7
VENTILATING
GRILLE
COMBUSTION
AIR GRILLE
A95594
Fig. 5 -- Air Openings for Closet or Utility
Room Installations
BOILER
FRESH AIR
DUCT
A95595
Fig. 6 -- Fresh Air Duct for Tightly Sealed House
Example: The boiler is rated at 100,000 Btuh. The water heater is
rated at 30,000 Btuh. The total is 130,000 Btuh. Two grilles are
needed, each with 130 sq. in. of FREE opening. Metal grilles
have about 60 percent FREE area. To find the louvered area
needed, multiply the FREE area required by 1.7 (130 X 1.7 =
221.0 sq. in. louvered area). In this example, 2 grilles each having
an 8 in. X 30 in. (240 sq. in.) louvered area would be used. Fig. 5
shows grille locations.
ALL AIR FROM OUTDOORS
The confined space shall be provided with 2 permanent openings,
1 commencing within 12--in. of the top and 1 commencing within
12--in. of the bottom of the enclosure. The openings shall
communicate directly, or by ducts, with the outdoors or spaces
(crawl or attic) that freely communicate with the outdoors. See
Table 2 and Fig. 5 or 6.
1. When directly communicating with the outdoors, each
opening shall have a minimum free area of 1 sq. in. per
4000 Btuh of total input rating of all equipment in the
enclosure.
2. When communicating with the outdoors through vertical
ducts, each opening shall have a minimum free area of 1
sq. in. per 4000 Btuh of total input rating of all equipment
in the enclosure.
3. When communicating with the outdoors through
horizontal ducts, each opening shall have a minimum free
area of 1 sq. in. per 2000 Btuh of total input rating of all
equipment in the enclosure.
4. When ducts are used, they shall be of the same
cross--sectional area as the free area of the openings to
which they connect. The minimum dimension of
rectangular air ducts shall not be less than 3--in.
Boilers With Tankless Heater Coil
Boilers may be factory packaged with a tankless heater coil. The
use of this coil eliminates the need for a hot water storage tank.
Instantaneous heating of water in the coil provides a flow of hot
water for domestic use if proper burner and water supply line
controls are used. Tankless coils are meant to provide domestic
hot water for intermittent draws, not continuous flows.
IMPORTANT
:
Do not use a tankless coil if water is
excessively hard with lime or other deposits which will
accumulate inside coil.
C. Mounting Aquastat Control
The control configuration on this boiler has been set up so that
the Honeywell L8124C Combination Hi/Low Limit Aquastat
Relay mounts on the tankless coil. This maximizes tankless coil
performance by making the burner respond more quickly to a call
for domestic hot water. The boiler is completely wired according
to schematic wiring diagram. (See Fig. 14.) The installer must
mount the L8124C Aquastat on control well in 3/4--in. tapping
on tankless coil. (See Fig. 7.)
D. Tankless Coil Piping
IN
1
⁄
2
IN.
NPT
3
⁄
4
IN.
NPT
CONTROL WELL
A95596
Fig. 7 -- Tankless Heater Coil
Piping is as shown in Fig. 8. A tempering valve (mixing valve) is
recommended. A flow restrictor may be required on tankless coil
inlet piping so that flow rates are matched to boiler heat input.
See Table 3.
BW
4
/BW
5
