Cold Start Auxiliary Unloader Valve for Air Compressors, 1/8 and 1/4 in
A cold start auxiliary unloader bleeds the pressure trapped between the pump and the check valve so the compressor starts against no load. It is the part that decides whether a cold compressor spins up or just sits there humming and tripping the overload.
On a cold morning the oil in the crankcase is thick, the motor is at its weakest, and any residual head pressure is working against it. An auxiliary unloader takes that pressure out of the equation.
Sizes
- S1005: cold start auxiliary unloader, 1/8 in, reference AU100
- S1006: cold start auxiliary unloader, 1/4 in, reference AU200
When you need one
The classic symptom is a compressor that starts fine when warm and will not start when cold, or one that trips its overload or pops a breaker on the first start of the day. Single phase motors are the usual sufferers because they have the least starting torque of anything you will find on a compressor. Before blaming the motor or the starter, check whether the machine is unloading properly at shutdown.
Choosing the size
Match the port on the discharge tube or head where the unloader goes. 1/8 in is the common size on smaller single stage pumps, 1/4 in on larger ones. If the existing fitting has been bushed down at some point, measure the thread rather than trusting what is in it now.
Related parts
An unloader works with the pressure switch unloader and the discharge check valve. If the compressor is not unloading, all three are worth checking. We also stock Lefoo pressure switches with unloader, CDI pilot valves, and horizontal inline, vertical and in tank check valves in sizes from 1/4 in to 2 in.
Questions
Tell us the compressor make, model and port size and the Warthog Air Compressor Store team will confirm the right valve before you order.
Cold start auxiliary unloader valves for air compressors in 1/8 in and 1/4 in, releasing trapped head pressure so the motor starts unloaded.
NOTE: Actual product may be different from pictured!
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