HomeMy WebLinkAboutAttach 3_Northway Biomass Design Narrative
Wood Fired Heating System
Northway School
Northway, Alaska
65% Design Report
December 21, 2018
Presented by
CTA Architects Engineers
For
Alaska Gateway School District
CTA Project: AGSD_NORTHWAY
Wood Fired Boiler System 65% Design Report
Northway School December 21, 2018
CTA Architects Engineers 1
Introduction
This report summarizes the basis of design for a new wood fired boiler system for Northway
School in Northway, Alaska. The school is part of the Alaska Gateway School District. The
report will provide information on the existing heating system, fuel use, boiler plant location
options, boiler manufacturers, and provides estimates of probable cost. A site visit to review
existing conditions was performed by Todd Schaper and Nathan Ratz with CTA on September
25, 2018.
Existing Building Information
Northway school is approximately 27,700 square feet and is heated with two oil fired, hot water,
Burnham model V1108, cast iron boilers, each rated at 1,517,000 Btu/hr output. The heating
hot water is pumped through the school to various heating equipment by a single vertical inline
pump. The boilers operate in a lead, standby configuration, with each boiler sized to provide
approximately 50% of the connected building heating load. This equates to a peak building
heating design load of approximately 3,000,000 Btu/hr. Domestic hot water for the school is
generated by a fuel oil fired water heater, rated at 1,000,000 Btu/hr input with a 400 gallon
storage tank. Because of permafrost the school is constructed off the ground on thermopiles.
The garage is located north of the school and is approximately 1,400 square feet. It is heated
with a fuel oil fired, warm air furnace rated at 105,000 Btu/hr output. The garage is constructed
on grade utilizing an insulated slab.
The duplex is located east of the school across the parking area and is approximately 2,000
square feet. Each unit of the duplex has a mechanical room with a Toyotomi Model OM-128HH
fuel oil fired boiler that heats the living unit and also provides domestic hot water through an
indirect water heater. The heater is rated at 148,000 Btu/hr output. The duplex is also
constructed off the ground on thermopiles.
The existing boiler rooms in the school and duplex are not large enough to add a wood fired
boiler. The garage is large enough to house a boiler plant, however, it is needed for school
operations and therefore is not available to be re-purposed. A new addition to an existing
building or a new freestanding boiler plant is required to accommodate a wood heating system.
Current Heating Energy Use
Over the past five heating seasons, the school is using on average 25,000 gallons of fuel oil
annually, and the garage is using on average 740 gallons of fuel oil annually . Over the past 4
heating seasons, the duplex is using on average 550 gallons of fuel oil annually. See the
appendix for a summary of fuel use.
The heating Energy Use Index (EUI) for the school is 124.1 kBtu/SF, for the garage is 73.8
kBtu/SF, and for the duplex is 38.1 kBtu/SF.
Wood Fired Boiler System 65% Design Report
Northway School December 21, 2018
CTA Architects Engineers 2
Biomass Boiler Size
Wood fired boilers do not modulate well, so it is best to size them so they can operated at full
load as much as possible, which allows them to operate at maximum efficiency as much as
possible. The peak heating load of a building also does not occur very often, usually less than
10 hours in a typical year. For this reason, CTA does not recommend sizing a wood boiler for
the peak heating load, but to size it large enough to meet approximately 85% of the typical
annual heating energy use of the building. The existing heating systems would be used for the
other 15% of the time during peak heating conditions, during times when the biomass boiler is
down for servicing, and during swing months when only a few hours of heating each day are
required. In general, previous energy models of various school buildings have shown that a
boiler sized at approximately 50% of the peak load will accommodate approximately 85% of the
heating run hours.
A basic temperature bin data heating energy analysis was performed to help determine the best
wood boiler size. The analysis estimated energy use from envelope losses for all three
buildings for all hours from September through May. It also estimated heating the ventilation
(outside) air for the two main air handling units and the kitchen make up air unit for five days a
week from September to May. The school air handling units utilized the hours from 6:00 a.m. to
4:00 p.m. and the make up air unit utilized the hours from 6:00 a.m. to 2:00 p.m. Based on the
2001 HVAC renovation drawings, the classroom AHU had 3,555 CFM of outside air, the gym
AHU had 3215 CFM outside air, and the make up air unit had 2,500 CFM of outside air.
In order to approximate the average annual fuel oil use for all three buildings, the peak load was
estimated to be approximately 1,850,000 Btu/hr, with the envelope load being approximately
735,000 Btu/hr and the outside air load the remainder. A basic heat loss calculation was also
performed, which validated the 735,000 Btu/hr envelope loss. This analysis estimated
approximately 26,900 gallons of fuel oil use compared to the actual annual average of all three
buildings of 26,200 gallons.
