STOVES questions and answers here(see mod note in post 1)

JMSE

Having read up on the Esse 350GS tonight, the writeup on the stovecentre.ie is confusing. They mention operating range up to 14.7kw/h and then they say its output is 7 , heres the text....

The 350 GreenSwitch™ is a room heating stove
with thermostatic boiler. It has an operating rangeof 14.7kW/h but gives only a modest 3.6kW/h to the room and a generous 11.1kW/h (38,006 Btu) to water. These figures are based on wood burning and will be slightly higher when burning mineral fuel.The 350 GreenSwitch™ is equipped with a control (the Green Switch) that adjusts the airflow to maintain the most efficient combustion whether burning wood or mineral fuel. Its large capacity firebox makes the it a versatile woodburner.Like the rest of the 300 series it fits into a standard fireplace, however a depth of 372mm must be created to allow for its larger capacity firebox.
Size: 541mm h x 400mm w x 372mm d
Stock No (SKU): Esse Green Switch
Flue: 6"/150mm
Weight: 0 Kg
Output (KW): 14.0000



Features and specification
- Fits standard fireplace with brick fire back
removed
- Suitable for continuous burning
- Additional room vent required
- Suitable for class 1 chimneys
- Operating range up to 7kW/h (Logs)
- Efficiency - 72% (Logs)
- Fuel consumption – 2.1kg per hour (Logs)
- CO emissions - 0.43 (@ 13%O2) (Logs)
The 350GS is available with a choice of 6 doors



Anyone know what the difference between the 14 and the 7 is?

Stove Fan

joec1 wrote: »

Stovefan,
If I could get some advice please regarding which stove to buy.
I have figured out that I need around 6kw and no more to the room and much as possible to the boiler (need to heat about 13 rads). I have been researching the henley blasket, mulbery beckett, charnwood 16b, olymberl aidan.
I know the charnwood is a good bit more expensive than the rest, but I have a feeling that is because it is better built. Is this true, and what would you recommed that I go for. Maybe you could suggest something different. Some guys in the shops say things like "the henley is too new and we are wary" or "the mulbery is crap and we have people bringing in worn out parts".
I find it difficult to get impartial advice,

Any thoughts on this would be very much appreciated, as we are ready to make the plunge in the next week or so.

I really need the required output:) as 13 rads could be a very large output if they are all doubles.

Stove Fan:)

Stove Fan

MightyMunster wrote: »

Hi,
Looking for some advice on inset stoves.
Have a width of around 670mm and looked at a Tripp TR8C (€1500), a Bodart & Gonay Infire 683 (€2500), and a Wanders Square 68 (€2000).
Besides the additional fans and thermostat on the Bodart & Gonay would there be much of a quality difference between these or are there any better alternatives?
We want a minimalist inset style with maximum glass on the front.

Also the budget isn't huge, hoping for a total installed price of around €2000 as minimal work is required on the fireplace.

Would be grateful for any tips as its all new to me!

Thanks

Hi:) I don't know anything about the above inset stoves. Have a look at Esse inset stoves. These would allow enough for installation.

Stove Fan:)

Stove Fan

mariskalisa wrote: »

Hi

Could someone help me please? I would like to get a boiler stove fitted to provide hot water and to heat radiators but am unsure of what output I would need. I have asked several plumbers and they all gave me different answers from 9KW to 14KW to 28KW so I'm a bit confused.

The measurements of my rads are as follows: 2 doubles 1700mm x 500mm, 1 double 2400mm x 600mm, 1 double 1300mm x 700mm, 1 single 2000mm x 600mm, 1 single 950mm x 700mm, 2 singles 1700mm x 500mm and 1 single 1450mm x 500mm.

Any feedback would be really helpful

Mari

Hi:) based on the rad sizes given then your looking for a 24kw boiler stove. Aarrow stratford TF90 is a possible.

