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papavino 12-01-2009 02:54 PM

Oil to gas furnace conversion
I'm looking to deep-six my oil heat in favor of natural gas. I've talked to a two places so far and for a 95% efficiency furnace, I'm looking at about $5000+. Tack on a water heater and it is up to $7000 after I factor in our wonderful 9.5% sales tax. Does this sound about right? This work doesn't include decommissioning the oil tank (another $600), but does include removal and recycling of the old furnace and water heater. Ugh. Money.

dmun 12-01-2009 04:59 PM

Re: Oil to gas furnace conversion
Watch out for the oil tank. I had a friend who had a leak in the underground oil tank and the excavation, disposal, and soil remediation was a five figure expense. It was so expensive that the new furnace seemed free.

The geniuses also planted it under the driveway, so repaving the driveway was a separate, large, expense.

papavino 12-01-2009 07:21 PM

Re: Oil to gas furnace conversion
So they didn't have PLIA insurance? I'm thinking of having it pumped, cleaned and filled in place. The whole tank thing just scares me.

tfasz 12-01-2009 10:11 PM

Re: Oil to gas furnace conversion
We did the same oil to gas swap about 5 years ago and if I remember it was ~$3500 for the new furnace (80,000 btu 2-stage ~92% efficiency - the variable speed one was about $1k more). The tank decommissioning was $600 like you said. In WA state they changed the law about 10 years ago to no longer require soil testing to decommission an oil tank. You will just want to have proof of cleaning and filling if you ever sell the house.

Yeah - we get killed with sales tax but some states have comparable sales tax and then also have a 10% income tax (no income tax in WA). I'm just so glad I don't have to do 2 tax returns anymore... ;-)

BTW - I do miss our oil heat somewhat. The gas furnace feels like it puts out twice as much air to do the same heating and you end up with lukewarm air coming out of the vents. Especially since the ducting was designed around an oil furnace.

altamont 12-02-2009 08:01 AM

Re: Oil to gas furnace conversion
A word of caution! I know of a lot of people that have converted from oil to gas and they made this one mistake. Even without the high efficiency step a change from oil to gas requires looking at resizing the chimney - generally requiring a reduction (most often accomplished by dropping in an appropriate metal liner).

Without this being done a LOT of water vapor condenses in the chimney, migrates out and causes extensive water damage. Happened to my father and those others I mentioned at the top of this post.

The problem is even worse when the efficiency of the gas furnace gets better and better! As efficiency improves, the temperature of the flue gases (exhaust) drops more and more. That leads to less and less draft (i.e. tendancy to rise within a chimney).

Now, IF your gas furnace has a pressurized exhaust that literally blows the exhaust outside of the house you should be okay. I could bore you to tears on just that tube going from the furnace to the outdoors. I designed a whole system (new way to join metal pipes plus the high-temp gasket) for ProTech Systems in Albany, NY that manufactured my design under the name "Vintinox". Wish I had a penny for each pipe made using my design. I would avoid any systems that use plastic pipe for that exhaust as the plastic gradually breaks down from the very tiny amounts of acid that form inside the pipe.

Find out if our new furnace will have a brand new exhaust system that blows the exhaust outside or what the installer will do to properly size the chimney. Otherwise look forward to some big expenses in just a year or two...

papavino 12-02-2009 11:13 AM

Re: Oil to gas furnace conversion
Yeah, the quote included running pipe directly out the side of the house. The water heater will also be relocated and the exhaust from that will go up the chimney. We looked at tankless, but the cost seems a bit prohibitive at the moment.

Doing our part to keep people employed...

dmun 12-02-2009 06:33 PM

Re: Oil to gas furnace conversion
Maybe you want to install an electric hot water heater so you can divert the existing flue for an indoor oven!

papavino 12-03-2009 09:28 AM

Re: Oil to gas furnace conversion

Maybe you want to install an electric hot water heater so you can divert the existing flue for an indoor oven!

Maybe I can convince my wife that it will be worth our while after a winter's worth of trudging outside in the cold and rain to cook pizzas and bake bread.

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