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#1
12-28-07, 05:00 AM
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Join Date: Dec 2007
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Below are the readings from my boiler tag. It is a oil fired hot water boiler. Are these reading good or bad?

CO2 = 9.9
Draft = -1-2
Temp = 413
Combustion efficiency = 83

My house is 1500 sf built in 1900. I keep the thermostat on 70 degrees F. The average temperature in the past week was around 40 degree f. The boiler burned 62.5 gallons. I think that is way too much. The boiler is 20 years old. The R rating of the poorly installed attic insulation looks to be around r-13 to r-19. Next week I plan to blow in loose insulation to bring it up to r-38 to r-45. Will the extra insulation make a big difference or should I just order a new boiler to stop the bleeding?

#2
12-28-07, 05:55 AM
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An efficiency of 83% for a boiler that is 20y/o is very good.
smoke free I hope!
CO2 is a bit low, but not sure how much better can one expect from a 20y/o unit.

Your draft reading is puzzling. I imagine you do not mean -1 -2 but rather -.01 -.02. If so, this draft would be O.K. over the fire, but at the breeching a -.02 to -.05 is what the readings should be.

If you consumed 62.5 gallons in 1 week (I hope I understood you correctly here), that means 52,083 Btuh worth of heat generated by the boiler [on average; assumes #2 oil with a FHV of 140,000 Btu/gal].
52,083x0.83=43,229Btuh available to heat the house.

43,229Btuh/1,5000sq-ft=28.82Btuh/sq-ft.
29 Btuh/sq-ft for a 100+ y/o house is great!!!
You're too strict with this boiler, cut it some slack

Will insulation in the attic help? you bet!
How about infiltration stoppers in windows and doors too?

The chart below is from a good manual called "Guide to Oil Heat", from a very reputable burner manufacturer

Last edited by pflor; 12-28-07 at 06:04 AM. Reason: add chart
#3
12-28-07, 10:48 AM
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Based on pflor's excellent summary of the numbers, I too vote for cutting the boiler some slack. (BTW, that cracked me up!)

Just another vote for insulating and air sealing. The basic idea is to get your building envelope tightened up to get the heat loss down. Then, when you finally retire the old girl, you have an efficient structure for which you have a good heat loss estimate that can be used to size the new boiler.

It is _amazing_ how much room for improvement there is in older structures. Nearly all of the insulating and sealing you'll do is very, very cost effective. Think of insulation as fuel that you buy only once.

#4
12-28-07, 12:58 PM
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Thanks for the fast replies. I just purchased the house at the end of November. It came with double pane windows so I will start by weather stripping the doors and adding enough loose attic insulation for a r-49. I plan add green fiber to the attic next week and if that helps.

#5
12-28-07, 02:48 PM
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29 BTU/SF in 40* weather ? Yeah man, think real hard about insulation and sealing infiltration... when it gets cold, yer gonna be hurtin'.

My place isn't 100 y.o. (about 50) and is reasonably well insulated and sealed up, appx 1800 sf, two floors. 25 y.o. boiler. Temp here past week around the same, and I have burned around 25 gall ... just for point of reference.

By the way, a better 'benchmark' would be BTU / Degree Days / SF ... this takes into account the weather, and will yield a number that is a 'constant' rather than varying with outdoor temps.

#6
12-28-07, 07:49 PM
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Jameseric:
Beware of double-pane windows, for they do leak too.

I have 2-panes at home and 2 yrs ago I added tape where the sash and frames meet. The difference was astonishing. Prior to that, one could not sleep well at night if the thst was below 68F (70F on those single digit nights we at times get over here)...it was drafty, especially on windy nights.
Now I keep the thst at 65F overnight and feels great...I could no doubt bring the temp. even lower, no problem.

Give it a try. Any hardware store has this clear tape.

#7
12-29-07, 01:31 AM
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Originally Posted by NJ Trooper
29 BTU/SF in 40* weather ? Yeah man, think real hard about insulation and sealing infiltration... when it gets cold, yer gonna be hurtin'.

