Nature's Comfort NCB-120-COAL User manual

Installation and Operating Manual for
2010-2015
NCB-120-COAL
NCB-175-COAL
NCB-250-COAL
NCB-275G-COAL
NCB-325G-COAL
NCB-400G-COAL
Non-Pressurized Outdoor Coal Boiler
Manufactured by Nature s Comfort LLC.
Made in the USA
www.naturescomfortllc.com
Built Like A Tank
With Laser Precision
SAVE THESE INSTRUCTIONS
Revision 2015-1.9

INTRODUCTION
Thank you and congratulations on the purchase of your new Nature s Comfort boiler!
With the purchase of this Nature s Comfort boiler, you can now appreciate the high degree of
craftsmanship and reliability that are a result of every boiler being carefully hand-built as well
as taking control of heating your home. Your choice shows the recognition you have for high
quality products.
We deem it important to provide you with this operation and maintenance manual, allowing
you to use your equipment under the best possible conditions and in the most optimal
manner and furthermore, to increase its operating life. Read thro gh caref lly before
beginning installation, follow all instr ctions and keep this man al handy.
THIS MANUAL INCLUDES IMPORTANT SAFETY INFORMATION ON PAGE 5
Again, thank you for purchasing a Nature s Comfort Boiler.
We appreciate yo r b siness!
If you are in need of insulated pex, heat exchangers or other parts for your new
boiler call your dealer or call us at 877-251-7740 for the lowest prices!
Boiler water treatment and test required at time of installation and annually to
validate warranty. See warranty page for complete details.
Visit www.naturescomfortllc.com each year to confirm the most up-to-date
installation, operation & warranty information or if you need to see any page in
color.
Please keep this manual with all other important papers. The information in this manual is
necessary for the installation, operation and proper use of the boiler. If you should ever have
a problem or question refer to this manual or call your dealer. If your dealer does not have
the information you need, request they contact Nature s Comfort and your dealer will be
further educated to provide the best possible customer service. Please keep in mind that
Nature s Comfort built the boiler but did not install it and has no control over the installation,
the efficiency of the building s insulation or what is burned in the boiler.

Table of Contents
I. General Information
A. Terminology ............................................................................. 6
B. Clearance to Comb stibles Req ired .......................... 6
C. Boiler Dimensions & Specs .............................................. 6
D. Safety Preca tions ................................................................. 7
E. Controls & Pl mbing Connections ................................. 8
F. Heating the Home ................................................................... 9
II. Installing the Boiler
A. Location of Boiler .................................................................. 10
B. Chimney, Extensions & Rain Cap ................................ 11
C. Undergro nd Ins lated Pex Pipe .................................. 11
D. Pl mbing Hook p ............................................................... 12
E. Wiring the Boiler ................................................................... 12
F. Forced Air Systems -Thermostat Wiring ................... 12
G. Adding Bypass Valves ...................................................... 14
H. Installing A Water-To-Air Heat Exchanger ................. 14
I. Installing In A Small Plen m ............................................ 15
J. Adj sting Plen m Air Flow .............................................. 16
K. Installing On An Existing Indoor Boiler ..................... 16
L. Filling The Boiler with Water ............................................. 19
M. Float Level ................................................................................ 19
N. Bleeding Air From Heat Exchangers .......................... 19
O. Pre-conditioning Rope Seals .......................................... 19
III. Heating Domestic Water, Pools and Spa’s
A. Sidearm Or Plate Heat Exchanger For Domestic Hot Water .................................................................................. 20
B. Heating a Pool or Spa .............................................................................................................................................................. 21
IV. Operation
A. Coal Req irements ................................................................................................................................................................... 22
B. Starting A Fire .............................................................................................................................................................................. 22
C. Loading Coal ................................................................................................................................................................................ 22
D. Blower O tp t Damper ........................................................................................................................................................... 23
E. Power Loss Proced re, R nning On A Generator .................................................................................................... 23
F. Warm Weather Operation, Bypass For Domestic Hot Water Only ..................................................................... 23
V. Maintenance
A. Cleaning ......................................................................................................................................................................................... 24
B. Disposal Of Ashes .................................................................................................................................................................... 24
C. Creosote – Formation And Need For Removal ........................................................................................................... 24
D. F el Door & Cover Seals ........................................................................................................................................................ 24
E. P mp ............................................................................................................................................................................................... 25
F. End of Season Care .................................................................................................................................................................. 26
Going Away ................................................................................................................................................................................... 27
Disclaimer ....................................................................................................................................................................................... 27
Tro ble Shooting .................................................................................................................................................................... 28
Warranty .......................................................................................................................................................................................... 29
Warranty Cards ...............................................................................................................................
30

