25
Common Vent Installation
Systems
In MCU with common vent systems, only GU195M models can be used. This is a condensing water heater and
therefore combustion gases are discharged at a very low temperature. It is therefore necessary for the vent system
to be perfectly impermeable to combustion condensate and to be made of corrosion resistant materials. The various
funnel joints must be well sealed in order to avoid any condensate drain and leakage of flue gas.
Power venting of multiple units should be installed in a well ventilated room which has a suffficient supply of combustion
air. The air intake should come from a well ventilated and heated room with a clean supply of air. It may be necessary
to use an air filter.
Power Vent
The direct vent system can use the same materials for air intake as the power vented system.
The connection for the flue gas and air intake system can be positioned on the right as well as on the left side of
multi control units.
Direct Vent(Sealed Vent)
Multi Units With Common Vent
POWER VENTED
Dimensions Of Installation
DIRECT VENTED
The maximum length is the sum of the equivalent of straight horizontal runs, vertical runs and elbows of common vent pipe.
One 90º elbow is equivalent of 5 feet.
Example: when installing 2 units on 4” common vent, the maximum vent length is 50’ and if 3 elbows are used
then the run cannot be more than 35’.
Horizontal runs shall be sloping upwards not less than 1/4 inch per foot to the vent termination.
Number of units
Common vent size (inches)
Maximum length of vent (L)
Allowed number of 90º elbow
2
4 inches
50 ft
3
3
6 inches
60 ft
5
4
6 inches
60 ft
5
Number of units
Common vent size (inches)
Maximum length of vent and
air intake (ft)
Allowed number of 90º elbow
2
4 inches
20 ft
3
3
6 inches
30 ft
4
4
6 inches
30 ft
4
●
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Exterior View
Condensate drain
17"
max 1ft
max vent length (L)
12"
Air filter
6"
Intake
Intake
45°
45°
Exhaust
Exhaust
Exterior View
Condensate drain
17"
max 1ft
max vent length (L)
12"
Air filter
6"
Intake
Intake
45°
45°
Exhaust
Exhaust
Exterior View
Condensate drain
17"
max 1ft
max vent length (L)
12"
Air filter
6"
Intake
Intake
45°
45°
Exhaust
Exhaust
●
Applicable Model
GU195 (M) / 508 (11,12,21,22)1195 (M)
WARNING
!
Please note that only up to 4 - GU195Ms can be common vented together.
!
min 1ft