Using this analysis, a boiler sized at 850,000 Btu/hr output is estimated to generate just over
90% of the total heating energy. For this project, a boiler with an output in the 800,000 Btu/hr to
850,000 Btu/hr output range was targeted.
Wood Fuel Use and Cost
The school district currently produces chips for the combined heat and power plant at the school
in Tok, and for the district wood fired boiler system for the community of Mentasta Lake, which
also serves the school there. The school district uses a smaller screen for the chips in
Mentasta, and this would be the same type of ground fuel used for Northway. It is estimated the
chips can be delivered to Northway for $75/ton. There is sufficient wood resources in the region
to serve all three plants.
The estimated amount of wood fuel needed for each building was calculated and is listed in a
summary in the appendix. If the entire heating energy was supplanted by wood fuel for all three
buildings, it is estimated that 402 tons of chips would be needed, and for 85% offset, 341 tons.
This assumes white spruce with 30% moisture content.
With a peak output of 850,000 Btu/hr, assuming a bulk density of 15 lb/ cu. Ft., approximately
2.75 tons or 366 cu. Ft. of chips would be needed for one day.
Wood Fired Boiler System 65% Design Report
Northway School December 21, 2018
CTA Architects Engineers 3
Boiler Plant Location and Site Access
A new addition or stand-alone building will be required to house a new wood boiler system.
Because of the permafrost and because the school and duplex are constructed on thermopiles,
a building addition is not really viable, so a stand alone plant was pursued. There is ample
room on site to accommodate a new plant. The west side of the school was avoided because of
the close proximity of the tree line, the grade change, and the sewer treatment plant. The south
side of the school was avoided because of the close proximity of the tree line. Immediately
north of the school was avoided because of the fuel tanks and the garage. There are two
buildings east of the garage that are not being used, and per the school district, can be
moved/removed.
Two viable spots are (A) east of the garage and (B) north of the duplex. (See the attached site
plans.) Both locations stay to the perimeter of the developed areas of property and don’t impact
student areas or parking areas but are readily accessible. The stronger location appears to be
location (A). It is closer to the school, so will have lower costs for utility connections. It is also
close to the garage where the school has normal operations, so the road will be regularly used
(plowed). The new plant will be at least 30 feet from any other buildings to maintain good
separation and not trigger any parts of the building code that may require extra requirements for
the building construction.
The new plant will require power and domestic water, but not a sewer. There will also be
heating water distribution piping running between the plant to other buildings.
Access to the new boiler plant would be from the Alaska Highway and Northway Road. Large
tractor trailers already deliver other goods to the school and community and are able to access
the site without any problems, so there should not be any issues with wood fuel delivery.
Integration with Existing Heating Systems
Integration of a wood fired boiler system would be relatively straight forward. The field visit
confirmed the location of the boiler and mechanical rooms and identified the points of
connection boilers or furnace in each building.
School:
Preinsulated PEX piping from the biomass boiler plant would run below ground from the new
boiler plant to under the northeast corner of the school building. Special detailing will be
required for running in permafrost. Once under the building, the piping would rise up and run to
the boiler room via one of two routes:
(1) Run attached to the bottom of the school to the boiler room. It would be extra insulated
and covered. It would run to under the boiler room, and then rise up into the boiler room
through the boiler room floor.
(2) Rise up through the school itself to the ceiling space and run to the boiler room. It would
run through the ceiling and the mechanical mezzanine to the boiler room.
Wood Fired Boiler System 65% Design Report
Northway School December 21, 2018
CTA Architects Engineers 4
Once the heating water piping enters the existing boiler room it would be connected to the
existing heating piping return header utilizing a new primary/secondary piping in the return
piping main upstream of the boilers.
Heating the domestic hot water could also be done similar to what was done for the school in
Tok. Branch piping would be connected into the existing heating water piping (NOT the wood
boiler heat injection piping) and serve a heat exchanger. On the other side of the heat
exchanger, a small circulating pump would circulate domestic water from the inlet of the water
heater back to the tank. However, this may be marginally beneficial. ASHRAE reports that
schools use on average 1.8 gallons of hot water per student per day. Assuming 50 students,
and 23 school days in a month, that would be approximately 2,100 gallons of water per month.
Heating that amount of water from 50 deg F to 140 deg F, with an 80% efficient heater, would
take approximately 150 gallons of fuel oil per month, or approximately 1,500 gallons per year.
This could easily be an alternate to help with the budget and can be evaluated further as the
design progresses.
