Wood boiler in series with low temperature oil boiler

[newstarnord]

Hello,

I am considering new solutions to save fuel in our home; insulation, etc, etc ...

I am wondering about heating. I'm studying the possibility of putting a log-fuel boiler in series with our Viessmann Vitola Biferale low-temperature oil boiler. In this way, most days (but not constantly because some days we will forget or we would be absent), we would do an outbreak to heat a ball of 1000 l of water to 90 °.

The dwelling has a potential area of ​​160 m2 but only 100 m2 is currently operating.

The problem is that in the presence of a water temperature 90 ° how will behave the regulation of the fuel boiler?

Then, with the chain regulator of the wood boiler (which would be a fairly basic boiler), can we set a precise water temperature?

Already can the heating element of the oil boiler support 90 °?

Thanks in advance,

Xavier

[Christophe]

Hi and welcome here.

The heating in wood boiler is binding, it's only interesting if you can have cheap wood (= you do it yourself ...). Personally I tried 2 years but I quickly gave up, especially because of the ECS ... had to load wood 6h mat to take a shower at 8h ... I had a deom 15 kW with regulation zipper also.

Why do you think of a serial editing?

I would rather a parallel editing rather than series ... just do not forget the flaps in the right places.

Here is a subject that shows a wood + fuel assembly in parallel: heating-insulation / coupling-boiler-wood-and-fuel-map and-schema-t8843.html

My editing (low temperature too) was this one: heating-insulation / wood-boiler-new-schema-installation-DHW-and-pcs-t4589.html, since I replaced the boiler Deom wood log with a boiler stove pellets that I improved with a few personal tips: heating-insulation / THERMOROSSI-h20-34-error-no-temp-resis-improve-the-burning-at-home-t15658.html but the hydraulic diagram remains exactly the same!

To answer your questions:

The problem is that in the presence of a water temperature 90 ° how will behave the regulation of the fuel boiler?

She will not start!

But we must see the pattern that you have in mind to answer precisely!

Then, with the chain regulator of the wood boiler (which would be a fairly basic boiler), can we set a precise water temperature?

No, do not count! But you can put a regulation on the circulator of the boiler wood.

Already can the heating element of the oil boiler support 90 °?

Yes and thank you!

Do not hesitate to use the search engine of forums: search.php

[Christophe]

You will find other wood + fuel schemes here: autoconstruction-and-Craft / schema-heating-central-with-boiler-wood-t6264.html

[newstarnord]

Thank you for the answers, I will read and compile all this, just to get a better idea of ​​the project.

Why am I thinking of a serial connection of the boiler? Because if we want the water to circulate in the two boilers in parallel, we need a Tickelman loop if I understood correctly; off my second boiler (the one in the wood) would be connected far from the first.

For the DHW, this would be managed by the oil boiler or the wood boiler, but it is true that something else would have to be provided to control the DHW circulator than the regulation of the oil boiler, since when the wood boiler is active, the DHW circulator must be triggered without triggering the oil burner (of course if the tank temperature is too low). Unless the oil boiler manages this independently of the burner, but I don't think so because it must temporarily switch to "high temperature" to heat the DHW.

Other than that there would be problems of draw, in fact, the chimney would be a chimney of 10m of length approximately, it would have therefore a regulator of draw? And a double skin flexible casing that is appropriate at first sight?

All this is to get an idea of ​​the costs involved.

[Did67]

For a log boiler, draft regulation is an ecological disaster. We surpass everything we can imagine and trucks in the valley of the Arve is a joke ... I exaggerate a little ...

http://www.bois-energie.ofme.org/docume ... 7_2007.pdf

For this to be bearable, it is necessary to maintain a sharp combustion, without smothering the fire, in the absence of controlled combustion (on high-end boilers, the combustion is controlled by electronics). Thus, at high temperature, the emissions are contained. Provided the wood is dry!

And for that you need a buffer: you do not heat the house directly; we heat a large volume of water, in which then a regulation will take just what is needed ...

It also helps to get rid of the stress of reloading the boiler. It is no longer the boiler that commands you. But it's you who put a layer of calories back when it goes down. Bine calculated, the buffer can heat the night. And to have hot water (by a submerged balloon).

But that has a cost.

etude_ademe_emission_atmo6_07_2007.pdf

(91.14 KB) Downloaded times 659

[Christophe]

Yes you are right but I think I still saw regulation by "zipper" not so long ago in new log wood boiler!

It is, in my opinion, very difficult to regulate the combustion of logs electronically efficiently *: simply because neither the quality nor the quantity of fuel in the combustion chamber are known!

After we can still operate in excess of air (forced so) but it will make Nox lack of soot ...

The ideal is what you say: a good outbreak and buffering (but it induces losses ...)

* as much for the yield as for the pollution ...

[newstarnord]

Yes, I am considering the buffer solution actually.

After I do not understand, there is possibility to regulate the fire other than by acting on the draw (ie the air intake)?
Is it necessary to regulate the draft, otherwise the temperature will be "unlimited"?

If I understood correctly, we set this chain regulator on 85 °, and at the moment when the temperature of the boiler water reaches this value, which means that the buffer tank has reached its target temperature, the fire gradually decreases to be completely suffocated.

Now, for sure, without a lambda probe and ad-hoc electronics, the air regulation is less precise and therefore no more polution?
But what is the cost of a boiler with lambda probe?

[Did67]

It is necessary to determine respectively buffer (capacity) and boiler (power) so that the whole load can burn at high speed, without the regulation intervening by "reduction of the draft" ...

Of course, there is a "certain" regulation, by the sizing of the fireplaces and the air inlets.

I'm talking about "smothering the fire". This is because regulation by "pull tab". Of course, the boiler temperature should not exceed 85/90 °, otherwise it will boil. This is where parameters such as pump speed come into play.

If there is "suffocation", two extremely harmful things happen:

a) "gases" (VOCs - volatile organic compounds) then escape without having been burned, for lack of oxygen; it is doubly harmful: the efficiency drops and this results in polluting emissions (VOCs and particles - the famous soot)

(b) the temperature of the fire decreases, and thus some compounds, more difficult to burn, are only incompletely; same consequences.

[Christophe]

It is necessary to determine respectively buffer (capacity) and boiler (power) so that the whole load can burn at high speed, without the regulation intervening by "reduction of the draft" ...

This topic can help this: heating-insulation / wood-energy-calculation-volume-of-a-balloon-buffer-thermal-t4267.html

[Philippe Schutt]

In bulk:
The wood boiler is never directly in series with the fuel oil, it is incompatible with the thermal valve against cold returns.
We have got in the habit of putting a thermostatic touch set to 40 ° to the bottom third of the balloon, which lights a light near the stove. So people know that you have to stop charging, otherwise they continue to overheat even with 1000 L!
The only way to have a correct combustion over a long time is the inverted flame. 4h flame is a common thing for these boilers. The yield is really in the 85% and the emissions are low.
For the ECS, I use a plate heat exchanger that takes a little heat on the boiler side, the balloon side turns thermosiphon. Simple, and it can heat any balloon.
For sizing, you need to know the need of the house.