Water Pressure Switch; Automatic Chlorinators And Chemical Feeders; Unitherm Governor Operation; Companion Flange Connections (Models 926-1223) - Raypak raytherm p-1826 Installation & Operating Instructions Manual

Water Pressure Switch

On Models 926-1223 built with a Unitherm Governor
(UG), a water pressure switch is provided in the heater
instead of a flow switch, 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 adjusted for proper operation by a
qualified service person at the time of installation and
periodically checked thereafter. Refer to pressure
switch servicing instructions on page 24).
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 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.
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 thermo-
static 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 with an inlet temperature below 105°F.
It is also needed to inhibit scale formation in the tubes
by maintaining temperatures well below accelerated
scaling temperatures.
The Unitherm Governor is the default configuration on
models 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 with UG)
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 with UG)
11