Heinbloed is right though in that it really needs the heat loss calculated as generally not all installers size the rads to the required heat loss for a certain room. This can lead to a radiator being too big or sometimes even too small. Unfortunately though if all the rads are all oversized there isnt much point in fitting a much smaller boiler stove.

Stove Fan:)

Stove Fan

Rob_talisman wrote: »

Well ive finally received all my parts for the stove, turned into a bit of a mess..

My next stage was to get the chimney lined. But ive just been speaking to someone about doing this and i think im getting mixed advise.

I currenly have a gas fire in the room which is connected to a 6" steel flue liner already. i was under the impression id have to remove it and fit a new one, but ive now been told there is no need when i have a steel liner there already and its drawing nicely...

so confused. obviously if i didnt need to change it it would save a lot of messing about let alone the expense.

any advise?

Hi:) If the existing liner is suitable for solid fuel use and the installer has verified it's condition then yes you could use it.

I would be very surprised if when the gas fire was fitted they used the better dearer grade liner for solid fuel and not the cheaper gas/oil liner only one.

If there is any doub't fit a new one:)

But you never know:)

Stove Fan:)

Stove Fan

ravendude wrote: »

Hi there,

I'm considering installing a stove to heat a reasonably size-able open plan area in an existing house (approx 16 years old).
The area is approx 60sq metres. It comprises a kitchen area, dining area and sun-room (used as a living room). This open plan area is where we spend most of our time in the house. Each of the 3 areas is approx 20sq metres of the overall 60sq metres, and the sunroom has vaulted ceilings.

We're looking at a circa 9KW solution.

We would be after a very contemporary looking stove to fit in with the overall style of the area.

We have 2 options:
1/ Convert an existing fire place in the dining area to an inset one.
2/ Block off the existing fireplace (maybe just with a chimney balloon), and install a new free standing stove into the sunroom area.

I've looked into number 1 and it looks like it could get very pricey, - ie. with flue lining, widening of fire opening, installation, removal of existing surround etc. I think you're looking at 1500euro minimum in installation work, at a conservative estimate.

I've just thought of number 2 (new free standing stove in the sunroom) as another option.
This would involve bringing a flue up and out of the sun-room. Actually it would probably need to exit at the top of the wall rather than the roof, - because there are decorative wooden beams on the roof. There are also quite a few windows in the sunroom which isn't ideal, - but, it is a very pleasant room in which we spend a lot of time.
We'd actually prefer this (option number 2) as we would get more enjoyment of the stove because it would be where we watch TV etc. and could act somewhat as a focal point.

I'm just wondering, - is the installation of such a free standing stove (obviously flue is required) generally more or less costly than converting an existing fireplace?
Are there any important factors to consider?

Thanks in advance!

(PS, this thread has already been most helpful)

Hi:) both options could be pricey:( The stove in the sun room could cost more depending on the height of the new insulated twin wall chimney. Are you sure 9kw is enough heat? I may be wrong but think 12 kw would be wiser with having an open plan layout and one vaulted ceiling.

It would be best to get 3 quotes and see what they suggest:)

Stove Fan:)

Stove Fan

JMSE wrote: »

Having read up on the Esse 350GS tonight, the writeup on the stovecentre.ie is confusing. They mention operating range up to 14.7kw/h and then they say its output is 7 , heres the text....

The 350 GreenSwitch™ is a room heating stove
with thermostatic boiler. It has an operating rangeof 14.7kW/h but gives only a modest 3.6kW/h to the room and a generous 11.1kW/h (38,006 Btu) to water. These figures are based on wood burning and will be slightly higher when burning mineral fuel.The 350 GreenSwitch™ is equipped with a control (the Green Switch) that adjusts the airflow to maintain the most efficient combustion whether burning wood or mineral fuel. Its large capacity firebox makes the it a versatile woodburner.Like the rest of the 300 series it fits into a standard fireplace, however a depth of 372mm must be created to allow for its larger capacity firebox.
Size: 541mm h x 400mm w x 372mm d
Stock No (SKU): Esse Green Switch
Flue: 6"/150mm
Weight: 0 Kg
Output (KW): 14.0000



