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Roof Cleaning Katy Texas (281) 392-2304 wrote:

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Now that we have a member’s only section I will post a relay replacement wiring diagram for the Delavan Fat Boy.  The relay that it comes with will not hold up to our roof cleaning environment.  This article replaces the relay with a car starter solenoid.  I used a Ford Starter solenoid but any will do with one exception.  The solenoid must be rated “continuous duty” which means it can be energized continuously without burning out.  I also used a terminal block because my solenoid is mounted inside a Nema 4 enclosure.  This protects it from our chemicals and prevents it from getting shorted out accidentally.  If the pump quits working you just hook another one to the terminal block and do not have to rewire anything.

 

Cut the wires coming from the Delavan Fat Boy pump but leave them as long as possible.  

 

From my 12 Volt battery “+” post I ran a 6 gauge red wire to an electrical switch so I could turn the pump on or off.  From the electrical switch I ran the +12V, 6 gauge red wire to the “In” terminal of the solenoid.  From the “Out” terminal of the solenoid I ran the +12V, 6 gauge red wire to the terminal block and then I hooked the +12V red input wire of the Delavan Fat Boy to the terminal block.

 

From my 12 Volt battery “-” post I ran a 6 gauge black wire to a terminal block and then on to the Ground mounting bolt of the solenoid.  I hooked the -12V black wire of the Delavan Fat Boy to the terminal block.

 

Then I ran a 12 gauge red wire from the “In” terminal of the solenoid to the terminal block and hooked one of the Fat Boy Pressure Switch wires to it.   

 

Last I ran a 12 gauge red wire from the “coil” terminal of the solenoid to the terminal block and hooked the other Fat Boy Pressure Switch wire to it. 

 

It does not matter which pressure switch wire you use from the Fat Boy as the switch is no polarized.

On the ends of each wire I stripped I back ¼” and coated the bare wire with electrical grease to prevent corrosion.  Then I slide a 2” piece of shrink tubing over the wire and crimped it to a 6 gauge ring terminal.  After that I slid the shrink tubing over the crimped area of the lug and applied heat to it to shrink the shrink tubing to make an air tight fitting over the connection to protect it.

 

I used 6 gauge wires because my pump is more that 6’ from the battery.  6 gauge wire can handle the amperage that the pump can draw without a voltage drop or over heating of the wire.  I also applied electrical grease to the terminal block.  This protects it from corrosion.  Using red & black color coded wiring will make it easier to diagnose and help prevent wiring mistakes.

 

After it was wired and running I adjusted the pressure switch screw on the pressure switch of the Fat Boy so that it only turned the pump on/off when I turned my gun on/off.  This will prevent pulsating headaches.  It also prolongs the contacts of the solenoid.

 

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Sorry Joe, but I would not know how to add on a pressure switch to a pump that does not have one.  Check with Graingers and see if they offer one.  They are local.