Wood boiler for greenhouse

[dedeleco]

If the gas boiler is about 40KW comparable, you can take a circulator comparable (or a little stronger) to the one that currently works, which depends a lot on the pressure losses in the current exchangers and therefore on their structure, (diameters and length).

[antoine35]

good here I come back from vacancy and I attack incessantly shortly the building site ....

to clarify the greenhouse is currently slightly heated by a large air heater running on gas so no circulator or even operation via the buried network.

the underfloor heating system was implemented when the greenhouse was designed, but never tested.

for the amount of soil on the floor it is really very thin or even non-existent in places so I don't think the buffer is enough, I have to recover a 1000 liter balloon so given the zero investment of it I think that it should not be private because I am perplexed about the fact that 90 ° water comes back too quickly hot on the return and begins to pose problems of regulation.

if indeed as said manitou it walks on 3 legs this boiler.

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[antoine35]

Happy New Year everyone.........

I come back to you because I went to a plumbing supplier and the products they sell as a safety valve and thermal valve are in 15/21 and or 20/27, so I understand that the safety valve is mounted simply on a reduced pipe of the instalation, but I thought that the thermal valve "it" was mounted on the direct outlet of the boiler (type 40/49).

sorry for this basic question but I am a refrigeration specialist and therefore I am not used to these specific equipment for heating plumbing

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[antoine35]

I forgot, by the way someone with an idea to drive a three-way to stay on an output temperature about regular without the regulation at 400 euros but so that it does not make the yoyo too much anyway?
thank you A +

[dedeleco]

It is necessary to mount an order by carrying out a simple electronic circuit while having sufficient knowledge in electronics !!!
You must first have the specifications of the 3-way valve (which model and brand and specifications).
If it is all or nothing, the motor must be turned in one direction or the other with simple relays. Easy enough.
But yoyo all or nothing certain, not very serious.

If it is proportional, it is necessary to know how the position is detected in order to turn the motor to this position.

However, the working time if paid to carry out will be greater than that of the purchase of the order.

In order not to overdo the yoyo, you have to understand the PID regulations !!!

[antoine35]

the valve motor shall be a "3-way valve actuator 66" 3-point control with a stroke time of 140 seconds.
I was thinking of putting an eliwell type recovery regulator which will be able to detect the starting temperature and therefore send the info to the servomotor but it will close completely and will not be progressive, that's what annoys me. ... I also thought of putting a tempo of a few seconds so that it does not close completely at the first try but there I am not sure either of the result.
what is PID regulation? I worked two years in PAC troubleshooting and I settled several times the regulation of 3-way valves on heated floors so I know a bit about the same thing. I would like some additional explanations if you have .....
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[dedeleco]

what is PID regulation?

unclear abstract answer except good scientific level:
http://fr.wikipedia.org/wiki/R%C3%A9gulateur_PID
A little clearer in English because more concrete and less mathematical:
http://en.wikipedia.org/wiki/PID_controller

Much more basic:
http://www.energieplus-lesite.be/energi ... _15797.htm
Inexpensive operational amplifier diagrams:
http://gtv.free.fr/elec/?Regulateur_PID ... oProjet=24
An operational amplifier for less than € with a few capacities may suffice if you don't ask too fast !!

In a few words we try to anticipate and compensate for the heating response times of the radiators and of the house which takes time to heat.
We find the same problems of regulation with risks of oscillations and chaos everywhere, in electronics, to drive a car, for snowfall on cars and airports, agriculture and crops, economic crises, etc.
So lots of studies to drown!
http://www.google.fr/search?num=100&hl= ... ID&spell=1
with very different vocabularies but the same mathematical concepts !!
http://fr.wikipedia.org/wiki/Diagramme_de_Nyquist
For the valve, if proportional, it is necessary to know its position, or equivalent, the temperature of the water which leaves mixed and its error compared to the desired value to regulate and maintain at this temperature.
The response time of the water and the thermometer requires PID regulation or a simplified version with a long response time to avoid oscillations.
Since the position is fixed by the running time of the motor in one direction or the other, it is more complicated, the control signal roughly proportional to the error of T must be converted into an operating time of the motor , which corrects, then wait for the result on the new position, with the new T to correct.
If you don't want to go fast and never have any oscillations, you can go there by very small steps of very 1s or 2s of motor rotation and wait a time ta much greater than that of changing the water and the thermometer (2 to 5 minutes) and correct.
In this almost all or nothing case, we have an amplifier which measures the error of T which fixes the sign of rotation of the stepping motor by controlling one of the two relays with a pulse of tr 1s spaced from ta which stops as soon as that the delta error T is less than the change in T with a rotation of tr 1s.
This version is the simplest in assembly and understanding.
We do the same thing by hand! we try little by little.

[antoine35]

thank you for these complements.bon I understand the principles but I do not have the level to assimilate formulas and electronic circuits. So I allow myself to come back to my basic idea: is it possible with a cold room type regulator, I take the compressor output; if the water outlet temperature is not reached the contact closes and supplies the actuator, the valve opens. the temperature is reached the switch switches and triggers the closing of the valve, by associating a tempo it will close a little but randomly compared to the new temperature ........ this is where it arises a concern but I am not to the degree because the plants will accept some differences more or less important.
does this seem achievable while maintaining acceptable temperatures or do I risk having variations that are far too random according to you?
or better has someone already carried out a kind of regulation of this kind which works not too bad without having a level of engineer?
thanks again and A +

[dedeleco]

if the leaving water temperature is not reached, the contact closes and supplies the actuator, the valve opens. the temperature is reached the switch switches and triggers the closing of the valve, by associating a tempo it will close a little but randomly compared to the new temperature ......

The difficulty is that the engine turns too fast compared to the time that the temperature takes to reach the thermometer exactly and therefore it is necessary to slow down the speed of rotation of the engine by short pulses of 1s separated from the time necessary for the thermometer to reach the new T (5 minutes sometimes) if not, we open quickly May T is not reached fast enough, so we think too cold and we close and therefore inconsistent oscillations !!
So it can only work with short pulses on the motor to slow the rotation !!
Otherwise, you will be like the mechanical flashers of old cars, oscillating between too hot, too cold without stopping !!
It is possible to determine by regulating by hand and looking at the thermometer to know the time necessary to have the correct T after changing the valve.

The formulas and circuits only realize this basic idea.

You need at the mini a timed relay in short time repeating at a slow rate adjustable over the minute and an all-or-nothing thermometer regulating thermostat which controls this pulse relay which makes the motor turn like a turtle slowly, subjected to these pulses .

This pulsed relay can be composed with a NE555 making the pulses which control the relay under 5 or 12V.
http://fr.wikipedia.org/wiki/NE555

If you find it too difficult, the NE55 is conceptually identical to a mechanical flashing light old car, where a bimetallic strip is heated quickly, which cuts the current and which cools afterwards, to restore the current, thus without stopping !!
In place of the NE555, you can tamper with such a broken flashing light, by extending the cooling time to the minute by isolating the heating resistor !!!


But make the effort to understand electronics, which uses the same concepts !!

[antoine35]

I did a test this afternoon (in a vacuum) with an eliwell ewpc 902 regulator which allows me to modify the differential and the activation time of the output.
basically it once the temperature reached, wait for the time I set before activating the output. so I think that by playing on the differential and the tempo I should get there.
I think the servomotor will wander a little while the temperature of my balloon is close to the max and then it should not be too yoyo ... well I think ......
on the piping maybe the reactions will be different.
inch allah, otherwise thank you for the combination of the flashing it is African .............. I like ....
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