boiler coupling wood and oil: map and diagram

[Christophe]

Ok I understand better ... I think.

So your wood outlet T ° must be> fuel oil inlet. I speak in relation to boilers.

As you operate at high T °, ​​the wood boiler pump should not rotate when the T ° is not higher than that of the radiator return (60-70 ° C).

In your place I would therefore rather have mounted them in series with a Bypass valve when you are not using wood: the wood will therefore preheat the return. In fact this is what Looping did on its diagram from a thermal point of view: it is bypassable series with the 3-way valve. So I'm +1 looping.

On the other hand, I don't really see the point of automating it except keeping the wood loop hotter ... but it is hot only when we load the wood so good ... a physical presence is there. ..

[loop]

To respond to letitus

the AB valve is a motorized mixing valve?

with the info from the aquastat, it switches to the wood and fuel position if the wood is not on the way?

I would like the fuel boiler to start automatically when the wood is no longer heating enough, AB's motorization is therefore the best, right?

one expansion vessel is enough?

if my AB valve does not work (failure), will my valve protect the installation?

The valve required for this type of application is a sector valve. It closes one side to open the other and vice versa.
A mixing valve is a little different and above all less "tight" in the extreme positions.

If this valve is motorized, it can be automatically switched to B if the wood boiler is operating.
To detect it, a thermostat in the heating body is sufficient. A relay to start the circulator and supply the valve to position B and voila. In this case, the same relay (with inverter) can cut off the supply to the oil burner.

The volume of the expansion tank must be approximately 10% of the volume of the installation (simplified calculation, but largely sufficient)

The advantage of automating the tilting is precisely not to risk forgetting to switch to B, otherwise overheating ensured, but also so that the oil boiler does not unnecessarily heat the other (with wood) when it is off (position A)

Good cogitation

A+

[Christophe]

Well, I don't think that the motorization is necessary since as it is a wood-fired boiler, someone has to load it! But hey it is sure that the engine would be a significant "plus".

3-way motorized valve with an all-or-nothing thermal regulation is sufficient and see to put a linear regulation later (costs the electronic part dearly).

For the expansion tank: yes 1 is enough and +1 for the 10% but be careful it must always be, whatever the configuration of the valves, that it is the circuit, even if no fluid passes nearby!

In short, do not isolate it hydraulically from one or the other circuit, otherwise it is the catamaran provided for the isolated circuit that would heat up!

For example, with us, I had to add a second vase when I put our wood boiler because the 2 circuits are not 2% of the communicating time: https://www.econologie.com/forums/chaudiere- ... t4589.html

[letitus]

ok for the sector valve, I have to put it in 1 "or 3/4?
my piping is in 1 "!

for the changeover relay I already wanted to put one to activate the circulator above the three-way valve by cutting at the same time the power supply which comes from the fuel (managed by a room thermostat)

the vessel is on the cold water supply to the fuel boiler (will always be in operation on the circuit)

[Christophe]

Unless advised by your plumber, I think 3/4 will be enough, what is the price difference between the 2?

Ok for the vase it's ok!

[letitus]

I would have a question about your thermal valve, can you explain to me its role and how it installed on your assembly?

I have no coil in my boiler how can I mount it?

please

[letitus]

good bah I burned my first logs today, for the moment it's not bad, there are two or three things to settle (water temperature (80 ° at the moment) primary draft shutter ...) but otherwise I'm pretty happy with the result.

for information I followed the looping scheme, I just have to buy the servo motor

thank you to all

[stoa]

Hello,

I resume the subject because I did not succeed in applying the diagrams proposed in the previous messages for my case. I try to set up the diagram with a hydrolic wood insert in series with an oil boiler (and with an accumulation tank). I attach the connection diagram that my plumber / heating engineer has set up.

https://www.econologie.com/fichiers/partager2/1297103465d88k9z.pdf

It does not work quite as expected and the professional does not know what to do.