Domestic water is required for the new boiler plant to help fill the system and also be connected
to the boiler for burn back protection. This line would be come from the school. A pre-insulated
PEX line with two carrier pipes would be run from the school to the boiler plant in the same
trench as the heating water piping. A heat exchanger would be installed and connected to the
existing heating system. On the other side of the heat exchanger, a small circulating pump
would circulate the domestic water through this line and be heated by the heat exchanger to
keep the water above freezing. One carrier pipe would be the supply pipe, and the other pipe
would be the circulating line.
Since the school currently uses 60% glycol for the heating system fluid, the current design
concept is a direct connection from the wood fired boiler heating loop which also must be run at
60% glycol. This is how the system was installed in Tok. If there is a concern about keeping
the two systems isolated, then a heat exchanger could be added along with a pump. This can
be evaluated further as the design progresses.
Garage:
Preinsulated PEX piping from the biomass boiler plant would run below ground from the new
boiler plant to the garage. It would enter the garage and rise up the wall where it would serve a
new hot water unit heater. Special detailing will be required for running in permafrost. The
existing fuel oil furnace will remain as back up heat, but the new unit heater would be the
primary heat source.
Duplex:
Preinsulated PEX piping from the biomass boiler plant would run below ground from the new
boiler plant to under the duplex. Special detailing will be required for running in permafrost.
Once under the building, the piping would rise up and enter the north unit boiler room. Once the
heating water piping enters the existing boiler room it would be connected to existing heating
piping return header utilizing a new primary/secondary piping in the return piping main near the
boiler. A branch piping from the boiler plant would also continue to the adjacent boiler room to
serve the other unit.
Wood Fired Boiler System 65% Design Report
Northway School December 21, 2018
CTA Architects Engineers 5
Wood Fired Heating System Options
The targeted boiler output range of 800,000 Btu/hr to 850,000 Btu/hr, fits very well in the range
of a wood pellet boiler system. However, wood pellets are not viable nor desired for this project.
Typically, the high capital cost of a chip system make project economics very challenging unless
fossil fuel costs are in excess of $100,000 per year. The school falls into a gap where it is too
large for a typical cord wood boiler, and too small for a typical chip system, so potential boiler
options are a bit limited. To keep capital costs down, the chip storage/fuel handling will have to
be simpler and will require some on site fuel management. There will be the primary wood fuel
storage that will feed the boiler. A larger bulk storage area will also be required, and a skid
steer or front end loader will have to fill the primary storage on a regular basis, every few days.
There are also two construction options to consider. One option is to construct a building for the
boiler plant and wood fuel storage on site, and then install the equipment in the buildings. The
other option is to construct pre-fabricated buildings with the boilers, fuel handling, pumps,
piping, etc installed at the factory, and they shipped to the site. The building sizes would be
limited by what can be normally shipped via highway with tractor trailers (8 foot wide, 9.5 feet
tall, and 40 foot long). In either option, work will be required on site to connect to the existing
buildings and utilities.
Three options were considered and are shown on the drawings:
A. Single containerized system.
B. Containerized system, two containers.
C. Site built boiler plant with prefabricated fuel bin.
Option A, Single containerized system.
In this option the boiler plant and fuel storage and fuel handling would be within a single 40 foot
container. A insulated structural slab would be constructed on site, and the container would be
shipped to the site and set on the slab. The piping and utilities would then be connected
between the buildings and the boiler plant.
Option B, Containerized system, two containers.
In this option the boiler plant and fuel storage and fuel handling would be in separate containers.
This will allow for more room to install the heating system components (pumps, piping, etc), and
would allow additional fuel storage. A insulated structural slab would be constructed on site, and
the containers would be shipped to the site and set on the slab. The two containers would then
be connected on site. The piping and utilities would then be connected between the buildings
and the boiler plant.
Option C, Site building boiler plant with prefabricated fuel bin.
In this option a simple site built building would be constructed to house the boiler and heating
system components (pumps, piping, etc). A prefabricated fuel bin would then be installed on a
insulated structural slab adjacent to the boiler plant.
The attached drawings show these options.
The following manufacturers have products that would fit one or more of these options: Portage
and Main, Solagen, TwinHeat, and WoodMaster.
Wood Fired Boiler System 65% Design Report
Northway School December 21, 2018
CTA Architects Engineers 6
Portage & Main
These boilers are constructed in Manitoba, Canada. They are atmospheric boilers (not ASME
rated) so an additional pump and heat exchanger are required. Portage and Main do not make
prefabricated systems, so would apply to Option C. They have 500 MBH and 800 MBH boilers,
and fuel bins that can hold 7, 15, and 30 cubic yards of material. A Portage and Main system is
in use in Mentasta for the community district heating system.
Solagen
These boiler systems are constructed in Oregon. They utilize ASME rated boilers and can
match any boiler output required. Solagen has made containerized systems, but they have
typically been pellet types.
