The Fenwal 35-705701-005 Microprocessor-Based Direct Spark Ignition Control is a 120 VAC DSI control designed for gas-fired equipment requiring reliable ignition sequencing and flame supervision. As part of Fenwal’s 35-70 Series, this ignition module uses microprocessor-based timing to provide consistent startup operation, spark ignition control, flame sensing, and safety shutdown response.

This model is configured with one trial for ignition, remote flame sensing, and a 10-second trial-for-ignition period, making it suitable for applications where the flame sensor is separate from the ignition electrode. The potted construction helps protect the control in demanding equipment environments, while onboard diagnostic LED output assists technicians during troubleshooting.

The 35-70 Series is designed for use in gas-fired appliances and supports natural, LP, or manufactured gas applications. Manufacturer specifications list 102 to 138 VAC input power, 50/60 Hz operation, 1.5A maximum gas valve rating at 120 VAC, 1.0 microamp minimum flame sensitivity, and 0.8-second maximum flame failure response.

 

Frequently Asked Questions

• What is the Fenwal 35-705701-005 used for?

The Fenwal 35-705701-005 is a 120 VAC direct spark ignition control used to manage burner ignition sequencing, spark generation, flame sensing, and safety shutdown in gas-fired appliances. The Fenwal 35-70 Series is designed for gas-fired appliance applications and uses microprocessor-based timing for repeatable operation.

• What type of ignition control is this?

This is a direct spark ignition, or DSI, control. It creates a spark to ignite the burner directly instead of using a standing pilot.

• What voltage does the Fenwal 35-705701-005 require?

This model operates on 120 VAC. Manufacturer data for the 35-70 Series lists an input power range of 102 to 138 VAC, 50/60 Hz.

• What does “10-second TFI” mean?

TFI means trial for ignition. On this model, the control allows a 10-second ignition trial for flame to be established before the control locks out or stops the ignition sequence.

• Does this model use remote flame sensing?

Yes. The Fenwal 35-705701-005 is configured for remote flame sensing, meaning the flame sensor is separate from the spark electrode.

• How many ignition trials does this control provide?

This model is configured for one trial for ignition. If flame is not proven during the ignition trial, the control goes into lockout.

• How is the control reset after lockout?

This model uses a thermostat or power-off reset. Power must be cycled before another ignition attempt is made.

• Is the Fenwal 35-705701-005 potted?

Yes. This model is listed as a potted direct spark ignition module, which helps protect the electronics in demanding operating environments.

• What gas types can the 35-70 Series support?

Manufacturer specifications list the 35-70 Series for use with natural gas, LP gas, and manufactured gas applications.

• Does this ignition control have diagnostic features?

Yes. The 35-70 Series includes onboard diagnostics with LED output to assist with troubleshooting and service checks.

• What is the flame failure response time?

Published specifications list a 0.8-second maximum flame failure response time.

• What should be confirmed before ordering?

Confirm the full part number, voltage, flame-sensing method, ignition trial timing, reset method, and appliance compatibility before ordering. Similar Fenwal 35-70 Series controls may have different timing or sensing configurations.