dpmiller

while there are stats that can be switched between heat and cool (chinesium wifi ones, for example) and some manual stats with changeover contacts, you might not actually need anything? The ASHP is just looking for the dry contact closure to turn on, so setting the heating stat to max (a programmable one, so you can choose a time period for the cooling) will bring it on and the buffer will already be at setpoint once the mode is changed on the controller. Alternatively give Chris a shout, there are a couple of undocumented inputs on the unit that might help. I've been meaning to ask myself, but it hasn't been pressing. The normal on-off control is on the "AC linkage switch" ID3, but there are also inputs ID2 "linkage" ID4 "cooling linkage" and ID6 "heating linkage"; maybe he can clarify whether these can be used as demand inputs or whether they hard code the unit to a single function on demand?

have you looked at the valve yourself?

No discrete buffer tank here, but all heating flow passes through the 35kW coil in the bottom of the thermal store.

Doesn't the surrounding volume of water act as the additional volume? The ASHP isn't measuring any volumes, it just wants a manageable DeltaT to stop short-cycling...

Monitor the temp of the pipe from the diverter valve to the DHW tank when the buffer is heating. It should drop to ambient. If not, the diverter *isn't*...

another vote for beechwood here, they're just down the road from us.

do it if you really want it. And if that changes in the interim, sell it again...

I hate fancy setups with a vengeance (having been an installer in my teenage years) yet in a previous life was the one called on to debug the MD's £4k car system... I'm pleased therefore to say that just tonight I fitted the rear speaker sockets in our "good room" for the 5.1 system that I'll be happy with til I'm removed feetfirst hopefully...

and that's where I'd start looking. Diverter or mid-positio? Make sure it's going the whole way over and back.

got a schematic for your system? Are DHW and buffer on zone valves?

yes, should work fine. the OSB should be a bit lighter than PB I'd think?

gotcha. can you remove the NRV and preload the spring with a spacer or give it a stretch out?

where is the NRV?

I've the opposite issue with my system- *too much* flow from the manifold to the ASHP. Thankfully the pump set has a bypass and a restrictor, so you can throttle back the return flow even if the thermo valve is wide open; I'm playing with that currently to control the DeltaT at the ASHP.

I wonder if adding a restrictor (disc with hole in) at the joint between return rail and the bottom pump manifold might upset the flows enough to force more return out and back to the buffer?

@vfrdave I picked up an AGS Gardencare hydrostatic machine for good money and - you know how rough our site is yet- it cuts perfectly well at the fully-raised "travelling height" setting. /for info the AGS machines are the same as Starjet and made by Seco in the Czech republic. The same factory produces for a number of the bigger names too...

SBR in this case isn't a brand, it stands for "Small Batch Reactor".

All of the above, yes, kinda. Variable limits actually... I think Carel and whoever wrote the GUI show a bit more of the inner workings of these than some of the more mainstream consumer brands tbh and I'm pretty nosey The control system is modular with an internal ModBus between portions- Inverter, fan drive, analogue ins, EV stepper motors. The inverter and mainboard both have stored profiles for the compressor tying expected pressures vs power inputs etc, as an envelope that rest of the sensors and controls work within.

don't you need to consider the Delta as well tho, both across the source (the ASHP's internal heat exchanger) and the "radiator", whether it be UFH or wall panel? The controller we're looking at here is smart enough to consider the compressor and gas combo's efficiency islands and will throttle back based on energy transfer- it'll slow the compressor down, speed the water pump up, adjust the superheat levels and fan speed to keep the gas pressures sensible.

we used Corvum pre-split for our windows. Easy to use and sticks like sh*t to a blanket.

...photo please. The boiler's own stat is normally a dual-stat and there should be a knob beside the black cap. what is it set to?

Show us a picture of the boiler.

because it's set too high (is max 85?) and overshoot is hitting the limit stat (92 IIRC)

turn the temp down, how hot do you need your hot water to be???

if you had the super secret magic password, you could change the slope for DHW to disable WC for it... :cough: Prg- 9999- Fan configuration- last page (F18 I think) ?