Burnham PVG - Manual (Page 37)

7
A. General Guidelines
1. Read and follow all venting, combustion air,
water piping, gas piping and electrical instructions
contained in this manual unless otherwise instructed
in this section.
2. Consult Local Building Codes or National Fuel Gas
Code, NFPA 54/ANSI Z222.3 for restrictions and
instructions on modular boiler installations.
B.
Module Sizing
Burnham recommends sizing each boiler in a modular
system to provide 20 % of the combined heating load
where ever possible.
C. Venting
1. Each boiler must have an individual vent pipe.
Refer to Venting Section of this manual for venting
guidelines and options.
WARNING
Do not manifold vent pipes together.
2. The maximum vent length for each boiler is fifty
(50) equivalent feet.
3. The minimum horizontal distance between vent
terminations is one (1) foot. Additional horizontal
distance is desirable to avoid frost damage to the
building. Vent terminations must be at least twelve
(12) inches above the ground plus the expected
snow accumulation.
CAUTION
Installing multiple vent terminations close
together promotes frost buildup on buildings.
To minimize this possibility, extend the distance
from the building to the end of the vent
termination and increase the horizontal distance
between terminations.
4. Multiple vertical vent pipes may be piped through
a common conduit or chase so that one roof
penetration may be made. Each vent termination
must be one (1) foot from other terminations.
D.
Water Piping (See Table 9 and Figure 21)
Installing a low water cutoff in the system piping of
modular systems is strongly recommended and may be
required by Local Codes.
E.
Gas Piping
1. Refer to National Fuel Gas Code, Local Codes and
Tables 7 and 8 for gas pipe sizing.
VII. Modular Installation
Table 9: Modular Boiler Water Manifold Sizing
2. Each boiler must be piped as shown in Figure 13.
WARNING
If gas pressure in the building is above ½ psig,
an additional gas pressure regulator is required.
Using one additional regulator for multiple
boilers may result in unsafe boiler operation.
The additional regulator must be able to properly
regulate gas pressure at the input of the smallest
boiler. If the regulator cannot do this, two or
more additional regulators are required. Consult
regulator manufacturer and/or local gas supplier
for instructions and equipment ratings.
F. Electrical
1. Each boiler must be provided with a fused
disconnect and service switch.
2. Install wiring in accordance with requirements of
authority having jurisdiction. In the absence of such
requirements, follow the National Electric Code,
NFPA 70 and/or CSA C22.1 Electric Code.
G. Modular Boiler Control Systems
Contact a controls manufacturer such as Honeywell or
Tekmar to properly apply a modular control system.
Common systems may use outdoor temperature, return
water temperature or both to stage the boilers.
Combined Output
(MBH)
Recommended Minimum
Common Water Manifold
Size (NPT)
< 166 1¼”
< 260 1½”
< 550 2”
< 900 2½”
< 2000 3”