Recovering heat of the flue

[pieroxy]

Hello,

I have a fireplace (open hearth) on the ground floor of my house and the conduit goes into a room on the 1st floor. In order to recover heat from my fire more efficiently, I have two projects:

1. Close the fireplace and install "piping" above the fireplace to make the fireplace more efficient. It looks standard, and all the chimney fitters seem familiar with it. I will get one or two quotes on this subject. (notably by a Cheminées Brisach installer)

2. Insofar as there is hot air passing through the duct on the first floor, I intended to install a heat recovery unit and distribute the air thus heated by my VMC double flow. .. or by some other means. The idea would be to heat the air through the double flow exchanger and then pass it through the recuperator before distributing it in the dry rooms.

My questions for the experienced econologist:
- Point 1 seems to be well known to the railroaders I contacted. Is this the most efficient way to do it?
- Point 2 left the contacted track workers a little haggard ... They do not even understand what I mean. Is this a realistic concept? Who can help me on this? I can tinker with something but I would first of all like to have an installation up to standards for insurance reasons and "I don't want to die of burns or suffocation".

Thank you in advance !

[clasou]

Hello,
First, the best would be to insert if you can a closed hearth in the open hearth, because otherwise it should not be obvious.

If you just want to recover the heat from the simplest duct it is the hot air recuperator, are very expensive and not complicated to assemble yourself.

Only worries, the passage of the sheaths and their concealments.

On the other hand, the double flow is to bring in fresh outside air while taking advantage of the calories in the air that you eject. But in the case where you recover the hot air already present, I don't see the point, if not make it very complicated.
a + claude

[pieroxy]

Do you know where I can get a recuperator and what type of contractor can ask me without farting everything?

For the double flow, the point is that I will have air vents in all the dry rooms, with all the piping that goes with it. Suddenly, it is infinitely more practical if I can use the same piping to bring back the heated from the recuperator.

Basically, the incoming air flow of a double flow CMV follows the following path:

outside -> pipe -> exchangerVMC -> engine -> pipe -> Y -> pipe -> dry room

So, what I will add is the recuperator (in bold):

outside -> pipe -> exchangerVMC -> engine -> pipe -> recuperator -> pipe -> Y -> Pipe -> dry room

So at first glance it doesn't seem to be "very complicated", but I may have missed something ...

[Gallic]

We had, it was a time, installed a similar system at the grandfather. The system was simple: it consisted of a helical heat exchanger wrapped around the flue. This exchanger made it possible to preheat the water before sending it to the boiler. A secondary exchanger also preheated the water from the sanitary network before sending it to the water heater.

However, you have to be careful !! This kind of system is particularly interesting in the best of the worlds of beautiful theories on paper, but we noted two problems.

First, degraded regimes were particularly difficult to manage. For a little that the water does not circulate (or very little) in the circuit, if it is poorly drained, there is a risk of vaporization of the water, with all the consequences that go with it !! And do not think that it is negligible: imagine, it is April / May, heating off because the weather is good, and cold weather! You are making the fire again, and BANG !!

Second, in nominal operation, the fact of recovering part of the heat of the fumes seemed to alter the good draft of the chimney ... This can be explained by means of simple calculations of mecaflu ...

Good idea, therefore, but to handle with care !!

Economically,

Gallic

[pieroxy]

First, degraded regimes were particularly difficult to manage. For a little that the water does not circulate (or very little) in the circuit, if it is poorly drained, there is a risk of vaporization of the water, with all the consequences that go with it !! And do not think that it is negligible: imagine, it is April / May, heating off because the weather is good, and cold weather! You are making the fire again, and BANG !!

A priori, in series on my VMC it will circulate all the time. Thank you anyway for the warning!

Second, in nominal operation, the fact of recovering part of the heat of the fumes seemed to alter the good draft of the chimney ... This can be explained by means of simple calculations of mecaflu ...

Good idea, therefore, but to handle with care !!

Economically,

Gallic

Come to think of it, the hot air rises because ... it's hot! If we cool it too much, I understand that this poses a problem indeed ... Thanks again :-)

[Former Oceano]

The problem also is that we favor the deposits of tar and soot.

[bernardd]

To properly recover the heat from the fumes, you first need a forced circulation, and then very good combustion.

For wood, pellet boilers have been made for this.

[chatelot16]

a double flow vmc, it's a joke: it passes a small flow rate just good for ventilation: the flow of smoke that an open fire is much greater than the flow of a vmc

in addition a vmec with an exchanger absolutely not provided for high temperature: often plastic

therefore complete overload of a double flow exchanger: too much flow, too much temperature

then I confirm, a big special chimney exchanger (which I have never seen in the trade, but which I made for test) completely breaks the draft: electric draft fan compulsory

in order not to smoke an open fireplace must draw in its hood a flow rate much greater than the smoke flow rate of the fire ... this flow enters all opposite corners of the house and cools as much as the chimney heats: this is the misfortune of the open chimney

good on a double flow style exchanger, much larger and in sheet metal to support overheating could be done, but what good is it because there are stove inserts and boilers that work

[sspid14]

Be careful not to use a conventional double flow exchanger which is not suitable for heat or smoke and grime. In fact, for a good heat exchange, the fumes generally pass through small tubes. These tubes are already clogged very quickly with ambient air (that's why we put filters to change every 6 months - 1 year) so with fumes it's even worse (put a filter for filtering the fumes can be dangerous with such temperatures and in addition it would clog up too quickly).

There are nevertheless stoves that allow you to recover the heat to send it to other rooms, but you need different sheaths than those of your VMC.
Example, see page 7: http://www.stuv.com/files/S21_I_1205_FR_NL.pdf

I would also advise you not to put a fresh air supply (coming from the VMC) in a room where there is a hot air supply (coming from the fireplace, see example above). The VMC will surely be more powerful than natural convection and therefore the hot air will not go into the desired room. Finally, for all this you have to make calculations, when the air comes in somewhere it comes out at the same flow elsewhere.

Besides, a fireplace with indoor air supply and VMC hardly goes well together ...

If your house is well insulated and caulked, the VMC will distribute the heat throughout your house even without a convection duct for the hot air in your home. By this I mean that the heat produced in the room where the fireplace is located will eventually be found in the room (for example) thanks to the heat exchanger and the VMC which will restore the heat in an equitable manner in the dry rooms.
Example: the fresh air arrives in the living room, it is warmed by the hearth present in the room, this air is sucked by the extraction mouth of the bathroom (and at the same time pushed by the mouth of insufflation of the living room), this air passes through the heat exchanger where fresh air heats up and returns to the living room or bedroom to start the circuit again.

[hic]

Hello,
I have a fireplace (open hearth) on the ground floor of my house and the conduit goes into a room on the 1st floor. In order to recover heat from my fire more efficiently, I have two projects:
My questions for the experienced econologist:
- Point 1 seems to be well known to the railroaders I contacted. Is this the most efficient way to do it?
- Point 2 left the contacted track workers a little haggard ... They do not even understand what I mean. Is this a realistic concept? Who can help me on this? I can tinker with something but I would first of all like to have an installation up to standards for insurance reasons and "I don't want to die of burns or suffocation". Thank you in advance !

Hi pieroxy Alternative already proposed in this forum !

* Outside air inlet tube directly into the combustion chamber *

This saves the cold air flow in
by house leaks, due to the chimney draft

1. energy saving
2. Zero energy to make it work
3. security! no more risk of carbon monoxide poisoning
so waterproof
4. easy installation without risk


question!
there is a closed, therefore watertight fireplace, with an outside cold air inlet.