Burnham PVG manual VII. Modular Installation, Module Sizing, Do not manifold vent pipes together

VII. Modular Installation

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.

Table 9: Modular Boiler Water Manifold Sizing

Combined Output	Recommended Minimum
	Common Water Manifold
(MBH)
	Size (NPT)

< 166	1¼”
< 260	1½”
< 550	2”
< 900	2½”
< 2000	3”

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.

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