HeatStation™ CONDENSING WATER BOILER
18
34-1161 05/17
7.2 Maximum Allowed Remote Combustion Air Inlet Length (Equivalent Length)
A vertical or horizontal remote air inlet system can be connected to this appliance without modification.
The maximum
length of field supplied single wall pipe, such as galvanized ventilation pipe, is shown in the chart below titled Maximum
Air Inlet Duct Equivalent Length. Use metal tape or RTV sealant to seal each pipe joint.
Maximum Allowable Equivalent Duct Length / Max Elbows
Duct Size
6
″ Duct
8
″ Duct
Max Equivalent Length all Models
230 feet/8
350 feet/8
To determine the maximum straight length of duct allowed, use the Duct Fitting Equivalent Length chart below to find
the total equivalent length for all duct fittings in your combustion air system. Then subtract this number of feet from the
total equivalent length allowed in Maximum Air Inlet Duct Equivalent Length chart above. The sum of this calculation
is the maximum length of straight duct allowed. If a longer length is required, repeat the calculation using a larger duct
size. No additional deduction is required for the addition of the duct system terminal.
Duct Pipe:
6
″ Duct
8
″ Duct
90º Elbow
20 feet
10 feet
90º Long Radius Elbow
12 feet
6 feet
45º Elbow
12 feet
6 feet
The following remote air duct information is provided for use in design calculations, if needed.
Remote Air Duct Specifications
Input MBtu/h
Required Air (SCFM)
1000
220
1250
275
1500
330
1750
385
2000
440
7.3 Remote Combustion Air Termination
A suitable remote air termination must be used to prevent water, debris, animals or obstructing material from entering
the remote air supply.
7.4 Vertical or Horizontal Remote Air Duct Termination
Air inlet must be located no less than 3 feet (0.91m) below the exhaust terminal if they are within 10 feet (3.05 m)
of each other, unless the flue outlet terminates with a straight discharge. If the flue outlet terminates with a straight
discharge, the air inlet can be located no less than 18 inches (0.46m) below the exhaust terminal.
If terminating through the roof, the air inlet must terminate at least 12 inches (0.3 m) above roof level and at least
12 inches (0.3 m) above snow levels.
If terminating through a sidewall, the air inlet must terminate at least 12 inches (0.3 m) above grade and/or at least
12 inches (0.3 m) above possible snow levels.
Vertical Remote Air
Horizontal Remote Air
*
When flue outlet is terminated with a straight discharge, separation of terminations must be a minimum of 18
″.
