Thanks, it does the job.
Costs;
To be honest I'm not sure.
It's all eBay / Amazon sourced.
If I did it again I'd either change the 7" touchscreen to 10" or get rid.
At 7" the touchscreen is a bit hit 'n miss with my fat fingers.
Everything is accessible via web so I tend to use my phone.
Case was sub £20
SSRs around £5 each from Amazon (Chinese knock offs, so I've well oversized them)
Pi was sitting around but say £40
Cable was sitting around - you get the idea.
Switches & PSU were from AliExpress say £40
Still not cheap when you add it up.
Lots of planning, case cutting and wiring eats into your time.
Something you will also need to consider is your incoming feed.
I went 3.5Kw for my heaters, so a 7Kw heat load plus pumps, controller et al.
You will need to either size accordingly or have a set up to ensure both heaters are not on at the same time.
I _think_ the All in One systems are designed to run from a standard plug socket.
A different dimension to think about
Have fun pondering :hat: