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Heating system hysteresis and efficiency
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Siwastaja:
Small temperature differences between rooms may be an OK micro-optimization, but keeping some rooms cold requires adding thermal insulation between the rooms to actually save anything.

Instead, use the same money and effort to put that insulation on the outer envelope of the house -> now you can just keep all the rooms warm with basically the same cost and stop thinking about it.

Really, insulating pays off pretty quickly. You may want to get a thermal camera to look at the discontinuities, to find where the problem is. Most insulation materials also require measures to stop air flowing through them so basically you need to make those vapor proof plastic film / paper / Housewrap / whatever seams completely tight, even small gaps let the wind in your insulation compromising its thermal conductivity value. The material stopping the air flow should be water vapor proof on the inside (typically plastic), but even more importantly, the outside material must let the water vapor through.
tom66:

--- Quote from: paulca on January 30, 2021, 11:04:39 am ---I wish I had a gas flow meter to really see how much I'm saving or wasting, as I tune things.  Maybe should consider asking how much having one installed is.  Although I'm not sure I trust the "Smart" offerings from china as a gas flow valve, so a better solution would be a proper rated flow meter and make it smart myself somehow.

I'd like to have dynamic flow/loop temp control, the boiler does support it, but its a bit of a "not quite standard" EMS protocol.  An adapter product exists, but it's very DIY and carries warnings about breaking your boiler.

Until I finally go that way, I'm going to make my zone targets slightly more complex to add temperature hysteresis and also implement heating as many zones as needed while the heating has been triggered.

--- End quote ---

I have a gas smart meter and get half-hourly consumption figures.  No price variability on gas so no benefit to shifting usage like electricity but could help you gather an idea. Most suppliers will put them in for free.

I think I do need to optimise this home, in winter we are using cca. 50kWh per day of gas.  3 bedroom detached new build.
nctnico:

--- Quote from: Siwastaja on February 02, 2021, 09:24:17 am ---Small temperature differences between rooms may be an OK micro-optimization, but keeping some rooms cold requires adding thermal insulation between the rooms to actually save anything.

Instead, use the same money and effort to put that insulation on the outer envelope of the house -> now you can just keep all the rooms warm with basically the same cost and stop thinking about it.

Really, insulating pays off pretty quickly. You may want to get a thermal camera to look at the discontinuities, to find where the problem is. Most insulation materials also require measures to stop air flowing through them so basically you need to make those vapor proof plastic film / paper / Housewrap / whatever seams completely tight, even small gaps let the wind in your insulation compromising its thermal conductivity value. The material stopping the air flow should be water vapor proof on the inside (typically plastic), but even more importantly, the outside material must let the water vapor through.

--- End quote ---
OK in theory. The downside of such measures is that you'll also need a ventilation system otherwise you get a large amount of moisture inside the house. This can get really expensive quickly because of the remodelling needed to install the pipes. In the end you can only add a limited amount of extra insulation to an old house (from a financial perspective).
paulca:
I seems to be a balancing point thing.

By example.  If I keep my bedroom at 16C all day it uses about 10-15 minutes of heating an hour when it's 3C outside.

Before lockdown and WFH became the norm, I would have been out all day for 9-10 hours and let it cool to 14C, which only pinged the heating every few hours.

However, 14C is too low a temp to ramp up from quickly to 17/18C when the room becomes in-use.  The heating responds within a minute, gets to temp within 5 and warms the room pretty quickly, but... the furniture is still 14C, which makes the room feel colder.

This switch between 14C and 16C is triggered by me being home.  As I'm pretty much always home now, modifying the vacant target from 16C down to 14C isn't the best option.  I think I have to accept it and adjust this schedule based on time instead of "presence".  Let the bedroom be 14C during the part of the day I am least likely to use it and warm it to 16C during the time I'm likely to use it.  Like evenings and mornings.

Last year I only had a 3 programme day timer. At this time of year I typically had 2 hours morning, 3 hours evening, 1 hour bedtime, usually 2 or 3 additional 1 hour boosts at the weekend or advancing schedules.  Probably 6-8 hours a day with all radiators on (with TRVs).

While I have seen run times as high as 11 hours with the new system, that was what started to prompt this tuning process.  That said, 11 hours run time with 2-3 radiators closed most of it.

I have brought that down to 8 hours with a few tweaks but I think I can get it lower and still retain comfort.

Insulating the bedroom will make a huge difference too.  The installation job on the upper roof insulation failed to realise, as my house is a chalet-bungalow, I have a lower roof space too which surrounds the bedroom floor and living room/hallway ceiling.  Venting the upper roof has also vented the lower part, which has no insulation.  Making those walls freezing cold.  I will have to get them to cut into that inaccessible roof space to insulate it.  Probably costing me a grand or more :(
GlennSprigg:
I haven't really worked with 'domestic' systems, but used to be responsible for certain large industrial and
commercial multi-story control systems.  Although (as some people mentioned) P.I.D. (Proportional, Integral
& Derivative) controllers can 'smooth' things out and make cooling/heating valves more efficient, 'Hysteresis'
is most important in that regard when it comes to energy saving!  (More on that shortly)...

However, the main problem is Common Heating/Cooling calls!!  We can't have a situation where just one
sensor/setpoint in just one zone/room/floor, (which may have say a warm computer too close to it!), for being
responsible for starting say a whole buildings Chiller-Plant or Boiler. That requires a pre-programmed number
of sensors, and pre-programmed time delays at times. Otherwise, arses are kicked!!  :)

Regarding Hysteresis, that is a two-pronged attack!!  One is the cycling on/off Range, either heating or cooling,
but the other is 'Time Of Year Perception' !!  I don't know what other colder countries do, but here in Australia,
'experts' have determined that in our Winter, let's say it's say a 'freezing' (haha..) 14-deg-C outside, then the
general public/workers actually feel comfortable with a cycled range inside, of say 18-21 deg-C. And when it is
say 34-deg-C outside, people are comfortable/happy when the cycled range inside is say 25-28 deg-C inside!!  ;)
The happy 'Norm' here, is calculated to be 23-deg-C, but maintaining that will cost the owner Heaps! 

I'lll throw in one other factor, which is where a 'Company' is the sole multi-story owner/occupier, and where the
building is almost totally sub-letted to numerous other paying tenants!!! If it is a case of the 'latter' here, then the
owners have the control of all the metering, and re-sell the power to all the tenants, making a huge profit there!!  8)
You try to talk about energy management to them, and they just laugh!! (True!).
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