TwinHeat
These boilers are fabricated in Denmark. They have made boilers in Europe for years, but are
relatively new in North America. They have arctic experience with installations in Norway and
Finland. They are atmospheric boilers (not ASME rated) so an additional pump and heat
exchanger are required. They have extensive experience with containerized systems. Their
boiler line runs from 300 MBH TO 850 MBH.
WoodMaster
These boilers are constructed in Minnesota and are ASME rated. WoodMaster does not
fabricate containerized system directly, but works with company to build a prefabricated plants.
Their boiler line runs from 400 MBH TO 6800 MBH.
It would be advantageous to utilize a prefabricated fuel storage system with fuel handling.
WoodMaster typically uses a cylindrical storage unit with a sweep arm at the bottom that feeds
an auger that transports the fuel to the boiler metering bin. Portage and Main and TwinHeat
utilize a hydraulic floor scraper system that moves chips forward to an auger that then feeds the
boiler metering bin. Portage and Main makes 7, 15, and 30 cubic yard (190, 400, 810 cu. Ft. )
containers. TwinHeat would utilize a shipping container type storage so can vary the amount of
storage greatly. The initial selection and layout for this project with a 40 foot container, would
provide 920 cu. Ft.. The wood fuel usage at peak output is approximately 366 cu. Ft. per day,
so the largest bins from TwinHeat and Portage and Main would be able to last between 2 – 3
days during peak heating times.
The 30 cu. Yd. Portage and Main bin does not have a lid, so some sort of roof or covering would
be required. TwinHeat can put the lid of the container on rails where it can be moved over the
boiler section of the container to allow the fuel side to be filled. They also can provide a hinged
lid. This will be evaluated further as the design progresses to make sure a reliable system is in
place to allow regular filling during extreme winter conditions that are typical for Northway.
Information on these boiler systems are included in the appendix.
Because TwinHeat has good experience with container systems and excellent documentation, it
was used as the basis of design at this point.
Wood Fired Boiler System 65% Design Report
Northway School December 21, 2018
CTA Architects Engineers 7
Electrical Service
The new boiler plant will require power. There is an existing 100A fused switch in the school’s
main distribution panel that is labeled “hockey” and appears to no longer be used. This switch
will be used to feed the new plant. A new conduit and feeder would be run from the school main
electrical room to the boiler plant. If the boiler plant is a prefabricated unit, it will be pre-wired
and come with a single point power connection that the feeder would connect to. If the plant is
site built, the new feeder would connect to a new 100A sub panel in the boiler plant. This sub
panel would then feed the various pieces of equipment and LED lights in the plant.
Estimate of Probable Costs
Estimates of probable cost were developed for a single containerized system and for a site built
boiler plant. Options are shown with and without covered fuel storage and are separated
between the school, garage, and duplex integration. The costs range from $500,000 to
$800,000. The costs will be refined further as the design progresses and can also take into
account work that the school district could self perform.
Attachments
Building Fuel Use, Heating Load, and Boiler Load Summary
Wood Fuel Use Summary
Temperature Bin Energy Analysis
Estimates of Probable Cost
Boiler Information for Portage and Main, TwinHeat, and WoodMaster
65% Drawings
Wood Boiler System Integration
Alaska Gateway School District
Northway School
Northway, Alaska
Historical Fuel Oil Use Summary
School Garage Duplex
Fiscal Yr Gallons $/gallon $ Total Gallons $/gallon $ Total Gallons $/gallon $ Total
FY14 19,008 $3.68 $69,726 741 $3.72 $2,757 578 $3.72 $2,155
FY15 26,890 $3.58 $96,827 1,017 $3.78 $3,934 525 $3.48 $1,795
FY16 33,042 $2.43 $79,658 443 $2.80 $1,244 0 $0.00 $0
FY17 20,690 $2.17 $45,034 730 $3.05 $2,242 1,100 $3.03 $3,335
FY18 24,959 $2.96 $72,716 760 $3.35 $2,566 0 $0.00 $0
Average 24,918 $2.92 $72,792 738 $3.45 $2,549 551 $3.31 $1,821.28
Total Site Average: 26,207 Gallons
Heating Equipment Summary
Output
Building Equipment Fuel MBH
School Boiler 1 Fuel Oil 1,517
Boiler 2 Fuel Oil 1,517
DWH Fuel Oil 1,000
Total 4,034
Garage Furnace Fuel Oil 105.0
Duplex Boiler Fuel Oil 148.0
Heating Load Summary
Heating Heating
Building Heating Load Estimated Load
Area Output Index Peak Load Index
Building Sq. Ft. Btu/hr Btu/hr/SF Btu/hr Btu/hr/SF
School 27,740 3,034,000 109.4 1,800,000 64.9
Garage 1,388 105,000 75.6 52,000 37.5
Duplex 2,000 148,000 74.0 60,000 30.0
CTA Architects Engineers December 21, 2017
Wood Boiler System Integration
Alaska Gateway School District
Northway School
Northway, Alaska
Annual Energy Use and Potential Wood Fuel Use Summary
Avg. Current Current Gross Gross
Building Annual Fuel Est. Energy Energy Heating
Area Heating Fuel Cost Annual Convers. Use EUI
Building Sq. Ft. Energy units $/Unit Cost Btu/unit Therms kBtu/SF
School 27,740 25,000 Gal $3.00 $75,000 138,500 34,625 124.8
Garage 1,388 740 Gal $3.00 $2,220 138,500 1,025 73.8
Duplex 2,000 550 Gal $3.00 $1,650 138,500 762 38.1
Totals 31,128 26,290 Gal $78,870
Chips/Ground Fuel 85.0%
Fuel Oil Building Wood Gross Equiv. Equiv.
