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converting Oil boiler to burn natural gas

My wife and I are interested in converting from oil to natural gas for a few reasons....however needing a new boiler is not one of them. The boiler that came with the house when we bought it a little over a year ago is a Columbia EM 85, 120,000btu/hr furnace that now is only 2 years old. We'd like to convert, but only if it is possible to convert this boiler to burn on natural gas. I know there are many variables to consider when switching fuels, (usage, cost in our area, insulation etc) but need to know if this is even a possibility. One of the main reasons we want to swtich is to get the oil tank and propane tank out of our back yard so that we can put on a deck off the back of the house. right now they're both in the way and the oil company gave us a quote of $2,000 to put a new tank in the basement...if we can put that money into the gas conversion, then we'd rather do that. Thanks for any help and for listening to my rambling!

Re: converting Oil boiler to burn natural gas


You're right! There are a lot of issues to consider with a possible conversion.

Generally speaking, I recommend staying with the fuel for which the boiler was designed---oil.

I take it you don't have natural gas pipelines available in your area (since you mention propane)---if by chance you DO have NG available, the gas co. is often anxious to offer you a deal that will take out the present boiler & install a gas-fired boiler at low cost---sometimes at NO cost.

There are gas-fired burners (designed to replace just the oil-fired burner portion of the system you have now) made by Wayne (P250 series) and others that cost approx. $500 plus labor designed to be installed in oil-fired boilers, but you'll probably get a drop in efficiency with a boiler combustion chamber designed for oil.

You should also Google "fuel cost comparison" to get some on-line charts that will compare the local cost of propane to the local cost of fuel oil in your area---call the local dealers of both fuels & get the current prices---if one fuel is drastically less expensive than the other, then this will be a factor to consider in your decision.

This brings us around to your current relationship with your oil dealer---if you have a yearly contract (as most homeowners do) you will have to decide if you want to go outside this relationship & seek the estimates of other oil dealers & heating contractors in the area.

The $2k estimate for an inside oil tank seems way high to me---a Granby or Highland 275 gallon steel oil tank is designed to fit down most cellar stairs & costs the dealer under $300--there is additional cost of fill piping in and out of the cellar so that the tank can be filled thru the outside foundation with a vent pipe required according to code, but material cost would be under $500--I can't see $1500 labor for such a job, unless you have some unusual basement configuration where access is greatly limited---for this there are Roth double-wall polyethelyne tanks which have a slimmer configuration.

If your current outside oil tank is not rusted, even THAT can be used & brought into the basement---outside steel tanks are unsightly & rust out eventually due to weather exposure---they will last for decades inside a basement.

Most town codes allow storage of up to 1000 gallons (check your town hall for storage limits) in the basement (4 steel tanks or Roth tanks)---if there is room in the basement, this is an option that pays for itself in a few years, since you can buy all your oil in June/July when the price is low on the spot market for a much lower price & avoid the expense of connective piping to the outside.

Fuel oil has no danger of exploding, & in fact under normal conditions, won't even ignite in its liquid state---it has to be atomized by the oil burner & a high voltage spark applied for ignition---granted, it is a slightly dirtier fuel, requiring a combustion chamber /heat exchanger cleaning once a year.

If you can get additional estimates from other heating contractors (Yellow Pages: "Heating Contractors", "Oil Dealers") you'll probably get a much better sense of what to do in this circumstance for a more reasonable price.


Re: converting Oil boiler to burn natural gas

Thanks for the in-depth reply! I'm interested in the Wayne burners since they may work, however I'm concerned with a reply I received from the boiler manufacturer....

"The EM 85 does not have a gas conversion kit. The unit is too small to fire with gas and get the necessary BTU’s. Because gas only has 100,000 btu’s per therm you would cause condensation in your boiler and your chimney and have the potential of corroding both very quickly."

Any thoughts on this...would the wayne burners reccomended still be applicable, or should we just forget about the conversion until this furnace wears out down the road. Thanks!

Re: converting Oil boiler to burn natural gas


The middle paragraph in your last post has considerations that would seem to lessen the likelihood that a conversion should be done--but it wouldn't hurt to get several additional opinions from other installers.

Since you have a late-model oil-fired boiler, they are usually more "moveable" than older models; one of the prospective installers may have a waiting customer that needs such a unit and can make you a reasonable offer for a trade over to a propane-fired install.

jim hankinson
Re: converting Oil boiler to burn natural gas

Many boilers are not suitable for conversion to gas. If the manufacturer says no and it's done anyhow, if you ever had a malfunction that caused damage the person that did the conversion would be liable. Actually, considering that there would most likely have to be a permit taken out to do the job it may not pass inspection.

Many gas utilities do give away free boilers but consider this: they are in the business of selling a product. The more you use, the more money they make. Therefore, the "free" boiler they give you is not all that efficient.

If you are set on converting to NG then shop for a high efficiency model. The difference in cost between the "free" boiler and the high efficiency will be made up in a few years.

Re: converting Oil boiler to burn natural gas

Well, the manufacturer would know. On the other hand, they may be simply covering their ass incase it doesn't work out for you.

I would not be surprised if it could be done. Sorry I am not qualified in that area because I don't do natural gas boilers.

Yours is a good boiler. It is low mass, steel which can be shut down when there is no call for heat. That saves you way more than higher afue would. It is similar in that way to the Laars Max boiler which has a gas burner, as well as the Energy Kinetics boilers that use either gas or oil burners. I would find out what burners they use and have your local tech decide.

In any case, to improve the system efficiency, I would not use the in boiler "tankless coil". I would change to an indirect tank system which is another zone.

Re: converting Oil boiler to burn natural gas

As for fuel tanks, here in Alaska they get buried and NEVER put in a basement.

When I went to learn about boilers in Concord, MA, I was shocked to see that.

Our tanks are coated with tar or something like that to keep the soil off of them. They last indefinitely down there. Even on the very old houses in town you never hear of problems. Leaks would be evidenced by high oil use in summer when the usage should be low, for hot water only.

So, if you can get a reasonably priced contractor, maybe there is a location for the tank that would work for you.

Re: converting Oil boiler to burn natural gas
JC80 wrote:

Thanks for the in-depth reply! ....The unit is too small to fire with gas and get the necessary BTU’s. Because gas only has 100,000 btu’s per therm you would cause condensation in your boiler and your chimney and have the potential of corroding both very quickly."

This statement makes no sense in that a therm is defined as 100KBTU no matter what fuel you are talking about.
Nat. gas is explosive if it leaks out. On the other hand, oil burners are only about 85% efficient and gas furnances may be 96% efficient.
If the manufacturer doesn't make a burner for Nat. gas forget the conversion. As a licensed boiler person, I would never go against the Manufacturer's recommendations even if I thought they didn't know what they were talking about. Its a liability thing.

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