Features and specification
- Fits standard fireplace with brick fire back
removed
- Suitable for continuous burning
- Additional room vent required
- Suitable for class 1 chimneys
- Operating range up to 7kW/h (Logs)
- Efficiency - 72% (Logs)
- Fuel consumption – 2.1kg per hour (Logs)
- CO emissions - 0.43 (@ 13%O2) (Logs)
The 350GS is available with a choice of 6 doors



Anyone know what the difference between the 14 and the 7 is?

I think the stove centre has got it wrong as on the esse website it does not mention 7kw.
http://esse.com/multifuel-stoves/350gs/

Stove Fan:)

Planet X

Just put in this week.
I like it.

heinbloed

JMSE quoted

It has an operating rangeof 14.7kW/h but gives only a modest 3.6kW/h to the room and a generous 11.1kW/h (38,006 Btu) to water. These figures are based on wood burning and will be slightly higher when burning mineral fuel.

and asks

Anyone know what the difference between the 14 and the 7 is?

The 14 kW are for mineral fuel (propably coal meant here) and the 7 kW are for timber fuel.

The moisture content is important, standard calculations take 10-12% water content for timber. Timber stored outside but sheltered will have about 20% water content. The higher the water content the lower the output.

- Operating range up to 7kW/h (Logs)
- Efficiency - 72% (Logs)
- Fuel consumption – 2.1kg per hour (Logs)

The output numbers quoted by Esse seem to represent the efficiency
of their boiler when using soft wood logs at 10% moisture.

With 0 % moisture pine and spruce have an energy content of 5.03 kWh/kg
With 10% moisture 4.51 kWh/kg.
with 20% moisture 4.08 kWh/kg.

A 2.1 kg load with 10% moisture content burned at 72% efficiency would deliver 6.81 kWh of thermal energy.

If we take oak the energy content would be 5.03 kWh/kg at 0% moisture.
4.51 kWh/kg at 10% moisture and
4.08 kWh/kg at 20% moisture.
If the oak logs hold 20% moisture the thermal energy created would be 6.16 kWh when burned with a 72 % appliance efficiency.

You see that only kiln dried soft wood timber will give the stated efficiency. And this is expensive.
Lidl has a special offer at the moment selling 8 kg kiln dried soft wood for around € 3.50. Which works out at 9 cents per kWh when burned with a 72 % efficiency.
Only electricity is a more expensive fuel to heat a home - under the circumstances described.

JMSE

Just to be fair to the Esse 350 GS, here is the correct spec from the esse website....

Model
350 GS
Fuel
Logs
Output KW EN13240(ST)
14.6 total split by 3.6kw to room and 11.1kw to water
Efficiency %
75.7 (wood) - 72.7 (mineral-anthracite)
CO Emissions Corrected to 13% O2
0.4
Fuel/Hr Kgs
3.8
Flue temp Mean °C
395

So to use Heinbloed's formula, a 3.8 kg load of pine/spruce with 10% moisture content burned at 75.7% efficiency would deliver 12.97 kWh of thermal energy.

heinbloed

So to use Heinbloed's formula, a 3.8 kg load of pine/spruce with 10% moisture content burned at 75.7% efficiency would deliver 12.97 kWh of thermal energy.

Yes, but:

The efficiency ( %) drops the more water is in the fuel. First the water has to be evaporated and blown out. Then the remaining dry timber can be burned.
The decrease of the stove's usefull output performance (it's room heating efficiency) is not linear but dynamic.
There is 0 output from timber with ca. 75% if burned in a non-condensing appliance.
The 25% of dry timber contained in a load with 75% moisture will be needed to avaporate the water. With zero output to the heatexchanger, to the room side.
Timber at 50% moisture can be burned in special devices but with only little heat made available for thermal usage, most energy will be going up in steam. Out of the chimney, being lost.
Unless a condensing device is installed!

