LAARS Mighty-Stack TL00-199 - Installation, Operation and Maintenance Instructions - Manual (Page 15)

Mighty Stack Water Heater Page 15
2B. Starting the System After Extended
Shut-Down
1. Hydrogen gas can be produced in a hot water
system that has not been used for a long period
of time (usually two weeks or more.) Hydrogen
gas is extremely flammable. This gas can easily
burn or explode if it is ignited by a flame or
electrical spark.
2. To prevent any chance of injury, you must take
special precautions when starting the unit after a
long shut-down. Before you use any electrical
appliance which is connected to the hot water
system, you should clear any gas which has
collected. Put out any cigarettes or open flames
in the area around the appliance you want to
use. Open the hot water faucet near the water
heater.
3. If hydrogen is present, you may hear an unusual
sound when you open the tap. This is the sound
of the gas escaping through the pipe as the hot
water begins to flow.
4. When the sound stops, turn off the tap. Open
windows and doors in the space around the tap.
Allow at least 15 minutes for the gas to clear
before you use any open flames or electrical
appliances.
2C. Shut-Down Procedure
1. Turn off the power to the unit.
2. Turn off the gas valve to the unit.
3. Turn off the valve on the cold water supply.
2D. Extended Shut-Down –
Cold Weather Areas
If the water heater is not going to be used for
long periods of time in locations where freezing
occurs, it should be completely drained of all water.
1. Follow the shut-down procedure listed in Section
2C.
2. Open the drain valve on the contractor supplied
water storage tank.
3. To help the draining action, hold open the
pressure relief valve.
4. It is also important to drain the heat exchanger. If
the heat exchanger is not drained, the water may
freeze inside, and the casting may be damaged.
The heat exchanger is located inside the heater
on the top of the unit (see Figure 2) . Remove the
sheet-metal covers. Each side of the heat
exchanger includes two rows of brass plugs. To
drain the heat exchanger, remove any two of the
brass plugs in the lower rows.
5. Before starting the system, refill the system
(contractor supplied tank) with water. Follow the
procedure in Section 1P. When refilling the unit,
remember to replace the brass plugs and release
the pressure relief valve.