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Eco Fan


mrsmelly

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2 minutes ago, WotEver said:

You could run down to the other end of the boat with it, distributing its heat throughout the boat’s length. Then run back and heat it up again. Not only would it have more effect than an Ecofan but you’d be getting your daily exercise to boot. 

On a cold winter's night the OH used to wrap it up in a tea cosy and put it in the bed half an hour before bedtime.

Try doing that with and Ecofan.

Edited by carlt
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18 hours ago, mross said:

I read this report and it was done by a respectable Canadian University.  But their beautiful colour graphic is just a simulation and shows what they think is happening.  There are no infra-red videos.  The report seems to be very well designed.  But, if I were trying to determine the efficacy of a stove fan I would have used an electric heater to represent the heat source so as to have had a constant heat level.  The report is too reliant on the 'technician' keeping the wood burner's output constant. 

Their conclusion is a bit woolly; "Test results shown in the preceding section of this report strongly suggest improvement in fuel saving...."

Does anyone know if their promised follow-up report was ever published?

 

 

http://www.ecofan.ch/pdf/Studie_Energieeinsparung_Ecofan_komplett.pdf

I'm surprised there haven’t been more comments on this paper that Andy3196 initially linked to. My first thoughts were the date it was published. I thought maybe 1st April 2010 but they claim mid July. Then it was the university – Waterloo. I thought there was just a station there? The results just seem too perfect. I believe the Ecofan does work but only the 'environment thermal comfort' and no way I would claim it saves fuel. They used Ash as the wood. I would have used Larch.

I thought it useful to post some of the stuff in the paper. First the temperature map image shown below. Mross is right that it is a simulation but the data seems to fit the tabulated data in the paper and the temperature differentials given in the graph (also shown below). In the graph they have used a temperature differential between knee height and head height so the numbers are smaller than foot to head.

Mross suggests that it would have been better to use an electric stove as a heat source and that would have been the ideal if the purpose of the work was to show how the fan spread the heat around – but it wasn't. The main purpose of the paper was to show that the fan reduced fuel usage and for that you need a stove. The key findings of the paper are:

 

Test results shown in the preceding section of this report strongly suggest improvement in fuel saving and occupant thermal comfort when an Ecofan 800 fan is used with wood stoves.

In all the tests, a consistent and considerable percentage in fuel saving is reported when the thermo electric fan is used with the wood stove. The fuel saving is from 6% to 28% with an average of 14.1%.

 

There is also a strong trend and indication that use of a Ecofan 800 fan improves the environmental thermal comfort. In every test, the VerticalTemperature Difference between occupant head and knee is less when a fan is used. The difference is from 0.2 °C to 0.9 °C

with an average of 0.5 °C. The difference would have been even greater if the difference had been evaluated between occupant head and ankle.

 

Note that they say 'Ecofan 800' rather than 'fan stove'. There are fan stoves and fan stoves. Some must be better than others give the price points.

So there we have. Concrete evidence (unless this was a 1st April report) that the Ecofan 800 works. I dont think I could ever claim that our fan is saving fuel (but we have only used 4 bags of coal in the last 2 weeks instead of 5!) but my feet are definitely warmer – thermal comfort at its best. Go buy a decent stove fan and warm your feet.

 

graph.png.1bd0246b161c76019e2173acf54efcc2.png5a103a7a12ce2_stovefan.png.ae5c0cb4531710b2a2a2c05a7220979c.png

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59 minutes ago, Dr Bob said:

The main purpose of the paper was to show that the fan reduced fuel usage

But people who swear by these fans claim that they spread warmth through the boat.  I don't think people are buying them to save fuel.  The report seems overly complex.  I wonder if this was done because other tests showed that the fan had very little effect. A back boiler and radiators is a much better way of spreading the warmth.

If I win the lottery I think I will build a well-insulated boat with a central stove and underfloor heating!