My place isn't 100 y.o. (about 50) and is reasonably well insulated and sealed up, appx 1800 sf, two floors. 25 y.o. boiler. Temp here past week around the same, and I have burned around 25 gall ... just for point of reference.

By the way, a better 'benchmark' would be BTU / Degree Days / SF ... this takes into account the weather, and will yield a number that is a 'constant' rather than varying with outdoor temps.
Thanks for giving me a point of reference. Where can I find degree day data?

Pflor, I will tape all of the windows over the weekend and see if that make a difference over the coming week. Plus I will install the insulation before next weekend.

James

#8
12-29-07, 06:29 AM
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Jameseric:
Where in the country you live? HDD (= Heating Degree Days) vary depending on that. I have a manual called Guide-2000 by IBR that has this info. Example: New Brunswick, NJ has 5,400 HDD; Billings, Montana 7,150 HDD...etc.

BTW, Trooper is quite right in being doubtful about 29 Btuh/sq-ft being a top notch figure in your case.
Yes, 29 Btuh/sq-ft is a top of the heap number for a house when we're talking 14F outdoor temperatures. In you case you said that temperatures were 40F on average (I rushed & overlooked this and assumed 14F which is what I always use for my region). Doing the math, if we recalculate for 14F, your house factor would be 54 Btuh/sq-ft, and you'd have used 116 gallons of oil instead of the 62.5. There is plenty of room for energy improvements here.

Consumption is high indeed...my bad! ...but the boiler at 83% efficiency is not the one to blame. Attic insulation will help, so will infiltration stoppers.
I know Automatic Vent Dampers work great with gas units and typically increase system efficiency by about 10%...but oil stack temperatures are much higher. Any member out there that knows of auto-vent-dampers for oit heat systems?

#9
12-29-07, 07:23 AM
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I too latched onto 83% and said "decent." Trooper is correct.

I suggest doing a heat loss calculation. There is good free software at:

http://www.slantfin.com/heat-loss-software.html

http://www.crownboiler.com/educate/heatloss.asp

The nice thing about the slantfin-ware is that you can plug in your house as it is currently, then add insulation to the attic, walls, change the quality of the windows, etc. and see where you get heat loss reductions.

One thing to remember is that although these heat loss calcs figure in a presumed infiltration (air leaks around windows, doors, ceiling penetrations, etc.), that factor is perhaps the least well understood. I've heard it said that up to 30% of heat loss can be due to infiltration. Yet another reason to pick up a few cans of foam, tubes of caulk and have at it.

Which reminds me, before you blow in insulation in the attic, get up there with the foam and caulk and seal up as many penetrations as you can. A good starter guide to air sealing is at

http://www.energystar.gov/ia/home_im...OR_100_dpi.pdf

and the parent page for that PDF has a bunch of other links as well.

http://www.energystar.gov/index.cfm?...vement_sealing

Degree day data is sometimes provided by your energy company, but you can find current and historical degree days at Weather Underground, among other places.

#10
12-29-07, 07:59 AM
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Originally Posted by pflor
Jameseric:
Where in the country you live? HDD (= Heating Degree Days) vary depending on that. I have a manual called Guide-2000 by IBR that has this info. Example: New Brunswick, NJ has 5,400 HDD; Billings, Montana 7,150 HDD...etc.

BTW, Trooper is quite right in being doubtful about 29 Btuh/sq-ft being a top notch figure in your case.
Yes, 29 Btuh/sq-ft is a top of the heap number for a house when we're talking 14F outdoor temperatures. In you case you said that temperatures were 40F on average (I rushed & overlooked this and assumed 14F which is what I always use for my region). Doing the math, if we recalculate for 14F, your house factor would be 54 Btuh/sq-ft, and you'd have used 116 gallons of oil instead of the 62.5. There is plenty of room for energy improvements here.

Consumption is high indeed...my bad! ...but the boiler at 83% efficiency is not the one to blame. Attic insulation will help, so will infiltration stoppers.
I know Automatic Vent Dampers work great with gas units and typically increase system efficiency by about 10%...but oil stack temperatures are much higher. Any member out there that knows of auto-vent-dampers for oit heat systems?

