1 Direct Fired Gas Heating Presented by Jim Jagers of Applied Air

2 Direct Fired Heating - Training the basics controls start-up service

This is important.3 Direct Fired Heating - Training Direct Fired Heating - Basic System cold air in warm air out

4 Direct Fired Heating - Training

This is important.5 Direct Fired Heating - Training Direct Fired Basics –100% combustion efficient –92% thermal efficient –products of combustion go into the air stream –high turndown of 25:1 or more –no flue required

6 Direct Fired Heating - Training Direct Fired Basics –92% efficient 92% of the heat content of the gas is used to raise the air temperature. That is why we use the equation: BTUH input = CFM x delta-T x 1.08 (8% of the heat content is consumed putting water vapor into the air stream) 0.92

This is important.7 Direct Fired Heating - Training Direct Fired Basics –92% efficient –products of combustion go into the airstream –high turndown of 25:1 –no flue required –all products of combustion into space –indirect fire heater 400ppm CO vs 5ppm CO for direct fired

8 Direct Fired Heating - Training ACGIH = American Conference of Governmental Industrial Hygienists

This is important.9 Direct Fired Heating - Training If air velocity across the burner is not correct: too high too low added CO concentration added aliphatic aldehydes added CO concentration added NO 2 concentration flame length will increase flame could impinge on unit components Optimum velocity fpm

10 Direct Fired Heating - Training Burner location: small unit profile plates

11 Direct Fired Heating - Training Burner location: large unit

This is important.12 Direct Fired Heating - Training Burner Turndown High fire input Low fire input High fire temp Low fire temp

13 Direct Fired Heating - Training High Burner Turndown of 25:1 - how is this accomplished? –carefully controlled aeration patterns –factory set profile plates for proper air velocities across the burner –burner positioned for uniform air velocities across it Unit Turndown – how does it compare to burner turndown? –typical control valve is capable of 20:1 –some loss due to capacity/input mismatch –some loss due to pilot and low fire adjustment –17:1 realistic maximum to as low as 4:1

14 Direct Fired Heating - Training Profile uniformity: same space at top and bottom

15 Direct Fired Heating - Training Burner aeration pattern: large holes for high fire intermediate holes for midrange fire small holes for low fire flame rod spark rod pilot connection gas manifold

16 Direct Fired Heating - Training Controls –temperature –safety

17 Direct Fired Heating - Training Temperature controls –discharge –room –other –Maxitrol Series 14 discharge temperature control Series 44 room temperature control SC10 signal conditioner –RTC Solutions DFC-1 discharge temperature control RTC-1 room temperature control SC-1 signal conditioner

This is important.18 Direct Fired Heating - Training Temperature controls –Series 14 discharge temperature discharge temperature control only main burner low fire start timer setpoint dial won’t turn off burner 2 conductor shielded or separate conduit override stat

19 Direct Fired Heating - Training Discharge air temp is sensed here Discharge air temp is set here System 14 controls

20 Direct Fired Heating - Training Location of discharge air temperature sensor

This is important.21 Direct Fired Heating - Training Temperature controls –Series 44 room temperature room control w/discharge temperature override main burner low fire start timer max and min discharge setpoints room setpoint dial & sensor won’t turn off burner 2 conductor shielded or separate conduit averaging room sensors

22 Direct Fired Heating - Training Space temp sensed here Space temp set here System 44 space temp control

23 Direct Fired Heating - Training Maxitrol series 44 amplifier

24 Direct Fired Heating - Training Maxitrol series 44 amplifier with cover removed

This is important.25 M-611 Direct Fired Heating - Training Temperature controls –modulating/regulating vlv –low fire bypass –not a shutoff vlv Adjust low fire here

This is important.26 MR-212 Direct Fired Heating - Training Temperature controls –modulating/regulating vlv –low fire bypass –not a shutoff vlv Adjust high and low fire here

This is important.27 Direct Fired Heating - Training Temperature controls –High fire 15 – 24Vdc –Modulated fire 5 – 15Vdc –Low fire 0 – 5Vdc –Series 14 discharge temperature high fire remove wire from terminal 4 low fire remove wire from terminal 8 –Series 44 discharge temperature high fire remove wire from terminal 2 & 4 low fire remove wire from terminal 8

28 Direct Fired Heating - Training Temperature controls –SC10 signal conditioner 0-10vdc or 4-20mA input 0-24vac output always use a discharge sensor

29 Direct Fired Heating - Training Maxitrol SC10 With the SC10 you get just this This will accept a 4- 20ma or 0- 10VDC signal “by others”

30 Direct Fired Heating - Training Safeties –high gas pressure limits over firing located after control valve manual reset –low gas pressure located at start of gas train ensures enough gas to get full low fire manual reset

31 Direct Fired Heating - Training Safeties –high temperature limit located in discharge airstream regardless of setpoint should trip when discharge is 185ºF temperature control failure manual reset –low temperature limit (freeze stat) located in discharge airstream shut off fan timed cycle power to reset

32 Direct Fired Heating - Training High temperature limit control sensor

33 Direct Fired Heating - Training High temperature limit control

This is important.34 Direct Fired Heating - Training Safeties –high and low airflow sense  P across profile ensure operable velocity auto reset –flame relay and sensor checks for flame prepurge pilot main flame post purge manual reset

This is important.35 Direct Fired Heating - Training Flame rod Spark rod Pilot gas line UV flame sensor

36 Direct Fired Heating - Training Gas Train Approvals Includes IRI for ETL units

37 Direct Fired Heating - Training Common duct “Pants leg” in duct Short pieces of duct “by others” from bottom of unit to damper damper Bottom of unit End view of DFC with twin fans, down discharge Temperatures may not be equal in these two ducts

38 Direct Fired Heating - Training Pipe train schematic and components:

39 Direct Fired Heating - Training

40 Direct Fired Heating - Training Inlet On/Off Duct Stat:

41 Direct Fired Heating - Training

42 Direct Fired Heating - Training UV Flame Sensor (UV Mini-Peeper) –flame sensor checks to make sure the pilot flame has ignited before gas is sent to the main burner. Operates by sensing the light of the pilot flame. –If the flame sensor does not sense the pilot flame, the unit shuts down (fan and burner go off) and the flame failure light on the optional remote panel goes on. –The unit has to be reset by pushing the reset button on the burner relay. –Differences between UV Flame Sensor and Flame Rod: both are used for the same purpose - to check if the pilot flame is on. The flame rod is “standard”. The UV sensor needs to be ordered as an option. –If condensation forms on the flame rod while the unit is off, it may give a false signal and prevent the unit from coming on. The wet flame rod does not sense the pilot flame and shuts the unit down. This nuisance tripping can be avoided with the UV sensor.

43 Direct Fired Gas Heating Sheet Metal Workers 265 Training