I don’t visit the forums much anymore but have been asked by many about using a solenoid to replace a pump relay switch.
Here is a video I did on that. Because our solution is different for cleaning cedar roofs we tend to use more solution and the pump works a lot and puts wear on the relay switch. Those pump relays don’t stand up well and the solenoid last forever.
[video=youtube_share;FeFbgEsgT9M]Roof Cleaning | How To Connect Solenoid To Roof Cleaning Pump - YouTube
@Sullivanroofcleaning, thanks for that very informative video. I look forward to seeing more!
I just have one technical question: Shouldn’t the 30A fuse go between the solenoid and the battery, not between the switch and battery? That’s only a 15A or 20A switch, which is fine because it’s controlling a low-current circuit that is actuating the solenoid. So if you wanted a fuse on that part of the circuit, I believe the fuse should have a much lower rating (corresponding to the specs of the solenoid). And then the 30A fuse would be used to protect the high current part of the circuit. Please correct me if I’m wrong.
No the fuse should go from the switch to the battery. 30 amp is standard but you can use what you want to.
Personally I have never had a problem with such. It is more having piece of mind.
If you have ever seen let’s say the pump in the box from pressure tek that are placed in the same spot.
You’ll only have an issue if the pump get to hot. I use a heat shield, no issues.
Why did you choose to interrupt the negative side instead of the positive side through the solenoid?
Because it works. LOL I showed the solenoid working in the video. Works just fine.
But you can hook it anyway you want. Whatever works for someone.
I didn’t know if there was a benefit because most solenoids interrupt the positive side.
Yeah, I think that’s an automotive/manufacturing standard. But interrupting the circuit at any point, will prevent current from flowing. The negative side may not be the 100% kosher method due to the remote possibility of a short-to-ground being introduced at some point before the solenoid. Essentially you want to keep as many possible points of failure after a switch/relay/solenoid or fuse device. The same principle applies in residential electrical- except instead of positive and negative, you have hot and neutral. You always want the switch installed in-line with the hot lead, so it interrupts the current going into an appliance, which could potentially short-to-ground (in worst case, via a 3rd party conductor, such as a human)
And from an electrical theory perspective, I stand by my understanding of having the high-current fuse installed between the solenoid and battery, and a lower-current fuse between the switch and battery. If you have an overload in the high-current portion of the circuit (such as an overheated pump), there’s no reason for the fuse on the switch side to blow. All the current is going right past the switch through the solenoid. That will eventually cause the contacts in the solenoid to weld together, so that it spirals into an explosive/combustive mess. At the point where contacts start to weld shut, the switch (and the fuse on the switch) become useless.
Great explanation well thought out. This setup has been used for years as is and I know of no one in my network that has had any of the issues stated.
But everything can be improved. If I have the issue going forward I will try relocating the fuse. Like I said in the video I use the inline fuse. Most don’t even have or use a fuse. Truthfully, if your not having any issues with relay switches on your pumps then the solenoid isn’t needed. I was have issues with relays giving out, since the solenoid not one issue in 4 years. Thanks for the feedback, I see your point from your viewpoint.
The only reason I posted on the forums was the many phone calls and emails I get asking about the solenoid on my rig.
Goes back to, “if it isn’t broke don’t fix it”. LOL