Page 6 of 34
I. General Information
A. Terminology In This Man al
Boiler: Refers to the Nature s Comfort boiler.
Furnace: Refers to the existing indoor gas or oil fired unit which heats the air or radiant water
heat for the home.
B. Clearance to Comb stibles Req ired
Top, Front, Rear and Sides: 36”
Flooring: Non-Combustible
C. Boiler Dimensions & Specifications
NCB-120 160,000 BTU, 120-gallon water tank, 3,000 sq ft.*
COAL 65"x40"x87" tall, 1646 lbs
NCB-175 220,000 BTU, 175-gallon water tank, 4,000 sq ft.*
COAL 67"x50"x90" tall, 1933 lbs (3/8” firebox)
NCB-250 300,000 BTU, 250-gallon water tank, 6,000 sq ft.*
COAL 85"x50"x90" tall, 2314 lbs (3/8” firebox)
NCB-275G 380,000 BTU, 275-gallon water tank, 8,000 sq ft.*
COAL 73"x50"x89" tall, 2313 lbs
NCB-325G 460,000 BTU, 325-gallon water tank, 10,000 sq ft.*
COAL 85"x50"x89" tall, 2613 lbs
NCB-400G 500,000 BTU, 400-gallon water tank, 12,000 sq ft.*
COAL 85"x50"x96" tall, 2813 lbs
* Will heat up to (x)sq ft (This must include all heated areas of home as well
as basement.) with proper installation, properly insulated building and
when dry coal is used.
Deduct a minimum of 500 sq ft if heating domestic hot water.
Firebox Sizes
Model (Coal) C /Ft Description Width Depth Opening Ash Pan
NCB-120 15.0cu/ft oval 25.5”W x 31”H 36” 21.75”W x 22”H 39” X 11.75”X 4”
NCB-175 13.5cu/ft 29” cylinder 29.25” 36” 25.75”W x 17.75”H 39” X 11.75”X 4”
NCB-250 20.5cu/ft 29” cylinder 29.25” 54” 25.75”W x 17.75”H 39” X 11.75”X 4”
NCB-275G 23.4cu/ft oval 30”Wx36”H 42” 27”W x 25.5”H 39” X 11.75”X 4”
NCB-325G 28.5cu/ft oval 30”Wx36”H 54” 27”W x 25.5”H 39” X 11.75”X 4”
NCB-400G 40.0cu/ft oval 30”Wx46”H 54” 27”W x 25.5”H 39” X 11.75”X 4”
Steel thickness
Model (Coal) Water Jacket Firebox
NCB-120 10ga. (approx. 1/8”) ¼”
NCB-175 7ga. (approx. 3/16”) 3/8” or ¼”**
NCB-250 7ga. (approx. 3/16”) 3/8” or ¼”**
NCB-3275G 7ga. (approx. 3/16”) ¼”
NCB-325G 7ga. (approx. 3/16”) ¼”
NCB-400G 7ga. (approx. 3/16”) ¼”
**Firebox thickness depends on option ordered by customer

Page 7 of 34
D. Safety Preca tions
Do not operate this equipment for anything other than its intended purpose or for anything other
than in accordance with the instructions contained in this manual and all other instructions
accompanying the boiler. It is important to observe safety precautions to protect yourself and others
from possible injury. Observe all safety labels on the boiler.
All electrical and pl mbing sho ld be done by q alified personnel and conform to national,
state and local electrical, pl mbing, fire and b ilding codes.
1. DO NOT USE CHEMICALS OR FLUIDS TO START THE FIRE. Never use chemicals or any
type of petroleum based product, charcoal starter, lighter fluid, lantern fuel, kerosene or any other
flammable accelerant to start the fire in the firebox of the boiler. Keep all such liquids well away
from firebox.
2. If using antifreeze, use only non-toxic, follow manufacturer s recommendations on mixing ratio
and test annually per manufacturer s specs. Keep containers of antifreeze, which is flammable, well
away from the boiler.
3. The use of treated wood (painted, treated, etc.) and any other salvaged material that can emit
toxic gases into the environment and is corrosive towards the components of the appliance is not
allowed and voids the warranty.
4. DANGER! Risk of fire or explosion – DO NOT BURN GARBAGE, GASOLINE, NAPHTHA,
ENGINE OIL OR OTHER INAPPREPRIATE MATERIALS. Flammable liquids household or yard
waste can reduce the life of the boiler, will void the warranty and is illegal in most areas.
5. Pause for 30 seconds between the first latch and the safety latch to allow any combustion gases
to burn off. Always keep fueling and de-ashing doors closed and maintain all seals in good
condition.
6. In the event of a runaway fire, make sure all doors are tightly shut, unplug the control power,
keep the pump running, make sure the blower damper is closed and keep the water jacket full.
7. WARNING! Risk of fire – Do not operate with fuel loading door open. Do not store fuel or other
combustible material within the marked installation clearances. Leaving a small crack or opening
can cause over-heating in the firebox, boiling the water off, damage of the unit and voiding the
warranty. Inspect and clean the firebox, ash pan and chimney regularly.
8. CAUTION! Hot surfaces. Keep children away. Do not touch during operation. Always use proper
care when installing, operating and maintaining the boiler.
9. Always wear protective gloves and glasses and be aware that hanging and loose clothing can
catch fire.
10. All doors and covers must be maintained in place at all times, except during maintenance and
servicing.
11. Do not modify the boiler or controls. Do not connect this unit to a chimney flue serving another
appliance.
12. Failure to heed these warning or any additional warnings on the boiler may result in an accident
causing personal injury and damage and void the warranty.
All installation and operation m st follow federal, provincial, state and local codes

Page 8 of 34
E. Controls & Pl mbing Connections
The outside boiler has a hot water thermostat (aquastat) with a thermocouple that is inserted into a brass
drywell that senses the water temperature of the unit. When the temperature of water in the boiler falls
below the “low” temperature setting on the aquastat, the solenoid lifts the cover off the blower which turns
on, feeding oxygen to build a hotter fire and remains on until the water temperature in the boiler reaches
the “high” temperature setting of the aquastat.
Temperature should be set at 180F and no higher with the differential setting at 15 degrees. This provides
for an “on” point of 165F and a long burn cycle to burn off any creosote buildup. Running below 150F at
any time will result in condensation from too great of a temperature difference between the water jacket
and firebox (same principle as a glass of ice water left out on a hot day) which increases creosote and
when mixed with ash is very corrosive and will shorten the life of your boiler.
Boiler shown is set up as a single-zone. You
may install fittings to have ports for up to 4
zones (Consult your dealer. Additional port setups with pumps
are also available from Nature s Comfort when ordering a new unit.)
Single-Zone set p
1. Power from home feeds lower outlet
2. Control power for pump, aquastat, solenoid,
blower and light is fed through main plug by
lower outlet.
3. Switch for shutting off power to aquastat
(which will shut down blower & solenoid).
4. Aqua-stat sensor for controlling blower and
solenoid.
5. Solenoid (behind cover) to lift intake cover off
blower.
6. Blower to feed oxygen to fire.
7. Damper to control air flow.
8. Pump to circulate water. (One pump is
included.)
9. Red Pex pipe goes from the pump to heat
exchanger(s) in home.
Please note! The pump
that came with your boiler may not be the correct size
for your installation. Please consult your dealer for
sizing as water flow is essential to the proper & efficient
operation of your installation.
10. Blue Pex pipe returns from home to upper
port. (Use of additional valve is
recommended for ease of servicing. Not
included.)
11. Extra Port (This is for a low water cut-off
switch if required by an inspector. Call your
dealer to obtain if needed)
12. Wires to outdoor light. (If applicable – may be
provided with solar rechargeable LED light)

Page 9 of 34
F. Heating the Home
The NCB boiler saves energy and provides the most comfortable heating available. It heats the
home by burning seasoned hardcoal to heat a firebox surrounded by a steel tank filled with water.
The boiler is non-pressurized with an atmospheric vent and includes an easy-to-read water jacket
float indicator. The heated water must be circulated through insulated underground pex pipes to a
heat exchanger that must be installed in the existing furnace system.
If you have a forced-air system, a water-to-air heat coil must be installed in the ductwork. When air
travels through, heat is extracted and hot air is emitted out of the registers.
A water-to-water plate heat exchanger must be used if you have a hydronic radiant heating system.
When connecting to an in-floor heating system in concrete, a mixing valve is also required to keep
temperatures below 110F or damage to the concrete will occur over time from too much heat
expansion.
Complete parts packages at the lowest prices are available from Nature s Comfort or your dealer!