Boiler Energy Boiler Energy Energy Wood Wood
Est. Use Est. Use Convers. Fuel Fuel
Building Eff. Therms Eff. Therms Btu/lb tons tons
School 0.82 28,393 0.65 43,681 5,712 382.4 325.0
Garage 0.82 840 0.65 1,293 5,712 11.3 9.6
Duplex 0.82 625 0.65 961 5,712 8.4 7.2
Estimated Wood Boiler Size and Fraction of Total Energy
Biomass
Boiler Fraction
Size of Total
Btu/hr Energy
400,000 0.685
500,000 0.749
600,000 0.798
700,000 0.843
800,000 0.887
850,000 0.903
900,000 0.917
1,000,000 0.936
Based on Temperature Bin Energy Estimation
Unit Fuel Costs
Net
Gross System System Delivered Gross
Fuel Type Units Btu/unit Effeciency Btu/unit $/unit $/MMBtu $/MMBtu
Fuel Oil gal 138,500 0.82 113,570 $2.90 $25.53 $20.94
$3.00 $26.42 $21.66
$3.25 $28.62 $23.47
$3.50 $30.82 $25.27
$4.00 $35.22 $28.88
Chips tons 1.142E+07 0.65 7,425,600 $60.00 $8.08 $5.25
$75.00 $10.10 $6.57
$80.00 $10.77 $7.00
CTA Architects Engineers December 21, 2017
Northway SchoolWood Fuel Storage EstimateDecember 21, 2018Chip UseBiomass Boiler Output 850,000 Btu/hr249 KW24 hrs per day20,400,000 Btu/day MAX Output0.65 Eff31,384,615 Btu/day MAX Input5,712 Energy Converstion Btu/lb (30% MC White Spruce)5,495 lbs wood2.75 tons wood15 lb/cu ft bulk density366.3 cu ft chips13.6 cu yd chips30% MC Bulk Den. VolumeGross Chip Chip Chip Bin SizeTime Period Days Btu tons lb/cu ft cu ft width (ft) length (ft) depth (ft)1 day peak 1 31,384,615 2.75 15 366.3 10 10 3.71 week peak 7 219,692,308 19.2 15 2564.1 20 20 6.41 month peak 30 941,538,462 82.4 15 10989.0 20 20 27.51 month avg 55.0 15 7333.3 20 20 18.3Average Annual Use (Assumes 85% fuel oil offset) 325.0 15 43333.3 40 40 27.1CapacityBin Size Bin Size Days at Peakcu. Ft. cu. Yd. Output400 14.8 1.1780 28.9 2.1910 33.7 2.5CTADecember 21, 2018
Northway SchoolEstimated Peak Heating Load:CFM dTNorthway, Alaska3,555 120 426,600 Btu/hr Ventilation Air ‐ School AHUDecember 14, 20183,215 120 385,800 Btu/hr Ventilation Air ‐ Gym AHUBy: N. Ratz/J. Mortensen2,500 120 300,000 Btu/hr Ventilation Air ‐ Kitchen MAUBin data based on Northway Intl Airport Data734,234 Btu/hr Envelope1,846,634 Btu/hr TotalIndoor Design Temp: 70 °FASHRAE 99% Htg DB: ‐32 °FDesign Htg DB: ‐50 °FBuilding Area: 27,740 SF Calculations Based On These Calculations Based On TheseSchool Gym Kitchen850,000Annual less June ‐ Aug Annual less June ‐ AugVentil. Ventil. Ventil. Est. Est. Est. Btu/hrBase 69 Base Envelope Air Air Air Total Est. School Gym Kitchen Est. Total Biomass5 day/wk 5 day/wk 5 day/wk 7 day/wk 5 day/wk 5 day/wk 5 day/wk 7 day/wk 70 % Peak Est. Est. Est. Est. Est. Envelope Vent Air Envelope Vent Air Total % of Cumm TotalLow Upper Avg School Gym Kitchen Total School Gym Kitchen Total Heating % of Cumm Heating Heating Htg Ld Htg Ld Htg Ld Htg Ld Htg Ld Energy EnergyEnergy Energy Energy Total % from 69 EnergyTemp Temp Temp 06‐16 06 ‐ 16 06 ‐ 14 Hours 06‐16 06 ‐ 16 06 ‐ 14 Hours Hours Total % from 69 dT dT Btu/hr Btu/hr Btu/hr Btu/hr Btu/hr Btu Btu Btu Btu Btu Energy Ttl Energy