And without using the entalphic energy (for example with a condensing boiler) nothing or very little will be gained.

Despite that there is 50% of the fuel's weight dry timber we do not get 50% of the thermal energy contained in the fuel for usage. Only a very small fraction of this. Since most of the energy contained is used to boil the water away.

I see people ' making use ' of wet timber throwing it into a blazing fire. This is idiotic, but try to explain this. Daddy did do so, grand dad did so .....so it must be right.

Imagine the open fire has a pot of water hanging over it, a cauldron. All energy going into the pot will be carried away. The more water there is in it the more energy will be carried away.
We will get to a point when there isn't enough fuel (heat) available to boil it all away. Zero output to heat the room, all thermal energy created up the chimney.

There are charts available for the actual usefull energy output of heating appliances fueled with damp or dry timber, with fuel containing various grades of moisture.
Before deciding for a timber or solid fuel stove ask for this chart, for the particular device/boiler. And compare this with your fuel source.

As said: the output of a combustion device decreases the wetter the fuel is - in a non-linear slope on the efficiency chart.

Timber logs stored outside but sheltered will have an average moisture content of 20%. Average means seen over the year, the moisture will vary from 15-18% in summer and from 25-28 % in winter.
And in winter the stove will be used.

Maybe someone could publish or link such a chart here?

darkstream

We are thinking of getting a Dunsely Highlander 5 for a room 4.5m x 4.5m. It's for heating the room only. Got a quote of £635. Would this be a good stove or can anyone recommend an alternative.
Also, is a flue liner necessary or can you do without one?

Stove Fan

darkstream wrote: »

We are thinking of getting a Dunsely Highlander 5 for a room 4.5m x 4.5m. It's for heating the room only. Got a quote of £635. Would this be a good stove or can anyone recommend an alternative.
Also, is a flue liner necessary or can you do without one?

Dunsley stoves dont make a poor stove, they are all great. The yorkshire being a great boiler stove. You wont go wrong with buying a dunsley:D

If this is an old unlined brick or stone chimney then I would line it.
If this is a clay lineed flue it really depends on the condition of the clay liners and if the stoves flue pipe can be joined and sealed to the base of the clay liners with a clay adapter. This adapter stops any tar/condensation from running out at the base of the chimney and diverts it back into the stove to be burnt off. If this adapter isn't used you can get tar seeping out onto the stove and creating a smelly mess. Sometimes it's not possible to use this adapter as the clay chimney liners edges are covered by the brick support. If your liners have a good edge all around the adapter would work:) A photo would help.
If this is not the case I would line it as this would eliminate this problem:)

scroll down to see this clay liner adapter:)

http://www.stovesonline.co.uk/wood_burning_stoves/single-skin-flue.html



Stove Fan:)

darkstream

Hi stovefan, it's a new build so chimney would be in good condition and is clay lined. Of what I can remember there was a concrete slab support but not sure if this was flush with clay liners. We're not in it yet so will get a photo tomorrow and post then.

Qualitymark

Could I ask for a sister thread on firewood - quality, prices, sources, etc?

I got a first load of wood from a supplier in the midlands that was great, but the second load from the same seller was so damp as to be virtually un-burnable, ranging from 34% to 38% moisture. He's now going to come back to me with kiln-dried wood; I have no idea what this costs, but suspect that it's going to be well beyond my budget as a long-term customer.

