LAARS Mighty Therm IW (Sizes 500-1825) - Installation, Operation and Maintenance Instructions - Manual (Page 17)

Mighty Therm Volume Water Heater
Page 17
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:
a. Electrically Operating Controls:
Single, two-stage, four-stage or modulating
aquastats are provided in models VW, PW
and IW heaters to control the desired
service water temperature. The temperature
sensing bulb is located in the heater inlet.
b. Modu-snap Valves:
These valves are furnished in addition to
the main electric gas valve when heater is
ordered with mechanical modulation. Each
valve has a remote capillary bulb immersed
in a well at the outlet header to maintain a
constant outlet temperature. Consult Table
5 for desired temperature setting.
3. High Limit Controls:
The manual reset high limit switches are
provided as standard equipment on all heaters.
Automatic reset switches are optionally
provided. The temperature sensing bulb of the
switch is always located in the heater outlet.
Burners will automatically shut down whenever
overheating of water occurs.
4. Flow Switch:
Standard on all models: Models VW and PW, the
switch is mounted in the outlet “tee” connection.
Model IW, the switch is mounted directly in the
header outlet. The flow switch shuts down all
burners in case of low water condition or pump
failure.
5. Low Water Cut Off:
The low water cut off automatically shuts off
heater whenever water level drops below probe.
Located at heater inlet (model IW and PW) and
at return header (model VW).
3B. Initial Start-Up
Before placing the heater in operation, be certain
that the heater is filled with water and all air is purged
from the system. Once the heater is connected to the
Figure 18. Single Installation Piping Diagram, Model IW.
Dial No. 1 2 3 4 5 6 7 8 9+
Temp °F 120 128 135 143 150 158 165 173 180+
Table 5. Modu-Snap Temperature Settings.