dpmiller

Series works well here; if I was doing it again I'd do the whole circuit in 28mm as the 22mm is just a wee bit noisy and restrictive tho

@HughF Have you worked out what the PWM protocol is for the pump? Is it Grundfoss-specific? I've a series pump, but it's set to a fixed value to let the internal one handle the modulation. Even 8.5kW is very flow-hungry...

what is the deltaT across the tank coil when it first runs correctly, and then as the flow is reduced? Are there any other pumps in the circuit? Is this an inbuilt flow sensor, or an external flowsetter?

Picture is good if you click on it and open it... That's a capacitor.

Yes, the manufacturer is Sprsun

in which case it's under active control. I'll try to get a look at ours early in the morning if it's cold overnight and see if it's on, and if the run current is displayed. Certainly the PVE lubricant required for the panasonc compressor specced is less demanding of heat than earlier POE oils

Yes, if you can get past some dodgy chenglish terminology, it's a very competent controller. You don't find this kinda kit inside every supermarket freezer for no reaason... What amazes me is just how tuned the whole system is to the compressor and gas combo.

Yes then you can choose to control on the unit's internal flow sensor or the buffer "return" one

:unsure: , I'm going to look into it

I could, other than I'm currently controlling on the return temperature to give meaningful heat to a second manifold with oversized rads and towel rails on it. The system is currently running at a DeltaT of 7C and a return of 38C so there's 45C or so available to each manifold, but that drops a fair bit once the manifolds warm plus the flow runs through the TS coil continuously to buffer it. This is our first winter in the house so I'll be trying to bring things down a touch, yes.

So it looks like the Carel inverter is looking after crankcase heating, but I can't see any adjustable setpoints. As well as the enable in User Mask, there is a line in the inverter setup screen for auto/manual, and another showing current. Unsure whether this is a band heater or injecting into the motor coils tho... I'd opine that the 12h is very conservative, bearing in mind that the unit is rated for down to -20C, and also the Sprsun manual makes NO reference to this necessary delay.

I've been doing a bit of monitoring of recent days and find that our system (65mm of hemihydrate, pipes on roughly 200mm centres, 8.5kW ASHP vs worst-case loss of between 2.6 and 4kW) gives a useable floor temp rise in about 90 mins that takes about 4hrs to dissipate eg /testo 184 logger sitting on the screed surface. Ignoring the first drop as I'd been holding it in my hand, the small peak was to satisfy the hall to 19.5C in the evening, the larger one bringing it again to 19C in the morning after a frosty overnight.

Have a look in the IO mask, the new version has all of the above there, whereas previously weather comp was buried in the hidden setup menu and the other items didn't exist at all

where has it been stated that a 12h warmup is needed?

Just in case it's of use to anyone that has had an iVT unit in for a while, there is a software update that makes weather compensation a bit more user friendly (and some other functionality like run timers and legionella mode) for the 2020 machines.

Loop flow is constant in this case. Frankly I haven't seen the system on long enough yet to see a stable Delta-T for the whole manifold. The loops are in a 50mm flowscreed and the system is *very* responsive.

The flow pressure for the loops will not be anywhere near that. I've 600-odd metres over 12 loops and the pump is running at a head of 1.4m and using 12W in the process. I've no actuators installed so this is pretty much constant. Now the ASHP's circulating pumps Main and boost) are probably taking about 60W at the minute, but the main internal one is on PWM control and consumption falls to under 30W when the heat requirement tails off.

is the OP on a public sewer or a treatment plant?

got to be careful with those adaptors tho, they're not good at higher currents and I've seen the odd one that the earth tang doesn't contact the plug "as delivered", needing an bit of a bend to fit safely.

put a lock on the door?

The inverter looks like it tripped off the bus. I've had mine do this if power cycled too rapidly, have you seen any mains dips?

1m2 isn't an enormous coil...

Good Q. But adding zoning might be a complexity too far...

Yep, they're definitely a version of the Sprsun unit

Unpossible.