Temperature management between a pellet boiler and a buffer tank.

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oldjo26
I discovered econologic
I discovered econologic
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Registration: 18/07/19, 10:39

Temperature management between a pellet boiler and a buffer tank.




by oldjo26 » 18/07/19, 10:58

Hello everyone.

I wish my pellet boiler did not fire so often today. In fact, the differential is 3 ° (example: the boiler set at 70 ° therefore stops at 70 ° and restarts at 67 °).
I specify that the differential is not adjustable in the parameters from the protected menu of the electronic board of the boiler.
So these settings are not suitable for managing a buffer tank.
I searched in vain for a thermostat with a large differential (style 40 ° or more) that could do the trick but impossible to find.

I discovered and looking for an arduino editing could be done with all my requirements but given the complexity in my eyes of this company, I do not feel able to achieve such a montage.

That's why I'm calling on an Arduino specialist who would be interested in helping me by coding this project.
Of course we will find together some arrangement.

I will describe below my best wishes for this project.

I want to keep the T ° probe (named for probe suite N ° 1) which manages the shutdown of the boiler at the T ° programmed on the boiler management board.

My idea is to install a DS18B20 probe (named probe N ° 2) in the same place where the 1 probe is located which will cut the power supply of the general circuit of the boiler when the T ° will be identical to probe N ° 1 .

It will be necessary to provide an adjustable time delay (from 1 to 10 mn) for this break so as to allow time for the boiler to finish its heat and ash evacuation cycle.

A DS18B20 N ° 3 probe will be installed on the buffer tank in order to manage the restarting of the boiler by closing the general supply circuit of the boiler when the T ° of the balloon reaches a low value (ex: 35 °) .

An LCD screen will be necessary to view all the values ​​of the probes, the tempo and through this screen via buttons to be able to change these parameters without having to intervene in the coding of the program arduino it would be the top but I do not do not know if it's possible.


Thank you to all readers.
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Did67
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Re: Temperature management between a pellet boiler and a buffer tank.




by Did67 » 18/07/19, 14:56

Warning. You seem to skipper a problem: condensations in the boiler.

In fact, the control of pellet boilers (their electronic board) ensures that the temperature of the boilers (exchangers, internal water reserve) does not drop below approximately 60 °. Below, the "fumes" would condense in the exchangers, with the formation of bistre and risk of corrosion, in the long run. It can puncture the boiler body!

So the part reserved for the technicians foresees a setting of the temperature of stop, towards the 70 ° (that one can push with 75 °, but not too push otherwise the yield drops!), And the restart towards 65 ° (knowing in the phase of demand, the time that the pellets are reignited, etc ... the internal temperature of the boiler generally drops again because the samples continue) ... But one can also, millimetrically, according to the reaction of the installation (which depends on the quantity of water, the speed of circulators, etc ...) adjust this minimum. We should not flirt too much with the 55 ° exchangers, before it goes back.

So your boiler does the yoyo maybe normal or not ...

In any case, removing the yoyos without further precautions can be risky.

What is needed, in principle:

a) let your yoyote boiler between its two extremes, compromised to have a good performance (temp not too high), particles that remain dry, do not accumulate and escape through the cleaning system exchangers, and absence of corrosive condensations (so temp never too low) ...

For this, the pellet boilers modulate (they adapt their power to the demand) and yoyotent when the demand is too reliable and that they can not fall so much (one would then have pellets which are consumed, without really heating, and polluting Verry much).

b) within these two limits, it is necessary to manage the transfer to the buffer when there is, by management of the pump; some models of boilers have dedicated ports (often identified in UW - Germanic initials of the transfer pumps), with adequate settings (heterosis, delays, etc.) ...

c) in the absence of a system provided by the electronic board of the boiler (which would be surprising, or very low range model?), it is sufficient to slave this transfer pump with a high and low probe in the buffer; when at the top you go below the minimum temperature necessary for heating (for example 50 °), the transfer pump switches on; due to cold returns and hot water withdrawals in the boiler, the internal temperature of the boiler decreases; the automatism of this one makes it start; if you go under 60 °, the internal boiler probe should shut off the pump to protect the boiler; otherwise, the heat is transferred to the buffer, until at the bottom of the buffer, low probe of the buffer, you approach the maximum of the boiler (70 °); a little before, it is necessary to cut the boiler and to leave a little the pump of transfer to recover the last calories ...

Normally, if your buffer is well calculated, you are quiet for a few hours, boiler stopped (but hot, not to condense).

When the buffer is empty, the cold front in the buffer arrives at the level of the high probe, which detects the drop in temperature and restarts the boiler ...

Normally, the good electronic boards manage this, by means of an adequate parameterization. It is necessary indicate to the boiler that there is a buffer, and set everything accordingly.
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