Specifications

16
INDIRECT WATER HEATER OPERATION
The Forced Draft Boiler with a tankless heater coil for
domestic hot water supply is an efficient and easily
maintained system to provide large volumes of domestic
hot water. An indirect tankless water heater is one in
which domestic water is heated as it passes through a
copper coil immersed in hot boiler water. The boiler
water is maintained at 200°F or higher and circulates
around the outside of the coil transferring boiler water
heat to the domestic water in the coil. The domestic
water and boiler water are therefore separated, and the
domestic hot water provided is totally potable.
The tankless heater coil heats the domestic water
instantaneously as it passes through the coil. The coils
are designed for a predetermined flow of water in
gallons heated per minute. This flow rate should not be
exceeded, or the temperature of the domestic hot water
will be reduced.
If the domestic hot water demand will exceed the output
of the heater, then a storage tank should be considered
as illustrated on Page 21. It should be noted that a
circulating pump must be used with a storage tank
application since the design of a tankless coil prevents
the gravity flow of the water. The pump should be of an
all-bronze, corrosion-proof construction since continual
pumping of fresh water, which contains acids and
corrosive substances in varying amounts, frequently
causes rapid deterioration of circulator pumps. The
storage tank should be sized in accordance with that
required to provide the maximum amount of water over
a given period of time and allowance should be made
for that additional amount of hot water which the heater
will provide to replenish that in the tank.
An indirect tankless hot water heater is not
recommended for use with a hard water supply unless
the water is treated. Use of hard water in a tankless coil
results in internal mineral scaling and progressively will
build up to the point of total obstruction. It is
recommended that the local water supply be checked
and treated as may be recommended.
VENTILATION AND COMBUSTION AIR —
When the boiler is installed in an unconfined space in a
building of unusually tight construction, a single
opening in an outside wall shall be provided and
furnished with a properly louvered metal sleeve. This
opening shall have a free area of not less than one (1)
square inch for each five thousand (5000) Btu per hour
total input rating on all appliances.
When the Boiler is installed in a confined space, one of
the following provisions must be made to insure
adequate air for ventilation and combustion:
a. Two openings in a wall to an adjoining interior
area which has adequate air supply from
outdoors. One opening should be near the floor
and the other near the ceiling. Each shall have a
free area of not less than one (1) square inch for
each thousand (1000) Btu per hour input to all
appliances in the boiler room.
b. Two openings to outdoors or to spaces (crawl or
attic) that freely communicate with outdoors.
One opening should be in or near the ceiling and
one should be in or near the floor, and each shall
have a free area of not less than one (1) square
inch for each four thousand (4000) Btu per hour
total input. Horizontal ducts may be used if the
free area is not less than one (1) square inch for
two thousand (2000) Btu per hour total input and
minimum duct dimension is 3” or more.
c. Two openings through an interior wall (located
and sized as in provision (a) above) and an
additional opening to outdoors (as in provision
(b) above) in or near the floor having a free area
of not less than one (1) square inch for each five
thousand (5000) Btu per hour total input.
COMBUSTION AND VENTILATION AIR REQUIREMENTS
FOR BOILER ROOMS — MINIMUM AIR TO ACCOMMODATE
FORCED DRAFT BOILER-BURNER UNITS
The boiler room must have an adequate air supply to permit clean, safe combustion,
and to minimize soot formation. An unobstructed direct air opening of the sizes listed
below should be provided.
LIOROSAG
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371
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712
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643
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