Heater Pressure Switches 800120 - 800140

Pool & Spa Heater Pressure Switches by Len Gordon.
 
In 1993 Len Gordon introduced a pressure switch designed specifically for the pool and spa industry, this switch is designed with a 2-1/2 lb differential to completely eliminate oscillating or chattering relays. Now manufactured by Allied Innovations.
This pressure switch line includes variants with either 1/8 NPT or 1/8" barb adapters, plastic or stainless steel pans. Electrical ratings 6-25 Amps at 24-240 VAC. Also available in millivolt version for pool heaters.
The switch body may be found in Tan or Gray with blank or white micro switches. All new switches are SPDT with a boot on one terminal. Often the ID tag has weathered away and only the 'G' from Len Gordon & 'Increase PSI' with an arrow are visible on the switch.

All variants of the Len Gordon Pressure Switch are listed below. To view an image and purchase, please click the part number of the desired switch.

800120 Pressure Switches are 1-5PSI field adjustable, 21Amp, with 1/8" Plastic NPT.

• 800120-0 - Retail Package (same as 800120-3 w/fittings)
• 800120-3 - Universal
• 800120-2 - Specialty 25Amp & 1.5-2.2PSI

800140 Pressure Switches are all 6Amp, with 1/8" Plastic NPT.   

• 800140-0 - Retail Package (same as 800140-3 w/fittings)
• 800140-3 - 1-5 PSI Field Adjustable
• 800140-7 - 1.5-2.2PSI Range

Other Variants

• 800122-0 - 21Amp, 1-5 PSI Field Adjustable, Stainless Steel 1/8" NPT, Stainless Steel Pan (Retail Package)
• 800122-3 - 21Amp, 1-5 PSI Field Adjustable, Stainless Steel 1/8" NPT, Stainless Steel Pan
• 800122-5 - 25Amp, 1-5 PSI Field Adjustable, Stainless Steel 1/8" NPT, Stainless Steel Pan
• 800123-3 - 6Amp, 1-5 PSI Field Adjustable, 1/8" NPT, Stainless Steel Pan, Used on Millivolt Pool Heaters. 
• 800125-0 - 21Amp, 1-5PSI Adjustable, 1/8" Barb (Retail Package)
• 800125-3  - 21Amp, 1-5PSI Adjustable, 1/8" Barb.
• 800122-4 - NLA - Found on Comfortline Spa heaters.
• 800240-4 - NLA - Low Profile
• 800225-0 - NLA - Low Profile w/ Barb Fitting

Tecmark Pressure Switches 3900 Series 3902 3903

Tecmark 3900 Pressure Switch

Tecmark 3900 Series pressure switches are found in numerous pool & spa heaters, variants such as the 3902, 3903, 3903-BP & 3903-DF are common and will be located on or around the heater assembly. A pressure switch is a simple on/off device which controls the heater operation. 
These pressure switches use an internal diaphragm to convert a water flow pressure signal to an electrical signal. This electrical signal will open or close (based on manufactures design) the heating circuit when the pressure set point is reached. 

Tecmark pressure switches are made in the USA & are UL Recognized & CSA Certified as an operating, limit or safety control with SPST switching logic.

Variants:
3902 - 1Amp, 1-5psi Adjustable, 1/8" NPT (Universal) [Click to View]

3903 - 1Amp, 1-5psi Adjustable, 1/8" NPT (Univ. w/o screws) [Click to View]
 
3903-BP - 3Amp, PSI Factory Set Non-Adjustable, 1/8" NPT [Click to View]

3903-DF - 1Amp, 1.5psi fixed, 1/8" NPT w/o terminal screws [Click to View]

3902 Pool heater kit - 1Amp, 1-5psi Adjustable, 1/8" NPT (Universal) w/ brass adapter fittings. This kit is used to replace the following pool heater pressure switches, 3900, 3901, 3903, 3904, 3906, 3909, PRS-1100, PRS-1101, M3218, 71076, 26775, 26776, 26778, R-113, R-130, R-132B, S-1921173328, B600025, 600025, Comfortzone, Hobbs, Laars, Purex & Raypak [Click to View]

Tip# If you find your pool or spa heater is not working check both the pressure switch and the relay to which it connects. Usually it will be one of these two parts that has failed (if not the heater element) if you're getting the 'heater on' indicator light its the element. No 'heater indicator' means that heat is called for but the heater is not responding. 
The pressure switch sends an electrical signal to the heater relay which allows the heater to turn on/off.