Coal Stoker Holdfire Timers

Coal Stoker Holdfire Timers

The Will-Burt model 34170 Holdfire Timer provides periodic stoker operation during mild weather and other times when the system operating controller does not demand burner operation, in order to

  • maintain combustion, so that the fire does not have to be frequently restarted, and
  • prevent the fuel bed from burning down into, and damaging, the cast iron burner parts.

Generally utilized in residential applications, it is intended for use with 2-wire, 24 V thermostats.

Virtually identical in design and operation is the Will-Burt model 20350 Holdfire Timer, which fulfills the same function as the 34170 while working in conjunction with a boiler limit control.

34170/20350 Timer Interval Adjustment

Operating Interval 30 Minutes: 1-5 Minute Adjustable “On” Period
Operating Interval 60 Minutes: 1-10 Minute Adjustable “On” Period

Approximate 34170/20350 Timer Dimensions

Timer Case: 5″ X 4-3/8/” X 4-5/8″ High
Timer Cover: 5-1/16″ X 4-3/8/” X 4-5/8″ High