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Look closely at Dr Bob's graphs above. Look at the temperature difference between the red and the green. The pictures look very dramatic, but in fact they show no more than two extremes of a temperature range of a couple of degrees. I suggest that:

(1) The temperature change would not be readily detected by a human observer who was unaware whether the fan is there or not (ie it's not a blind trial, and certainly not double-blind, which would have removed observer bias);

(2) The publisher may have chosen the two most extreme-looking diagrams from a whole range of results with varying areas of reds, yellows and greens;

(3) The discrimination (accuracy) of the monitoring device is not stated - I'd think it was plus or minus a degree or two at best -- which means that the diagrams are showing nothing more than the experimental uncertainty. 

Bad science, no more, no less.   

2 hours ago, mross said:

If I win the lottery I think I will build a well-insulated boat with a central stove and underfloor heating!

If you're having underfloor heating, how about a heat pump transferring heat out of the canal water? 

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1 hour ago, Machpoint005 said:

Look closely at Dr Bob's graphs above. Look at the temperature difference between the red and the green. The pictures look very dramatic, but in fact they show no more than two extremes of a temperature range of a couple of degrees. I suggest that:

(1) The temperature change would not be readily detected by a human observer who was unaware whether the fan is there or not (ie it's not a blind trial, and certainly not double-blind, which would have removed observer bias);

(2) The publisher may have chosen the two most extreme-looking diagrams from a whole range of results with varying areas of reds, yellows and greens;

(3) The discrimination (accuracy) of the monitoring device is not stated - I'd think it was plus or minus a degree or two at best -- which means that the diagrams are showing nothing more than the experimental uncertainty. 

Bad science, no more, no less.   

If you're having underfloor heating, how about a heat pump transferring heat out of the canal water? 

Not my graphs. Waterloo Universities graphs.

(1) Whilst you may not recognise a 2 deg swing in temperature, I can tell the difference between 18 and 20 deg C in a 'blind' trial - I get used to that watching the telly. It is even more obvious when the temp differential between your head and feet swing from 1 deg to 3 deg. The writers of the paper also note that it is only 2 deg difference between the two extremes but still keep saying it makes a significant difference to thermal comfort.

(2) ...and he may not. Good papers do not pick and choose extremes. They present the real data. All these papers are peer reviewed and I would be surprised if the most extreme looking diagrams were chosen. That assumes it is not a 1st April paper....then all bets are off. How many papers have you had published? You dont fiddle results.

(3) Quite right. If the monitoring device measured only to 2 degs of accuracy, the report is totally useless. If I was doing it, I would have a device capable of 0.1deg. Universities, and Waterloo University, would certainly have access to one of these devices. I think you are wrong in suggesting the monitoring device was not capable of doing the job.

It seems too convenient to me that this paper has turned up with 'perfect' information and I cant find any other papers either saying Eco fans work or dont work. I am suspicious of the energy saving claims. Interested to see any papers that say the opposite. Surely there must be some given the thousands of these fans being sold - not just for boats - if they dont work.

Cue......banter starts again....

Edited by Dr Bob
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14 minutes ago, mross said:

The pictures don't actually show anything useful.  They are just simulations.  Did you not wonder why the stove and flue are not hot?

...but from the paper they are built using 30-40 temperature probes around the room with readings every minute so thousands of data points per run. Yes the simulation could be wrong but unllikely to be that wrong. Physics has moved on a lot in the last 30 years.;) Simulations are used to design lots of critical stuff these days in petrochems and nuclear instalations.

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14 hours ago, mross said:

I don't think the pretty pictures are based on the temperature measurements.  If they were they would not be 'simulations'.

"Oh yes they would".....:D

Seriously, if you read the report closely, you will see they take 56 seperate temperatures at various places round the room. To give the reader an indication of these temperatures, you create a heat map (as per the diagrams) from the 56 readings. This is typical of heat map simulation. You have 56 actual temperature points - you can  then using the simulation software predict the temps at any point in between if you know some other data - such as air flow. This 'simulation' has been used for years in really critical industries - we used it in work to check the design of steam cracker furnaces prior to building a $1Bn industrial plant. Based on a number of measured temperatures you can accurately predict the unmeasured temperatures in between.

