25
MB Pool & spa heater
All Models
PRESSURE SWITCH ADJUSTMENT
1. With pump and heater on, turn adjustment
knob (clockwise) until a click is heard
from the gas valve.
2. Turn adjustment knob
(counter clockwise)
1/4 turn.
3. Turn pump off and on several times.
Heater should shut off immediately. If it does
not,repeat steps above until proper
adjustments is made.
Adjustment
Knob
PRESSURE SWITCH ADJUSTMENT RANGE
NOTE: If heater is installed outside of the limits
shown, a fl ow switch must be used in place of the
pressure switch when mounted and wired adjacent
to the heater.
TWO SPEED PUMPS
In some cases, the fl ow on the low speed is insuf-
fi cient to operate the heater. This is apparent when
the pressure switch cannot be further adjusted or if
the heater makes banging noises. In these cases,
the pump must be run at high speed when heating
the water.
CAUTION:
Do not operate the heater without the
function of a properly adjusted pressure switch or
fl ow switch.
1.5 m Max
1.5 m Max
FLAME ROLL-OUT SAFETY SWITCH
The heater is equipped with a thermal cutoff device
to prevent fl ame roll-out in the event that the heat
exchanger becomes blocked. This is a "Single-use"
type fusible link or thermal fuse, that must be replaced
when disabled by an over temperature condition,
caused by excessive restriction in the heat exchanger
fl ue passage.
HIGH LIMITS
The heater is equipped with one manual reset over-
heat thermostat located in the return header, set to
open at approx. 100°C. the other is the Automatic
Gas Shut-off limit, set to open at 57°C and located
in the Inlet/Outlet header.
NOTE: An erratic high limit is often characteristic of
internal heat exchanger problem, i.e. scale buildup,
defective bypass. Refer to troubleshooting sections.
055, 105 & 155 Models
HIGH LIMIT & MANUAL RESET HIGH LIMIT THER-
MOSTAT REMOVAL
Disconnect top portion of unit. (See heat exchanger
removal procedure steps 1 thru 7 and step 10).
1. Remove Jacket Top,Flue Collector and Baffl e.
2. Remove defective high limit and replace with
new high limit.
Manual Reset
High Limit
Thermostat
Automatic
Gas Shut-off High
Limit Thermostat
range.tif
Automatic
Reset
Thermostat
