Dave Koesterer Dir. of Eng. Performance Systems Furnace Updates

Topics 95% With ECM Blower Motor Residential Furnace Product Improvements New Trap Pressure Switches Probe Access Terminals Cabinet Leakage Improvements Blower/Motor Failure – Case Study

*G7SD/MGCSD Up to 95% AFUE Single Stage Inputs – 38 kbtuh – 54 kbtuh – 108 kbtuh – 120 kbtuh ECM Motors – Constant Torque Orientation – Upflow – Horizontal Left – Horizontal Right Availability – Q4 2015

New PVC Trap with Cleanout Vent Trap with Cleanout 2” slip x ½” slip x 3/8” NPT Implemented - 8/31/15

Inducer Pressure Switch Changes New inducer switch opening pressures identified More reliable operation Current switches do NOT impose a safety issue Implementation in Q4, 2015 ModelOld SwitchSettingNew SwitchSetting *G7SA 108C-35C *G7SA 126C-45D *G7SC 054D-24B *G7SL 120D-45D *G7SM 118D-45D *G7TC 060D-VB / /0.43 *G7TC 100D-VC / /0.50 *G7TC 120D-VD / /0.40

New Style Pressure Switches Current Future Phase-in over next 2 years Increased Accuracy Wider Setting Range (0.1 to 5.0”) Slimmer Profile

Probe Access Terminals – Power input Line (L) & Neutral (N) – Limit Switches – Pressure Switches

Air Leakage Improvements 80% Upflow Models – Added seals around the lower blower door. – Implemented 6/19/15 All Upflow Models – Add seal to lower corners between Heat Exchanger, Blower Deck and Wrapper. – Implement in September, 2015

Loose Blower Wheels – 1 HP PSC Motors Field reports of Blower Wheels working loose Requested failed blower assemblies from customers 1 HP PSC Motor x 10 Wheel Root Cause Analysis Set Screw Sampled production models Torqued within proper range Set Screw is correct length Motor Shaft Proper hardness Dimensionally correct

Failed Blower Wheel Set Screw Loose Set Screw Loose Hub Separated from Blades Hub Separated from Blades

Failed Blower Wheel Internal Hub Wear

Vibration Testing of Motor and Blower Swaying Mode Movement of the motor and wheel as one body relative to the blower housing. The natural frequency is 17 Hz and should not be excited in transit. Rocking Mode Wheel rocking mode vibration involves the movement of the blades relative to the center plate, or the movement of the center plate with respect to the hub. The response frequency is 28 Hz, far above the maximum operating speed (1050 rpm, 17.5 Hz) of the motor and should not be excited.

Vibration Testing of Motor and Blower Torsional Mode (Wheel-Shaft-Rotor) This mode involves the relative torsional movement between the wheel and the motor rotor, while the shaft acts like a torsional spring. Types of Failures (Torsional Mode) Blade – Center Plate separation Hub – Center Plate setscrew loosening Motor shaft gouging Excessive noise

Vibration Testing of Motor and Blower The excitations are the 120 Hz and 240 Hz motor torque pulsations generated by a PSC motor with a 60 Hz line frequency. If a system is near resonance, the motor torque pulsation forces will be amplified and transmitted to the blower wheel. The natural frequency of this system was measured to be Hz. This is not close to 120/240 Hz torque pulsations. However, the forces were high. The solution Move the motor closer to the wheel hub 0.75” Shift resonance from to 185 Hz Reduce force amplitude by 25%

Vibration Testing of Motor and Blower

Loose Blower Wheel Solution TB15-106RA HP Motors R Blower Wheels was issued 4/15/15 TB15-106RA HP Motors R Blower Wheels was issued 4/15/15 Effective 3/20/15 Motors were repositioned in production Effective 3/20/15 Motors were repositioned in production.

Furnace Updates Thank you! Questions?