boiler coupling wood and oil: map and diagram

Heating, insulation, ventilation, VMC, cooling ... short thermal comfort. Insulation, wood energy, heat pumps but also electricity, gas or oil, VMC ... Help in choosing and implementation, problem solving, optimization, tips and tricks ...
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loop
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by loop » 08/02/11, 12:43

Bonjour,

Upon reflection, I think I have understood the principle of the heating engineer.
Unfortunately, in its system, you can only heat the radiator circuit if the buffer tank is very hot, which is not wise because you do not optimize the calories produced by the wood (below 80 ° C do nothing !! )

I propose the modification according to the following diagram:

Thermovar (essential) on the wood boiler (will ensure regular flow and longevity of the boiler)

Heating function:
Main circulator A control by thermostat (one must be somewhere)
Depending on the temperature at the top of the buffer tank, it is chosen or not to supply the circuit (position of valve V2 controlled by thermostat, for example set to 40 ° C)

DHW function and oil boiler temperature maintenance ensured by the regulation of the boiler, independently of the rest (calorstat at 60 ° C if this is sufficient)

Image

To heat the DHW (and therefore the oil boiler since the internal tank is in a water bath) by the buffer tank and / or the wood boiler directly, other temperature conditions are necessary, but in my opinion it is another independent regulation (we will come back to this later)
Do we already agree on the heating principle, does it work very well for me? (mounting more or less like the diagram above).

A+
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Alain G
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by Alain G » 08/02/11, 13:49

Hi Looping!

He mentioned that pump A is not enough for traffic!

In your circuit, there is an error, the thermostat must control the oil boiler which must stop its pump otherwise the heating element will overheat due to lack of circulation. Pump C is necessary to maintain a good flow to the radiators, the lack of flow will heat the first radiators more than the last.

For the thermovar I am mixed, the inlet temperature of the water will recover fewer calories at 60C than if the temperature is lower, of course must see if it will create condensation on the heating body of the boiler with wood but usually it only happened on ignition.
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by stoa » 08/02/11, 20:42

Good evening, thank you for your feedback

Looping, I did not represent it in my diagram of departure but there is a recirculation as on your diagram integrated with the insert with wood. However, it only works continuously when the return is ~ 10C below the outlet temperature (70-80 in my case).

The diagrams that you offer are parallel connections. Alain G is right - pump A is not enough to move the balloon water (I tried but going through the oil heater core). I see the difference between the two diagrams at pump level C is one more valve on Alain's plan. I'll show them to my heating engineer.
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by Alain G » 08/02/11, 23:33

stoa wrote:Good evening, thank you for your feedback

Looping, I did not represent it in my diagram of departure but there is a recirculation as on your diagram integrated with the insert with wood. However, it only works continuously when the return is ~ 10C below the outlet temperature (70-80 in my case).

The diagrams that you offer are parallel connections. Alain G is right - pump A is not enough to move the balloon water (I tried but going through the oil heater core). I see the difference between the two diagrams at pump level C is one more valve on Alain's plan. I'll show them to my heating engineer.


Good evening stoa!

Or do you see one more valve?

One more pump than Looping's diagram!
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Philippe Schutt
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by Philippe Schutt » 09/02/11, 01:25

often manufacturers of wood boilers require a very high boiler T ° to avoid condensation in the appliance, which could lead to early piercing. Some even make it a loss of warranty clause. The higher the efficiency of the boiler and the colder smoke, the hotter the return. At the head, the Atmos termovar is at 80 °.

6L / min is really not much. even in position 1 you must have within 20 to 30 L / min. This can already explain why 200L passed quickly. You might as well test with this circulator at minimum.

If the oil boiler turns on, it is because circulator C sent water to it at less than 50 °, therefore the tank thermostat is not fast enough (thermal inertia of the zone) or its hysteresis is too big. Certainly placing it lower would solve this problem.

what temperature was the ball when you started heating it up? Because if you start from 10 ° it makes a delta of 60 ° (70-10), of which you only get 20 ° (70-50). This would partially explain the 4 - 5 hours of heating.

I made some series assemblies without balloon at all and which give all satisfaction, So I will not be too positive that the losses come from the oil boiler.
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by stoa » 09/02/11, 20:26

Hi,

Alain G. - it seemed to me that there was one more valve on your plan but the parallel principle remains the same. I haven't seen my heating contractor yet.

Philippe, your experience in series interests me because if I can make the system work in series - I will also save on DHW.
If I start from the assertion that 50L of water from the oil heating core, once at 70C, lasts 20 min. (for a given opening of the 3-way valve), before falling to 50. Could you give me an idea why 800L of the buffer tank once at 80 wouldn't they last 16x20min = 320min, at least 5 hrs. before pumping cold water into the heating core? However, this is not the case. When the ball is hot - 70 at the bottom 80 at the top - it barely lasts 1hr - 1h30 max?

please
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by dedeleco » 09/02/11, 21:32

Probably the balloon is only half high at 80 ° C ?????
You have to look at how it is designed, where are the balloon's thermostat and thermometers. ????
Make sure that all the water in the flask is 80 ° C from top to bottom ???
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by Philippe Schutt » 09/02/11, 21:34

Some ideas, which may be wrong since your diagram is not complete.

1. to the 50L of the DHW tank the volume of boiler heating water must be added.
2. At what temperature does pump B stop?
3. if there is no non-return valve you probably have a thermosiphon on the insert side.
4. uninsulated pipes?
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by stoa » 12/02/11, 09:41

Hello,

Here are some answers:

1. The thermostats are placed at the highest entry and the lowest exit of the balloon. But on one side.
2. The 50L is the volume of the heating core. The DHW is still other 140L which are heated in a water bath by the heating core.
3. Pump B stops at 75C at the current setting. In general it stops ~ 5C below the temperature of the outlet water from the insert.
4. There should not be a thermosiphon at the insert level. The insert is fitted with the factory prerequisite kit.
5. The pipes between the tank and the boiler are not insulated. They are located in an isolated room and represent <2m in D28 copper.

Me, I believe that the pump C gives a too high flow. But how can it be reduced? With a special valve suggested by Alain G.? A different hydrolic scheme?
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Alain G
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by Alain G » 12/02/11, 14:36

Hello stoa!

I was talking about a simple cheap Ball Valve!

Note that if you give a restriction on the circulation water, the pump will consume less.

I was talking about pump B but I admit that if the C circulates too strongly, the cold water may mix with the hot water at the top of the tank.
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