Freeze Protection
The Raypak electronic temperature control includes a
freeze protection feature. In the event the water tem-
perature drops below 40°F at any of the heater
temperature sensors, the pump is turned on and will
remain on until the temperature at all heater sensors
rises to 45°F.
Controls
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Fig. 29: Outdoor Venting
The Raypak modulating temperature control is pro-
vided to maintain the desired system water
temperature. The control has various modes of opera-
tion which are described on the following pages.
The XTherm is designed for use with
Primary/Secondary pumping only, utilizing integral
injector pumps to maintain proper flows and tempera-
tures in the heater.
Set-point:
for a specific system supply temperature,
the system return (target) temperature settings, where
the sensor is located, should be reduced by the
difference between the system supply temperature
and the system return temperature. For example, to
maintain near 160ºF system supply temperature, and
if the system ΔT is 10ºF, then the system return (target)
set-point is 160-10=150ºF.
Deadband:
Deadband is a band of temperature sens-
ing where no action occurs. All temperature controllers
have a deadband and the purpose is to prevent short-
cycling of the heater. The on-board temperature
controller has a deadband of 2ºF around the differen-
tial.
Differential:
A heat source must be operated with a
temperature differential in order to prevent short-
cycling. The temperature differential is divided around
the “target” temperature or set-point. The Call For Heat
(CFH) contact will close in the controller when the
water temperature is below the target temperature by
1/2 of the differential setting, and will open when the
water temperature is above the target temperature by
1/2 of the differential setting. See Fig. 30.
WARNING:
Installation, adjustment and service of
heater controls, including timing of various operating
functions, must be performed by a qualified installer,
service agency or the gas supplier. Failure to do so
may result in control damage, heater malfunction,
property damage, personal injury, or death.
WARNING:
Turn off the power to the heater before
installation, adjustment or service of any heater
controls. Failure to do so may result in board
damage, heater malfunction, property damage,
personal injury, or death.
CAUTION:
This appliance has provisions to be
connected to more than one supply source. To
reduce the risk of electric shock, disconnect all such
connections before servicing.
CAUTION:
Risk of electric shock: More than one
disconnect switch may be required to de-energize
the equipment before servicing.
NOTE:
Condensate can freeze on the vent cap.
Frozen condensate on the vent cap can result in a
blocked flue condition.
WARNING:
Do not install the heater outdoors if
freezing conditions are typical. The condensate will
freeze and back up the flue system.
NOTE:
The vent cap and air intake hood must be
furnished by the heater manufacturer in accordance
with its listing (sales order option D-11).
Fig. 30: Differential Graph
California Hot Water Supply, Inc.
(800) 249-7244
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