Wood / fuel oil boiler with buffer tank (plan)

[Cowbois]

Hello everybody
Living in a small Alsatian village, I installed central heating 6 years ago in a house that was already built during the Molère era. I just changed my boiler. A Geminox T35. Mixed wood / fuel oil without DHW production.
I want to put a buffer tank so as not to waste the calories produced in excess by burning wood. Not being a specialist in the matter, I absolutely did not embark on complex calculations of pressure drops and other incomprehensible calculations for a neophyte.
I just want to know for the moment if I am or not !?






Connections

• VE
o The solenoid valve closes the arrival to the balloon as soon as the fuel starts. To avoid heating the balloon water with the fuel oil.
o It opens automatically at only 65 ° by a thermostat in order to heat the radiators as a priority.

• V4V
o The motorized 4-way valve managed by the boiler opens and closes on demand.

• P1
o The recycling pump operates continuously except when the water is at 20 °.

• P2
o The circulation pump in parallel with the V4V.
Apart from the ball, I am already in possession of all the equipment.

In advance, thank you for your comments and remarks.

[loop]

Hello Cow,

First question :
Is the 4-way valve a mixing valve?

Please note:
If EV is thermostatically controlled from 65 ° C, it will unfortunately close as soon as the temperature is slightly lower and prevent the use of hot water.

If not :
For the installation of the tank, models with several inputs / outputs must be preferred to connect it with hydraulic decoupling.
The installation with "tees" causes parasitic flows (which I encountered on my installation)

A+

[Cowbois]

Hello and thank you Looping for this quick response.

In fact the solenoid valve will only close when the oil burner starts or manually (push button) when I start a new outbreak.
The dedicated EV thermostat will only open it at 65 °.

For the V4V, it is indeed a mixer.

At first, I will use an old cumulus to test my circuit. If it works, I will invest in a real buffer tank.

Thanks again.

PS: I have not shown on my diagram all the safety devices but they are and will be present when the installation is modified.

[loop]

Cow,

Given your answers here are my remarks:

The 4-way mixing valve and the 3V recycling valve are redundant.
A 3-way mixing valve would suffice as you don't need to "heat" the return as that is the job of the recycling loop. You can possibly plug the return orifice (that's what I do on my instal in wood mode).

In addition, P1 pushes the water which will go easier in the circuit and I am ready to bet that it will pass to in the 4-way valve instead of going to the balloon (I have this problem on my installation because I could not place my buffer tank in hydraulic decoupling).

Regarding the use of an ECS recovery tank, I fear that you will be disappointed if you do not make any changes to it.
I had offered this "salvage" solution to one of my contacts, but he told me later that it was not working.
Today, with a little hindsight, I think we can quite get a really operational buffer tank if we can tinker, especially welding.
Personally I started by buying a buffer tank from the store (with solar exchanger). Lately I have boned a DHW tank to study its modifications in buffer and to consider increasing the stock. I can post a photo if you are interested.

Corrected diagram that I propose to you:


A+

[Cowbois]

Looping,
Yes, I want the photos and also the diagram. (he is not in the post!)

Thank you

[loop]

For the photos of the naked DHW tank, I am looking at this this evening (here I am at the office).

For the diagram, I re-edited my post so that it was included.

Otherwise photos of my buffer tank here

http://www.energies-libres.net/insert-chaudiere/installation-de-looping/208-estimation-des-performances-du-zuzia-sur-ballon-tampon

A+

[loop]

As promised, here are the photos of a recovery tank that I plan to transform into a heating buffer tank.
This balloon had finally pierced at the top, where the screw holding the magnesium anode created an initiation of oxidation.
The PU foam that provided the insulation was soaked in water and propagated the oxidation. I completely removed the skin.
The fully scaled electrode is HS but the seal still looks usable.

What you need to know about DHW recovery tanks.
We can get them back for a handful of euros, sometimes even for nothing.
These are designed to withstand an internal pressure much higher than a heating circuit. So no mechanical resistance. The domed bottoms are important.
The elongated shape (height / diameter ratio) is favorable for stratification (in DHW it is also important).
The interior enamel is sometimes altered, but this is not a problem for the heating application which is in a closed circuit (no oxygen or chlorine supply, very aggressive for steel)
On the other hand it is necessary to protect the external surface with an anti-rust paint otherwise the shiny steel surface will quickly give way to what you see on the photo (superficial nonetheless)
The inlet / outlet connections are generally of section 20/27, which is a bit small for the heating circuit.

For the modification in buffer, it is necessary to plan to add nozzles of large section 26/34 or +. This reduces the flow speed. Also provide a jet breaker system.
These precautions allow good stratification to be maintained during charge-discharge cycles.
To make a large capacity balloon, you can very well weld 2 balloons together after cutting the bottom on one side.
Otherwise an assembly by the flange side seems possible to me.





A+

[Cowbois]

Thank you looping,

I now have enough to meditate on the modification of my install.

See you soon.