HughF

Got it... yeah that's the exact same terminal strip pinouts as the older invertech units, with the exception that the invertech has an internal pump already wired in. It should 'just work'...

Looks like the primary pump is inside the unit... What do you need an external pump for, and where did you intend to get the PWM signal from as there's no terminal for this broken out on the main PCB.

Do you have the manual for the ET-10, I can't find it on the CE website...

As I've been digesting the Vaillant schematics for someone else, attached is the one that will give you what you asked for. Arotherm plus RADS + UFH no buffer.pdf

Same here. Weather comp, nest as a glorified on/off switch

Nope, that didn’t fix it…had to swap the valve for something less rubbish….

I still stand by my ‘nah, don’t bother’ statement…

Take the TRV heads off, turn the room stat right up. Leave it for a day.

This is exactly what I'd be doing... I know it's not what you asked for, but it's the right way to run the system for maximum efficiency.

You've got a couple of options: 1. Fit a dumb pumped manifold to the UFH, hydraulically decoupled from the radiator flow and return using close-coupled T's (this is what I use). Then increase the flow temp so the upstairs rads feel warm. 2. Fit a Vaillant mixing station to provide a mixed circuit independent of the radiators. 3. Upsize the rads in the upstairs rooms to suit the fixed flow temp of the UFH. In relation to option 3, do you know if the rads were sized for 35 degree flow?

What brand of heat pump?

It could be that my book of schematics is out of date, but I did find it annoying and slightly weird that the standard single zone, no buffer, single pump schematic was on page 75 of 99... Just looking at the Grant handbook now, nice to see such simple and well explained schematics.

Good luck getting that from any of the big heat pump installers.. Even the Vaillant big-book-of-schematics doesn't show any electronically mixed circuits, and Vaillant are often considered a premium product.

You got a warranty with your CE heatpump?

post pictures of your UFH manifold, please.