Hydronic Heating - Rheem Raypa DELTA 399B Installation And Operation Manual

Cold Water Run
Cold water run differs from cold water start in that the
system water entering the heater remains below 105ºF
(41ºC) continuously. Typically, this is the case in swim-
ming pool heating and water source heat pump appli-
cations as well as some others. If the system water is
kept in a narrow temperature range, a permanent man-
ual bypass can be employed and manually adjusted to
achieve an inlet temperature of 105ºF (41ºC) or high-
er. An injector pump arrangement may also be utilized
to keep the heater loop at or above 105ºF (41ºC). An
injector pump approach has the added value of being
able to adjust to changes in the system water coming
back to the heater take-off.
10°F ∆T
Model
GPM
No.
∆P (ft)
(lpm)
67
399B 5.5
(254)
649B
749B
899B
989B
1259B
1529B
1799B
1999B
2069B
2339B
Notes: 1. Basis for minimum flow: Models 399–899, 20 gpm or 40°F ∆T. Models 989–2339, 30 gpm or 40°F ∆T.
Basis for maximum flow: Models 399–899, 90 gpm. Models 989–2339, 132 gpm.
2. Flow switch will not operate if flow is less than 20 gpm.
16
20°F ∆T 30°F ∆T
GPM GPM
∆P (ft)
(lpm) (lpm)
34 22
1.4
(129) (83)
55 36
4.1
(208) (136)
63 42
5.7
(238) (159)
76 50
8.3
(288) (189)
83 55
5.2
(341) (208)
106 71
9.6
(401) (269)
129 86
15.7
(488) (325)
101
(382)
112
(424)
116
(439)
132
(500)
Table G: Heater Rates of Flow and Pressure Drops
Temperature & Pressure Gauge
The temperature and pressure gauge is factory-mount-
ed in the in/out header.

Hydronic Heating

Pump Selection
In order to ensure proper performance of your heater
system, you must install a correctly sized pump. Ray-
pak recommends using a 20°F ∆T as design ∆T. (∆T is
the temperature difference between the inlet and outlet
water when the heater is firing at full rate). If a ∆T of
larger than 20°F is necessary, see Table G and Table
H for flow rate requirements.
Min. Flow
GPM
∆P (ft) ∆P (ft)
(lpm)
20
0.6 0.5
(76)
27
1.8 1.1
(102)
32
2.6 1.5
(121)
38
3.8 2.2
(144)
42
2.3 1.3
(159)
53
4.3 2.4
(201)
64
7.1 4.0
(242)
76
10.7 6.0
(288)
84
13.8 7.9
(318)
87
14.8 8.5
(329)
98
21.4 12.1
(371)
Max. Flow
GPM
∆T ∆P (ft)
(lpm)
90
34 10.0
(341)
90
40 10.8
(341)
90
40 11.3
(341)
90
40 11.7
(341)
132
40 13.1
(500)
132
40 14.8
(500)
132
40 16.5
(500)
132
40 18.3
(500)
132
40 19.0
(500)
132
40 19.0
(500)
132
40 21.4
(500)
∆T
7
12
14
17
13
16
19
23
25
26
30