It is interesting there has been little discussion on the paper - and most respondants have gone over to the other thread! I am still thinking it might be a spoof. In my career I both wrote and peer reviewed many papers and I would not be happy to put my name to this one. If you write a patent, you HAVE TO put in sufficient data to make it so that anyone 'skilled in the field' can reproduce your experiments and final data. Papers do not have that restriction but it is good practice to help the reader understand what you have done. For me in this paper, there is a big piece missing and that is a flavor of the recorded data - and not just the final calculated data. Therefore if I was writing it, I would have included a number of pairs of graphs (with and without fan) of the key temperature sensor readings with time, and at least included the runs where the extremes of fuel differential useage were seen. I then would have produced the heat diagrams for these runs for comparison. Without this data it is impossible to determine if the writers were missing so key variables that could wreck the final results.

In the writers defence, they were not trying to demonstrate 'thermal comfort' (which is probably our only interest) so maybe that data would not be considered important, but in that case where is the data on fuel useage, ie which runs (and how often) did they need to refuel etc? So much information has been omitted to make it suspicious. On balance I would say it is a very poor paper (but I have very high standards). Is it a spoof? I dont know......but my personal experience does seem to accept the 2 heat maps published match up to with how our fan performs.

 

  • Greenie 1
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A heat map based on actual readings is completely different from a 'computational fluid dynamics' simulation.

As it says n the report, "To calculate and evaluate the impact of using an Ecofan 800 fan on a wood stove on the thermal
environment of the test facility, a computational fluid dynamics analysis was performed. FloEFD Pro 9 TM ,
a commercial CFD package by Mentor Graphics [5]was used to simulate the test facility real case scenarios with and without a fan"

I think you have misinterpreted.

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1 hour ago, mross said:

A heat map based on actual readings is completely different from a 'computational fluid dynamics' simulation.

As it says n the report, "To calculate and evaluate the impact of using an Ecofan 800 fan on a wood stove on the thermal
environment of the test facility, a computational fluid dynamics analysis was performed. FloEFD Pro 9 TM ,
a commercial CFD package by Mentor Graphics [5]was used to simulate the test facility real case scenarios with and without a fan"

I think you have misinterpreted.

I dont think I did. There is a huge amount of real temperature data (which the authors have not presented ...bad) that will have been used to assist in the task.

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2 minutes ago, mross said:

Your argument might convince me if the heatmaps had shown where the temperature sensors were positioned.  :)

Absolutely agree with you. Good spot. In my post above, I was quite negative about what I thought was missing from the paper. Some sort of visualisation of where the probes were would have also been good. You can get a bit of an understanding if you read Appendix 2 on the first paper (page 15 of the 42 I think). This lists the positions of the 56 temperature probes and you work out where they are, but even  then it is not clear as earlier in the paper it says 'To' (the temp where the user is sitting) is effectively a black box with temp sensors on all four faces (in front, at the back and 2 sides) - but the probe list doesnt show these. I cant see the data to convince you, but if I was doing the work it would be essential to incorporate the real data with the modelling.

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To, the operative temperature is the mean of four air temps at ankle, knee, sitting-head and standing-head position and the black box temps you mentioned.  This is at a position 3m directly in front of the fire (and presumably fan).  This temp was maintained at 22.5 by adding fuel and adjusting the air damper.  But how closely he was able to maintain the temp is not clear.  It seems an odd way to test an Eco fan!  You and I could have designed a much simpler and accurate test.

Edited by mross
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In our case Ecofan was sat on a centrally sited Villager Puffin angled backwards into a short corridor leading to the rear bedroom. The difference was quite noticeable during very cold weather, don't know the actual temp difference but it changed an uninviting cold bedroom into a welcoming one. I don't know if anyone has tried one with the same layout as us but I think it's intrinsic to the debate/argument.

Trying to prove one way or the other whether Ecofans work is pointless, no conclusion can ever be reached IMO because it seems to me all results are dependant on individual boats and conditions. 

Feel free to ridicule me! 

 

 

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