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| Heating system hysteresis and efficiency |
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| paulca:
--- Quote from: nctnico on January 30, 2021, 01:33:10 pm ---That is where an outside temperature sensor comes in which sets the outgoing water temperature of the boiler. In the end the temperature outside determines how much energy is needed. @Paulca: you are going the wrong way entirely; you are massively overcomplicating things. Just implement the loop system I described earlier (where the boiler shuts off when the return water gets too warm) and use an outside temperature sensor to set the boiler's outgoing water temperature. That is how these kind of heater systems are installed & operate. --- End quote --- Well, I already have the auto shut off when the return water gets too warm. The boiler does that and more automatically. If I ask it to sustain a given loop temp, it will, intelligently, modulating and load sensing. In fact if I purchase and install their (Worchester Bosch) smart "comfort" controls, it will handle the set point temp and monitor the outdoor temp. The problem with this, is it's expensive and exclusive to their boiler, has a cloud service etc. etc. Also it doesn't handle multiple zones with individual set points. I appreciate that one way to run these condensing boilers is to put them on and leave them on at low temp and just let the house build up heat over time. Lower the loop temp in summer, raise it in winter, or use the outdoor temp sensor for load prediction instead. That's fine. But it's not what I currently need or want. It would cost me much more money to do this. I live alone in a 3 bedroom house. It pains me to watch the bedroom get heated all day when nobody is using it. So I close rooms off and drop their temps on schedules. It also responds to certain events which denote the room is now in use which will expect that room to warm up until I leave. The heating equation is heat in versus heat out which is very dependant on the temperature delta. It costs a lot less to heat a room to 14*C with a 10*C delta to outdoor, than to heat the same room to 20*C with a 16*C delta. So the approach of keeping the house warm constantly with mild heat, versus heating it up from cold all the time with high heat really depends on how often you use each zone. I'm only really in one zone at a time. So it is more efficient for me to lower the deltas. In fact I may automate that, as I've found out, my bedroom radiator breaks even with heat lose around 14*C delta. In that the radiator is on constantly and only producing the amount of heat I'm losing due to poor insulation. But we aren't far off agreement, it just is a little more complex to manage. Yes, I have an outdoor sensor and as mentioned above, I can calculate the realistically efficient target temps for "vacant" or even sacrifice a degree off the comfort temps if it's particularly cold. Loop temp control is something I want to explore, which I would have driven off the current->target delta and outdoor->target deltas. It's risking a 3rd party interface to the boilers EMS bus that's daunting. |
| Zucca:
Read about passive homes and how the human body feels cold or hot. Basically air temperature is only an indirect parameter for your body temperature perception. Buy a thermal camera (even a cheap one) and check your home for thermal bridges. Then check humidity... |
| paulca:
Here is an imaging showing the last 6 hours. In my view it shows the system working as intended. Unused rooms are left to be cool, used rooms are kept warm. The office is easy to heat, as I'm usually in it and the PC provides a constant 100-300W of heat in addition to 100W of body heat. It's also the best insulated from the outside. Active overrides are in place trying to lower the demand coming from idle rooms even more. |
| james_s:
--- 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. --- End quote --- I assume you must have a gas flow meter somewhere, otherwise the utility would not be able to bill you accurately. Is that not located somewhere you can access? It's pretty easy to turn off any other gas appliances and then read the consumption over a specific interval on the meter. My gas meter is electronically monitored so I can log into my utility site and see a graph of daily consumption in almost real time. |
| paulca:
The issue is the frequency of the demands. or... as you might notice I have insulation issues with the bedroom in particular. This will be addressed in the Spring with the demand for insulation and heating engineers falls. EDIT: To avoid confusion the timescale on this graph is 24 hours, the last one is only 6 hours. |
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