Underfloor heating weather compensator help

Yes. Electronic controller. One 3-port control valve, infinitely variable flow temperature.

Weather compensations controls the heating flow temperature according to the outside air temperature. One of the pit-falls for the unwary is that simple weather compensation, whilst an advantage when the heating & building is up to temperature, can't respond to the indoor temperatures. On start-up the building is cold, but the heating is still run at a reduced temperature because the heating doesn't recognize this.

Most have room temperature influence.

Why 3 of everything? 3 zones?

Have one flow pipe from the boiler or thermal store. Have the compensator control this to give the right temp. Off the flow have a manifold., From this to the UFH zones. On the return the same, a manifold and the returns from the UFH zones

Each zone may have solenoid valves to switch off or on to local room temp, floor temp or whatever. The pump should be smart pump like a Wilo Smart or Grundfos Alpha, so when the zones are off the pump stops (well slows up). If the boiler requires flow then a by-pass valve needs to be fitted and no smart pump. Have pipe stat on the flow set to 60C so that over hot water is not sent into the zones.

Yes, Drivel, some do. But what the OP wrote was this;

Which clearly would have no inside sensor. Got it? Fool.

Danfoss Randall do a weather compensator for £160. I saw a few for sale on Ebay for £40 - now sold.

Crudest and cheapest is three outside stats and three pipe stats on the flow. Cascade three outside stats.

Outside temperature less than - 5C: ouside stat No 1 swiches in pipe stat set to 50C. Pipe stat switches boiler Temp rises above -5C outside stat No. 1 breaks on temp rise, switches over line to outside stat No. 2 set to 0C, pipes stat set to 50C de-energised. Outside stat No 2 energises pipe stat set to 45C Pipe stat switches boiler Temp rises above -0C outside stat No. 2 breaks on temp rise, switches over line to outside stat No. 3 set to 5C, pipes stat set to 45C de-energised. Outside stat No 2 energises pipe stat set to 40C

Have a high limit stat to cut out the boiler if it gets above flow temp of

Temp ranges: below -5C 50C flow between -5C and 0C 45C flow between 0C and 5C 40C flow

This is good.

This is not good.

Most of the electronics is simple. I have not head of electrically adjusted temp regulators.

I just run mine flat out, and use a thermostat to cut the thing off when the rooms are warm enough. A slightly smarter thermostat would be better as I get about 1 degree overshoot.

The wiring is quite large, but simple. In essence apart from a relay to wire or the boiler so that turning the boiler on for e.g. hot water doesn.t fire the auxiliary UFH circulation pump, it is essentially no worse than a normal CGH circuit with a couole of stat controlled TRV's on sub zones.

I don't see why you would want to modulate UFH water temp.

See my other post on how to so it. Better buying cheap waeether compensator as th cost may be about the same.

You run plastic UFH pipes at 80C? My God!!!

You don't know much about these things do you?