A friend told me about another supplier, in Wicklow; however when I asked about calling in to see their wood they were horrified. I really don't want to buy wood as a pig in a poke, and want to be able to stick a moisture meter in whatever I'm going to put in the stove.

darkstream

Stove Fan wrote: »

Dunsley stoves dont make a poor stove, they are all great. The yorkshire being a great boiler stove. You wont go wrong with buying a dunsley:D

If this is an old unlined brick or stone chimney then I would line it.
If this is a clay lineed flue it really depends on the condition of the clay liners and if the stoves flue pipe can be joined and sealed to the base of the clay liners with a clay adapter. This adapter stops any tar/condensation from running out at the base of the chimney and diverts it back into the stove to be burnt off. If this adapter isn't used you can get tar seeping out onto the stove and creating a smelly mess. Sometimes it's not possible to use this adapter as the clay chimney liners edges are covered by the brick support. If your liners have a good edge all around the adapter would work:) A photo would help.
If this is not the case I would line it as this would eliminate this problem:)

scroll down to see this clay liner adapter:)

http://www.stovesonline.co.uk/wood_burning_stoves/single-skin-flue.html



Stove Fan:)

Hi stovefan, here is the picture attached. What do you think? Would prefer to be able to go without expense of flue liner if possible

Stove Fan

darkstream wrote: »

Hi stovefan, here is the picture attached. What do you think? Would prefer to be able to go without expense of flue liner if possible

Hi:) The good news is that lining the flue can be avoided providing its fully sound and smoke tested:) I would use the sump adapter in the link I posted as its more suited to the flat concrete. Seal the sump adapter edges well to the concrete but not with silicone. Even the high temp bursts into flames:eek: I would use firecement.

The stovepipe flue will join to the clay sump adapter.

Stove Fan:)

dersawazzie

Hi guys , sorry to go over old ground here , but have read so many posts with differing opinions on installing a Stove I thought I would just post my circumstance and see what you think of it.

I am planning to install a Stove (room heater only 6Kw) using an existing fireplace , which I have never used. House is 6 years old , and clay 8" liner has been used. The fireplace opening is approx 540mm wide. Given that there has to be 150mm air gap either side of the Stove to non-combustible surface , this rules out installing the Stove into the fireplace recess. So it would appear that the Stove has to be fitted using the rear flue outlet , and this is where the majority of your help is reqd.

Given that the flue outlet from the Stove is 5" and I will be using coal , I plan on increasing this to 6" immediately. Herein lies problem #1 , this will join to a 150mm horizontal , will the extra length on the 5"-6" adaptor , prove a problem (too much combined horizontal).

Now once I have negotiated this , I will be connecting to a tee with cap then running a vertical flue up to the clay liner. If I used a register plate sealed at fireplace , would I be able to use 6" flue pipe up inside the 8" clay liner unsealed within the flue ?(I hope you understand that description) And if this method is ok , how far up should I go with flue.

Or is the clay sump adaptor sealed with fire cement the better way to go. Again lads , I understand some idea's aren't for all , but I would welcome your thoughts and guidance. Cheers.

Stove Fan

dersawazzie wrote: »

Hi guys , sorry to go over old ground here , but have read so many posts with differing opinions on installing a Stove I thought I would just post my circumstance and see what you think of it.

I am planning to install a Stove (room heater only 6Kw) using an existing fireplace , which I have never used. House is 6 years old , and clay 8" liner has been used. The fireplace opening is approx 540mm wide. Given that there has to be 150mm air gap either side of the Stove to non-combustible surface , this rules out installing the Stove into the fireplace recess. So it would appear that the Stove has to be fitted using the rear flue outlet , and this is where the majority of your help is reqd.

Given that the flue outlet from the Stove is 5" and I will be using coal , I plan on increasing this to 6" immediately. Herein lies problem #1 , this will join to a 150mm horizontal , will the extra length on the 5"-6" adaptor , prove a problem (too much combined horizontal).

Now once I have negotiated this , I will be connecting to a tee with cap then running a vertical flue up to the clay liner. If I used a register plate sealed at fireplace , would I be able to use 6" flue pipe up inside the 8" clay liner unsealed within the flue ?(I hope you understand that description) And if this method is ok , how far up should I go with flue.

Or is the clay sump adaptor sealed with fire cement the better way to go. Again lads , I understand some idea's aren't for all , but I would welcome your thoughts and guidance. Cheers.

