Posted by: @jeegnesh

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Whoops I meant suspended floor, which has celetox it was either 100 or 150mm between beams, and then floorboard, then 20mm wunda insulation boards which has the the pipes embeded into them, then ditra mat and finally 8-9mm tile.  The heat comes thru this brillantly and lasts.

Sounds good, I just wanted to check it was reasonably well insulated, there are some doubtful statements out there about UFH being sensible on uninsulated slabs

Posted by: @jeegnesh

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OK let me have another go at this continous running, i'm just scared that its going to 65-80kw of daily usage as in the cold it always running at close to full pelt.  So I can bring the curve down can you tell me what else I need to do please regards timer programme, and modes.

Unless your house cools a lot during the setback, its still losing heat at almost the same rate - houses dont stop losing heat because you turn the heating off!  All all that heat has to be replaced when you turn it back on, which makes your heat pump work harder = less efficiently. 

If you live in a house with the thermal characteristics of a tent its a different calculation.  If you have an oversized heat pump and a time of use tarrif there is an argument for playing games (eg for me it might make sense to turn it up at night, because my nighttime tarrif is one third of my daytime tarrif).  However a good starting point is almost always 24*7 and, if your heat pump isnt getting the house to temp in cold weather this is a no brainer.

So I would start with

• heating mode: manual (=24x7 other then when doing DHW)
• Target temperature = your target temperature (this shifts the WC curve relative to the one for 20C target temperature, idea explained in sensocomfort manual)
• Room temp mod: inactive (pure weather compensation)
• Heat curve 0.6 (0.6 ~ 42 @ -2)
• Max Flow Temperature 55C
• Min flow Temperature 22C

The first 2 parameters are on the user level settings menu, the last 4 parameters are in the installer menu on the sensocomfort

Leave for a day.  Then adjust the slope up or down by 0.05 at a time, adjusting no more than once every 24hrs, until the house is at the right temperature (If initially it overheats a lot then shift the slope by 0.1).  You may find you have to iterate a bit and you may need a bit of loop balancing if rooms dont settle at the right relative temperatures. If you want bedrooms cooler than living rooms then turn down the flow through those loops.

Expect to take a week or two and then have to tweak a bit when it gets very cold and maybe adjust the minimum flow temp when the temp is just below the point you switch your heating off (ie sometime early April most likely)

Any thermostats/trvs etc initially set to max so they have no effect.  Later on, once the curve is established, you may want to do something to deal with high solar gain in the shoulder season, when it can make a significant difference.

You will likely see a surge of consumption for the first couple of days as you heat the fabric up, but then it should slow down.

Feel free to ask any questions.

@jamespa - Target temperature so this isn't actually the temperature I want in the room, but it is just used to set the heat curve slope, is that right?

Posted by: @jeegnesh

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@jamespa - Target temperature so this isn't actually the temperature I want in the room, but it is just used to set the heat curve slope, is that right?

No.  Absolutely do think of it as the temperature you want the room.

In more detail:

The heat curve slope is set by the parameter: 'Heat Curve' in installer menu

The target temperature is used for various things depending on value of Room temp mod:.  If this is set to inactive then the target temperature, if its anything other than 20C, shifts the heat curve sideways.  If Room temp mod. is set to active or expanded, then it still shifts the heat curve but also affects when the heat pump shuts down due to room temp too high (expanded mode) or introduces a bit of auto-adjustment of the heat curve (active mode)

The bottom line is - set it to the temperature you want the room.  If its half a degree out it wont matter, and once you have got the heat curve set up, if you need a temporary adjustment its the easy one to go for.  The way it works - by shifting the WC curve, is actually rather clever because it does the right thing behind the scenes while presenting to the user a familiar interface.  Its the interface for the non techy persons in the house!

Incidentally programming a weekly schedule has the same effect as changing the target temp, so you can thus program setbacks/set forwards which actually have the effect of changing the flow temperature.  This is much better than many manufacturers where the only way to program a setback is to depart from pure WC and use the temperature sensor to control the heat pump through forced on/off cycles.

This is a bit complex to think about - but the intention is the average user doesnt and just regards it it as the target room temperature, once WC has been set up correctly.