12 Volt water pump causing errors with Espar temperature sensors

[2 bikes 2 brown dogs]

I recently installed an Espar hydronic system with a Rixen control board and interface. I noticed that the room temperature readung would occasionally flash ERR. Eventually I figured out that the error would only happen when our water pump was running. The water pump is a 7.5 amp Shurflow 3 GPM.

My thought is the pump is creating voltage spikes that are significant enough to cause hiccups in the temp sensor.

This is a problem because if the hydronic system is trying to bring the room temp up the brief error flash basically makes the system think it has met the heating demand and the furnace immediately starts its shut down process.

I'll get into the specifics of the electrical system next but, at the end of the day, I'm looking for advice on sizing and installing a capacitor on the water pump circuit.

I ordered a 63 Volt 22,000 micro Farad aluminum electrolytic capacitor and attached a wiring diagram that shows my plan.

Right now the questions I know to ask are:

1. It seems like the capacitor's voltage rating is more of a maximum than a target with some tolerance. Is that accurate? I don't need a full understanding of the hows and whys but if there is an upper bound voltage that would be a safe limit, or less stupid, ide love to hear that.
2. Is the farad rating sufficient? If not at what point is oversized a problem.
3. I should have lead with this but is there a cleaner or better solution? What I've tried so far will be discussed later.

I'm very comfortable with the sizing and installation that went into the overall electric system. The big wires However, when it comes to the design of this "small" circuit saying "I'm in over my head" is an understatement.


Now I'll dive into the background details.

 

[2 bikes 2 brown dogs]

Our current system is 12v 1200Ah (lithium).
From the battery bank the most positive wire goes to a disconnect then to a "master" bus bar.
The most negative wire goes to a Victron shunt then to the "master negative" bus bar.
Wires are 4/0 and about 3' long each.
I'm using a Paneltronics DC distribution panel. It has 2 bus bars, 6 breakers per bar. 12 circuits total. That distributuon panel is connected to the master bus bars with a ~5' run of 4ga.
The water pump is connected to that panel with an 8' run of 14ga. The espar system is connected with a 20' run of 10ga.

I replaced the existing pump with a new, smaller pump (Shurflow 2.3 GPM about ~5 amp). No improvement.

ORIGINALLY.....the pump and the Espar were on the same bus bar in the panel.
I moved the pump to the other bus bar and the error may have been a tiny bit less likely. Maybe.... (subjective observation).

I have a seperate slave fuse box for my exterior lights. That box is connected to the main bus bars with a 2'run of 4ga.
When I disconnected the pump from the distribution panel and wired it to the slave fuse box the error problem was almost eliminated.
This relocation to a second branch circuit, a'duct tape' repair, is what led me down the capacitor road. Filtering by design instead of by accident.
A good solution would allow me to flip a breaker in my existing panel box to turn off the pump and the heater.
That's the back ground.
Any feedback would be appreciated.

 

[Alloy]

Here's another more expensive option but it has more benefits.

HOME / IRVWPC

IRVWPC is the solution to loud and inefficient water pumps inside RV's, Boats and more! It intelligently regulates the water pressure, to give you a steady and consistent flow.

www.irvwpc.com

 

[2 bikes 2 brown dogs]

Thanks Alloy! That seems like a slam dunk.
The way I see this going down is that I will try my home made capacitor solution. Curiosity will kill the cat and Ill fry the pump, just the pump hopefully.
It'll be OK though because I already bought a spare pump so I'll buy the product you suggested and install the replacement pump for the win.

 

[Verkstad]

2. Is the farad rating sufficient? If not at what point is oversized a problem.

That farad rating is a good start. If you dont think its enough you can always parallel add another.
Aside from overvoltage or excessive bogging down, its pretty hard to damage a brushed DC motor.