Installation of a boiler stove on a boiler?

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Plop
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Installation of a boiler stove on a boiler?




by Plop » 27/02/12, 20:11

Hello!
I am new to this site and I have already read a lot about the connections to achieve to couple a boiler stove to a boiler oil unfortunately I can not find my happiness! : Cry:
I saw that there was real expert on this site so I appeal to you! : Cheesy:
To begin I will describe the current installation a little:
- Oil boiler 25 kw
- 10 radiators but I often use 5
- 1 circulator dedicated to ecs
- 1 circulator for radiators
- To control everything I have a compact vasco unit consisting of a motorized 4 channel, a circulator, a built-in bypass and I also connected an external sensor on it. (reference vasco VV23B-MP-B) I program the start of heating with.

So now the project! : Mrgreen:

I bought a wood stove with a power of 18kw (10kw water, 8kw radiation)
I would like to connect to my installation but I do not know how!
I think to put a buffer ball of 500l.
If it is possible I would also like to warm my ecs with.
I thought to plug it on the return of the radiators but if I do that the body of the boiler will be heated unnecessarily too. So how to isolate my boiler from the circuit?
And if my stove does not work how to isolate the buffer tank from the rest of the installation so that my boiler does not heat the 500l water?
I made a small diagram of the installation to see more clearly : Shock:

Image

I still have many more questions but I will wait a little before asking them all! : Mrgreen:
Thank you in advance for your answers!
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loop
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by loop » 28/02/12, 12:54

Bonjour,

Here is a diagram that I drew for 2 heat sources and 2 consumers.
The buffer tank is found as source A and the fuel boiler as B. In this case, the source A being maintained by the boiler (we could add a solar circuit with exchanger).
For consumers, there is the ECS circuit (usually a priority) and the heating circuit (radiators or floor heating etc ...).

Why so many valves?

The VT valve of the boiler is strongly recommended to avoid cold returns and improves the stratification at the loading of the buffer tank.

The mixing valve of the radiator flow circuit (3 or 4 channels) acts as a temperature limiter and can compensate for the gradual decrease in temperature from the buffer.

The zone valve makes it possible to use one or other of the sources (A or B) without heating each other.
I chose this principle in "parallel" at home to avoid heating the fuel oil boiler (heating only) when it is not in use, sometimes for several days.

For the regulation part, I simplified the assembly with thermostats but it is necessary in any case to adapt to the existing one and in particular with the regulation of the boiler which gives priority to the ECS.

A+

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Plop
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by Plop » 28/02/12, 19:20

Bonsoir : Mrgreen:
Super the answer! THANK YOU !!: cheesy:
that's exactly what I want to do. I noticed that there was only one expansion tank and sometimes on installations with boiler stove there is a second.
On my installation I have one of 25l will it be enough if I add a buffer tank of 500l on the circuit?
Then you talk about a valve VT for the boiler. I see the principle but can you give me an example of a valve?
I know the laddomat system but there is still another model?
If not I can perhaps put my regulation with my 4 channel valve at the exit of the stove since it also knows how to regulate the temperature of exit by doing the recycling?
And if I make a small fire in my stove and I do not reach the desired temperature, my boiler is not likely to start up? do not provide a kind of relay that stops the burner of the boiler when C2 is running?
Thank you in advance : Lol:
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loop
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by loop » 29/02/12, 12:56

Bonjour,

So, in order:

For the volume of the expansion tank, it is generally 10% of the total volume of water that will be heated and will expand.
From experience, I will say that 25L is over-sized for a standard installation like yours. For the buffer, one would normally count on 50L, but if you have a little margin with the other, an additional 25L would suffice.
In addition, the calculation of maximum expansion is made for a very hot water (90 °) while sincerely I see poorly the entire installation at this temperature. Personally I never load my buffer more than 65 ° (too many losses).

