Diverter and underfloor heating

Just thought I would share my experience of installing UFH in our kitchen.

My diverter is the immerSUN and I have tried various set-ups with it (well them actually as I have two). But as part of our kitchen refit we have gone tiled floor and electric UFH - all 1.8kW of buried heating cable.

I logically thought immerSUN but was dismayed when I read in the UFH installation instructions that the cables cannot be extended. A short exchange with the manufacturer and sharing the immerSUN manual with them confirmed that a) the "cold" part of the cables can be extended above ground (not jointed below the tiles) and b) the system is compatible with the immerSUN - great news.

It has been installed for a while but got turned on at yesterday and works like clockwork. Immersion heater is on output 1 with UFH on 2 and using the "external boost" connection to pass the thermostat state to the immerSUN. System raises the floor temp to 21 degrees which is nice on the feet or 23 degrees which begins to warm the room really quickly.

So, yesterday and today we got hot water by about 11am, following which the UFH cut in and jostled with the dishwasher for power. Then, about 1pm the floor was warm and the second immerSUN cut in to operate the oil-filled rads in the living room alongside the dishwasher.

From time-to-time immerSUN 1 checks back to see if immersion or UFH want power and delivers that as normal. immerSUN 2 can take any excess over that required by immerSUN 1. Unlikely when the immersion is sucking 3kW but frequent with the UFH taking only 1.8kW.

Export is down at about 10%, so happy with that.

It will be interesting to see how warm the floor will get in the dark months. We have water radiators in the kitchen too, so we might find the room is warm enough from those and the bit of PV the floor gets is enough to keep the chill off the tiles - fingers crossed.

Oh, and the extra cost of slotting the immerSUN into the UFH system? About 10m of additional cable to take the thermostat output to the immerSUN and the extension of the heating cables to reach the immerSUN.

Not sure yet how I will set the immerSUN's timer to boost the UFH when there is no sun but it looks quite flexible with 6 or so timers that can work on 1 or up to 7 days just like a GCH timer/thermostat - something to play with once we get used to a nice warm floor...:beer::beer:
Wiltshire - 5.25kWp
3.5kWp: 14 x Phono Solar 250 Onyx, Sunny Boy 4000TL, WSW 40 degrees, June 2013
1.75kWp: 7 x Phono Solar 250 Onyx, Sunny Boy 1600TL, SSE 45 degrees, March 2014
This discussion has been closed.
Latest MSE News and Guides