Raypak 902B, 302B manual 87%-EfficiencyBoilers - Special Instructions, Water Piping, Venting

87%-Efficiency Boilers – Special Instructions

NOTE: The constructions of the 84%- (standard) and 87%-efficiency (optional) boilers are very similar, and they are installed to the same requirements, except as noted in this section.

Water Piping

An 87%-efficiency boiler requires a minimum inlet water temperature of 120ºF (49ºC) to prevent exces- sive condensation in the combustion chamber. An 87%-efficiency boiler operated with an inlet tempera- ture of less than 120ºF (49ºC) must have a manual bypass or an approved low-temperature operation system to prevent problems with condensation. A man- ual bypass, shown in Fig. 15, must be piped into the system at the time of installation. This piping is like a primary/secondary boiler installation with a bypass in the secondary boiler piping. Raypak strongly recomm-

ends that a thermometer be placed into the boiler inlet piping next to the in/out header to facilitate tempera- ture adjustment. Inlet water temperatures below 120ºF (49ºC) can excessively cool the products of combus- tion, resulting in condensation on the heat exchanger.

Venting

CAUTION: Proper installation of flue venting is criti- cal for the safe and efficient operation of the boiler.

Appliance Categories

See Table T for appliance category requirements for the 87%-efficiency Hi Delta.

NOTE: For additional information on appliance categorization, see appropriate code NFGC (U.S.) and B149 (Canada), or applicable local building codes.

Model	10°F	T	20°F	T	30°F	T	Min. Flow			Max Flow
No.	gpm	P (ft)	gpm	P (ft)	gpm	P (ft)	gpm	P (ft)	T	gpm	P (ft)	T
302BE	52	3.3	26	<1.0	N/A	N/A	20	<1.0	26	90	9.8	6
402BE	69	5.8	35	1.5	23	<1.0	20	<1.0	35	90	10.0	8
502BE	87	9.1	44	2.5	29	1.1	22	<1.0	40	90	10.4	10
652BE	N/A	N/A	57	4.4	38	2.0	28	1.1	40	90	10.8	13
752BE	N/A	N/A	65	6.1	44	2.8	33	1.6	40	90	11.3	15
902BE	N/A	N/A	78	8.9	52	4.1	39	2.3	40	90	11.7	17

Note: Basis for minimum flow is 20 gpm or 40°F ∆T. Basis for maximum flow is 90 gpm.

Table S: Heater Rate of Flow and Pressure Drop

Combustion	Exhaust	Heater Venting	Certified	Combustion Air
Air Supply	Configuration	Category	Materials		Inlet Material
	Vertical Natural Draft	II	Stainless Steel
From Inside Building	Venting		(Gas Tight)
(Non-Direct Venting)	Horizontal Through-	IV	AL29-4C
	the-Wall Venting
	Vertical Natural Draft	II	Stainless Steel	Galvanized Steel
From Outside Building	Venting		(Gas Tight)		PVC
(Direct Venting)	Horizontal Through-	IV	AL29-4C		ABS
	the-Wall Venting				CPVC

Table T: Category Determination for Venting Purpose and Venting Arrangement

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