Pentair MT Sizes 500 - Manual (Page 11)

MegaTherm Commercial Pool Heating Boiler Page 11
Figure 13. Controls Location.
Rating Plate
Manual
Pilot
Valve
Water
Circulating
Pump
Safety
Gas
Valve
Operating/Safety
Gas Valve
Ignition Control
Flow
Switch
Pressure
Relief
Valve
Power
(On/Off/Auto)
Switch
Pump Time
Delay Relay
Operating
Control
Terminal Strip
In
Out
Hi-Limit
Manual
Main
Gas Valve
SECTION 3.
Operation
3.1 Controls - General
(see Figures 12 and 13)
1. Electronic Ignition Controls:
a. Intermittent Ignition:
Pilots are automatically lit when the
operating control calls for heat (Systems #4
and #9). The unit performs its own safety
check and opens the main valves only after
the pilot is proven to be lit. Whenever the
pilot flame is interrupted, the main gas
valve closes within 0.8 seconds.
b. Electronically Supervised Standing Pilot
System (System #16):
When pilot flame fails, the ignition control
module responds in less than 0.8 seconds
and provides 100% safety shutdown.
2. Operating Controls:
An electronic temperature control is provided on
model MT boilers to control the pool water
temperature. The temperature sensor (thermistor)
is located in the filter circulation piping (see
Section 2.8).
3. Boiler Power (On/Off/Auto) Switch:
This provides for constant or automatic pump
operation.
4. High Limit Controls:
The manual reset high limit switch is provided as
standard equipment on all boilers. The
temperature sensing bulb of the switch is always
located in the heater outlet. Burners will
automatically shut down whenever overheating
of water occurs.
5. Flow Switch:
Standard on all model MT pool heating boilers.
The switch is mounted in a tee fitting on the
outlet header. This is a paddle type switch which
is deflected by the water flow in the fitting. Any
condition which interrupts or decreases the flow
through the secondary loop will shut down the
burners.
6. Low Water Cut Off (optional):
The low water cut off automatically shuts off
boiler whenever water level in the heat
exchanger drops below probe level. It is located
in the inlet header.
3.2 Initial Start-Up
WARNING
Do not use this appliance if any part has been
under water. Immediately call a qualified
service technician to inspect the heater. the
possible damage to a flooded appliance can be
extensive and present numerous safety
hazards. Any appliance that has been under
water must be replaced.