LAARS Mighty Therm VW-PW (Sizes 175-400) - Installation, Operation and Maintenance Instructions - Manual (Page 17)

Mighty Therm Volume Water Heaters
Page 17
WARNINGS
Vent pipes, drafthoods, and heater tops get hot!
These surfaces can cause serious burns. Do not
touch these surfaces while the heater is in
operation. Adding a vent cap reduces the
temperature on the top.
For your safety, when starting the heater, keep your
head and face well away from the lower firebox
opening to prevent any risk of personal injury.
LP GAS: To avoid possible injury, fire and
explosion, read and follow these precautions and all
instructions on this heater before lighting. This
heater uses LP gas which is heavier than air and will
remain at ground level if there is a leak. Before
lighting, sniff at ground level.
If you smell gas, follow these rules:
1. DO NOT light matches. DO NOT turn electric
lights or switches on or off in area. DO NOT use
an electric fan to remove the gas from area.
2. Shut off gas at LP tank.
3. Telephone gas company and fire department for
instructions. Give your name, address and
phone number.
If your LP tank runs out of fuel, turn off gas at the
heater. After the tank is refilled, the heater must be
relit in accordance with the instructions found on the
inside of the heater. DO NOT attempt repairs on the
gas control or heater. Tampering is dangerous and
voids all warranties.
3.2 Start-Up Procedure
Lighting instructions can be found on the inside
of the heater. To start up the heater:
1. Make sure the system pump is running and there
is water flow.
2. Remove the control access panel.
3. Set the temperature control (see Figure 28) to its
lowest setting.
4. Turn electric power to the appliance to off.
5. Turn manual gas valve off.
6. Wait 5 minutes to clear out any gas, then smell
for gas, including near the floor. Be sure to smell
next to the floor because some types of gas are
heavier than air and will settle on the floor.
Caution
This heater is equipped with an ignition device which
automatically lights the burner. Do not try to light the
burner by hand.
sure heater is wired for 120 volts alternating
current (VAC). If 240 VAC, contact local factory
representative or Laars.
2. Wire the heater and pump exactly as shown in the
wiring diagram supplied with the heater. See
Figure 26 and 27 for a typical example of a
wiring diagram.
3. Electrically interlock the pump and heater so the
heater cannot come on unless the pump is
running.
4. Connect all field-installed devices (draft
switches, relays, timers, outdoor temperature
reset devices, etc.) (see Figures 26 and 27) to the
heater wiring at points labeled Field Interlock.
2.9 Combined Space Heating/Potable
Water Heating Systems
2.9.1 Combined Space Heating
NOTE: These systems are not allowed in the
Commonwealth of Massachusetts.
Piping and components connected to this water
heater for the space heating application shall be
suitable for use with potable water.
Toxic chemicals, such as used for boiler
treatment, shall not be introduced into the potable
water used for space heating. Do not use solder
containing lead in the potable water lines.
This water heater when used to supply potable
water shall not be connected to any heating system or
components(s) previously used with a non-potable
water heating appliance.
When the system requires water for heating at
temperatures higher than required for other uses,
an anti-scald mixing or tempering valve (see figure
25) shall be installed to temper the water for those
uses in order to reduce scald hazard potential.
Some jurisdictions may require a backflow preventer
in the cold water line. In such cases, the temperature
and pressure relief valve may discharge water due to
expansion. A diaphragm type expansion tank will
normally eliminate this condition. Follow the
manufacturer's instructions for installation of the
expansion tank.
SECTION 3.
Operating Instructions
3.1 Normal Operating Sequence
NOTE: Safe lighting and other performance
criteria were met with the gas manifold and control
assembly installed on the heater during tests specified
in ANSI Z21.13.