Page 10 of 34
III. Installing Boiler
Installation is to be performed by a q alified installer and shall comply with all the
req irements of the a thority having j risdiction over the installation.
A. Location of Boiler
The NCB boiler must be located to comply with the clearance requirements. Keep the firebox door
positioned so as not to point toward a structure so all fire danger is removed from the home. The
boiler may be installed as much as 250 feet away using an appropriately sized pump and piping
and still heat the house and hot water. However, if the boiler is located more than 100 feet away,
you may experience inefficiency and heat loss. A larger pump than the one supplied may be
needed for distances over 100 feet and/or any rise in elevation over 15 feet.
Locate the NCB boiler where it will be convenient for refueling and coal storage. Pex pipe and
power lines are to be installed underground between the house and the boiler and must be buried
below frost lines.
1. It is recommended that the boiler be installed with chimney extensions for due consideration to
any neighboring residences and to the prevailing wind direction.
2. Do not locate the boiler within 100 ft of a residence not served by the boiler. Be considerate of
neighboring residences, properties, parks, etc.
3. Do not locate the boiler near any combustible materials, gasoline or other flammable liquids or
gases.
4. The boiler should be located away from dry, grassy areas and any buildings
to minimize danger of fires.
5. Check with the insurance company and local codes or ordinances.
6. Do not install the boiler in an area where nearby structures or trees might cause down drafts.
7. Typically, outdoor coal burning boilers are located 40 to 100 ft down wind from the structure
served.
8. To aid in smoke dispersal, extra chimney lengths may be required depending on the distance to
surrounding structures.
Fail re to keep the boiler area clear and free of comb stible materials, gasoline and other
flammable liq ids and vapors can res lt in severe personal inj ry, death or s bstantial
property damage.
A full concrete pad or footings just under the feet are not necessary for the installation for the boiler,
but is recommended to prevent frost heaving. Four concrete footing blocks 8” X 16” X 4” will suffice
if desired. You may add additional layers of blocks for ease of loading coal. The figure below is for
outside foot dimensions.

Page 11 of 34
If the unit is located in a windy area, it is recommended to install a non-combustible type of skirting
around the feet and control area.
B. Chimney:
A stainless steel rain cap (5” for 120 model, 6” for 175, 250 & 325G) must be purchased separately
for installation and can be obtained from Nature s Comfort or your dealer. If installing extensions,
use supports as directed by pipe manufacturer. It is recommended that the boiler be located with
due consideration to the prevailing wind direction.
1 It is recommended that the stack be at least 2 feet higher than the peak roof line the nearest
residence.
2 If located more than 100 feet but no more than 150 feet to any residence, it is recommended
that the stack be at least 50% of the peak roof line of that residence, plus an additional 2 feet.
3 If located more than 150 feet but no more than 200 feet to any residence, it is recommended
that the stack be at least 25% of the height of the peak roof line of that residence, plus an additional
2 feet.
Example of chimney height relative to nearest downwind neighbor
Always comply with all applicable state and local codes and laws.
C. Undergro nd Ins lated Pex Pipe
You must use underground insulated pex pipe for transferring the heated water from the boiler to
the home. Minimum pipe size permitted is 1”. Platinum 3 wrap (4” drain tile) & Platinum 4 wrap (5”
drain tile) insulated pipe is available for purchase through Nature s Comfort or your dealer. It may
contain twine for pulling electrical wire. If possible, do this with the pipe laid out straight for ease of
pulling.
CALL YOUR LOCAL MISS DIG HOTLINE BEFORE YOU DIG TRENCHES!
Bury the underground insulated pipe below frost lines (or just above water table level) and keep
underground as it enters the house. The depth of the trench varies in different regions of the
country. Be completely sure about the correct depth needed before the insulated pex pipe is
installed underground. Contact your local building inspector s office for this information. Make sure
to seal around the corrugated pipe to prevent water from entering. If conditions require the pipe to
be above ground for entering the home, make sure to insulate thoroughly.
Note: If only one color of PEX pipe is used, label the water lines or connect and test them before
back filling over pipe and lines. If you have rocky ground, make sure you use clean fill or place
straw or landscape fabric around the pipe before back filling, giving extra protection against
punctures.
If more than one building is to be heated, additional pipe and pump must be installed.