The idea is like this:

The oil boiler contains a 50L balloon which is kept at the temperature between 50 and 70C. In the absence of wood heating, the 3-way valve V1 mixes part of the radiator return and the hot water coming from the oil boiler. The zone valve V2 closes the passage to the tempon tank and the other part of the return water and directs it to the oil boiler.
The oil boiler also heats the ESC via water bath.

When the wood insert starts up, circulator B sends hot water between 75 and 80 degrees to the tempon tank. This circulator often works intermittently because when the water returning to the insert is cold, the insert can
take time to reach the required outlet temperature. The "peak" power of the insert is still 20KW.

As soon as the water above the buffer tank reaches 75C, the termostat starts the circulator C and changes the position of the valve V2 - this directs part of the water returning from the radiators to the tempon tank.

The problem:

- when there is only a "little" hot water in the buffer (eg 200L), the oil boiler intervenes after a few minutes. Besides, the 50L in the oil boiler usually last ~ 20min. (at the same position of the 3-way valve V1). Shouldn't the 200L of hot water in the tank last ~ 80min. ?
- In addition, the circulator C creates a flow (6 l / min I believe) such that the oil boiler is switched on more often than normally - hence higher fuel consumption.

- autonomy: I closed the termostat above the buffer tank
manually and I heated the balloon so that it reaches 70C below. The hot water that has accumulated had been enough for about 1 hours of heating. After that, the oil boiler starts (in addition as the circulator C continues to operate for a while I consume more oil than it takes). It seems hardly acceptable to heat the balloon for 4-5 hrs to have it only for 1 hour 30 minutes of heating. With 1000L of heated water I would have expected to be able to spend the night at least?

So, I think he has a problem with the water somewhere.

I tried to remove the circulator C. The circulator A is not sufficiently powerful and there is no circulation between the buffer tank and the oil boiler.

Could someone help me understand how to make the connections to put my oil boiler, my insert and my buffer tank to work well together?

Perhaps a serial link is not possible in this case?

What about a parallel coupling?

thank you very much in advance,

Arthur

[loop]

Hi Arthur,

I have never seen a diagram like yours, but hey, we learn it every day.


To begin :

This circulator often works intermittently because when the water returning to the insert is cold, the insert can
take time to reach the required outlet temperature. The "peak" power of the insert is still 20KW.

Hence the advantage of mounting a recycling valve which will avoid this yoyo operation and will ensure better stratification in the buffer tank.

As soon as the water above the buffer tank reaches 75C, the termostat starts the circulator C and changes the position of the valve V2 - this directs part of the water returning from the radiators to the tempon tank.

This mainly means that the buffer tank will empty in the heating circuit, even if it is not necessary.
Perhaps it is a security that the heating engineer has put in place?

In addition, the circulator C creates a flow (6 l / min I believe) such that the oil boiler is switched on more often than normally - hence higher fuel consumption.

The problem with the buffer tank is that it is often cold at the bottom, cold water eventually rises, which requires more energy from the boiler than the warm return from the radiators.
It is better to avoid heating the buffer with the oil boiler and leave this to the wood boiler.

Personally I chose a parallel installation, but I do not do the DHW with the oil boiler.
As long as my buffer tank is warm enough (up to 30 ° C) the oil boiler does not turn. Balancing flows is easier. It is also a choice of regulation.

A+

[Alain G]

Welcome to Arthur econology!


The hot outlet of the tank must absolutely not pass through the oil boiler to go to the radiators, because you will have a heat loss at the level of the heating body.

Try it like this because there is no saving in heating the tank with the oil boiler!



After the pump "B" of the wood-fired boiler you must have a valve to limit the flow of the pump and limit the circulation in order to have the coldest possible water return.

The temperature to switch to the oil boiler must be between 45C and 55C depending on your heating needs towards the radiators and must be positioned at the outlet of the tank, this probe must activate V2 and switch off the oil boiler.

There must be a delay on the transfer between the oil boiler and the tank to allow the heating body to cool down. oil.

If you have additional questions I will be happy to answer you!