1- FILLING THE INNER TANK
(Domestic Water)
Never operate combination heater unless
it is completely filled with water.
Always fill the inner tank before filling
the outer tank to prevent any damage to
the inner tank.
1. Close domestic water drain valve
2. Open domestic water isolation valves
for combination heater.
3. Vent air from inner (domestic water)
tank by opening nearest hot water
faucet. Fill domestic water tank com-
pletely by allowing water to run until
there is a constant flow of water.
4. Close hot water faucet
2- FILLING THE OUTER TANK
(Primary Water)
1. Close drain valve at system water out-
let of combination heater.
2. Open combination heater’s system iso-
lation valves.
3. Allow air to escape from outer (system
water) tank by opening cap on auto-
matic air vent, located on top of com-
bination heater.
4. Fill to correct system pressure. Correct
pressure will vary with each applica-
tion. Normal cold water fill pressure is
12 psig.
For proper combination heater opera-
tion, always leave vent cap unscrewed
one full turn.
5. When tank is
full, air will stop
escaping and
vent will close.
If air vent does
not seat proper-
ly (i.e., water
leaks out),
remove cap A.
Briefly push in valve B and release it
to clean valve seat. Screw cap A on
completely, then unscrew one turn.
6. If antifreeze is used in primary water,
ensure concentration never exceeds a
50/50 ratio. Primary water (including
additives) must be practically non-
toxic, having a toxicity rating or class
of 1, as listed in Clinical Toxicology of
Commercial Products. Inhibited
propylene glycol is recommended.
Follow antifreeze manufacturer’s
instructions.
Do not use automotive or ethylene glycol
antifreeze, or any undiluted antifreeze. This
can cause severe personal injury, death or
substantial property damage if ignored.
3- BURNER OPERATION
1. Check to see if the HM Combination
Heater is filled with water (10-12 psi on
Pressure & Temperature gauge on con-
sole).
2. Follow operating instructions on page
for start-up of the Combination Heater.
3. If appliance fails to start, check for the
following conditions:
• Loose connection or blown fuse at
power supply
• Secondary thermostat set below
water temperature
• Thermostat set below room temper-
ature
• Gas not turn on at meter or appliance
WARNING
NOTICE
CAUTION
CAUTION
20
COMBINATION HEATER START UP
A
B