replacement would also remove the oil tank, furnace, and existing indirect 60 gallon hot water tank. I assume the propane furnace should be a lot quieter, too, but I can't find any info for how loud this is. The oil furnace is quite loud.

Replace now or limp along a few more years?
 

ctviggen

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Oh yeah, we have propane for cooking and a fireplace. We'd need a bigger tank, though.

And I've tried to compare a 50-70% efficient oil furnace with a 95% efficient propane furnace, but this is an exercise in futility. We've paid anywhere between $1.32/gallon to $3.70/gallon for oil and $2.59/gallon to $3.09/gallon for propane, so you immediately run into a problem as to what to select. And since the propane furnace is only used for hot water and heating near/below zero degrees, I have no idea what actual usage will be. I assume not that much.
 

ctviggen

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Thanks. We already got three estimates. One for geothermal (more expensive, requires whole-house generator, since we lose power a lot where I live, another 20k for that). Another for geothermal (even more expensive) and heat pumps (more expensive than what we're paying with this contractor). And this one, from this contractor.

They did not estimate the water heater, so we would have had the same issue. One would have either used the oil furnace as only the water heater. (geothermal only) One would have used the oil furnace as both water heater and heat backup (geothermal), and I'm not sure for the heat pumps (his estimate was just a number, which is strange since the company is super well known).

We already have a relationship with this contractor, since he installed Mitsubishi heat pumps for the in-law apartment.

The issue is that one of our two AC units died last year. We limped through the season using portable AC units. The other AC unit I"m sure is about to go. 23 years is a long time for an AC unit.

And, the coils and piping has to be replaced, as the refrigerant is no longer supported. So, you're looking at basically a new system.

The contractor we're using does a ton of installs where we live. He's so well known that he's complained to Mitsubishi about certain things...and they listened to him and fixed it.

We could have just replaced the AC units, but since you have to (basically) replace anything anyway, why not go heat pump, which is way more efficient for both heating and cooling? The Mitsubishi hyper heat systems are interesting:


They maintain 76 percent heating capacity at -13F supposedly. Thus, there's still a need for some "make up" heating for the house during the coldest part of the winter.

Since we have solar panels, at least some of the electricity will be "free". Unfortunately, since I live in New England, the time we'll need the most electricity is the winter, when the panels make the least. There's nothing I can to about that, though.

Anyway, if I go to a random contractor for only the "make up" heating and hot water, would they know how to integrate this with the Mitsubishi heat pumps? I'm not sure.

I think I either limp along with a 23+ year oil oil furnace or replace it using the contractor we're currently using.
 

oldognewtrick

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If your luck is anything like mine, the AC fails on the hottest day and the furnace goes on the coldest.
 

lou-in-usa

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You might want to read through my posts from a couple of years ago about the decision making around replacement or repair of an oil burning furnace:
Replace heat exchanger or entire furnace?
Suffice it to say, I found nobody wanted to replace the heat exchanger and only quoted prices for an entirely new furnace. Look at the AFLU numbers of your current furnace, to get a handle on efficiency.

Also, anything electric is an expensive way to heat a house. Do the energy conversions and you will see...and heat pumps are not magical device that make them any more efficient than electric baseboard heating. As for propane, remember that it is a byproduct of petroleum distillation, and therefore subject to the price of oil, and more expensive per BTU than fuel oil. The thing that can be said is that it would be more efficient than oil due to heat-exchanger and burner design, but you'd have to calculate the efficiency gain against the overall cost of the new equipment, and the difference in dollars per BTU.

In my case it would have taken
39 years to recover the price of a new furnace with the extremely tiny efficiency gain.
REMEMBER:
THEY KNEW WHAT THEY WERE DOING 23 YEARS AGO, TOO!
 

Cody C

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I was faced with similar situation. Fuel oil costed me 200 every 2 weeks. I had no plans to get geothermal. Unit with desuperheater, 4 ton unit, heatstrips was almost 14000, my 4 ground loops & headline was 4000. There is a federal tax credit 26-30% in which I got more than 4000 back. Price included 5 air ducts & resized air intake & condensation line as geo is AC.

Propane furnace & mid to high efficiency unit was going to cost 8000-13000. (Heatpump+propane units). This did not include the 2-3k+ for propane tank I'd get put underground or initial propane cost. Neddless to say at 13k after install of cheap or 17k+ for high efficiency I found geo was more reasonable after present tax credit.

Electric bills look like this 70,80,128, 90, 280, 260, 250 (winter high bills)

1500sq ft brick home full basement minimal insulation in mid ohio.
 

BuzzLOL

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When you start using an A/C compressor year around for A/C and heat pump you may discover it only lasts about 3 years or so...
 

68bucks

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Why do you need a standby generator with a geothermal unit and not other units? If you're prone to power outages you need a standby regardless, true?
 

BuzzLOL

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Why do you need a standby generator with a geothermal unit and not other units? If you're prone to power outages you need a standby regardless, true?
Probably need a much more powerful generator for a geothermal unit or heat pump than for just a mere fossil fuel furnace...
 

68bucks

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I can see the greater power need for geothermal since it's all electric but any furnace would need some sort of generator and if you want it to work when you're not home that means a standby. So if that's the goal the cost would be similar regardless of the type of system selected.
 
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