Hi:)
If it was me installing it I would use a 45 degree bend on the stoves rear flue exit and a bit of pipe then another 45 degree bend and then vertical to the clay sump adapter. It would get rid of any horizontal runs and make sweeping easy. If space is tight and you need the stove more forward you could fit a 150mm length on the stoves rear outlet and then the 45 degree bend etc.
Fit a closure plate infront of the fireplace opening after fabricating the stoves fluepipe.

Stove Fan:)

Peterjones

Joe

Would stay away from Henley they import stoves from China and I am hearing
they are rubbish ...and if anything goes wrong or you need a part !!!
Charnwood I believe are a good stove but kinda pricey .... I have been highly recommended the new Waterford Stanley stove the Reginald which apparently is manufactured in Waterford and can heat min of 12 radiators so am thinking of going with it

Vince1974

Picked up a Stovax Riva 40 yesterday at Murphy Heating in Kinvara. The guy there was very helpful and we're looking to install it elevated from the floor on a stone hearth. I'll post some pics of how it looks, before and after and all that.

We should have it finished in the next couple of weeks.

dersawazzie

Stove Fan wrote: »

Hi:)
If it was me installing it I would use a 45 degree bend on the stoves rear flue exit and a bit of pipe then another 45 degree bend and then vertical to the clay sump adapter. It would get rid of any horizontal runs and make sweeping easy. If space is tight and you need the stove more forward you could fit a 150mm length on the stoves rear outlet and then the 45 degree bend etc.
Fit a closure plate infront of the fireplace opening after fabricating the stoves fluepipe.

Stove Fan:)

Cheers for quick reply , I was originally going to use 2 x 45 degree bends as you suggest but was put off it by some previous thread due to (I think) that a collection tee was the way to go. Obviously with 45's there is a continual rise so should be better than a 90 on a tee , and I'm sure that there is a 135 tee with cap av available so that again would fit both the continual rise aspect and the collection/cleaning point. As regards the closure plate , is this just for aesthetics , as I had planned to tile in around the fireplace and leave it open. Once again thanks for response.

Stove Fan

dersawazzie wrote: »

Cheers for quick reply , I was originally going to use 2 x 45 degree bends as you suggest but was put off it by some previous thread due to (I think) that a collection tee was the way to go. Obviously with 45's there is a continual rise so should be better than a 90 on a tee , and I'm sure that there is a 135 tee with cap av available so that again would fit both the continual rise aspect and the collection/cleaning point. As regards the closure plate , is this just for aesthetics , as I had planned to tile in around the fireplace and leave it open. Once again thanks for response.

fitting the 135 tee would be fine as well. The closure plate was just for aesthetics, but obviously not needed if you want acess to sweep the flue on the base of the 135 tee.

Stove Fan:)

ripcord

Hi. I have a real fire pretty similar to the one posted below. There is a gas connection at the side of the fire place, and I'd like to take out the fire and put in the gas stove shown below.

As some background: It is a two-storey semi-D. The fire has never been lit (although I think there might be a nest in it). I don't have a flue for the stove. The stove runs from natural gas, and there is a natural gas connection beside the fireplace. I only want the stove to heat the sitting room.

I will obviously be getting an RGI to put it in. I was just wondering what is involved in the process? Do I need to mess around with the fire back? Or is it simply just about sitting the stove in front of the fire? Would it be cheaper to get the flue myself rather than let the RGI supply it?

I've also seen there are adaptors for stoves that bridge the gap between stove and fireplace. See below for example. Are these custom fit? Or is there a generic on I could use? Would look nice.

Thanks for any help!

FirePlace:

Aquos76 wrote: »

New Stove:



Adaptor:
[/QUOTE]


[/QUOTE]

Reyman

heinbloed wrote: »

JMSE quoted


and asks
The 14 kW are for mineral fuel (propably coal meant here) and the 7 kW are for timber fuel.

