Applications manual | 02.2009BOSCH THERMOTECHNOLOGY CORPORATION
GWH 345/450 ESR applications manual | 5
2 Bosch Water Heating Models
2.1 Bosch GWH 345 ESR
Features:
XSpecifically designed for recirculating applications
XElectronic ignition and built in power vent
XGWH 345 ESR thermal efficiency of 82%
XVents vertically or horizontally with 3" stainless steel (AL29-4C)
XDirect vent room-sealed combustion
XComputerized temperature control — ensures temperature
stability
XModel GWH 345 ESR N for natural gas (NG) supply
XModel GWH 345 ESR L for liquid propane (LP) supply
X10-year warranty on heat exchanger
GWH 345 ESR Technical Specifications
Gas input 32,000 - 95,000 Btu/h
Maximum flow rates 3.5gpm @ 45°F rise
Thermal Efficiency 82%
Dimensions 27.5" h x 15.75" w x 11.75" d
Weight 47 lbs.
Modulating gas valve yes
Ignition Electronic
GWH 345 ESR Installation Specifications
Gas connection ¾" Male NPT
Water connections ¾" Male NPT
NG gas pressure Minimum: 5.5" W.C.
Maximum: 14" W.C.
LP gas pressure Minimum: 11" W.C.
Maximum: 14" W.C.
Electrical supply 120VAC - plugs in
Venting 3" stainless steel (AL29-4C)
direct vent
room-sealed combustion
GWH 450 ESR Installation Clearances
Top (A) 12"
Front (B) 1"
Back 0"
Sides 1"
Floor (C) 12"
Fig. 1 Venting configurations
Installation guidelines:
Venting:
XMust be 3" or 4" AL29-4C sealed stainless steel vent pipe.
XSlope horizontal runs up to termination ¼" per foot. The
horizontal section between last elbow and termination must slope
down to the termination ¼" per foot.
XDo not combination vent with any other appliance.
XAlways install an external condensate drain except when
terminating horizontally with less than 3 feet of pipe.
XSee manual for vent terminator clearances.
Gas piping:
XHeater will not function properly without adequate supply gas
pressure.
XAny appliance connector should be ¾" minimum diameter.
Plumbing:
XInstall the included pressure relief valve and pipe to suitable
drain.
XMinimum piping diameter is ¾".
XDo not solder directly to the bottom of the unit.
XUse unions to facilitate easy future maintenance.
XUse full port ball valves or isolation valves.
XPartially fill condensate drain tube loop with water prior
to start up.