Btu959997 0000909492 0000858987 0000000080 84 82 6 6 2 14 0.0023971 0.0023971 0.0011142 0.001815675 79 77 21 21 9 0 0.0083899 0.0083899 0.0050139 0 070 74 72 17 17 13 4 0.0067918 0.0067918 0.0072423 0.0005187 465 69 67 18 18 10 21 0.0071914 0.0071914 0.005571 0.0027234 21 0.0027283 0.0027283 3 0.0250 18,356 10,665 9,645 7,500 46,166 3.85E+05 1.92E+05 1.74E+05 7.50E+04 8.26E+05 0.00026998 0.00027 826,05360 64 62 37 37 21 68 0.0147823 0.0147823 0.0116992 0.0088186 68 0.0088346 0.0115629 8 0.0667 48,949 28,440 25,720 20,000 123,109 3.33E+06 1.05E+06 9.52E+05 4.20E+05 5.75E+06 0.00188006 0.00215 5,752,44755 59 57 42 42 30 186 0.0167799 0.0167799 0.0167131 0.0241214 186 0.02416530.0357282 13 0.1083 79,542 46,215 41,795 32,500 200,052 1.48E+07 1.94E+06 1.76E+06 9.75E+05 1.95E+07 0.00636211 0.008512 19,466,23550 54 52 104 104 51 542 0.0415501 0.0415501 0.0284123 0.0702892 542 0.070417 0.1061453 18 0.1500 110,135 63,990 57,870 45,000 276,995 5.97E+07 6.65E+06 6.02E+06 2.30E+06 7.47E+07 0.02440152 0.032914 74,661,66445 49 47 108 108 106 866 0.0431482 0.0431482 0.0590529 0.1123071 866 0.1125114 0.2186566 23 0.1917 140,728 81,765 73,945 57,500 353,938 1.22E+08 8.83E+06 7.99E+06 6.10E+06 1.45E+08 0.04731889 0.080233 144,782,28740 44 42 176 176 168 1170 0.0703156 0.0703156 0.0935933 0.1517313 1170 0.1520073 0.3706639 28 0.2333 171,321 99,540 90,020 70,000 430,881 2.00E+08 1.75E+07 1.58E+07 1.18E+07 2.46E+08 0.08025862 0.160491 245,568,44235 39 37 163 163 169 1348 0.0651219 0.0651219 0.0941504 0.1748152 1348 0.1751332 0.5457971 33 0.2750 201,914 117,315 106,095 82,500 507,824 2.72E+08 1.91E+07 1.73E+07 1.39E+07 3.23E+08 0.10541471 0.265906 322,538,87430 34 32 177 177 133 1019 0.0707151 0.0707151 0.0740947 0.1321489 1019 0.1323892 0.6781863 38 0.3167 232,507 135,090 122,170 95,000 584,767 2.37E+08 2.39E+07 2.16E+07 1.26E+07 2.95E+08 0.09644531 0.362351 295,095,09525 29 27 173 173 112 476 0.0691171 0.0691171 0.0623955 0.06173 476 0.0618423 0.7400286 43 0.3583 263,101 152,865 138,245 107,500 661,711 1.25E+08 2.64E+07 2.39E+07 1.20E+07 1.88E+08 0.0613253 0.423676 187,637,87620 24 22 162 162 94 332 0.0647223 0.0647223 0.0523677 0.0430554 332 0.0431337 0.7831623 48 0.4000 293,694 170,640 154,320 120,000 738,654 9.75E+07 2.76E+07 2.50E+07 1.13E+07 1.61E+08 0.05275976 0.476436 161,429,79515 19 17 137 137 88 277 0.0547343 0.0547343 0.0490251 0.0359227 277 0.035988 0.8191503 53 0.4417 324,287 188,415 170,395 132,500 815,597 8.98E+07 2.58E+07 2.33E+07 1.17E+07 1.51E+08 0.04923479 0.525671 150,644,38110 14 12 150 150 102 177 0.0599281 0.0599281 0.0568245 0.0229542 177 0.022996 0.8421463 58 0.4833 354,880 206,190 186,470 145,000 892,540 6.28E+07 3.09E+07 2.80E+07 1.48E+07 1.37E+08 0.0446129 0.570284 136,502,7195 9 7 177 177 112 142 0.0707151 0.0707151 0.0623955 0.0184153 142 0.01844870.860595 63 0.5250 385,473 223,965 202,545 157,500 969,483 5.47E+07 3.96E+07 3.59E+07 1.76E+07 1.48E+08 0.04832785 0.618612 120,700,0000 4 2 151 151 104 76 0.0603276 