Panel fi lter assembly mounted on a blower. With two panels 
removed, a 2936 Silencer can be seen mounted to the inlet of 
the blower. This is the 2941 Filter-Silencer assembly. Without the 
Silencer, the assembly number is 2921. Filters shown are wash-
able type, designated "W". Throwaway type is designated "T". 
(Support leg is furnished as part of the assembly.)

Inlet fi lters remove 95-99% of airborne dirt to help keep blowers 
and combustion systems clean and operating effi

  ciently.

Two types of panels are available:

  Washable (W) fi lters (cost more initially, but can be cleaned
 and 

reused).

  Throwaway (T) fi lter panels.

Washable panel fi lters remove 99% of airborne dirt; the throw-
away type is 95% eff ective fi ltering particles 5 microns and 
larger. Pressure loss in clean fi lters is minimal.

A 2921 Filter Assembly can be added to a blower with an existing 
2936 Silencer; or a Silencer can be added to an existing panel 
fi lter assembly.

BENEFITS OF CLEAN AIR

Today’s precision burner orifi ces require clean combustion air.

Some dirt tends to collect on blower impellers, imbalancing them 
and causing blower damage, noise, and ineffi

  ciency.

Costs of fi lter and maintaining it are small compared to costs 
assoc iated with dirt build-up in combustion air piping and 
manifolds, as well as in the burners themselves:

  Burner capacity may be reduced.

 Burner 

effi

  ciency--particularly air/fuel ratio--is likely to be

 aff ected adversely.

  Dismantling large pipe is expensive and time-consuming
 (espe 

c ially  harmful if it necessitates unscheduled furnace

  shutdown), but it may be necessary to remove accumulated
 dirt.

INSPECTION AND MAINTENANCE

T

o maintain its low pressure loss rating--less than 0.25 osi 

at maximum fl ow--fi lters should be inspected regularly, as 
 frequently as ambient conditions dictate. When dirty, "W" panels 
are cleaned as described below. Do not attempt to clean any 
fi lter while it is mounted on blower.

Keeping spare panels on hand is recommended, even the 
 washable (W) type, to avoid running blower without fi lter while 
 element is being cleaned.

To clean washable fi lters, remove them from the assembly and 
wash in kerosene or any commercial cleaning solution, such 
as Oakite and water. Allow to dry thoroughly, then immerse in 
 engine oil, SÆ 30 to 50 viscosity. Drain off  excess oil and reas-
semble unit.

WARNING: Do not clean fi lters in gasoline--doing so could 
cause an explosion in air piping.

2921 and 2941 Assembly designations are descriptive:

example: 2941-1402-8/33W 

example: 2921-2003-9/GT

 2941: fi lter and silencer 

2921: fi lter only

  14: 14" pipe connection (female)  20: 20" pipe connection
  02: two sections long 

03: three sections long

  8: eight panel fi lters  

9: nine panels

  33: case 

G: case

  W: washable type 

T: throwaway type

Each section has provision for four panel fi lters. When less than 
four are required, metal blanks are supplied (these could be 
replaced with panels later if additional capacity is required).

All Panels are 16" × 25" × 2". Washable fi lters (1-2873-2) are inter-
changeable with throwaway (1-2873-1).

NOTE:

 Panel fi lters are not oiled as shipped.

Bulletin 2921/2941

Page 2

Product Overview | Panel Filters/Silencers