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The 35-70 is a 120 VAC direct spark ignition control for controlling a gas valve and igniting LP or natural gas fired equipment and gas burner applications that provide a 120 VAC operating signal.
?The microprocessor circuit design provides precise, repeatable timing sequences for ignition times and purge times (pre- and inter-) as well as multiple tries for ignition, one hour automatic reset and flame sensing during pre-purge. The on-board diagnostics with LED output provide assistance with trouble-shooting to ensure safe and efficient burner operation
| Input Power | 102 to 138 VAC, 50/60 Hz |
| Input Current Drain | 350mA@ 120 VAC, 60 Hz |
| Gas Valve Rating | 1.5A@ 120 VAC |
| Operating Temperature | -40F to +175F, -40C to +80C |
| Flame Sense Voltage | 120 VAC |
| Flame Sense Current | 1.0 microamp minimum |
| Flame Failure Response Time | 0.8 seconds maximum |
| Types of Gas | Natural, LP and manufactured |
| Spark Rate | Line frequency (50/60 Hz) |
| Moisture Resistance | Conformal coated to operate to 95% R.H. |
| Size (LxWxH) | See drawings on Page 8 |
| Weight | Integral stand-offs: 7.1 oz Potted:14.3 oz Case and Cover: 10.1oz |
CONTROL CONFIGURATION | |
Enclosure Configurations and Wiring Options or Assemblies or Non-Standard Configurations | Non Standard Configuration |
Combustion Blower Control, Post-purge time and Power Options | 0 second post-purge and no full-time power |
Number of Ignition Trials, Flame Sense Method and Lock Out Reset Method | 3 try, single spark and sense Automatic reset |
Pre-Purge Time | 15 seconds |
Inter-Purge Time | 15 seconds |
Trial for Ignition Time (TFI) | 15 seconds |
Fenwal offers a complete range of ignition control products including:
?Designed, developed and manufactured by Fenwal, these components integrate seamlessly providing maximum system performance.
To ensure proper system design and operation, Fenwal provides sample ignition controls, high-voltage wires and electrodes for trial and evaluation at no charge. To get you started quickly, Fenwal has identified our most popular ignition controls, see Page 8. Whether it is an individual control, complete start-up kit or customized control, Fenwal is ready to provide your gas ignition solution.
?Send your equipment to us and we'll design, install and qualify a control to meet your exact application requirements. Fully equipped and staffed with trained technicians, the Fenwal Ignition Development Center has proven extremely beneficial for many customers focused on product quality and reducing time-to-market for their appliances.
?120 VAC is supplied to the L1 terminal, either from a thermostat or other control device. When this occurs the control will power up and perform a self-check routine and if selected, begin a pre-purge. Following the pre-purge, the gas valve is energized and sparks commence until flame is detected or the Trial for Ignition (TFI) period expires.
When flame is detected, the spark is shut off and the gas valve and combustion blow- er remain energized. The thermostat, pressure switch and main burner flame are constantly monitored to ensure that the system is functioning properly. When the thermostat is satisfied and the demand for heat ends, the gas valve is de-energized immediately and a post-purge is initiated (optional) and the flame is extinguished. When the post purge is complete, the combustion blower is de-energized.
Fenwal controls are configured with several options for managing loss of flame.
Should the burner fail to light or flame is not detected during the TFI period, the gas valve is de-energized and the control will go into lockout mode.
Should the burner fail to light or flame is not detected during the first TFI period, the gas valve is de-energized and the control will attempt two additional ignition trials with inter-purge. If these attempts are unsuccessful, the control will go into lockout mode.
There are two methods for re-starting the burner after loss of established flame. The Re-ignition option is the default configuration for re-establishing flame and does not need to be specified when ordering. If the Recycle option is desired, please specify this when ordering so that a special part number is assigned to the control by Fenwal.
If the established flame signal is lost, the control responds and begins sparking within 0.8 seconds of loss of flame. This is considered the first re-ignition attempt. The spark will be energized for the duration of the TFI period in an attempt to re-light the burner. If flame is re-established, normal operation resumes.
If the burner does not light after the first re-ignition attempt, the control will de-energize the gas valve and go into lockout mode.
If the burner does not light after the first re-ignition attempt, the inter- purge sequence is completed between the next two attempts to re-light the burner. If the burner fails to light after the third attempt, the control will de-energize the gas valve and go into lockout mode.
If the established flame signal is lost, the control responds by shutting off the gas valve within 0.8 seconds.
The control will begin the ignition cycle with the pre-purge cycle, if a pre-purge cycle is programmed into the control. Controls without pre-purge immediately commence sparking for one TFI period. If flame is re-established, normal operation resumes. If the burner fails to light after the first try, the control will de-energize the gas valve and go into lockout mode.
The control will begin the ignition cycle with the inter-purge sequence and attempt three tries for ignition including inter-purges. If flame is re-established, normal operation resumes. If the burner fails to light after the third try, the control will de-energize the gas valve and go into lockout mode.
In normal operation, the control monitors the combustion air flow by reading the pressure switch (PSW) input to confirm that the blower is operating in the proper sequence. Initially, the control checks the PSW input to be sure that it is open. Once the blower is energized and the PSW closes the control proceeds to trial for ignition.
If during a call for heat 120 VAC power is present at the PSW input prior to the blower being energized, the control will wait 30 seconds, for the condition to change. Possible reasons for this condition includes a stuck or mis-wired pressure switch, or the blower is spinning down and keeping the switch closed. If the condition does not change, an airflow fault will be declared and the LED will flash the one flash pattern.
If the combustion blower is energized and the PSW does not close within 30 seconds, an airflow fault will be declared and the LED will flash the one- flash pattern. The blower will remain energized until the condition changes.
If the PSW signal is lost while the burner is firing, the control will immediately de-energize the gas valve and the combustion blower will remain on. If the call for heat remains and the PSW signal returns within 30 seconds, the control will restart with the pre-purge period. If the PSW input does not return within 30 seconds, the blower remains on and LED will flash the one-flash code indefinitely. If the PSW closes, the LED stops flashing and the control resumes oper- ation with the pre-purge function.
After single or multiple attempts to light the burner have failed or flame is not estab- lished, the control automatically enters lockout mode. The control will not open the gas valve unless there is intervention by the user or one hour has passed depending on the model chosen. See Lockout Recovery
There are two options for recovering from lockout mode. When selecting the control, please specify one of the following methods for lockout recovery.
The 35-71 is not position sensitive and can be mounted vertically or horizontally. The control may be mounted on any surface and fastened with #6 sheet metal screws. Secure the control in an area that will experience a minimum of vibration and remain below the maximum ambient temperature of 80C (175F).
All connections should be made with ULapproved, 105C rated, 18 gauge, stranded, 0.054 in. thick insulated wire. Refer to the appropriate wiring diagram when connecting the 35-71 to other components in the system. High voltage spark cables and control wiring harnesses are detailed on Pages 5 and 6.