0.0603276 0.0579387 0.009856 76 0.009874 0.870469 68 0.5667 416,066 241,740 218,620 170,000 1,046,426 3.16E+07 3.65E+07 3.30E+07 1.77E+07 1.19E+08 0.03883218 0.657444 64,600,000‐5 ‐1 ‐3 124 124 88 27 0.0495406 0.0495406 0.0490251 0.0035015 27 0.00350790.8739769 73 0.6083 446,659 259,515 234,695 182,500 1,123,369 1.21E+07 3.22E+07 2.91E+07 1.61E+07 8.94E+07 0.02921901 0.686663 22,950,000‐10 ‐6 ‐8 162 162 99 42 0.0647223 0.0647223 0.0551532 0.0054468 42 0.0054567 0.8794335 78 0.6500 477,252 277,290 250,770 195,000 1,200,312 2.00E+074.49E+07 4.06E+07 1.93E+07 1.25E+08 0.04081927 0.727482 35,700,000‐15 ‐11 ‐13 145 145 96 230 0.0579305 0.0579305 0.0534819 0.0298275 230 0.0298818 0.9093153 83 0.6917 507,845 295,065 266,845 207,500 1,277,255 1.17E+08 4.28E+07 3.87E+07 1.99E+07 2.18E+08 0.07131429 0.798797 195,500,000‐20 ‐16 ‐18 119 119 81 319 0.0475429 0.0475429 0.0451253 0.0413695 319 0.0414447 0.95076 88 0.7333 538,438 312,840 282,920 220,000 1,354,198 1.72E+08 3.72E+07 3.37E+07 1.78E+07 2.60E+08 0.08513124 0.883928 260,477,247‐25 ‐21 ‐23 31 31 27 89 0.0123851 0.0123851 0.0150418 0.011542 89 0.01156290.962323 93 0.7750 569,031 330,615 298,995 232,500 1,431,141 5.06E+07 1.02E+07 9.27E+06 6.28E+06 7.64E+07 0.02498246 0.90891 75,650,000‐30 ‐26 ‐28 22 22 14 58 0.0087895 0.0087895 0.0077994 0.0075217 58 0.0075354 0.9698584 98 0.8167 599,624 348,390 315,070 245,000 1,508,084 3.48E+077.66E+06 6.93E+06 3.43E+06 5.28E+07 0.01725793 0.926168 49,300,000‐35 ‐31 ‐33 36 36 30 102 0.0143827 0.0143827 0.0167131 0.0132279 102 0.0132519 0.9831103 103 0.8583 630,218 366,165 331,145 257,500 1,585,028 6.43E+07 1.32E+07 1.19E+07 7.73E+06 9.71E+07 0.03173837 0.957907 86,700,000‐40 ‐36 ‐38 23 23 17 63 0.009189 0.009189 0.0094708 0.0081701 63 0.008185 0.9912953 108 0.9000 660,811 383,940 347,220 270,000 1,661,971 4.16E+07 8.83E+06 7.99E+06 4.59E+06 6.30E+07 0.0206025 0.978509 53,550,000‐45 ‐41 ‐43 22 22 19 63 0.0087895 0.0087895 0.010585 0.0081701 63 0.008185 0.9994803 113 0.9417 691,404 401,715 363,295 282,500 1,738,914 4.36E+07 8.84E+06 7.99E+06 5.37E+06 6.58E+07 0.02149095 1 53,550,000‐50‐46‐48 00000000000.9994803 118 0.9833 721,997 419,490 379,370 295,000 1,815,857 0.00E+000.00E+00 0.00E+00 0.00E+00 0.00E+00 0 1 0‐55‐51‐53 00000000000.9994803 123 1.0250 752,590 437,265 395,445 307,500 1,892,800 0.00E+000.00E+00 0.00E+00 0.00E+00 0.00E+00 0 1 0‐60‐56‐58 00000000000.9994803 128 1.0667 783,183 455,040 411,520 320,000 1,969,743 0.00E+000.00E+00 0.00E+00 0.00E+00 0.00E+00 0 1 0‐65‐61‐63 00000000000.9994803 133 1.1083 813,776 472,815 427,595 332,500 2,046,686 0.00E+000.00E+00 0.00E+00 0.00E+00 0.00E+00 0 1 0‐70‐66‐68 00000000000.9994803 138 1.1500 844,369 490,590 443,670 345,000 2,123,629 0.00E+000.00E+00 0.00E+00 0.00E+00 0.00E+00 0 1 0‐75‐71‐73 00000000000.9994803 143 1.1917 874,962 508,365 459,745 357,500 2,200,572 0.00E+000.00E+00 0.00E+00 0.00E+00 0.00E+00 0 1 0Totals 2503 2503 1795 7711 7697Btu 1.93E+09 4.72E+08 4.27E+08 2.34E+08 3.06E+09 Btu 2.764E+09% Total 0.630 0.154 0.140 0.076 1.000 Fraction of Total 0.903kBtu/SF 69.46 17.02 15.39 8.43 110.30 Heating EnergyBoiler Eff: 0.82 0.82 0.82 0.82 0.82Btu 2.35E+09 5.76E+08 5.21E+08 2.85E+08 3.73E+09kBtu/SF 84.71 20.75 18.77 10.28 134.51Btu/Gal 138,500 138,500 138,500 138,500 138,500Net Gallons 13,913 3,408 3,083 1,688 22,092Gross Gallons 16,967 4,157 3,759 2,058 26,941Total Hours Percentage of Total By Group
