ometimes there is confusion as to whether a dryer is an Air Heat dryer (AH) or a Ratio Air dryer (RA).
The Physical Difference is Visble
An Air Heat burner is rectangular and has an air gap around the burner where it mounts to the burner box. The combustion fan uses a big air filter assembly bolted to the fan housing. This burner modulates
gas flow and uses a constant air supply.
A Ratio Air burner is completely enclosed at the mounting to the burner box. The burner shape is round, and the combustion fan has no filter. We sometimes call the ratio burner a "Thermjet". This burner modulates the
air supply and the gas flow changes based on the combustion air pressure. A gas regulator uses combustion air pressure to change gas pressure. The more combustion air, the more fuel.
Part numbers for burner assemblies by model number at
bottom of this page.
Ratio Air (RA) Burners
From the outside of the dryer, a Ratio Air dryer can be determined by the shape of the burner.
If the burner is round, you have a ratio air dryer.
Were you to look inside the Ratio Air burner you would find something akin to the end of a jet engine. Please see pictures below.
The Ratio air or Thermal Jet is a nozzle-mix burner that is designed to
fire an intense stream of hot, high velocity
gases through a combustor using ambient combustion air. A Ratio Air burner pulls in air directly from the room. There is no combustion air filter screen.
Ratio Air Burners also use
Air Position Actuators to fine tune the fuel/air mixture within the thermal Jet. This part is circled in the pictures below.
TG1L
 | TG1R
 |
If you have a Left Air Ratio Dryer (Model that ends in TG1L) the Air position Actuator is
25AB442PBL / AIR POSTION ACTUATOR LEFT 12 SECOND SEIMENS.If you have a Right Air Ratio Dryer (Model thay ends in TG1R) the Air position Actuator is
25AB442PBR / AIR POSTION ACTUATOR RIGHT 12 SECOND SEIMENS
25AB442PBL
 | 25AB442PBR
 |
Air Heat (AH) Burners
Air Heat burners are rectangular in shape.
As these pictures don't show the full burner box here is a drawing for better description.
Note that this is not a drawing of a Milnor Blower/Burner assembly.
The drawing above shows you what you would see from the inside of the dryer.
An Air Heat burner is a line type burner constructed of cast iron or aluminum burner bodies and diverging stainless steel air wings. The burner bodies supply fuel to the center of the air wings. These air wings can be damaged by lack of combustion air. So, keeping the combustion filter and blower clean is extremely important.
Repair and replacement instructions along with part numbers can be found
HEREAn Air Heat burner will also have a filter screen for the air it draws into the burner.
Ratio Air (THERM-JET) Part Numbers
| PART NUMBER | DESCRIPTION | MODEL NUMBERS |
|---|
| 25AB340BL | RATIO AIR 1MIL/COMB BLOWER 1M BTU/H GAS LEFT/12 SECOND ACTUATOR SEIMENS | 6450TG1L |
| 25AB340BR | RATIO AIR 1MIL/COMB BLOWER 1M BTU/H GAS RIGHT/12 SECOND ACTUATOR SEIMENS | 6450TG1R |
| 25AB343BL | RATIO AIR 2MIL/COMB BLOWER | 6464TG1L / 6458TG1L / 6450TG1L |
| 25AB343BR | RATIO AIR 2MIL/COMB BLOWER | 6464TG1R / 6458TG1R / 6450TG1R |
| 25AB442BL | RATIO AIR 3MIL/COMB BLOWER | 7676TG1L / 8282TG1L |
| 25AB442BR | RATIO AIR 3MIL/COMB BLOWER | 7676TG1R / 8282TG1R |
Air Heat (Combustion Box) Part Numbers
| PART NUMBER | DESCRIPTION | MODEL NUMBERS |
|---|
| 25AB240 | BURNER-AIR/HEAT #240TAH-R
(burner only / blower motor part 25AB240B)
(REPLACEMENT BLOWER WHEEL 25AB242BW) | 7272TG1 (pre 2003) |
| 25AB241 | BURNER/BLOWERWHEEL MODEL 80AH
(REPLACEMENT BLOWER WHEEL 25AB241BW) | 5040TG2L / 5040TG2L
5050TG1L / 5050TG1R |
| 25AB242 | BURNR/BLWWHEL 160AH 2MLW/201AH
(REPLACEMENT BLOWER WHEEL 25AB242BW) | 6464TG1L / 6458TG1L / 6450TG1L
6464TG1R / 6458TG1R / 6450TG1R |
| 25AB243 | BURNER/BLOWRWHEL #240AH W201AH
(REPLACEMENT BLOWER WHEEL 25AB242BW) | 7272TG1L / 7676TG1L
7272TG1R / 7676TG1R |
