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.

So I may as well set it to 20c, no? then use the heat curve as needed.

Right now the house overall is all at a good temp, so I've set:--

• heating mode: manual
• Target temperature = 21c
• Room temp mod: inactive (pure weather compensation)
• Slope 0.5
• Max Flow Temperature 50c (i actually want to set this lower to safeguard UFH as i have no mixer valves, I think 45c if not lower)
• Min flow Temperature 22C

DONE.  Was nice to see the heat pump immediately ramped down from 81.8% to something like 30 something% but obviously i'll need to watch is it keeps up with the loss, i will leave well alone now for 24 hours and see how it goes.

One last bit, as you know the weird setup I had with the virtual zoning and 2 mods to shutoff the UFH, what I've done is made the settings identical on both circuits to avoid any strange behaviour.

Posted by: @jeegnesh

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So I may as well set it to 20c, no? then use the heat curve as needed.

Yup that will do!

Posted by: @jeegnesh

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Max Flow Temperature 50c (i actually want to set this lower to safeguard UFH as i have no mixer valves, I think 45c if not lower)

I cant see a problem with that in principle but this is something worth checking in the app.  According to the app (I havent verified it) the min flow temp parameter does seem to bend the curve a bit not just act as a limit, its possible the max flow temp does similar. 

Posted by: @jeegnesh

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One last bit, as you know the weird setup I had with the virtual zoning and 2 mods to shutoff the UFH, what I've done is made the settings identical on both circuits to avoid any strange behaviour.

Cant comment on that as I dont understand the setup.  However it sounds like you know what you are doing!

Good luck; only time (and another bout of cold weather) will tell

I know I should wait at least wait 24 hours and then some, but early report is very positive even running super low flow temps, in fact the temp kept rising through the evening so I moved it down to 0.45 so settings are now:

• heating mode: manual
• Target temperature = 21c
• Room temp mod: inactive (pure weather compensation)
• Slope 0.45
• Max Flow Temperature 45c 
• Min flow Temperature 22C

So 19 hours later my efficiency for today is at 3.94 and pics below of the rest and most importantly house is feeling good for now.

at 11:00: target 33c, current 32.9c, 1.6kW, 4.3c

Now to see how we go when the temp drops, from 00:00 to 11:00 total power consumption for heating is 20.6kw so prob looking at 40kw and we are not in the cold cold yet.

Posted by: @jeegnesh

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So 19 hours later my efficiency for today is at 3.94 and pics below of the rest and most importantly house is feeling good for now.

Thats very comparable to my experience.  Do be patient as you get closer, it takes time to get the heat curve right and zones/radiators perfectly balanced, not least because houses take a day to react and perhaps several days fully to reach equilibrium.  Its worth the effort!

I’m gonna try for sure. 

so what should I be looking out for now?

Posted by: @jeegnesh

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so what should I be looking out for now?

Mostly house comfort! 

The overall temperature will for sure continue to fluctuate still a bit, due to things like wind and solar gain.  You need to try to ignore these for now and get the 'big picture' right. 

• If the house overall is too warm, reduce the heating curve, if its too cool overall, increase it.  Note it may take a couple of days or more to stabilise so, now you are in the right ballpark, don't change anything by much or too often and try to do some mental integration of what happened over the past day or two.  Also note that the key test is when its <0 outside so you may find yourself tweaking again then.
• If some rooms are too hot and some too cool then tweak the balancing, but again dont overdo it.

In terms of the fluctuations due to solar and wind, think about what you feel comfortable with.  I can personally tolerate excursions upward more than excursions downward, so my set temperature is perhaps half a degree higher than the 'ideal' so there is some wiggle room.  Solar gain in my house only becomes excessive at the extreme ends of the season  (more sun and less natural heat loss); for these only I operate in 'expanded' mode, the rest of the time in pure WC.  I also moderate solar gain by the use of curtains.  This is of course house dependent. Also note that when its more humid the house will feel cooler even though it isn't.  If you suffer from large humidity variations then the occasional use of a dehumidifier may help, or just bumping the set temp up half a degree.

Finally don't obsess about it (I know that's difficult).  If you (or anyone else in the house) are comfortable, thats the purpose achieved.  If the annual cost is acceptable, then the key constraint is also achieved.  Obviously some days are going to cost a lot as we get into the colder months, but that will even out in the warmer months.

Good little test tonight and tomorrow morning weather says it will hit 0/-1

UPDATE: Very happy wife, since 24*7 I've actually had to move the heat curve down to 0.4 as you can see from the charts the temps are staying pretty stable, even overnight drop to 0/-1 no issues at all, will keep running but honestly I think I may still be able to drop (surprising)

With the changing temperatures, I've run into a new problem that I thought I would never have, so yesterday while temps were super low, my wife for the first time in her life said its actually too warm in the house, she reached her dream temperatures but then realised its too much and too stuffy.  I started running at 0.3 curve and temps are all fine.  But the new issue is overnight and today the outside temp went up its been 10c since the morning.

The heat pump is now cycling because the demand is so low it is overshooting and then switching off, personally I have no issues with this assuming its not bad for the heat pump and i know once the temp drops it would return to its long running which will be in a few days i guess.  Is it ok to leave it running this way? When outside temp is 8 and above I need very little heat to replace the loss. I'm not sure how to leave it running when outside temp rises, and would be nice not to constantly have to change.