Page 12 of 34
D. Pl mbing Hook Up
Plumbing connections should be well insulated after installation. Cover bottom access holes as
well.
Minimum pipe size permitted is 1”. Install the outgoing pex line on the pump flange that is already
mounted to the lower end of the circulation pump. Install the return line on the 1-1/4” fitting located
in the top-middle of the rear control area. Add a valve to the ret rn line so if repair or service is
needed on lines or eq ipment, the water in the boiler can be isolated witho t having to be
drained. (Valves and PEX fittings can be purchased from Nature s Comfort or your dealer.)
Install a fill line from the domestic water into the return line at the house using a T, 2 valves and a
union to disconnect or a backflow preventer when not using to keep 100% isolated so no boiler
water can ever enter the domestic side if pressure is lost.
Use sweeping bends for PEX pipe keeping 90 s to a minimum (no more than 6) as each one adds 1
foot of head pressure, reducing the rate of water flow. For tight radiuses use ¾” rubber heater hose
in short lengths (fits 1” PEX fittings and is available from Nature s Comfort or your dealer).
For a forced air system, run the line from the pump first to the heat exchanger for the domestic hot
water then to the one in the furnace plenum. For a hydronic radiant system, reverse this order.
Note: For larger homes, 1-¼ pipe may be needed for maximum BTU output. A 1-¼” pipe can carry
up to 37% more BTUs due to higher water flow. The fittings above would need to be changed to
accommodate 1-¼” Pex. The Armstrong E9.2 pump available from Nature s Comfort or your dealer
has the ability to do this in a 1” pipe within distance & height limitations.
E. Wiring the Boiler
A q alified electrician m st wire this boiler in accordance with the National Electrical Code.
A dedicated GFCI protected 15amp, 115vac circuit needs to be installed to power the lower outlet.
Land power & neutral wires to the back of the outlet and wire nut the ground wire to the green wire
that is fastened alongside the ground of the outlet. See controls section for an electrical diagram.
The size and type of electric wire to be installed depends on the distance from the boiler to the
house. If the boiler is less then 100 feet from the house, #14 AWG UF cable is the smallest wire
that may be used. If the distance is greater than 100 feet, #12 AWG UF cable must be used.
A maximum of 5 amps is used by the boiler if all standard equipment is running. The extra outlet will
provide a total of 10amps for convenience use.
For ease of loading at night, it is suggested to install an outdoor light on a pole, 10 -20 from the
front of the boiler and offset slightly so a user can see inside the firebox when loading.
F. Forced Air Systems - Thermostat Wiring
The next example drawings are for controlling the blower on a forced air system independently of
the existing heat source (i.e. propane, electric, fuel oil, etc). Nature s Comfort can provide custom
diagrams for other types of control setups as well upon request.

Page 13 of 34
Use this example diagram if you have a typical, basic 4 wire system:
Use the example drawing below if you have a 2 wire system or the thermostat is the advanced
computerized type that communicates back and forth between the furnace (typically found on heat
pump systems). Do not se this method if yo r HVAC system tilizes a m lti-speed blower. All
of the parts below are available through your dealer or Nature s Comfort.

