Bradford-White Corp B4 warranty Gas Supply and Piping, Thermal Circulation of Hot Water

Internet Version for Reference Only

Copper Brute B4 Volume Water Heaters Page 15

2.6.10 Thermal Circulation of Hot Water

in Cold Water Supply Lines Under certain circumstances, thermal circulation

will occur in the cold water pipe supplying the water to the heating system. This happens in a multi-story building when the cold water pipe rises from its connection to the system. To correct the problem, a check valve in the cold water line supplying the heater will prevent thermal circulation, and a small expansion tank will permit heated water to expand without popping off the relief valve.

2.7 Gas Supply and Piping

2.7.1 General Instructions

Review the following instructions before continuing the installation.

1.Gas piping installation must be in accordance with the latest edition of ANSI Z223.1. In Canada, the installation must be in accordance with CAN1-B149.1 or .2 and all local codes that apply.

2.Check the rating plate to make sure the heater is fitted for the type of gas being used. Bradford White heaters are normally equipped to operate below a 2000 foot (609 m) altitude. Heaters equipped to operate at higher altitudes have appropriate stickers or tags attached.

3.If a gas pressure regulator is required, the installation must be in accordance with the latest edition of ANSI Z223. In Canada, the installation must be in accordance with CAN1-B149.1 or .2 and all local codes that apply.

4.The figures in Table 5 should be used to size the gas piping from the gas meter to the heater.

5.Install a sediment trap (drip leg) ahead of the gas controls (see Figure 24 ). Fit the trap with a threaded cap which can be removed for cleaning.

6.Install a manual gas shutoff valve for service and safety. Check the local codes.

7.Disconnect the heater and its individual shutoff valve from the supply gas system during pressure test of the system at pressures higher than 1/2 psi (3.4 kPa).

8.Gas supply pressures to the heater are listed in Table 6.

NOTE: The heater and all other gas appliances sharing the heater gas supply line must be firing at maximum capacity to properly measure the inlet supply pressure. Low gas pressure could indicate an under-sized gas meter and/or obstructed gas supply line.

Distance from Gas Meter or Last Stage Regulator

	0-100 feet		100-200 feet		200-300 feet
	0-30 m		30-60 m		60-90 m
Boiler		Nat.		Nat.		Nat.
Size	in.	mm	in.	mm	in.	mm
175	1	25	11⁄4	32	11⁄4	32
250	11⁄4	32	11⁄4	32	11⁄2	38
325	11⁄4	32	11⁄2	38	11⁄2	38
400	11⁄4	32	11⁄2	38	2	51

Notes:

1.These numbers are for natural gas (0.65 Sp. Gr.) and are based on 1⁄2 inch (13mm) water column pressure drop. Check supply pressure with a manometer, and local code requirements for variations. For liquefied petroleum gas, reduce pipe diameter one size, but maintain a 1⁄2 inch (13mm) minimum diameter.

2.Check supply pressure and local code requirements before preceding with work.

3.Pipe fittings must be considered when determining gas pipe sizing.

4.For propane gas: Reduce pipe diameter one size, but maintain a 3⁄4 inch (19mm) minimum diameter.

Table 5. Natural Gas and Propane,

Pipe Size Requirements.

MANUAL SHUT-OFF

VALVE

GAS		UNION
SUPPLY
INLET	T-FITTING
		TO
	3" (76 mm)	BOILER
		INLET
	MIN.
		NIPPLE
		CAP

Figure 24. T-Fitting and sediment trap.

Supply Pressure	Natural Gas		Propane Gas
Water Column
	in.	mm	in.	mm
Minimum	6.5	165	11	279
	See Rating Plate
Maximum	9	229	14	356

Table 6. Gas Supply Pressure Requirements.

9.Do not exceed the maximum inlet gas pressures specified. Excessive pressure will result in damage to the heater's gas controls. The minimum pressures specified is for gas input adjustment.

10.The correct burner manifold gas pressure is stamped on the rating plate. The regulator on the gas valve is preset at the factory, and does not normally need adjustment.