Bradford-White Corp BJVS, BJVT Flow Requirements, Damage from improper flow is not warranted

Brute Mini Hydronic Boiler Page 15

		To
		System
From
System	Balancing
	Valve
		Balancing Valve
		or optional
		thermostatic union,
		P/N 2400-030.
		(Primary/Secondary
		only)
In		Out
(Return)		(Supply)
		Drip
		Leg

Left Side View

A full size by-pass must be installed.

Figure 7. By-pass Piping.

5.3 Flow Requirements

All high recovery, low volume water boilers must have adequate flow for efficient operation. Pump selection is critical to this goal, and pumps should be selected to provide for system design water temperature rise. Table 6 details temperature rise and water flow (GPM) for the Brute Mini boilers.

Damage from improper flow is not warranted.

Failure to insure proper water flow through the heat exchanger of the boiler will void the warranty. Flow can be verified by measuring the difference in water temperatures between the boiler inlet and outlet. For example: For a BJV-100 installation, the inlet

water temperature is 160°F (71°C), and the outlet temperature is 180°F (82°C) at Normal Input Rate from the rating plate. That means there is a 20° (11°C) temperature rise through the boiler. According to Table 1, that would indicate a flow rate of 8 GPM (0.5L/S). Temperature rise must be measured with the longest (highest head) zone calling for heat alone.

Other factors to be considered before selecting a pump are pipe size, the number of fittings throughout the system, smoothness of the interior surface of the pipe, the quantity of water flowing through the pipe, whether a glycol solution is being used, and the total length of piping in the system. Table 7 provides examle pump selection criteria using Type L copper piping, one zone valve and up to eight elbows for single zone systems. Consult the factory or a qualified system designer if you have more fittings, different size or type of pipe (especially in retrofit situations), or some other unique system configuraiton not illustrated in this manual.

	1/2" Pipe		3/4" Pipe				1" Pipe		1-1/4" Pipe
Size	Pump			Pump			Pump			Pump
	H.P.			H.P.			H.P.			H.P.
	1/25	1/12	1/25 1/12		1/6	1/25	1/12	1/6	1/25 1/12		1/6
50	50	99	390 680		*	*	*	*	*	*	*
75	*	35	160	300	460	640	*	*	*	*	*
100	*	*	77	150	260	330	620	*	*	*	*
125	*	*	27	80	140	170	360	600	*	*	*
160	*	*	*	25	72	57	160	330	190	480	*
225	*	*	*	*	*	*	*	110	*	69	330

*A circulator and/or primary/secondary piping are required. Consult factory.

1. Chart is based on 30°F (17°C) maximum temperature rise.

2. Calculations are based on Type L copper tubing with one zone valve and eight elbows.

3. Typical circulating pumps: 1/25 HP=Taco 007, B&G LR-20 or SLC-25, Grundfos UP15-42F, or equivalent. 1/12 HP=B&G LR- 12, Grundfos UP26-42F, or equivalent. 1/6 HP=B&G series HV, Grundfos UP43-75, or equivalent.

Table 7. Maximum Suggested Circuit Length in Feet.

			15°F	8°C			20°F	11°C			25°F	14°C
Size		Flow Rate		Headloss		Flow Rate		Headloss		Flow Rate		Headloss
		gpm	l/s	ft	m	gpm	l/s	ft	m	gpm	l/s	ft	m
50		5.3	0.3	0.3	0.1	4	0.3	0.2	0.1	3.2	0.2	0.1	0
75		8	0.5	0.6	0.2	6	0.4	0.3	0.1	4.8	0.3	0.2	0.1
100		10.7	0.7	1.3	0.4	8	0.5	0.7	0.2	6.4	0.4	0.5	0.2
125		13.3	0.8	2.2	0.7	10	0.6	1.3	0.4	8	0.5	0.8	0.2
160		17	1.1	2.5	0.8	12.8	0.8	1.8	0.5	10.2	0.6	1.2	0.4
225		24	1.5	5	1.5	18	1.1	3.1	0.9	14.4	0.9	1.9	0.6
				gpm = Water Flow in gallons per minute. l/s = Water flow in liters per second.
ft = Pressure drop (headloss) through the boiler in feet of water.							m = Pressure drop (headloss) through the boiler in meters of water.
				Notes: 1. Shaded area is the recommended flow and temperature rise.
	2. Temperature rise and associated flow rates are based on high fire operation at the Normal Input Rate from the rating plate.

Table 6. Temperature Rise °F °C.