I speak of the valve VT on the site that I quoted in mp (I give you the link + commercial site in mp)
A laddomat is neither more nor less than a circulator + valve + valve AR + thermometers.
You can achieve the same function with items purchased separately (cheaper in the end?)
It is not necessary to focus on this VT valve, it is not an additional complexity. As another advantage, it automatically closes the circulation in the insert as soon as the temperature drops.


The 4 channel valve is regulated for the flow temperature to the radiator circuit. In the principle of the 4 channels, the return water is mixed also to be reheated, but without guarantee of minimum temperature.
I looked to integrate this function in the circuit, but this is in my opinion not compatible with the circulator of the insert.
The flows are very random as soon as there is too much "tee". Between the 4-way valve and the buffer, the water will never go where you want it to be (I had to find a tip to remedy this problem on my installation).

For boiler shutdown mode A, simply use a relay switch that cuts the burner control when the valve is in A
(which I did on my installation).

A+
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Philippe Schutt
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by Philippe Schutt » 29/02/12, 19:05

The flows are very random as soon as there is too much "tee". Between the 4-way valve and the buffer, the water will never go where you want it to be (I had to find a tip to remedy this problem on my installation).


what as trick? Whenever possible I use 4 channels, I think we master better. I also saw valves coupled to circulators, so when the circulator stops, the circuit is locked.
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Plop
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by Plop » 29/02/12, 20:32

Hello,
Another big thank you for your answer!
Now all that is much clearer :D
But then in terms of my valve 4 lanes its ideal place would be just before the radiator circuit?
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loop
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by loop » 01/03/12, 13:00

Bonjour,

I will try to make it simple to answer Philippe and Plop.

Case No. 1:

In the diagram below, you will find the 4 channel valve on the circuit to the radiators.
The wood boiler is here connected to the buffer tank with hydraulic decoupling. This means that the boiler loop is separate from the consumption circuit.
Advantage:
The water pushed by C2 will inevitably charge the buffer tank without disturbing the flow of the heating circuit. Attention, for this buffer tank must have enough taps.

Disadvantage:
The buffer tank must be between the boiler and the start circuit otherwise it doubles the lengths of the pipe. That's why at home I have not retained this connection (see the case 2).
Another disadvantage is that the balloon must be put into service at the same time as the boiler if there is no bi-pass circuit planned.

Image
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loop
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by loop » 01/03/12, 13:27

Case No. 2:

The boiler is connected to the circuit between the buffer tank and the heating flow.
This is the formula that I adopted because better suited to my implantation with balloon at the end of the line (cellar)

Advantage:
The balloon can be installed in a second time and isolated for intervention.

Disadvantage:
The C2 circulator pumps the water to the buffer as well as to the heating circuit. Even if C1 is stopped (heating needs = 0) the water will go to the 4 channel (motorized or not).

Image
Last edited by loop the 02 / 03 / 12, 02: 26, 1 edited once.
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loop
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by loop » 01/03/12, 19:44

In the 1 case, such as the 2 case, the 4 channel valve returns heated water on the return. In the case of using oil boiler as a source of heat, it is normal since it is its role.
On the other hand, this idea did not please me at all for the operation from the buffer tank. This for 2 reasons:

My buffer tank has a solar heat exchanger, the water arriving at the bottom must be as cold as possible (better performance).
The flow of hot water is unnecessarily increased.

So, I've made sure that this 4 channel valve becomes an 3 track thanks to a trick in the hydraulic diagram.

Subsequently, once the installation was in service, I encountered a problem of parasitic circulation in the mixing valve.
This problem would have persisted with operation in 4 channels.
With the motorization of the mixing valve and its automated tilting depending on the need for heating, finally everything is back in order.

I leave you the night to propose the solution. : Mrgreen:
Tomorrow I will post the diagram.

A+
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Plop
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by Plop » 01/03/12, 19:54

lol at night to propose the solution : Mrgreen:
Uh, you're the scheming king :P
If not, I still have a question:
Why does the zone valve go on the radiator return and not on the start?
: Wink:
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