Improving the efficiency of a hydraulic pellet stove (EcoTherm Thermorossi H2O)

[Christophe]

After improving the fireplace itself (see: heating-insulation / THERMOROSSI-h20-34-error-no-temp-resis-improve-the-burning-at-home-t15658.htmlHere is an 2ieme improvement made on a Thermorossi EcoTherm H2O 34 hydraulic pellet stove in order to boost its efficiency a little ...

This is create a baffle for the flame and the flue gases to improve heat exchange on the water slide (which surrounds the fireplace). The method may be a little less interesting on an air pellet stove ... although: the longer the flame and gases stay in the home, the better.

a) At the beginning of wanted to directly sold plates on the plates of the stove but the non-removable and unalterable character made me give up the idea, more weld on a blade of water is not terrible ... short the demountable is better!

b) I therefore made 2 "tables" in welded mechanic, simply placed in the hearth and which make a beautiful gas baffle (at maximum power, the flame reaches the height of the 2nd table at the entrance of the 2nd chicane).

c) The "hot" baffle is on the left because this is where the water is hottest, on another stove model you will have to think about this.

d) As the stove is operating in depression, it is important not to create too much pressure losses, so I calculated a cross section of 2,5 times that of the exchanger (which is located after the focus at the top).

e) There is a gap of a few mm between the trays and the walls of the fireplace to compensate for dilatation

Chicane_pellets.jpg (343.7 Kio) Viewed 9183 times

I added 2 7mm holes on the left inclined plate to add tertiary air and "guide" the flame

Chicane_pellets_bas.jpg (410.83 KIO) Viewed 9183 times

Chicane_pellets_haut.jpg (344.43 Kio) Viewed 9183 times

After a few hours of use:
- you see that I do not clean ...
- a lot of ashes are deposited on the trays: it is less ashes in the duct and the original exchanger (less maintenance, less sweeping)
- These accumulations certainly reduce the heat exchange in these places (but good considering the thermal conductivity of steel ... I do not know if it is significant)

Chicane_pellets4.jpg (457 KIO) Viewed 9183 times

We see that it heats more at the level of the hearth:

Chicane_pellets3.jpg (299.23 KIO) Viewed 9183 times

I did not find any pictures of the flame in operation ...

Subsidiary question: it is not a red snake that tries to enter the home from above on the 1ere photo but a spring tip of the main heat exchanger (see manual: download / file.php? id = 5767 ). Question: where does this red color come from ???

[Ahmed]

ChristopheI think you're getting ridiculous!

[Christophe]

Ah ah ah !!

I bicker for less biting pellet ash dust!

So what is this red coloring according to you? You who know metallurgy well?

[Ahmed]

Probably oxidation?

[Christophe]

Yes probably a kind of oxidation but it is strong because the metal has become soft (I broke the tip by touching it by hand ...) ... I hope the rest of the stove is not going not suffer the same fate!

A photo?

[Did67]

Iron oxides are red ... What is disturbing is that it is a beautiful red! They are "dust", so no wonder it can be "taken apart" with your finger ...

But indeed, it worries about what can happen higher!

For your "baffles": at this level, do you already have "pockets" of water on the other side of the burner ??? [on my Okofen this is not the case. The lower part, in which the burner is located, does not "bathe" in water, it happens above]. Therefore, I wonder if it is relevant to "slow down" the flow at this level. Or even if it is not counterproductive? This will increase the temperature in the fireplace, the losses (and possibly oxidation!). It is at the level of the exchangers, above, that we must play, where the calories are transferred to the water. But normally this is the role of the "turbulators" which must be in the exchangers ... And possibly, recirculations, double / triple flow, counter-flow of water and gas ...

[Christophe]

Yes, very red, more than rust that is more orange, hence my question about it, there is surely a chemical reaction and more! Especially since it is not very humid inside a stove eh!

Yes, I reassure you, the entire bottom of the fireplace is "under water" I obviously checked this before thinking about this improvement. We can guess it on the instructions (hydraulic inlet and outlet at the bottom) download / file.php? id = 5767

Stove seen from the front, the left part of the fireplace is the hydraulic outlet, so hot.
The entrance being on the right and the main exchanger is at the top of the foyer (ideally it should be cleaned 2 or 3 times per season ... but I'm lazy ... I only did it once. curious to see how it is after the baffles, which logically "capture" a lot of dust in the fireplace)

Hence the choice of the direction of the baffle that imitates a heat exchanger against the current.

The stove has a water capacity of 34 L (hence its name, its power being 25kW), therefore quite large inertia (for a "stove") hence the rise in temperature which is long.

Here are pictures of the end of the spring ... if metallurgical specialists can give their opinion?

corrosion_4.jpg (138.17 KIO) Viewed 9115 times

corrosion_2.jpg (98.04 KIO) Viewed 9115 times

corrosion_1.jpg (111.95 KIO) Viewed 9115 times

ps: the stove is second-hand, I don't know the year of manufacture, it was approved in 2004 according to the instructions, I think it is over 10 years old and I don't know how many hours it has already turned ... the salesman, a pro, told me that the starter "spark plug" was new (which seems fair) as well as the brush motor. The other electrical wearing part is the blower but it is a rotating cage brushless motor ... It is "almost immortal" ...

[Christophe]

About the broom, another improvement is necessary and I cogit on it but I do not have the solution yet ...

The trouble is that some pellets are locked in the holes of the home (which certainly 6mm ... they should have been in 4 or 5 mm ...), which blocks the broom and creates shocks and noises ( the force of the brush being sufficient to burst the pellets ...). We see some pellets exploded on the photo with the ashes above (but normally there is not as much: it was the end of the silo at the end of the season).

So what are the options?

I do not see many ...

To put a mesh under the broom is not an acceptable solution, except if it is in tungsten, because given the temperatures, it will not take a long time ...

So I see the solution to reduce the diameter of each hole a little bit (1 weld point by hole then grinding) but it will reduce the primary air ...

Other suggestions?

[Did67]

Yes, very red, more than rust that is more orange, hence my question about it, there is surely a chemical reaction and more! Especially since it is not very humid inside a stove eh!

At these temperatures, it is not the humidity that plays (the humidity makes "rust" in the cold, by creating small piles, in connection with the impurities; there, in a flame, it is oxidation direct; there is necessarily oxygen!; when I was still chatting a lot about the pellet boiler here, someone told me that he had shot the stainless steel "burn pot" of an Okofen - the mine is 10 years old! - in one year because there were chlorinated solvents in his boiler room; a priori, it was chlorine - chlorine, that's from memory).

[Christophe]

Really? A chemical pollution of the environment therefore?

I have some pots of paint and some chemicals stored in the technical room next ... but everything is closed ...