Harwil - 35 mm Flow Switch with 1/2 Inch Thread for 3/4 Inch Tee - Q12DS-3-3-4S-1

Harwil – 35 mm Flow Switch with 1/2 Inch Thread for 3/4 Inch Tee

The Harwil Q12DS-3-3-4S-1 is a hot tub flow switch with a 35 mm reed and a 1/2 inch male thread, used to detect water flow in 3/4 inch pipework. It is fitted to spas from Sundance Spas and Jacuzzi (part number 6560-852), as well as Cal Spas, Artesian Spas, Dimension One and LA Spas models with the white PVC tee. It is a pilot-duty switch, so it is not meant to cut the heater power directly.

Compatibility

This replacement spa flow switch is installed on spas made by Sundance Spas and Jacuzzi, where it is listed under part number 6560-852. It is also found on spas from Cal Spas, Artesian Spas, Dimension One and LA Spas that use the white PVC tee, among others.

It screws into a suitable tee fitting, so check that your plumbing uses a 3/4 inch pipe tee with a matching 1/2 inch thread before ordering.

Electrical rating and pilot duty

The switch can handle a maximum current of 1A. It is therefore designed for pilot duty only: it signals flow to the spa control system, but you cannot use it to switch the power to the heater directly.

Dimensions and thread

The switch corresponds to size “Medium” (shown in red on the manufacturer diagram). The key measurements are:

• Thread diameter: 21 mm (1/2 inch MPT)
• Length of contact pin: 35 mm
• Total height (excluding contact pin): 79 mm

How to choose the right flow switch

Compare the part number on your current switch with the numbers below. This Harwil switch is also listed as a replacement for Q-12DS50/3/4/4S/NO/1.

• Harwil: Q12DS-3-3-4S-1
• Sundance Spas and Jacuzzi: 6560-852
• Replaces: Q-12DS50/3/4/4S/NO/1

Also measure the contact pin length and the thread, as flow switches are made in several sizes and they are not all interchangeable.

Fitting and documentation

Switch off the power to the spa before working on the pipework. The installation instructions can be downloaded below on this product page.