I am in Waldorf, Maryland. I think 40F was closer to the highs for last week. I don't know what we had for an average. I will try and check and get back to everyone. Today we are going to tape all windows and seal doors. This is a great board. Thanks for the help.

#11
12-29-07, 08:11 AM
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The average temp over the week that I checked was 45.25F according to the Weather Underground website. When I stated that I used 62.5 gallons that was based on my 250 gallon tank showing a 25% drop on the glass meter. I know that is not accuarate but I had to start somewhere. Even if it is 50 gallons it is way too much. Is there a better way to record oil flow?

#12
12-29-07, 08:20 AM
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Degree day data

It's possible to take your own data if you are so inclined and have a high-low recording thermometer... but you can get lots of data from www.wunderground.com and also from the NOAA govt websites. Poke around in wunderground and see if you can find a 'personal' weather station near you. You can download months worth of data.

A Heating Degree Day is very basically the average of the HIGH and LOW temp for the day, subtracted from 65*F .

example: High 56 , low 40

56+40=96 divide by 2 for average = 48
subtract from 65 = 17 heating degree days.

Problem is, to use this on a daily basis is rather difficult because you don't have a way of knowing exactly how much oil you burn on a daily basis. It's much easier to record the amount that you use from fill-up to fill-up, then download data for that period and do the calc, much as you would if you were figuring MPG on your car.

Another point of reference: Last winter I averaged right around 7 BTU per HDD per SF . Which isn't bad... not the greatest, but not bad considering the construction. Before the past few years of insulation and infiltration improvements, I was running pretty consistently in the low 10's ... that's 30% savings right there. It adds up!

#13
12-29-07, 08:40 AM
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Originally Posted by NJ Trooper
It's possible to take your own data if you are so inclined and have a high-low recording thermometer... but you can get lots of data from www.wunderground.com and also from the NOAA govt websites. Poke around in wunderground and see if you can find a 'personal' weather station near you. You can download months worth of data.

A Heating Degree Day is very basically the average of the HIGH and LOW temp for the day, subtracted from 65*F .

example: High 56 , low 40

56+40=96 divide by 2 for average = 48
subtract from 65 = 17 heating degree days.

Problem is, to use this on a daily basis is rather difficult because you don't have a way of knowing exactly how much oil you burn on a daily basis. It's much easier to record the amount that you use from fill-up to fill-up, then download data for that period and do the calc, much as you would if you were figuring MPG on your car.

Another point of reference: Last winter I averaged right around 7 BTU per HDD per SF . Which isn't bad... not the greatest, but not bad considering the construction. Before the past few years of insulation and infiltration improvements, I was running pretty consistently in the low 10's ... that's 30% savings right there. It adds up!
I just purchased the house in November so I'll need to wait for another fill-up before I can get usable numbers. I had my first fill-up on 12/19. However, I should be able to observe a slowing of the flow after I seal and insulate. Thanks for the examples. I have printed them for reference.

#14
12-29-07, 09:02 AM
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Ya know, there's actually an even easier number that you can generate to give an idea of fuel useage. Oil delivery companies use what they call " K factor " . It doesn't take into account the amount of BTUs in gallon of oil, or the SF of the home. It's simply HDD / GALLONS . So, on your next delivery, note the gallons delivered, and get the cumulative HDD data for that period, and do a simple division.

A 'K factor' of 8 is pretty reasonable. Higher is better. SIX is just barely OK, FOUR would be pretty poor.

If you are on an automatic delivery plan, with a single delivery company, you may even find this data printed on your delivery ticket.

#15
12-29-07, 09:08 AM
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One more...

Sorry for the multiple replies, I keep thinking of things...

I didn't see where anyone asked, or if you offered, how you heat your domestic hot water ? Does your boiler do that for you ? That could certainly account for higher fuel useage!

Also, when you do insulate the attic, be aware that if you have "soffit vents" that you do not want to block them with insulation. Leave any attic ventilation in place and open. You don't want to trap humid air from the home in a sealed up attic space.

