I think I have improved my stove

[SawdustSA]

I bought a new stove since I moved into a new house. I bought the identical one to which I had before since it was value for money and the design was ok.

I noticed when I installed the new one that it had an additional vent at the back, in line with the secondary air inlet. The previous one did not have this. On the previous stove, the air was sucked from the floor, via the metal jacket and into the secondary inlet. This pre-heated the air.

On the new one, cold air is sucked in via the new vent into the secondary combustion baffle plate and only then heated.

I noticed during the 1st week of running the stove that it was not as efficient as the old one with lots more smoke from the chimney.

So today, being a rainy Sunday, I stuck a piece of sheet metal with high temperature silicone over the vent. Within 10 mins I noticed the improved glow in the stove, with less smoke out the chimney. I managed to run the stove at 40% primary air compared to 100%.

Am I missing something or did I actually improve the stove's function? Surely I am not supposed to improve a design with a small piece of sheet metal while some guys in white coats spent years designing it?

 

[Oldman47]

Nobody can argue with your results. On my own stove there is a rear entry vent point that needs to be closed if I use an outside air kit. Maybe what you found is something like that.

 

[DougA]

No stove should run at 100% primary air, except to get a fire started. Even 40% seems high.

I would contact the manufacturer and see what the reason is for the new opening. Oldman may be correct that it's for an outside air kit, but still, something seems very wrong. Nothing showing in your manual?

 

[Ashful]

All designs are a compromise of performance goals and installation flexibility, so what you did is likely just shift the compromise in your favor, for your set of circumstances. The guys in white coats (actually, we usually wear plaid and khakis) may have eliminated that part of the design for reasons that don't favor your particular installation.

 

[SawdustSA]

No stove should run at 100% primary air, except to get a fire started. Even 40% seems high.

I would contact the manufacturer and see what the reason is for the new opening. Oldman may be correct that it's for an outside air kit, but still, something seems very wrong. Nothing showing in your manual?

That reminds me, I need to remove the plastic off the user manual!

 

[peakbagger]

From your description it looks like you have defeated an air emission modification. The most emissions on the stove are when someone fills it up full and then shuts off the air to try to stretch the burn time. By adding a set of tertiary ports (frequently hidden) that don't have air controls on them, the owner cannot turn the air off. It makes a big difference on emissions but does impact the flexibility of the stove.

 

[Isaac Carlson]

I feel fairly confident when I say that most stove designers don't know what they are doing. It is not hard to design a good, efficient stove with easy to use controls.
It is hard to sell a simple stove to people looking for the newest and most modern model with "technology" in it. People are too eager to fall for a fancy sales pitch in search for something "cool" or "new" or "better".

A friend of mine bought a very shiny and expensive dodge truck a few years ago. It was a lemon and had engine, transmission, and many other problems. He insisted that it was a very good truck and paid many times to have it "repaired" only to find out it was not fixed or the part was replaced with the same thing it had in the first place. It cost him more than it was worth and he was finally forced to get rid of it.

A number of years ago we were looking at building a log cabin up north and wanted to be off grid. We were looking at popular vendors of cook stoves and we were shocked at the prices, which could easily exceed $10,000 for something that was an exact replica of a small antique stove with the same problems as the old ones, and with a lot of chrome added to make it look expensive. The stove we bought cost a third of that and exceeds claims by a fair margin. It does not look fancy or expensive, just great. Coaly has the same stove.

 

[SawdustSA]

From your description it looks like you have defeated an air emission modification. The most emissions on the stove are when someone fills it up full and then shuts off the air to try to stretch the burn time. By adding a set of tertiary ports (frequently hidden) that don't have air controls on them, the owner cannot turn the air off. It makes a big difference on emissions but does impact the flexibility of the stove.

The secondary air inlet has not been shut off by closing this vent. It is now directed to enter via the lower end of the firebox, up the back of the stove and then into the baffle plate, just like on my old stove. My understanding is, is that the secondary air is better pre-heated before it enters the secondary air baffle plate.

I have attached a rough sketch showing what I did. The purple cover at the back is what I fitted and that blocked off the cold air entering the secondary ar baffle. The remaining secondary airflow is illustrated with the blue/red arrows.

 

[Isaac Carlson]

The hotter your secondary air, the better. 800 degrees is good and anything above that is even better.

 

[velvetfoot]

That reminds me, I need to remove the plastic off the user manual!

Believe it or not, I just looked at the manual, and I couldn't find any reference to that hole. I guess you should contact the mfr. to find out anything. Or, just keep it the way you have it now!
(broken link removed to http://www.yeomanstoves.co.uk/download/Boca%20Stoves/Aresta_Limit_Firepoint%20Installation%20and%20User%20Instructions.pdf)

 

[SawdustSA]

Yes, my manual is also very generic and only gives the basic info and instructions.

I also found that the draught of the stove was not as good as the previous one. I would have to clean the glass more often even though my wood is well seasoned.

I then raised the chimney cap just under an inch and voilla, problem solved. Strange how small things can make such a difference. I now get overnight burns and a very clean secondary burn too.

 

[velvetfoot]

Excellent. I kind of forgot it was a new stove in a new house.