Raypak RAYTHERM P-926 - Manual (Page 11)

11
Water Pressure Switch
On Models 926-1223 built with a Unitherm Governor
(UG), a water pressure switch is provided in the heater
to shut down the gas valves in the event the water sup-
ply 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 inter-
rupted.
Otherwise, rapid and severe damage to the heater will
likely occur. (The water pressure switch should be
checked and adjusted for proper operation by a quali-
fied service person at the time of installation and
periodically checked thereafter. Refer to pressure
switch servicing instructions in this manual).
Automatic Chlorinators and
Chemical Feeders
All chemicals must be introduced and completely dilut-
ed 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 anti-siphoning device to prevent chemical
backup into the heater when the pump is shut off.
WARNING: Operation of the heater without water
circulation will cause rapid and severe damage to
the heater.
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 (UG) is a thermosta-
tic mixing valve specifically designed to maintain
constant heater internal temperature between 105°
and 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 burners which will occur if the heater runs for any
length of time below 105°F. It is also needed to inhibit
scale formation in the tubes by maintaining tempera-
tures well below accelerated scaling temperatures.
The Unitherm Governor is an available option on mod-
els 926 through 1223. Where installed, it is built into
the inlet/outlet header. The larger sizes, models 1287
through 4001, do not have a UG option. Instead, they
have an externally mounted bypass pump that is
designed to maintain the water entering the heater at
the proper temperature to prevent condensation and
scale. Thermometers are provided on the inlet and
outlet to the heater.
Companion Flange
Connections
(Models 926-1223)
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.
Fig. 10: Companion Flange Connections
(Models 926–1223)