External-Mount Heat Sink for 25A SSR

Product Update (2026): The HS25ET now features rounded fins with no sharp points for easier and safer handling.

This externally mounted heat sink dissipates heat from a 25A solid-state relay (SSR), allowing it to handle up to 25 amps without forced-air cooling. The SSR and its wiring remain inside the controller box, while the heat sink mounts outside, eliminating the need for ventilation holes or a cooling fan in the box. The user will need to cut a 70 x 55 mm (2.75" x 2.2") rectangular hole in the enclosure for the SSR.

What's Included:

• 1 x Heatsink HS25ET 
• 6 x M4-0.7 mounting screws
• 1 x Thermal grease (SI-07)

Specifications:
Dimensions (W x D x H): 100 x 90 x 30 mm (4" x 3.5" x 1.2").
Mounting Holes: 6 x M4-0.7 threaded mounting holes.

• Four holes at the corners with 90 x 79.5 mm spacing.
• Two holes in the center for the SSR with 48 mm spacing.

Thermal Resistance: 2.0 ºC/W.

A 25A SSR (SRDA25) mounted to an HS25ET heatsink.
 

A total of 6 mounting holes (M4) are available for installing an SSR and mounting the heatsink. 

Mounting cutout

Note: Refurbished HS25ET might be in limited stock. Please check MISC-ES.