Modu-Snap Valve Temperature Settings; Figure 19 - Control Components; Pilot Burners (I.i.d.) - Natco VW Installation And Operating Instructions Manual

Dial No. 1 2 3
Temp °F 120 128 135 143 150
Table V – Modu-Snap Temperature Settings
IW). Each valve has a remote capillary bulb
immersed in a well at the outlet header to
maintain a constant outlet temperature. The
valves can be staged to give greater flexibility
of control. Consult Table V 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 gas
supply, the automatic safety shutoff devices must be
checked.
1. Before beginning the tests, make sure the main
manual gas valve, and any other heater firing
valves are in the "OFF" position.
2. Make sure the heater's power switch is in the
"ON" position. After placing the manual pilot gas
valve in the open position and resetting all safety
devices, (high limit, pressure switch, low- water
4 5 6 7 8
158 165 173 180+
Manual Reset
9+
High Limit
T.L. Part # E159
Gasl Modulating
Valve
T.L. Part # V710
Figure 19 – Control Components
Honeywell
T.L. Part # W343
Figure 20 – Pilot Burners (I.I.D.)
18
Flow
Switch
T.L. Part # E130
Low Water
Cutoff
T.L. Part # 679
Johnson Controls
T.L. Part # W345