Raypak NH User Manual
Page 20
20
The table above provides data for selecting in-line pumps for use in a Uni-Temp 80 system for a single heater
and tank according to the following:
1. Flow rates are based on water hardness as measured in grains per gallon.
Soft: 0-4 grains per gallon.
Medium: 5-15 grains per gallon.
Hard: 16 and over grains per gallon.
2. Maximum Flow Rates:
133
22 GPM
181-401
45 GPM
514-1826
90 GPM
2100-4001
200 GPM
3. Pressure drop values ( P and SHL) and minimum pipe sizes are for two-pass heaters.
4. Sizing based on heater and tank being placed 5 feet apart. The equivalent length of pipe
valves and fittings in the system is as follows:
1-1/2" NPT = 70 Ft (181-401)
2-1/2" NPT = 80 Ft (926-1826)
2" NPT = 75 Ft (514-824)
3" NPT = 85 Ft (2100-4001)
Additional pipe fittings will increase the system head loss.
5. Select a pump based on the water hardness, flow, and system head loss.
6. If heater is more than two stories above the tank, consult the factory.
NOTE:
GPM flow rates are limited by maximum acceptable velocity through heat exchanger tubes. Heater models 514
through 1826 may be provided with an integral rear-mounted pump. This must be specified at time of order. The
integral pump will provide sufficient flow to meet the conditions listed in the table.
PIPING - DOMESTIC HOT WATER SUPPLY HEATERS
GENERAL SPECIFICATIONS
UNI-TEMP 80 HOT WATER SUPPLY SYSTEMS
T = Temperature Rise, Degree F@GPM FLOW
GPM = Gallons per Minute Flow
P = Pressure Drop, Foot thru Heat Exchanger
MPS = Minimum Pipe Size, NPT
SHL = System Head Loss