The moisture content is important, standard calculations take 10-12% water content for timber. Timber stored outside but sheltered will have about 20% water content. The higher the water content the lower the output.



The output numbers quoted by Esse seem to represent the efficiency
of their boiler when using soft wood logs at 10% moisture.

With 0 % moisture pine and spruce have an energy content of 5.03 kWh/kg
With 10% moisture 4.51 kWh/kg.
with 20% moisture 4.08 kWh/kg.

A 2.1 kg load with 10% moisture content burned at 72% efficiency would deliver 6.81 kWh of thermal energy.

If we take oak the energy content would be 5.03 kWh/kg at 0% moisture.
4.51 kWh/kg at 10% moisture and
4.08 kWh/kg at 20% moisture.
If the oak logs hold 20% moisture the thermal energy created would be 6.16 kWh when burned with a 72 % appliance efficiency.

You see that only kiln dried soft wood timber will give the stated efficiency. And this is expensive.
Lidl has a special offer at the moment selling 8 kg kiln dried soft wood for around € 3.50. Which works out at 9 cents per kWh when burned with a 72 % efficiency.
Only electricity is a more expensive fuel to heat a home - under the circumstances described.

A most useful post Heinbloed - many thanks! It's nice to see concise figures explaining the 'sums' of burning wood.

May I add my small input to this by calculating the energy cost of boiling off the water in wood at 20% moisture by weight

1 kcal = Energy required to boil one 1kg of water by 1deg centigrade.
20% moisture means there is 200gms of water in each 1 kg of wood.
If we assume the wood is at room temperature 20 deg centigrade, we need to heat it to 100 degrees to boil it off i.e. an increase of 80 deg centigrade

So energy needed is 0.2kg x 80 = 16kcals.
Conversion factor : 1 kcal = 0.001163 kWh
So energy used = 16 x 0.001163 = 0.019kWh
Energy in 1kgm of wood at 20% moisture = 4.08kWh so the available energy is reduced by 0.019kWh to 4.06kWh. – A negligible amount.
Conclusion: Ignore the energy cost of evaporating moisture from normally dried wood (20% moisture)
(Please feel free to comment on my methodology – I’m a bit rusty at this kind of physics)

heinbloed

Hello Reyman!

Well done to calculate the theorie. I have not checked your numbers, only the logic behind it, the plausibility of the method.

So the following has to be considered to get realistic results:

20% moisture means there is 200gms of water in each 1 kg of wood.

Not correct as such, better: 20% moisture means there is 200 gramms of water in 1 kg of fuel. 1 kg of this fuel contains 800 gramms of timber.

Next:

If we assume the wood is at room temperature 20 deg centigrade, we need to heat it to 100 degrees to boil it off i.e. an increase of 80 deg centigrade

Wrong assumption: the min. temperature for the flue gases are usually around 300 degrees Celsius (read the stove's manual), colder flue gases ask for condensation, a wet chimney, a rusting stove and taring of the chimney. Risk of total material loss and more.

The min. temperatures of the flue gases which has to be kept at the oulet of the combustion device at all times are given by the stove/boiler manufacturer.

Next the thermodynamic behaviour of the chimney has be calculated:

The length of the chimney, it's internal surface temperature and the gas flow rate have to be considered. The inner surface temperature of the chimney has to be above 200 degrees at all times. To get a non-condensing effect.

Further:

During the starting of a fire the internal surface temperature of the chimney causes condensation. Which is unavoidable. This first condensation has to be evaporated away by bringing the flue gas temperature ( the steam temperature ) above criticality. Criticality is reached at about >300 degrees Celsius.

So to dry the condensed water away a flue gas temperature of over 300 degrees has to be met. This exact number can be found in steam engineers handbook's, not many stove installers are aware of this basic rule.