#16
12-29-07, 09:12 AM
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Join Date: May 2007
Location: Lehigh Valley
Posts: 71
This could be happening also

We picked up our house in March 07 and had the paperwork for the past seven years and the fuel records for the past year. An average they were buying about 100gallons of oil a month and the boiler did not provide domestic hot water.

I had one guy come out and look at and wanted \$500.to change the gauge and flush out the boiler. Needless to say he will never return. I grab the booklet and started cleaning out my boiler this summer and replaced pretty much everything that I could for about \$250. (nozzle, sight glass, pressure relief, etc)

In my discovery I found out they were using the wrong size nozzle and static plate inside the oil burner. The difference in the sizes of nozzles with the boiler running for 24hours a day would burn 7more gallons of oil per day. The paperwork had all the readings in spec. but the nozzle size list on the paperwork since day one and what the spec was on the boiler was two different things.

I have put in a programmable thermostat so that has helped quite a bit also you will see a big difference if you dropped the temp 1 degree. Definitely use the plastic on the windows.
I am lucky to only have used a half a tank of oil(since Nov 1) on a non-insulated, single pane window 2100sq ft house.

BOB

Last edited by mrboyd; 12-29-07 at 09:47 AM.
#17
12-29-07, 09:15 AM
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I called the company and they gave me a starting k factor of 4.93 but since I only had one delivery they really won't know until I get one or two more. I am prepping the attic so I can add 10" loose fiber next week.

#18
12-29-07, 09:23 AM
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Originally Posted by NJ Trooper
Sorry for the multiple replies, I keep thinking of things...

I didn't see where anyone asked, or if you offered, how you heat your domestic hot water ? Does your boiler do that for you ? That could certainly account for higher fuel useage!

Also, when you do insulate the attic, be aware that if you have "soffit vents" that you do not want to block them with insulation. Leave any attic ventilation in place and open. You don't want to trap humid air from the home in a sealed up attic space.
While I was crawling in the attic I checked for mold and I did not find any. I do not have soffit vents. I have 4 gable vents and no mold in 100 years so I plan to just add more insulation and check for mold annually. Yes, I do have a hot water coil in the boiler that is used during the heating season. But there are only 2 people living in the house.

Mr. Boyd,
That is a great point because the company that serviced the boiler for the previous owner did not sell this brand. I wonder if they used the wrong size rather than making a speacial order?

#19
12-29-07, 09:38 AM
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Sorry for having so many posts but I am learnign a lot and getting new information each time I read another reply. I spoke to oil company that serviced the house last year and here is the data.

oct 2006 thru april 2007 = 705.1 gallons
K factors = 5.8 - 12.2 but they delivered based on 6.2.

The old owner claims to have run the thermostat at 70 degrees which I am also using so maybe the reading the glass on the tank has caused me to over react. But I still plan to continue sealing and insulating to keep my bills down.

#20
12-29-07, 03:59 PM
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AAAHHHHH...the boiler does both huh? Heat and DHW...that changes the picture. Your Btuh/sq-ft is starting to look a bit better. 54Btuh/sq-ft is horrible if the boiler is doing only heating.

I'm on my way to the airport but after my return I'll get back to you with the HDD and a new look at the performance of your system.

#21
12-29-07, 09:07 PM
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HDD...
The closest to your place my table shows is the HDD for Washington National Airport --> 4,240 HDD

From ASHRAE, average daily DHW consumption, per person: 30 gallons

Without boring you all with the math, take about 2MBH off the original load calc to account for the DHW share [DHW=Domestic Hot Water], so heating only we're talking 41MBH heat loss @ 40F outdoors. Adjusted for a design O.D. temperature of 14F we'd be talking 76.5MBH, which for your 1,500 sq-ft home results in a heat loss factor of 51 Btuh/sq-ft.

Pretty high a number indeed...go for the energy conservation measures, and the sooner the better.

#22
12-30-07, 02:17 AM
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Thanks again for all of the detailed input. the previous owner averaged 100 gallons per month so I think my numbers are very wrong but I did the sealing yesterday and will insulate later in the week. Unless they lived in one room with an electric heater over the winter I expect to have lower consumption for the season.