dpmiller

before you give up, try reversing the tube end-for-end and re-try. Don't ask why...

might be a zone valve closing down and obstructing the flow, prior to the pump turning off. An auto bypass valve would help here?

Those Danfoss coils are quite unreliable. They're quite small for a mains coil... They were hard to get for a while and I found that the coil out of a washing machine inlet valve was a physical fit

I built our hearths straight off the subfloor in thermal block.

And... (now that I think about it) Get the literature for that exact controlbox- they come in many configurations- There might well be a list of faults that take it straight to lockout, and there may be a way of getting blink codes out of it too

^ photocells, control boxes, and oil solenoid valves all have a terrible habit of failing intermittently. A clean photocell is a good start, but I'd expect that to cause a near-immediate lockout. Beyond that... can you view the flame any way when it's running? IE does it go out then trip Does the sound change in the seconds before it trips out? Motor slowing down, squealing or a click Does it go *straight* to lockout or does it retry once first? Have you confirmed the supply voltage isn't dipping because of an external issue? If it doesn't attempt a re-start at all I'm going to suggest controlbox. Pop it open if you're brave and have a look for dodgy capacitors and dry joints, give any accessible relay contacts a wee clean

So the white knob on the mixer is set to 45 yes, but... a. that's the return temperature so hot flow will enter the UFH until the return warms up to 45 b. the knob is adjustable for calibration and may not even be set right. c. are you sure the gauge is accurate? Does it read ambient when the heating has been off for some time? Turn it down to 35- or 30 even- and watch what happens when the system stabilises.

Actuators are normally slow-acting devices. The flow pulsing as it does seems too fast to me. I'd be checking that any non-return valves, pressure regulating valves, mixing valves, and pressure vessels attached to the system are all in good order as it looks more like a hydraulic resonance. Like water hammer...

^ Yep. Even the updated short red flap isn't much better tbh

chop a row of brick out and set a sill in?

why can't the original guy come back?

I've attached a document on phosphorus reduction, and PremierTech are aware of this thread following me logging in to download it. Further infos may then follow. WIJ_removal_of_phosphorus_in_off_mains_wastewater_treatment_UK-EN.pdf

^ that's not the Phosphate version, you're looking for the +P...

I have no idea. You could always try asking them?

the +P version of the Solido Smart that we installed is a single tank solution with a built-in dosing system for Polyaluminium chloride https://www.premiertechaqua.com/en-gb/wastewater-treatment/solido-smart-p-phosphorus-removal#product-description

check specs carefully- some brands need a costed upgrade to carry out Phosphorus reduction I think, and this is a fairly recent thing.

not sure if you're worried about the cost or the consumption, but an E7 tarrif might help /we've just received the last quarter's bill and for our 260m2 non-passiv it's an average of 30kWh/ day total consumption. On a cooler day a full half of that is for heat into the slab during the E7 period.

triggering DHW production 5 or 10 mins before a large demand certainly works- but it takes this long for the ASHP to ramp up in my experience.

isn't that what you're paying the removals firm for?

Inside rubber looks like it comes out first?

how does the pump know to turn on, is there level sensing in the trap or does the pump run pulling air in too?

Do it yersel.

neither cheapo gauges nor thermo actuators are known for beong terribly accurate. You can dial them all in to match a standard device if you've the time and patience...

what "rating" do they need to have?

I've used the same pump that's used on these, in a solar HW system. The pump is actually surprisingly powerful for the current involved.