Solarpump control

A

alfadir

New member
Hi,

I have to change pumps in my solar heating and hence need to change to PWM pumps.
The system today consists of 5 temperature sensors PT1000, and 2 Pumps and 1 Valve.

I am toying with the idea to test to use "Building Automation V4 8-Layer Stackable HAT for Raspberry Pi" for this work.
But I am more confortable on the digital side of things.. :)

The current Pumps (one broken) is rpm controlled, but new pumps would be PWM controlled.

I am checking optional pumps, but the target would be a Wilo Pump, as the system has such pumps now.

The PWM signal Wilo has specified is bidirectional.
Wilo PWM Input Specification on page 9 and the PWM Output Specification on page 12.

1) does the PT1000 work with the 1K thermistor input (or is the RTD Data Acquisition hat needed )?
2) can the 0-10V input / output be used to read/generate PWM as is (switching 0-10V in 100Hz or something that fits Wilo Spec) ?
2b) if yes, is extra hardware needed here (pullup resistors etc) or can the port just be used.

Input 1-5 - PT1000
Input 6-7 - PWM from Pumps
Output 1-2 - PWM to Pumps
AC 1 - Valve
AC 2-3 ev Pump shutdown
AC X controlling a 6A 230V Relais or 16A 230V Relais using the 24VAC 30VA Powersupply or would 10VA do ?

If this does not fit, any other pointers would be helpful.

Fred
 
alexburcea

alexburcea

Moderator
Staff member
Hi,
It is a good idea to use the PWM converters, but you have to match the frequencies.
You can use PT1000 with Building thermistor inputs but you will have low-resolution measurements, hard to tell how low, so we have to calculate, we never thought someone would use PT1000 there. The RTD hat is designed only for PT100 sensors.
Everything else looks ok, you can control relays with the thermistor outputs.
 
A

alfadir

New member
Ok,
I am not only looking into this for a personal project, but for something we are using in custom cooling control system.
There you see in the Specifications that this would fit here as well. It is just I am looking for something open, and programmable. The easy way out for Solar is some simple off the shelf controller.

Ah, good that you mention that the RTD Hat cannot do PT1000 out of the box, I actually found Sequent Microsystem via
this PT100/PT1000 hat from you RTD-Datenerfassungskarte HAT für Raspberry Pi. I'll just get this in EU, and have a start.
Is PT1000 not widespread in US ? I read just briefly about PT1000 readings, and is it not just the reference resistor that is different between PT100 and PT1000 ? (Well probably more stuff).

So I have to solve the Pump issue. Learn more about PWM.
RPi has 2 PWM Ports but if they would work, still it would not solve the feedback from the pump.
First things first, I need to get a clear recommendation for a replacement pump before I start looking how to control it.
If I can get a 0..10V version that would solve the issue.

@AutomataControls : Sorry, but not versed well enough in your jargon to understand what you are trying to say.
 
Top