What makes stoves so efficient?

[Big J]

19 minutes ago, openspaceman said:

In which case you will burn a similar  amount of energy in oil.

 

As I said earlier energy released has to be accounted for, it either goes up the chimney as hot smoke, remains in ash pan as unburnt fuel or it enters the room and is dissipated through roof, walls, floor, windows and vents.

 

In point of fact if the glass blackens the combustion is incomplete which means chemical energy is lost as carbon monoxide and other PICs and of course a decent gas or oil condensing boiler will have a flue gas temperature of less than 100C whereas not many stoves will be lower than 200C which represents a significant loss even with a clean burn.

 

 

The glass blackening was down to it not having an airwash system. It certainly had an effective secondary burn as it always burned cleanly, with little to no smoke emitted from the chimney. 

 

Interesting point on the comparison of heat loss through the flue on oil versus wood burning. Hadn't thought of that before.

 

I look at the stack of firewood at the back of the house and think for the value in it (even just collected, so not having to deliver it myself), I could buy about 6000 litres of kerosene.

[billpierce]

The glass blackening was down to it not having an airwash system. It certainly had an effective secondary burn as it always burned cleanly, with little to no smoke emitted from the chimney. 
 
Interesting point on the comparison of heat loss through the flue on oil versus wood burning. Hadn't thought of that before.
 
I look at the stack of firewood at the back of the house and think for the value in it (even just collected, so not having to deliver it myself), I could buy about 6000 litres of kerosene.

I know what you mean, quite an daily effort keeping fires in as well. Cant be doing with central heating myself though, always end up turning radiators off and opening windows when I stay elsewhere. Feel like a house has a good heart with a fire on in the middle of it.

Also always smug in power cuts still being able to cook, bathe and have a warm house.


Just starting the process of doing a lime and hemp Insulating render to the Inside walls of our stone house the now.

[slim reaper]

16 minutes ago, billpierce said:

Just starting the process of doing a lime and hemp Insulating render to the Inside walls of our stone house the now.

Have you got any info on that system, I am in the near future going to render some stone walls but was going to use lime with cork pellets incorporated. 

[difflock]

Well with our latest Morso, (and the previous 2 are still installed in living room and dining room, and 100% functional)

, despite the never yet cleaned glass being slightly hazy(and 2nd winter of use) but not in any way black,

shows absolutely zero "smoke", even immediately after lighting,

and the flue from this stove  is discharging into the same clay liner lined flue the other Morso used for 20 years.(back to back with the living room stove)

Which has honestly never yet been cleaned, and continues to pull like a train. (And when or if it starts to struggle I shall consider cleaning the flue).

Which is to say it must be burning very very efficiently indeed.

marcus

EDIT

Our bedroom is directly above the living room and it is noticeable how much heat is given off by the 18" square chimney breast running up through the ensuite, which was exactly as I had planned/hoped.

The builder wondered why I wanted the chimney breast inside the cavity wall, when he thought it would be tidier outside thus leaving the ensuite uncluttered!

Edited January 6, 2019 by difflock

[slim reaper]

An interesting read ?

http://www.soliftec.com/efficiency.htm

[Woodworks]

11 minutes ago, slim reaper said:

An interesting read ?

http://www.soliftec.com/efficiency.htm

Great link and look at the numbers for an open fire!

[difflock]

32 minutes ago, slim reaper said:

An interesting read ?

http://www.soliftec.com/efficiency.htm

 

Hmm, I recalled wood to have a calorific value of 4.xx kW,

I  just checked and got 4.44kW, so where does this site get 5kW, presumably for bone dry = zero % moisture content wood.

A tad offputting in respect of the likely veracity of the rest of this sites info imho.

 

[Woodworks]

12 minutes ago, difflock said:

 

Hmm, I recalled wood to have a calorific value of 4.xx kW,

I  just checked and got 4.44kW, so where does this site get 5kW, presumably for bone dry = zero % moisture content wood.

A tad offputting in respect of the likely veracity of the rest of this sites info imho.

 

Yes but the rest of it does have a ring of truth about it. 

[openspaceman]

16 minutes ago, difflock said:

 

Hmm, I recalled wood to have a calorific value of 4.xx kW,

I  just checked and got 4.44kW, so where does this site get 5kW, presumably for bone dry = zero % moisture content wood.

hardwoods bone dry are about 18.6 MJ/kg lower heating value, softwoods a bit more, this is about 5.2kWh(t), at 20% mc wwb this would only have 4.13 kWh(t)  potential energy but would also have to boil off 200 grams of water.

 

I think we should really work in higher heating values and then work out total losses as steam in the exhaust.

 

As an old chemist once told me wood is a good energy source but a poor fuel.

16 minutes ago, difflock said:

A tad offputting in respect of the likely veracity of the rest of this sites info imho.

 

I gave up reading as soon as I saw he didn't know the difference between power and energy.

[billpierce]

Have you got any info on that system, I am in the near future going to render some stone walls but was going to use lime with cork pellets incorporated. 

Not really no, a local builder has done it to the inside of his house and really rates it as it still allows the stone to breathe I.e no damp condensation issues. Also gives a nice finish. Will try and get back to you with details, think it will be many thin coats totalling about 2inchs of render.