Friday, January 13, 2012

Blacksmith Artisan Inset Stove Comment


Problems with the 
Blacksmith Artisan Inset Stove

Blacksmith Artisan Inset stove with door open

I have just received a comment from a reader outlining their experience with the Blacksmith Artisan inset stove. It would seem their experience echoes the "Artisan" case I have documented.

I am beginning to believe that most if not all inset stoves have an over-rated output figure - through no fault of the manufacturer/vendor company, but perhaps more likely due to the methods of testing used by the test and certification companies.

I have contacts in the building trade, and the word out there is that inset stoves are nowhere as good as free standing stoves of similar rating.

I am inclined to think that it would be a good idea to mentally subtract say 33% from the certified output figures of inset stoves. This would give you a more realistic idea of the heat output. For instance, an inset stove boasting a certified 6Kw output, might perhaps more realistically achieve an actual 4Kw.

The Comment Letter

CK has left a new comment on your post "Blacksmith Stove Review Part 4 - Alert -":

Tony,  I too am from Co.Kerry and have recently purchased the "Artisan" inset stove. My experience is similar to yours - disappointed with the product.

We opted for the inset based on the product description - "Fits into any 16" or 18" fireback". Buyer beware - it does not!

We installed the inset and were so disappointed with its performance that we questioned the installation. We then removed the fireback and fully lined the chimney with a 6" flexible flu liner (which was not needed for the inset stove) believing that this would maximise the output from the stove. Again, this was not the case.

We removed the stove again and had a registered Blacksmith installer (recommended by the retailer) install the stove. He completely sealed the chimney recess with fire cement before reinstalling. The heat output improved slightly,but still disappointing.

I agree with your findings - nowhere near the 5KW output as specified.

Our only option now is to contact the Blacksmith technical department and have someone call to inspect the stove. Is there anyway of measuring the heat output from the stove? Please let me know! 

A Partial Answer to above Question

To accurately and scientifically measure a stoves heat output into a room would require complex laboratory conditions and a lot of equipment.

However, that said, there is a fairly simple test you could do yourself at home. It would not be highly accurate, but it would establish roughly the heat output.

1.  The experiment would need to be carried out on two separate days with very similar weather conditions. It would require a calm day with little or no wind.  The outside temperature would need to be within a degree or so on both test days. For instance a calm day with outside temperatures of 10C.

2.  You would need to let the room go cold overnight to the same temperature on both test days. For instance the room should be at a starting temperature of say 17C on both occasions.

3. You will need to buy or borrow 3 electronic thermometers - these are not expensive and can be got on EBay for €5 - €7. They respond rapidly and are moderately accurate.

4.  You would have two sensors in different parts the room well away from the direct source of heat, - and one measuring the outside temperature.

5. You would need a 3Kw electric convection heater or use two heaters -one 1Kw and one 2Kw. These will provide a reference point. Remembers that electric heaters will reach temperature within a few minutes. A fire will need time to fully ignite, and an iron stove will take time to warm up - so the timing points will need to be offset by roughly 30 minutes, (Assuming an efficient and full ignition of the fire - you may need to add some more time until the fire is good and red)

6. On Test Day ONE.  (a) note the inside and outside temperatures. (b) Switch on the electric heater/s, (c) turn the thermostats up fully and (d) time how long it takes the room to reach a steady 23C.

7. On Test Day TWO. (a) Note the temperatures as before. (b) Light the fire using plenty of firelighter and kindling, and allow 30 minutes for the stove to heat up.  (c) Time how long it takes for the room to reach 23C.

This simple method will give you a ball park idea of the thermal output of the stove against a reference point. My bet is that the electric heaters will have the room up to temperature as quickly as the stove, even though their output is nearly half the rated output of the stove.



1 comment:

Craig Swanson said...

I used this formula to calculate radiation output from my dissertation project - room temperature should be recorded using a sheilded sensor.

Equation 2.1 Qstove=εxσxAx(T⁴s - T⁴surr)
Boltzmann’s Law for Calculating Radiation Loss
• Qstove = radiation heat transfer (watts/m²K)
• ε = emissivity, a ratio between 0 and 1 that varies with surface type. The values for the
stove body and the glass viewing window have been taken as 0.8 for mild steel and 0.94 for the glass window [4]
• σ = 5.6703 x 10⁻8 (Stefan Boltzmann constant )
• A = surface area of the front of the stove
• (T⁴s - T⁴surr) = (stove temp⁴) – (room temp⁴)

You'll need a fairly high temp sensor for the stove though - approx 300˚C
hope this helps, Craig