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Installation vent terminator Clearance 
 
 
Gas Supply and Gas Piping Sizing 
 
This unit needs a manual gas control valve 
(System Shutoff Valve) that must be placed on 
the unit before it is connected to the gas line. 
Check the gas inlet pressure and the type of 
gas matches the rating plate located on your 
water heater. Insufficient gas pressure and 
volume will cause your MOBIUS Water Heater 
to be inefficient performance and not work 
properly. Sizing of gas piping system correctly 
following ANSI233.1/NFPA 54, or by local code. 
 
 
The minimum and maximum inlet gas 
pressures are listed below 
 
Natural Gas  Min. 5” WC 
Max. 10.5” WC 
Propane Gas  Min. 11” WC 
Max. 14” WC 
 
When measuring the inlet supply pressure, the 
water heater and all other gas appliances 
sharing the water heater gas supply line must 
be firing at maximum capacity. Maximum gas 
pressures must not exceed this value. Low gas 
pressure could be caused by an undersized 
gas pipe, this will cause the MOBIUS water 
heater’s performance to diminish and unable to 
reach maximum performance. 
When connections are completed, check for 
gas leaks by applying soapy water to all gas 
fittings and connections. Soap bubbles are a 
sign of gas leaks.  
This appliance and its individual shut-off valve 
must be isolated from the gas supply piping 
system by unplugging the unit and turning off 
the main gas valve during any pressure testing 
of the gas supply piping system at test 
pressures equal to or less than ½ Psi. The 
appliance and its gas connections must be 
leak tested before placing the unit in operation. 
Always use approved connectors to connect 
the unit to the gas line. Always purge the gas 
line of any debris before connecting to the 
heater gas inlet. 
 
WARNING: Conversion of this unit from 
natural gas to propane or propane to natural 
gas cannot be done in the field. Contact your 
local retailer or distributor to get the correct unit 
for your gas type. Conversion done by anyone 
other the manufacture will void any and all 
warranty.