Preliminary Estimate of Probable Cost
Wood Fired Heating System
Northway School
Northway, AK
Option 1: Containerized System School School Garage Duplex
Structural/Insulated Slab $36,000 $36,000
Covered Fuel Storage $0 $50,000
Containerized System with Boiler, Pumps, Fuel Handling $151,500 $151,500
Mechanical within Boiler Building (includes pumps): $20,000 $20,000
Temperature Control Work in Wood Boiler Plant $2,500 $2,500
Electrical Feeder to Boiler Plant and Data Line $15,000 $15,000
Electrical in Boiler Plant for Equipment $2,500 $2,500
Underground Trenching and Piping $36,000 $36,000 $8,000 $45,000
Boiler Room Integration (piping, valves, etc): $37,500 $37,500 $5,000 $15,000
Domestic Water Heater Integration (piping, valves, HX): $12,000 $12,000 $0 $0
Electrical in Existing Boiler Room for Integration Work $2,500 $2,500 $1,500 $1,500
Temperature Control Work in Existing Boiler Room $5,000 $5,000 $1,000 $1,000
Subtotal: $320,500 $370,500 $15,500 $62,500
Location Factor 25% $80,125 $92,625 $3,875 $15,625
Subtotal: $400,625 $463,125 $19,375 $78,125
Contractor OH&P 10% $40,062.50 $46,312.50 $1,938 $7,813
Subtotal: $440,688 $509,438 $21,313 $85,938
Contingency: 15% $66,103.13 $76,415.63 $3,197 $12,891
Total Project Costs 506,791$ 585,853$ 24,509$ 98,828$
610,363$ 709,191$
Option 2: Wood Chip Boiler in Site Built Building School School Garage Duplex
Simple Building on Structural/Insulated Slab $90,000 $90,000
Covered Fuel Storage $0 $50,000
Wood Boiler System $85,000 $85,000
Fuel Bin and Fuel Handling Equipment $40,000 $40,000
Mechanical within Boiler Building (includes pumps, HX, etc): $40,000 $40,000
Temperature Control Work in Wood Boiler Plant $2,500 $2,500
Electrical Feeder to Boiler Plant and Data Line $15,000 $15,000
Electrical in Boiler Plant for Equipment $8,500 $8,500
Underground Trenching and Piping $36,000 $36,000 $8,000 $45,000
Boiler Room Integration (piping, valves, etc): $37,500 $37,500 $5,000 $15,000
Domestic Water Heater Integration (piping, valves, HX): $12,000 $12,000 $0 $0
Electrical in Existing Boiler Room for Integration Work $2,500 $2,500 $1,500 $1,500
Temperature Control Work in Existing Boiler Room $5,000 $5,000 $1,000 $1,000
Subtotal: $374,000 $424,000 $15,500 $62,500
Location Factor 25% $93,500 $106,000 $3,875 $15,625
Subtotal: $467,500 $530,000 $19,375 $78,125
Contractor OH&P 10% $46,750 $53,000 $1,938 $7,813
Subtotal: $514,250 $583,000 $21,313 $85,938
Contingency: 15% $77,138 $87,450 $3,197 $12,891
Total Project Costs $591,388 $670,450 $24,509 $98,828
$694,959 $793,788
CTA December 20, 2017