When local codes permit the use of less than four feet high temperature piping or two elbows, provisions should be made to always shut the heater off a minimum of 15 minutes prior to pump shut down in order to carry away residual heat and prevent damage to the low temperature piping. A fireman switch included in the time clock may be used for this purpose with instruc- tions not to override this sequence manually. See wiring diagram section for electrical hookup location of the fireman switch in the electrical circuit.
NOTE (Models
CONTROLS
WATER PRESSURE SWITCH
A water pressure switch is provided in the heater to shut down the gas valves in the event the water supply to the heater is interrupted. It is very important to verify that the switch electrically opens and shuts off the gas valve when water flow to the heater is interrupted. Otherwise, rapid and severe damage to the heater will likely occur. (The water pressure switch should be checked and adjustedforproperoperationbyaqualifiedserviceperson at the time of installation and periodically checked thereafter. Refer to pressure switch servicing instruc- tions in Section 4 of this manual).
WARNING: Operation of the heater without water circulation will cause rapid and severe damage to the heater.
AUTOMATIC CHLORINATORS AND CHEMICAL FEEDERS
All chemicals must be introduced and completely diluted into the pool or spa water before being circulated through the heater. Do not place chlorine tablets or bromine sticks in the skimmer. High chemical concen- trations will result when the pump is not running (eg, overnight).
Chlorinators must feed downstream of the heater and have an
NOTE: High chemical concentrates from feeders and chlorinators that are out of adjustment will cause very rapid corrosion to the heat exchanger in the heater. Such damage is not covered under the warranty.
UNITHERM GOVERNOR OPERATION
The patented Unitherm Governor is a thermostatic mixing valve specifically designed to maintain constant heater internal temperature between 105° to 115°F despite continually changing flow rates from the filter and changing pool temperatures. This narrow range is needed to prevent damaging condensation on the burn- ers which will occur if the heater runs for any length of time below 100°F. It is also needed to inhibit scale formation in the tubes by maintaining temperatures well below accelerated scaling temperatures.
The Unitherm Governor is built into the inlet/outlet header on models 926 through 1223. The larger sizes, models 1287 through 4001, have an externally mounted bypass pump that is designed to maintain the water entering the heater at the proper temperature that will prevent condensation and scale. Thermometers are provided on the inlet and outlet to the heater.
COMPANION FLANGE CONNECTIONS (Models
DO NOT use petroleum base assembly fluids (such as Petroleum Jelly or Lubricating Oil). If assembly lube is required use a silicone base such as Armoral etc.
The inlet/outlet header flange accepts a 2" copper tube as a slip connection directly into the header. The flange is also threaded for a 2" NPT copper male adapter.
MODELS 926 - 1223
INLET/OUTLET HEADER
FLANGE GASKET
OUTLET
INLET
HEADER FLANGE
Fig. #8221.0
8