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Heating system hysteresis and efficiency
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paulca:
I realised, I have data that could give me stats for how much heat a zone demands per *C delta, per hour or quarter day might be better.

I'm just not sure my database skills are up to it.  It would querying multiple non-synchronised timeseries states and values in a join query.  That sounds rather unpleasant actually.
paulca:

--- Quote from: GlennSprigg on February 02, 2021, 12:48:11 pm ---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)...

--- End quote ---

PID controllers.  They are value homing mathematical based systems aren't they?  Like whatever that thought experiment was, that if you divide the distance you have to travel by 2 each time, you will always be half way to go.

So I imagine PIDs try to turn things up when the delta is high and slowly back off towards zero and the delta "approaches 0"? 

I'm not good with Calculus how did I do?

My idea was similar, but a bit more cavalier and flavoursome.

I would first determine the present demands.  I would look at the target->current temp delta for all of them.  Modify/weight them based on their target to outdoor delta.  Take the highest modified delta from all demanding zones .  Then make a determination from a limited range as to where to set the boiler flow temp.  This would need either manual tuning over time or some form of learning function.

This would certainly solve both sides of the issue, heating up fast, but not cycling too much when sustaining.

Again, it would require purchase of a 3rd part interface board to the boiler to control the flow temp.

On temperature perception.  I totally get it.  Although I would have a higher tolerance of cooler rooms in summer from a heating point of view than in winter. 

Other things to consider are the rooms are not one temperature.  There can be difference of several degrees across a room and possibly a few more degrees on top of that in drafty cold spots or near radiators.  So a sensor side you near the sofa is much better than one near the radiator or the door way draft.  The actual reading on the sensor itself is not so relevant.  I have changed my sensor types and seen a 1.5*C increase in the reported temperature.  So when I set my heating to 21*C in my office, I don't actually expect it to be 21*C anywhere accurately, just that is the temp it feels comfortable set to.  Although for fruggleness I dropped it to 20.5. :)

Oh and on cooling.  I have been keeping it at the back of my mind.  I do own a portable aircon and I could modify it to start up the AC on power on, but, it honesty the number of times a cooling demand would trigger in a year would be limited to a dozen days or so.  Also that portable aircon is inefficient (the hot side is in the room) and noisy. 

Side rant:  The portable AC unit, in order to raise their class efficient rating, they shut off the hot side extractor fan when it's thermostat turns it off.  The immediate effect is for the hot side to heat up the cold side, heat up the room generally and re-triggering the unit.  So the best way to use it, is to not use it's temp sensor and remove it from the room as soon as it's cooler!  Dumb as shit.
Siwastaja:

--- Quote from: nctnico on February 02, 2021, 10:29:11 am ---
--- 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).

--- End quote ---

No, you misunderstood what I was saying, or I miscommunicated.

The key is understanding the separation of ventilation and insulation. Both have a reason, neither can replace the other.

Ventilating through insulation materials is never a good idea. If it is happening, it needs to be fixed for both air quality and energy consumption reasons.

Indoor air going out, and outdoor air getting in obviously results in loss of energy. But because we need to vent out moist, high CO2, dirty air and get fresh air to breathe anyway, this is a loss that has a benefit: breathable air and smaller risk of condensation. So we accept the lost energy and vent.

On the other hand, if outdoor air is blown into the insulation materials such as mineral wool through any holes, this air necessarily doesn't even get inside the rooms, or if it does, it carries fiber dust or possible microbiological contamination inside, creating an air quality problem; at the same time, it prevents the insulation material from working, causing excessive energy consumption.

So both from the perspective of theory and practice; also from the perspective of building code, the key is to stop air from moving inside doors, ceilings, floors, insulation materia, making them airtight (not vapor tight). At the same time, ventilation must be allowed to happen, in a way or another. Ventilation goes through direct holes, or clean ducts, possibly through HVAC technology designed for it, but definitely not through building materials like gaps in the walls, floors, ceilings, through wool...

Adding ventilation systems containing fans and ducts is completely separate issue, and not necessarily needed. Old houses such as one I have work with passive ventilation. It's not perfect but the concept is that air is moved in from windows that can be opened, or basically simple ventilation holes made in the walls. Exhaust is in the firewall in this case. Works well when there is temperature difference, i.e. in winter. Doesn't work that well during summer, but you can still open the windows to do manual ventilation. It's OK.

But preventing heat flow through the envelope pays off even if you ventilate. Only after your insulation is in a good order, only then the ventilation part starts to be a significant part of energy loss in which case you can open the can of HVAC heat recovery worms, if you want to optimize even further.

What comes to moisture, poor and uneven insulation adds a problem that condensation may occur somewhere in the inner envelope. In any case, the inner envelope should be air tight so that moist indoor air can't get into the insulation wools where it might condensate when it hits colder temperature. Building codes, at least here, nowadays require completely vapor tight (i.e. plastic) material inside of the envelope, but traditionally stopping the air with paper works good enough and has some advantages (depending on who you ask); most important is to prevent large amounts of indoor air getting into structures.

Outdoor air flowing into structures just kills the efficiency of the insulation and must be stopped for this reason. It has no upsides. Similarly, having seriously thin layer (or complete lack) of insulation somewhere has no upsides.
Siwastaja:

--- Quote from: paulca on February 02, 2021, 01:42:37 pm ---Side rant:  The portable AC unit, in order to raise their class efficient rating, they shut off the hot side extractor fan when it's thermostat turns it off.  The immediate effect is for the hot side to heat up the cold side, heat up the room generally and re-triggering the unit.  So the best way to use it, is to not use it's temp sensor and remove it from the room as soon as it's cooler!  Dumb as shit.

--- End quote ---

I think the portable AC units work best when you don't have an oversized one. So that you manage without running it at all, until you don't, then you let the poor small unit run 100% continuously. Such small machines dehumidify quite well too (running the evaporator cool enough to condensate - don't turn the fan fully on, if adjustable!); at least here, the summertime problem is not the temperature alone, it's the humidity which makes you feel uncomfortable.

They can be made somewhat better by adding extra cardboard casing and ducting so that the condenser cooling loop running on outside air doesn't mix with the inside air.

For hot climates, you'd obviously have a real AC unit, not one of those portable pieces of shit. For Finland, the portable ones work fine and the cheaper and smaller it is, the better, you use it for a few days or maybe for a few weeks max per year, and I would guess the same mindset works in the GB as well?
nctnico:

--- Quote from: paulca on February 02, 2021, 01:42:37 pm ---Oh and on cooling.  I have been keeping it at the back of my mind.  I do own a portable aircon and I could modify it to start up the AC on power on, but, it honesty the number of times a cooling demand would trigger in a year would be limited to a dozen days or so.  Also that portable aircon is inefficient (the hot side is in the room) and noisy. 

Side rant:  The portable AC unit, in order to raise their class efficient rating, they shut off the hot side extractor fan when it's thermostat turns it off.  The immediate effect is for the hot side to heat up the cold side, heat up the room generally and re-triggering the unit.  So the best way to use it, is to not use it's temp sensor and remove it from the room as soon as it's cooler!  Dumb as shit.

--- End quote ---
I'd dump the portable AC. They make a lot of noise and are really inefficient. I'm planning on installing a new Panasonic split AC unit to upgrade the existing split unit. According to the specs the Panasonic could even be more economic for heating compared to regular heating (in my case district heating).
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