Bringing rooms up to temperature

[newhome]

I'm probably overthinking this but I've thought about it so I'll ask . 

 

I tend to have the UFH come on once a day in the evening during the week. Currently I set all rooms that I want to heat to come on at the same time a couple of hours before I arrive home from work regardless of size. The smallest room (utility) gets up to temperature pretty quickly but the largest room (kitchen / family) take 2+ hours so I wondered whether it would be more efficient to set the larger rooms to come on first and the smaller rooms a bit later. Or is that a crap idea and it would make no difference? 

[PeterW]

Errr ... in terms of absolute efficiency and ignoring any loss through walls/windows/doors, it doesn’t matter and the input heat required to raise the temperature by a degree is the same. Some of the “self learning” thermostats calculate the average delta change by time and then are supposed to be able to calculate the optimal start time for the heating to ensure its xC by xx:xx etc. I’ve never seen one do it accurately yet ..!

 

Staggering the times may mean the lounge / dining gets a slightly higher flow temperature but that is pretty unlikely to affect it. 

[newhome]

Cool - thanks! 

[Jeremy Harris]

FWIW, I've changed our heating so that it only comes on during the E7 period, between 11:30 and 06:30 at the moment.  This seems to work fine for us, as it just charges up the concrete slab using off-peak electricity (not a great saving as the ASHP rarely draws more than about 800 W) and the slab seems to still be plenty warm enough to keep the house warm in the evening.

 

The room stat will almost certainly not start to call for heat until the early hours, I suspect, as I've yet to see it calling for heat by the time I've gone to bed, and I would guess that the house doesn't cool down enough for the stat to switch the UFH on until maybe a couple of hours or so before dawn.

[newhome]

I'm on a sllighty different tariff and get 18 hours off peak so I don't need to have it on overnight although that would be a good plan if I was on Economy 7. It's mostly in the evening when I want the heat TBH. I'm either not here during the day or rushing about during the week. I do have slightly different settings at weekends though. 

[Ed Davies]

Somewhat off topic as it's about a much less well insulated and more leaky house but I did some experiments in November and December which seemed to say that running the heating continuously rather than timed for when I'm about did increase the heating bill a bit but nothing like as much as you might expect from the hours involved. Write up

 

https://edavies.me.uk/2019/01/continuous/

 

with additional notes in the preceding and following posts.

 

Extrapolating excessively, I doubt you'd save much fiddling with the heating hours.

[Temp]

We're on oil and have someone home in the daytime. Most of our stats are on 4 time periods. Something like..

 

5am-8am 20C 

8am-4pm 18c (some rooms 16C which is effectively off unless it's very cold weather)

4pm to 10pm 21C (Bedrooms 18-20C depending on occupant)

10pm -5am 16C (effectively off unless it's very cold weather).

 

Bathrooms are on their own stat to warm the floors at certain times of the day depending on season. Some rooms have slightly different timings at weekends - for example kids bedroom.