Page 14 of 34
G. Adding Bypass Valves
Adding a bypass valve system (3 valves, 2 T s and unions) at each heat exchanger is a good idea
so that if there is a potential problem such as a stopped up heat exchanger, it can be diagnosed &
serviced easily as well as being used for a summer bypass as explained in the “operation” section
of this manual.
H. Installing A Water-To-Air Heat Exchanger
The heat exchanger should be installed above an air conditioning condenser coil and must be
placed at least 2” above it so any ice that may from on the condenser due to improper operation
won t touch the new heat exchanger.
No air can be allowed to flow around it or out of the ductwork. Use adhesive backed foam tape
(used for insulating doors and windows) to seal around the frame and foil tape to seal off the
opening you make in the plenum heat for the heat exchanger.
Make sure the fittings for the supply and return lines are easy to get to once the heat exchanger is
installed.
You should be able to find a heat exchanger to fit most popular sizes of plenums. If you are unable
to the ductwork must be modified to accept the heat exchanger. Wear proper protective gear.
(gloves, safety glasses, etc…)
Measure the width of the heat exchanger (Dimension A in next diagram). Measure the thickness of
the heat exchanger (Dimension C).
Start by cutting a hole in the side of the ductwork the thickness of the heat exchanger (Dimension
C) and the full length of the ductwork (usually Dimension A).
WARNING! Metal edges are very sharp! Wear protective gloves and se ca tion!

Page 15 of 34
Slide the heat exchanger into the hole for a test fit. Ideally the header and tubes (F) should stick out
of the plenum.
While test fitting try to determine how much tape is needed around the frame of the heat exchanger
to seal and keep air from flowing around it. A different amount (thickness) may be needed on
different sides.
The heat exchanger must be secured so it won t move up or downstream in the plenum. Fabricate
some ‘L shaped braces and install the proper width apart as shown below (Dimension C). Secure
in place using pop rivets or self tapping screws.
Slide the heat exchanger carefully into the plenum to check the fit again. Once proper fitting is
verified, you can seal off the ends of the heat exchanger and the hole you made in the plenum with
foil or duct tape.
I. Installing In A Small Plen m
You can install a heat exchanger in a plenum that is smaller than the length of the heat exchanger
as follows. Make cuts at the top and bottom of the plenum, usually 4 inches long (the width of the
heat exchanger) as shown below. You may need to do this on both sides of the ductwork
depending on the heat exchanger size.
Slide the heat exchanger through the front hole to the back hole so it protrudes out the front and
back of the plenum the same amount. Ideally the core of the heat exchanger will be entirely within
the plenum.

Page 16 of 34
Crimp the sheet metal to the edge of the heat exchanger (item G) using channel-lock pliers. This
not only forms a virtually airtight seal, but also supports the heat exchanger as well.
J. Adj sting Plen m Air Flow
The motors on most force air furnaces have three speeds to provide various rates of air movement.
Please consult a local furnace specialist if you want to change the airflow of an existing furnace
system.
K. Installing On An Existing Indoor Boiler
The NCB boiler may be connected to an existing boiler system. A water-to-water plate heat
exchanger is needed to transfer heat from the outdoor boiler to the indoor hydronic system so that
the two systems remain isolated (see next diagram).
As shown in the above figure, the two systems are totally isolated from each other so that the
existing hydronic system remains undisturbed and functions exactly as it did before. Water that
circulates through the outdoor boiler is never circulated through the home s hydronic system or
vice-versa.
All pumps and controls remain essentially the same on the existing system but you will need to
keep the burner on the indoor boiler from firing. This can easily be done by strapping a thermal
snap disc limit control to the incoming line from the outdoor boiler and wiring it in series with the
indoor boiler s aquastat (see next drawing). This provides the means to solely heat the home with
the outdoor boiler if the water on the incoming line is over 140F. If it ever falls below 120, the indoor
burner will fire again to keep the home warm and also reverse heat the outdoor boiler to keep it
from freezing.

Page 17 of 34
The electrical diagram on the next page shows a typical control setup for operating a 2 zone radiant
system for a new radiant installation that does not use an existing hydronic furnace. Part numbers
are noted on each item for ordering from Nature s Comfort.

