Okofen Pellteronic: T limits comfort and reduces

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Okofen Pellteronic: T limits comfort and reduces




by Alex6 » 08/10/12, 10:26

Hello everybody

I just started my brand new Okofen boiler. Thanks to this forum, I understood the essential settings (law of water, fixed point, etc ...) but I have a doubt on the temperature values ​​T lim. comfort / reduced.

In the Pelletronic manual, it is written: "if the average outside temperature exceeds this value, the heating circuit is deactivated".

Let us imagine that we are in the "reduced" case, during the night for example. I want a temperature of 18 ° C at home. If I put a temperature T lim. reduced below 18, for example 10 ° C, the boiler will not activate if the average outside temperature is above 10 ° C. But if it is 11 ° C all night long, my house can drop below 18 ° C, depending on its thermal inertia.
However, here and there on the Web I have seen very low T lim values.

What is the logic for adjusting these values? Why is the system simply not based on its heating curve?

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by Did67 » 08/10/12, 14:07

The "heating limits" are used to completely "turn off" the heating; the boiler is no longer in "stand by" but in shutdown. Circulators too. It kind of replaces the manual action of turning off the chuaffage when it's too hot!

Alros that in night lowering, the ciruclator turns, the temp in the water circuit is simply abiassée. And the boiler is on "stand by": it maintains its minimum temperature of 65 °!

The heating curve is quite another thing: it is a question of indicating to the regulation at what temperature it must send the water so that the losses of the house are balanced by the contributions of the heating. And this does depend on the external temp. It is therefore a fairly simple mathematical formula, but it is not an "all or nothing" !!

The heating limit in the lowered mode (in light: the temperature at which the heating switches off at night) depends essentially on 3 things:

- insulation: a well-insulated house cools less and can withstand the nighttime decline of external temps to lower temperatures ...

- the inertia of the house: the more a house has thermal inertia (stone walls or bricks, concrete, stones, hard floors) inside the insulation) and the more it will withstand the change in temperature

- occupants' requirements and programming: for some people getting up at 19 ° is not a drama, for others if ... We can therefore, if this is a problem, either play on the heating limit, or also on restart; we can for example let the temperature "run" low enough, but start again one or two hours in advance or on the contrary, set a higher limit (so the heating will remain on, in lowered mode, for a higher external temperature) and restart later ...
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by Alex6 » 08/10/12, 15:22

We agree: To set the value of T lim. reduced, it is necessary to take into account the inertia and insulation of the house, ie the reaction of the house to the dynamics of the outside temperature.

The heating curve used to simulate this reaction, I thought that the boiler could cut itself off when the requested temperature (inside) is exceeded "largely" (according to this curve).

So with a high T lim (say 20 ° C) during a day at 19 ° C, the boiler would maintain its minimum temperature all the time, even if the temperature in the house is higher than the required temperature (with the contributions of the solar radiation for example)?
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by Did67 » 08/10/12, 16:05

I do not have any more in mind, but it seems to me, from memory, that in addition to the heating limit, there is put in stop (or in stand by ???) if the return is higher than the temp calculated starting point ... or something.

So in addition to the limit, there is normally a second conditionality ...

Another thing is the contribution of the sun: there, a room sensor (internal) is needed; this "corrects" the calculation of the starting temp, but never cuts off the heating (to avoid "all or nothing" "yoyo" operation, which would destroy the whole point of climate regulation!). Above all, do not assimilate a room sensor to an old-fashioned "thermostat", which controls the boiler - or electric radiators - by "on / off" ....
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by Alex6 » 08/10/12, 19:24

If the boiler can come to a standstill - and not standby - at the return temperature, then it seems to me that these comfort / reduced values ​​can be dispensed with.

If not, I conclude that the boiler continues to consume pellets to maintain the minimum temperature as long as the external temperature is below comfort / reduced.
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by Did67 » 09/10/12, 11:03

If the curve is well adjusted, it only consumes if it is needed!

Understand climate regulation: we maintain a "stock" of calories; the house is like a pierced bottle; The level must be maintained.

Two ways:

a) when it drops, I pump: "all or nothing" regulation by "thermostat", which notes the drops or the increases, and which "cuts" and "turns on" ...

It's like driving someone who is in a cork, who accelerates to stick to the previous car when it starts and brakes brutally as soon as it brakes in front:

b) I calculate the leaks and I put the same thing back: heating curve which calculates the average quantities lost and which replaces them, with a sliding calorie flow (thanks to the variable starting time) ... This is the coduite the "issée" of someone who sees that it starts but that there is still a traffic jam in front ... and which smooths its acceleration. A climatic regulation "knows" that the need will increase as soon as the external temperature drops while inside it has not happened yet!

So we have to get rid of the link: "my boiler is running, but it's hot enough, so it runs for nothing, so it wastes" ... This is only true if the curve is badly adjusted or the program badly configured ...
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by manet42 » 09/10/12, 11:29

Welcome to the club at Alex6 :P

I have a room sensor, it corrects the start T ° but also, cuts the heating circulator and closes the motorized valve if T ° ambient exceeds the set T ° + hysteresis (at home 0,5 °).
Setpoint 19 °, sun! the atmosphere goes to 19 ° 5, the heating stops.

After testing, I found that 11 / 12 ° for the reduced limit was fine for my insulation (average) and the inertia (high) of the house.

JC
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by Alex6 » 09/10/12, 12:01

Did67, I really expect that this type of boiler works in anticipation. And it seems to me that the brain of this system, here Pelletronic, could programmatically dispense T lim values.

Thank you Manet42 for your info on your value of T lim. Is there in forums a place which gives the values ​​of the users according to their type of house and their locality?
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by manet42 » 09/10/12, 14:15

Not in a systematic way ...
Data on
https://www.econologie.com/forums/suivi-du-t ... -1470.html
Must read everything!
I think that set off a new post where the owners would put their settings would be interesting.
I begin.
Kind regards.

JC
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by Alex6 » 09/10/12, 20:30

OK, thanks for the link.

I will put my parameters when I have a little more experience feedback. For the moment I am based on what I found on this forum before facing the winter for real.
By the way, thinking about it, most of my info comes from posts of ... Manet42 and Did67 ;-)
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