▶ Slowly open the front cover .
Open front cover
▶ Disconnect the wire from the HMI (display) .
▶ Lift the front cover to remove from the appliance.
▶ Install the appliance so that it hangs vertically.
General rules to follow for safe operation
H Warning: Safety Rules!
1. You must follow these instructions
when you install your heater. In the
United States: The installation must
conform with local codes or, in the
absence of local codes, the National
Fuel Gas Code ANSI Z223.1/NFPA
In Canada: The Installation must
conform with CSA B149.(1,2)
INSTALLATION CODES and /or local
Greentherm T9900 SE/i – 6 720 813 635 (2019/03)
2. Carefully plan where you install the
heater. Correct combustion air supply
and vent pipe installation are very
important. If not installed correctly,
fatal accidents can occur, such as
carbon monoxide poisoning or fire.
3. When the unit is installed indoors with
DIRECT VENT (exhaust vent and air
intake connected to the outside) it is
permitted to be located in bathrooms,
bedrooms and occupied rooms that
are normally kept closed. See
chapter 4.6 (page 18). If the unit will
be installed indoors and use indoor
combustion air (NON-DIRECT VENT),
the place where you install the heater
must have enough ventilation. The
National Fuel Gas Codes do not
allow NON-DIRECT VENT gas fired
water heater installations in
bathrooms, bedrooms or any
occupied rooms normally kept
closed. See chapter 4.6 (page 18).
4. You must correctly vent your heater.
See chapter 4.6 (page 18) on
5. The appliance and its gas connection
must be leak tested before placing the
appliance in operation.
The appliance must be isolated from
the gas supply piping system by
closing its individual manual gas
shutoff valve (not supplied with
heater) during any pressure testing at
pressures in excess of ½ Psig (3.5