Oil vs gas heating: apples to oranges comparison.

Jean-David Beyer

I have been keeping track of heating my house with my new gas fired mod-con. I also have my last few heating oil bills from before the conversion. I had a big oil tank (1000 gallons, sort of) that I had filled once a year.



2006   480.1 gallons   $1425.90

2007   516.9 gallons   $1535.19

2008   410.3 gallons   $1875.07



I do not know how much oil I used in 2009 because I knew I was going to replace the tank, so I did not have it filled after the end of that season.



2009-2010  484.92 TH    $ 688.58

2010-2011  470.35 TH    $ 690.60 (only 11 months)



The apples vs oranges is due to several factors.



The oil was with a GE boiler of about 1950 vintage, though running with a 1978 or so Beckett burner in it.



With the GE, the hot water was from an electric hot water heater. The cold water to it ran through the coil in the GE to take the chill off it, but I ran the GE at between 130F and 140F.

With the mod-con, the hot water is done with an indirect.

bob eck

oil vs gas

I went from a 30+ year old cast iron oil fired weil mclain with domestic coil to a Triangle Tube PE110 nat gas Prestige Excellence boiler with outdoor reset control.

The last year heating with oil it cost me $2100 for heat and hot water the first year with condensing boiler and nat gas it cost me $1050 for heat and hot water boy what a savings going from oil to nat gas. If I went to a oil boiler with indirect water heater I would have lowered the gallons used but it still would have cost more to stay with oil than going to a nat gas condensing boiler. Great investment

Jean-David Beyer

We are still comparing fruit of different kinds.

I do not think, in some sense, that it is fair to compare a 30 year old oil burner or a 55 year old one with one only a year or two old that burns natural gas. I do not have a state-of-the-art high efficiency oil burner that would make a fair comparison possible. On the other hand, who am I to be fair to? I think it is safe to say that my old boiler had to be replaced anyway, and if I did that with no matter what new boiler, I would have lower heating costs.



My old boiler was "always hot" as contrasted with the new one that is cold start. I did turn the old one off in the summer. The new one runs all year because I now have an indirect fired hot water heater insteas of an electric one.



My old boiler did not have outdoor reset, and the new one does. It changes the firing rate, not a motorized mixer, so it burns as little gas as it can to make the required water temperature. I do not suppose this is the entire reason for my lower heating cost (and additional comfort, since my big heating zone is radiant slab, so with the non-reset boiler I got large temperature swings).



My old boiler did not condense much, since it was not designed to do that. I had its aquastat set to keep the temperature between 130F and 140F, so I probably got some condensing, and I was lucky because I got no leaks. That condensing did not necessarily heat the house, though it did rust out a couple of vent pipes over the years. The new one does condense, a couple of gallons a day in mild weather. I suppose more in cold weather. This probably does help, but my guess is that the most I could get from that is 10% if I condensed all the water vapor in the heat exchanger. This clearly does not happen as quite a bit of "steam" comes out of the vent pipe, especially when it is heating the indirect.



Right now, my gas costs me $1.4577 per therm including delivery and monthly fixed charge. I do not know what heating oil costs, but gasoline was over $3.50/gallon the last itme I bought some. But it seems to me that there is a glut of natural gas on the market keeping the price down. At some point, my public coal-burning utility will find gas to be cheaper than coal, and then gas prices will go up.



So clearly, a new boiler is likely to be more efficient than an old one. But whether that is because of modulating, condensing, different fuels, outdoor reset, or just being a more apropriate size, I could not say. Probably a combination of all of these.

chapchap70

Oil Equipment could have done as well

There is oil non condensing equipment that could have easily saved you 15 to 30% on fuel usage.  If only oil prices would come down. 



Did you figure in the extra electricity costs of domestic hot water usage?

Jean-David Beyer

extra electricity costs

I do not know how to figure them. I have electric stove and electric clothes dryer and do not meter those things separately. Furthermore, I ran the cold supply through the hot water coil of the old GE boiler to take the chill off in winter. And the circulators on the new boiler are Taco 007s. So calculating this fine on the electricity and oil usage is just kidding myself due to lack of data.



I agree that new oil equipment would have done lots better than the old boiler, but I am not sure it would do as well as the gas. For one thing, unless it is cold start, I would have had to run it all summer. For another, I would have had to replace the oil tank, and I could not get permission to put a 500 gallon tank on the property. And since it is now two years since I had the old tank removed, and still trying to  get the almost $50,000 to do the remediation, I do not want to get a new oil system anyway. The state has a program to help, but it is out of funds.