Modcon vs fuel oil savings

Vernon P. James_2

As a contractor I get asked a lot lately with fuel oil hovering around $3.50 If replacing boiler which is more efficient oil or propane condensing. Now I know the answer. My old oil boiler a 48 dynatherm scotch marine with domestic hot water coil was getting in tough shape physically and definitely needed replacing. I had converted it to a Riello burner several years ago and down fired it from 1.8 gph to 1.10 gph. Combustion efficiency of 86 1/2 %. No outdoor reset just plain aquastat settings of on at 160 off at 180 to make the domestic. House about 3000 sq ft radiant max water temp needed 140. I pondered for several months what to replace it with. Born and bred on oil. 99.99% of service is oil kept leaning to oil. Had installed a Utica UB95-200 last year for a new house. Unit was very impressive with the modulation and outdoor reset. Logic says modulation has got to be the way to go as only using what is required. I finally decided to go with a Trinity 200 combi. The deep turn down modulation was the enticer. My heat loss is only about 105,000 but chose the 200 to get enough domestic capacity from the flat plate. (with wife, 2 teenagers, and a 2 1/2 year old we use a lot of hot water)

I closely monitored my fuel oil useage for November and December. Average of 6.4 gallons per day for heat and hot water at an average price of $3.40 per gallon equates to $21.76 per day cost. Fired up the Trinity December 28. Average of 8.48 gallons of LP per day at average cost of $3.00 per gallon equates to $25.44 per day cost an icrease of $3.68 per day average cost.

The Trinity is truely a mechanical wonder. It modulates and makes condensate like crazy. I love to sit there and watch it work. A lot of modcons are being installed in this area right now as the wave of the future. Unfortunately though my actual numbers show that the difference in 91,000 btu per gallon of LP and 140,000 btu per gallon of fuel oil is not enough to overcome the advantages of modulation, condensing , and outdoor reset unless the price of propane drops a lot lower than fuel oil. The history here though has been that LP usually runs about .50 lower than fuel oil so I don't think it will ever be cost efficient.

I am now pondering installing an indirect instead of the flat plate to buffer the domestic usage. Everytime a faucet is opened the Trinity comes on at high fire and then modulates down as set point is reached. I am not sure if an indirect would really save anything. The wife is already not impressed that my new boiler that was supposed to save us money is actually costing us more money to operate. Might have a harder time justifying more expsense for an indirect now.

Darin Cook_5

It is a toss up sometimes on savings

How cold has it been up in Saranac Lake? There is a condensing oil boiler coming out on the market in the near future that will give oil customers some really great cost savings ability. In your own case, the shoulder seasons will be when you will really see some savings out of your mod-con and thus reductions in overall operating costs.

How was winter carnival this year?






Darin

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Eric L._2

Darin Cook

Are there any details on the condensing oil boiler coming out on the market in the near future that will give oil customers some really great cost savings ability?!! Thanks

kpc_11

that confirms....

what I tell customers about using LP for heat. Th amt. of BTU don't even out the $$$ for oil vs. LP. Hindsight is always 20/20. Thanks for the info. I might think about putting on a 115 buderus before doing the indirect alone. Maybe you can find another home for the trinity....kpc

Unknown

I suspect that a large part of your expense is that your boiler is oversized. With an indirect instead of a flate plate you could probably get by with something like a Knight WBN150.

The result would be that your return water temp would be much lower and you would be condensing more.

My experience after a year an a half with a Knight KBN105 after replacing an old dry base Amer Std oil [appprox 70% eff.] is a 25% real dollar savings in overall annual fuel cost.

Darin Cook_5

Eric

Just watch the trade magazines!




Darin

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Mitch_4

you relate only

the cost divided by the number of days. Not really a fair compoarison in my mind..how many degree days were involved? in the time frame if the average temp in Nov / Dec was 35, and the ave temps since the mod con was installed was 20, then the mod con IS saving $$.

Its like saying I used the old oil boiler from june to sept, and the new from sept to dec, and my costs went up.

I know around here Nov and Dec while colder than last year was still pretty mild compared to the temperatures since Christmas.