Page 18 of 34

Page 19 of 34
L. Filling the Boiler with Water
Inspection: Before filling, inspect the pump shaft by removing the large silver screw to expose the
top of the shaft and turn back and forth with a screw driver to make sure the shaft was not broken
during shipping. Broken shafts are not covered nder warranty nless fo nd and noted before
installation and start p. Also read maintenance section in f ll.
Once all piping connections are complete, flush about 20 gallons of water into the float stack and
drain, repeating until it comes out clean. Close drain valve and pour Nature s Comfort boiler
treatment in – req ired for warranty. Fill the boiler with a hose through the float stack or if you
have installed a fill line, open the valve and allow it to fill, stopping once the float starts to rise.
Use water that is softened and has low iron content if possible for maximum boiler and pump life.
Do not start circ lation p mp ntil boiler is FULL and the impeller and bearings have been
primed! After filling, remove the top screw on the pump until a steady stream of water flows and all
air has been purged. Being a wet-rotor unit, if the pump runs dry at all, it will seize up as the
bearings rely on lubrication from the water. See maintenance section for f ll details on p mp
operation and care.
During the first heating cycle the water might expand and overflow. This is normal and will occur
anytime too much water has been added. Open the drain valve to keep the float indicator at the
bottom of the rubber cap. Any higher than this and hot water may push the float out and also cause
scalding water to spill out. (Over-fill when boiler is shut off and not in use)
After water has circ lated for 1 ho r, test Nitrite level to ass re req ired 1,000-1,500ppm and
add treatment if below this level. S bmit a water sample to yo r dealer or Nat re’s Comfort
for official warranty Nitrite testing and also once a year thereafter. REQUIRED! See warranty
for f ll details.
M. Float Level
After priming and starting the circulation pump and bleeding the heat exchanger (see next section),
let the boiler heat up and run for 24 hours then top off the water if needed. The ideal water level is
at the beginning of a heating cycle for the level indicator to be at the bottom of the rubber cap. The
water level will rise and fall during operation as water expands and contracts with temperature
changes. Be sure to keep the boiler full of treated water at all times including through the summer
as this will keep the boiler free from corrosion and when in use, from overheating causing
circulation pump failure.
N. Bleeding the Heat Exchangers
With the pump running (prime and flush bearings first!), simply close a valve on the return side, hold
for 1 second then open quickly. Repeat the procedure four times or until you cannot hear air rushing
through the line.
O. Pre-conditioning Rope Seals
Option 1: (Good) Wet the rope seals with WD-40 before firing the boiler to keep prevent hardening
from smoke and creosote and re-apply 1 or 2 times during the heating season or as needed.
Option 2: (Better) Purchase a tube of high temperature caulk from your dealer or Nature s Comfort
and lay a bead of caulk on the impression of the door jamb in the rope seals, placing a 2” strip of
wax paper over them. Over-extend the latch open and bounce the door/ash pan closed, then leave
open to fully cure before starting a fire to get a custom seal. Once cured, wet the rope seals with
WD-40 to prevent hardening from smoke and creosote and re-apply 1 or 2 times throughout the
heating season or as needed.

Page 20 of 34
Option 3: (Best but more hassle and messy) Purchase a tube of high temperature caulk from your
dealer or Nature s Comfort and brush over the entire surface area of the rope seals to permanently
seal out smoke and creosote. Place a 2” strip of wax paper over this. Over-extend the latch open
and bounce the door/ash pan closed, then leave open to fully cure before starting a fire to get a
custom, long term seal.
NOTE! Adjust fuel door if you ever see any amount of smoke. See maintenance section.
Door adjustment is done at the factory but may be required again after installation and before
starting a fire as the seals compress over time. See maintenance section for complete
adj stment and care instr ctions.
III. Heating Domestic Water, Pools and Spa’s
A. Sidearm or Plate Heat Exchanger For Domestic Hot Water
For a sidearm heat exchanger, the hot line from boiler must first go to the top side port. This creates
twice the domestic water flow through the sidearm as opposed to coming in at the bottom side port.
For the fastest recovery, install a small circulation pump on the domestic side that is controlled by a
strap-on thermostat or thermal snap disc placed on bottom line on the domestic side. Hookups to
the domestic side must be connected to the drain and pressure relief ports. Yo cannot se a
sidearm if the press re relief port is on top of the water heater tank. The domestic side will not
thermal siphon properly and will frequently air lock as well.
Make sure to keep drain & pressure relief in service & purge all air from piping and sidearm or it will
air lock.
The plate HX drawing shown is for a pre-heater setup. Leave utility energy on for this to maintain
the water temperature. As water is used it will then be heated by the plate HX for unlimited hot
water. You may also use a plate HX to bypass the water heater entirely for on-demand operation.
Always se a mixing valve to prevent scalding water temperat res.