87%-Efficiency Boilers - Special Instructions; Water Piping - Raypak Hi Delta 302A-902A Installation And Operating Instructions Manual

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-
10°F T
Model
No.
gpm
302AE 52
402AE 69
502AE 87
652AE N/A N/A
752AE N/A N/A
902AE N/A N/A
Note: Basis for minimum flow is 20 gpm or 40°F ΔT. Basis for maximum flow is 90 gpm.
Combustion
Air Supply
From Inside Building
(Non-Direct Venting)
From Outside Building
(Direct Venting)
Table Q: Category Determination for Venting Purpose and Venting Arrangement
20°F T
P (ft) gpm P (ft)
3.3 26 <1.0
6.0 35 1.5
9.7 44 2.5
57 4.4
65 6.1
78 8.9
Table P: Heater Rate of Flow and Pressure Drop
Exhaust
Configuration
Vertical Natural Draft
Venting
Horizontal Through-
the-Wall Venting
Vertical Natural Draft
Venting
Horizontal Through-
the-Wall Venting
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 Q for appliance category requirements for
the 87%-efficiency Hi Delta.
NOTE: For additional information on appliance cat-
egorization, see appropriate code NFGC (U.S.) and
B149.1 (Canada), or applicable local building codes.
30°F T Min. Flow
gpm P (ft) gpm
N/A N/A 20
23 <1.0 20
29 1.1 22
38 2.0 28
44 2.8 33
52 4.1 39
Heater Venting
Category
Stainless Steel
II
IV
Stainless Steel
II
IV
39
Max Flow
P (ft) T gpm
<1.0 26 90
<1.0 35 90
<1.0 40 90
1.1 40 90
1.6 40 90
2.3 40 90
Certified Combustion Air
Materials Inlet Material
(Gas Tight)
AL29-4C
Galvanized Steel
(Gas Tight) PVC
ABS
AL29-4C
CPVC
P (ft) T
9.8 6
10.0 8
10.4 10
10.8 13
11.3 15
11.7 17