Do you have the degree day comparison available?

Inquiring minds want to know

Scott OB

Knight

I was a complete oil guy until I started construction on my new home.I did research on the internet and found this awesome site,which I visit daily.I went with a Knight KBL-105 after lots of research.I just finished wiring it and fired it up two days ago.It is sooo quiet compared to the Buderus oil fired in my last house.Also I didn't have to put multiple oil tanks in my basement to purchase low priced oil in quantity.I didn't pay my mason to construct a chimney.I put a 1000 gallon underground LP tank in for the fireplace,clothes dryer,range and boiler.The propane I buy is about $1.00 a gallon less than oil.I have great buying power for both oil and propane beacause of my business.Also it is getting very costly to have a oil system cleaned annually.I like the clean burning LP unit.Oil is out for me for now.

Uni R_2

Propane *should* cost less per gallon...

#2 heating oil is 139,000 BTUs per gallon. Propane is only 91,000 which means that a gallon of propane has just under 2/3rds the energy of a gallon of heating oil. At $3 for oil vs $2 for propane, the prices are actually just about even (propane at even $/BTU would be 1.96/gal).

Vernon, as Mitch says, you need to add up the daily heating degree days for those periods (www.wundergound.com will have them, so will most oil suppliers) so that you can compare consumption and daily costing on a per HDD basis. Otherwise, it's not a very meaningful number. A typical house would burn twice as much fuel on a day averaging 5° compared to averaging 35° but they'd be even on a per HDD basis.

Don Knuth, isn't the minimum modulation of the Trinity 200 25 MBH vs 30 MPH for the Knight 150?

Unknown

Trinity modulation

Uni R -
You may be right about Trinity modulation. It used to be 5-1 but it may have changed. I just checked their website but all I could see is they have "Industry Leading mnodulation".

I hope I didn't give the impression that I was deriding the Trinity [I don't think that was your impression].

The fact is that the boiler will fire at 100% on occasion and decrease from there. The result will be high return temperatures and less condensation.

Rocky_3

Very timely discussion as I, too, am changing

Currently have a Weil Ultra gas heating a 7000 sq. ft. shop/apartment building. Have a personal beef with the gas supplier here in town. Am converting back to oil as a "personal protest" over something they did. A personal thing. But I digress. Am going to put in a System 2000 oil boiler. Hope to have it installed in the next two weeks. Will keep you informed how it compares on a degree day basis. Will be hard though as the last 4 weeks have averaged about -35 below (-25 during day, -45 at night). I HOPE we don't have that again but being the product of a fine public school here, I can do the math and come up with proper degree day comparison. Should be interesting to see the real time numbers. Will keep you all posted.
Warm regards,
Rocky

bob eck

you could look at installing a fiberglass holding tank (ut40, ut80, ut120 well mate) just before the plate heat exchanger to temp your incoming water temp before going into your heat exchanger. if your incoming water temp in the winter time is 50*F you could temp the water up to 60*F or 65*F before going into your heat exchanger. also how long does it take to get domestic hot water from your hot water storage tank to the bathrooms? you could install a grundfos comfort pump domestic hot water recirculation system and www.waitnot.com (pump with timer so pump does not have to run all day) you would use less water lowering your water and sewer bill or using less water from your well and dumping less water into your septic system. with the hot water recirculation system you would have instant hot water at your faucets when you need it and that also could save you on your energy costs to heat hot water.

Vernon P. James_2

I will be stopping in to my fuel oil supplier later this afternoon to get the actual degree days for the periods between fill ups. I will post after I get It.

Vernon P. James_2

Winter Carnival was very good this year. They were able to build a nice ice palace that is still up. Our weather has been very crazy this year. Lots of snow and cold then warm stretches and rain and melting. Seasonable at the beginning of carnival week. Mid week was 45 and raining but by end it was in the 20 & 30's with snow. Yesterday morning -21 at 6am rose to +38 by mid afternoon. -5 this am and now +22. Definite spring like weather even tho it is too early.

Mitch_4

Any update Vernon?

inquiring minds still want to know