Once the chimney's entire inner surface is hotter than 100 degrees Celsius ( which takes a time, depending on length, surface=m2 and thermal
conductivity) and after the previously present water has evaporated
the temperature of the flue gases can be reduced. Brought below cricality.
But not below the device's min. operational temperature.
This min. temperature can be found with the manual.

Since it takes much longer to get a 'hot' fire with damp wood compared to dry wood the condensation caused in the still 'cold' chimney flue will be larger (liters/m2 surface) than compared to dry wood (10% moisture). Not only because of the extended time it takes to bring the surface up to temperature but also because of the excess of water present in the fuel - from the very beginning of the combustion process, the start of the firing process.
On the one side we are heating up the surface and on the other side we are depositing condensation, both happens paralel until the flue gas reaches it's criticality.

This is a dynamic process, a non-linear calculation.

Therefore most stoves are legally limited to 20 % moisture in the timber fuel.
Some manufacturers tell the clients in the manuals they publish that it would be o.k. to fire timber with more than 20% moisture.
But this is only true with a direct connection to a flue which allows for condenstion and which is outside of the habitated space - the risk of chimney fire due to tar deposits !

The external flues which are double walled (insulated, closed, no air circulation between the two pipes) are suitable for such a very air polluting combustion method. This method would be fire-safe for the house and it's inhabitants but illegal because of environmental legislations. Illegal in most EU member states, not in all - still.

Now back to the calculation sheet. Take a real manual from a stove certified for all EU states as a sample as a point to start.
Here we can find the minimum outlet temperature for the stove.

Then compare the thermal behaviour of the external insulated stainless steel flue-gas pipe with the behaviour of a brick chimney.
We will get two different results due to the differing thermal conductivity and hygroscopical behaviour. Unglazed brick sucks up water like a sponge, clinker less so. Better here : glazed clinker.

The result of this comparrison will show us that a stove fitted into a brick/clay chimney will allow only for dry timber (<10% moisture) to be used legally. With glazed brick at maybe 15%, with glazed clinker at maybe 18%.
The stainless steel exterior flue gas pipe will allow for up to 20% moisture in the short time usage (an evening of usage) and for up to 25 % moisture in the 24h/day usage.
We are not looking at the enviromental problems here (PACs, fine particles etc.), only at the fire safety !

The results of the calculations will differ with glazed bricks/liners and the total length/surface.

If a stove seller would tell his clients the truth based on a calculation like this (which is legally required before comissioning the installation in most EU countries!) he would be out of business.
Well, most of them. Due to the high costs of a proper installation and the fuel inefficiency revealed beforehand.

Good luck with the calculation!

Basq

Hey gang,

My mother got a stove recently.. and is wondering what's best to clean the glass? She's tried both cream cleaner (Jif) and windolene but still finds it quite hard work. Is there any specialist product or anything else worth recommending?

Thanks in advance.

dersawazzie

A further question which I kind of already know the answer to ! I have seen many manufacturers offering systems for connecting to clay liners , which have 90 degree bends in them and horizontal piece longer than 150mm and a clay adaptor. I have read document J and this seems to contradict these units being up to legislation. How are they selling them as suitable for such situations ?

Stove Fan

Basq wrote: »

Hey gang,

My mother got a stove recently.. and is wondering what's best to clean the glass? She's tried both cream cleaner (Jif) and windolene but still finds it quite hard work. Is there any specialist product or anything else worth recommending?

Thanks in advance.

If coal used try mr muscle oven cleaner spray but wear the necessary protection. Or there are actual stove glass cleaners from stove shops.

If you only burn wood dip a damp/wet tissue/cloth in the wood ash and rub liberally. Use dry tissue to clean mess off.

This only works with wood ash as any coal residue will scratch the glass.

I just use a wet green backed sponge and rub the glass and use kitchen paper to dry.


See here also.
http://www.boards.ie/vbulletin/showthread.php?t=2055429828


Stove Fan:)

Basq

Thanks Stove Fan.. very helpful reply!