LAARS HP-M2 Series - Installation, Operation and Maintenance Instructions - Manual (Page 11)

H Series Page 11
2. For boilers in confined rooms, two permanent
openings shall be provided - one within 12" of
the ceiling, and one within 12" of the floor of
each room. Each opening shall be at least one
square inch per 1,000 BTU/HR boiler input, but
not be less than 100 square inches. These
openings shall freely connect with areas having
adequate infiltration from outside.
3. When all air is provided from outdoors, the
confined space shall be provided with two
openings as outlined above. These openings shall
connect directly, or by ducts, with outdoors or
spaces (crawl or attic) that freely connect with
the outdoors, and shall be of the size listed below
for that particular arrangement.
a.
One square inch of free area per 4,000
BTU/HR of boiler input for direct outdoor
air supply through an outside wall, or
through vertical ducting directly to outside.
b. One square inch of free area per 2,000
BTU/HR of boiler input for direct outdoor
air through horizontal ducting.
c. All ducting shall be of the same size as the
opening to which it is connected.
SECTION 4.
Gas and Domestic Water Piping
4A. Gas Connection to H Series
The H Series requires an inlet gas pressure of at
least 4" W.C and no greater than 13" W.C. Check with
your local gas utility or supplier for availability of this
pressure range.
Referring to Table 4, size supply piping to
minimize pressure drop between meter or regulator
and unit.
Run gas supply line in accordance with all
applicable codes. IF UNIT IS INSTALLED ABOVE
GAS SUPPLY, RUN PIPPING UP TO A POINT
ABOVE VENT CENTER LINE AND BACK DOWN
TO UNIT. THIS WILL PREVENT WATER FROM
ENTERING GAS SUPPLY SHOULD A LEAK
DEVELOP IN THE BOILER SECTION (see
Figure 12).
Locate and install manual shutoff valves in
accordance with state and local requirements.
Install drip leg, ground joint union and drip cap
to trap sediment and for test gauge access (see
Figure 12).
Support all piping with proper hangers.
All threaded joints should be coated with piping
compound resistant to action of liquefied petroleum
gas whether LPG is used or not.
The boiler and its individual shutoff valve must
be disconnected from the gas supply piping system
Figure 12. Gas Piping.
Length
of
Pipe
Capacity of Pipe in MBTU / HR
(.6 Specific Gravity)
½" ¾" 1" 1¼"
10' 132 278 520 1,050
20' 92 190 350 730
30' 73 152 285 590
40' 63 130 245 500
50' 115 215 440
75' 93 175 360
100' 79 150 305
150' 64 120 250
Additional
length to be
added for each
tee or bend
1.3' 1.7' 2.2' 2.7'
Table 4. Gas Pipe Capacity.
during any pressure testing of that system at test
pressures in excess of 1/2 psig (3.5kPa).
The boiler must be isolated from the gas supply
piping system by closing its individual manual shutoff
valve during any pressure testing of the gas supply
piping system at test pressures equal to or less than
1/2 psig (3.5kPa).
The boiler and its gas connection must be leak
tested before placing the boiler in operation.
Purge all air from gas lines.
Note: H Series’ are certified for 4" to 13" W.C.
We find on L/P the unit performs better when the low
pressure regulator is not set over 9" W.C. Use an
appliance regulator (maxitrol RV48 or equivalent) if
more than 3" lock up occurs in gas supply.
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