Eco Fan

[nb Innisfree]

54 minutes ago, mross said:

Can you make a video, on your phone, of you holding a tissue in front of the Ecofan and see how close you have to get to detect air movement?  I reckon it was less than six inches with my Stirling fan, even when the stove was at max output.

Who me? Not really as I don't own an Ecofan any more or a boat to go with it. 

[Dr Bob]

1 hour ago, nb Innisfree said:

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! 

 

 

Have a greenie. ....but its not only the conditions and boat, it also depends on an individuals abilitiy to feel temperature differences. I must be more sensitive to temperature as I certainly feel 'more comfort' with the fan. That always assumes however you have a fan that does move air. From what I see here, many fans do not.

[Dr Bob]

I'll try and do a video later in the week when we are back on the boat.

[nb Innisfree]

9 minutes ago, Dr Bob said:

Have a greenie. ....but its not only the conditions and boat, it also depends on an individuals abilitiy to feel temperature differences. I must be more sensitive to temperature as I certainly feel 'more comfort' with the fan. That always assumes however you have a fan that does move air. From what I see here, many fans do not.

If our boat had a front sited stove I doubt we would have felt any improvement in the bedroom, the aiming at the corridor immediately adjacent was the vital factor IMO. One visual improvement was getting rid of a bit of  incipient condensation in the bedroom during below freezing weather, wife noticed it under the mattresses. 

Edited November 19, 2017 by nb Innisfree

[carlt]

Just now, nb Innisfree said:

wife noticed it under the mattresses. 

Once you'd removed the pea?

[tree monkey]

13 minutes ago, nb Innisfree said:

If our boat had a front sited stove I doubt we would have felt any improvement in the bedroom, the aiming at the corridor immediately adjacent was the vital factor IMO. One visual improvement was getting rid of a bit of  incipient condensation in the bedroom during below freezing weather, wife noticed it under the mattresses. 

Is that allowed, making the wife sleep under the mattress? 

[mross]

A mistress is half way between a mister and a mattress!

[WotEver]

9 hours ago, Dr Bob said:

It is interesting there has been little discussion on the paper...

I think whoever it was who suggested that they should have used a constant electric heat source hit the nail on the head. There is way too much subjective reasoning in the paper as it stands. They could have powered the heater with a variable power source and given real figures for ‘fuel savings’ to boot. 

[mark99]

Some distances on this vid.

My own view is they work mixing the air and evening out the vertical temp gradient in the immediate surroundings say 6-10 foot in front.

Why not turn it on it's head. If that was ice cold air emanating from the fan would you stand for it? or stop the fan?

 

 

Edited November 20, 2017 by mark99

[mross]

At one metre the airflow is negligible!  Just like my Stirling.

[mark99]

Anyone think fan ovens don't work?

The decent stove fans do have some affect - it's only the magnitude in question.

 

 

 

[mross]

The fan, in a fan oven, is much more powerful and operates in a closed cycle.  I looked at spares and saw one rated at 35 Watts.

[mark99]

The stove fans alledgedly move 9 odd cubic metres per minute. I suppose the question is, is it the same 9m3 or part 9m3 it's recycling?.

But in a small confine of boat sitting in front of fan there will be an enhanced convection mixing affect from moving 9m3. They definately won't shift significant warmth right along a boat.

 

[mrsmelly]

25 minutes ago, mark99 said:

The stove fans alledgedly move 9 odd cubic metres per minute. I suppose the question is, is it the same 9m3 or part 9m3 it's recycling?.

But in a small confine of boat sitting in front of fan there will be an enhanced convection mixing affect from moving 9m3. They definately won't shift significant warmth right along a boat.

 

What make of Eco fan do you prefer? Its a serious question I would like to know because this week I need some more snake oil and a new chocolate fireguard and wondered what makes you would suggest?

Thanks

Edited November 20, 2017 by mrsmelly

[ditchcrawler]

3 minutes ago, mrsmelly said:

What make of Eco fan do you prefer? Its a serious question I would like to know because this week I need some more snake oil and a new chocolate fireguard and wondered what makes you would suggest?

Thanks

Go back to bed and pull the duvet up over your head.

[nb Innisfree]

1 minute ago, ditchcrawler said:

Go back to bed and pull the duvet up over your head.

Or a pillow applied with firm but gentle pressure. 

[mrsmelly]

5 minutes ago, nb Innisfree said:

Or a pillow applied with firm but gentle pressure. 

As a " Believer " what make of snake oil do you suggest? I think I have already decided on a Cadburys fireguard

[mross]

Here are details of an experiment which looks interesting.  http://www.reuk.co.uk/wordpress/heating/valiant-premiair-4-stove-fan-testing/

The temperature at the mantlepiece certainly drops, but the two room temperatures just rise slowly whether fan is on or not.  To me, it is conclusive proof that they are useless.

I love the idea that four blades must be better than two!  If you could increase the power of the motor by adding blades, why not make the diameter greater too?

[WotEver]

8 minutes ago, mross said:

The temperature at the mantlepiece certainly drops, but the two room temperatures just rise slowly whether fan is on or not.  To me, it is conclusive proof that they are useless.

I agree. They make the point that with the fan in place the temp rose between half and one degree. It was doing that prior to placing the fan!

[Dr Bob]

1 hour ago, mross said:

Here are details of an experiment which looks interesting.  http://www.reuk.co.uk/wordpress/heating/valiant-premiair-4-stove-fan-testing/

The temperature at the mantlepiece certainly drops, but the two room temperatures just rise slowly whether fan is on or not.  To me, it is conclusive proof that they are useless.

I love the idea that four blades must be better than two!  If you could increase the power of the motor by adding blades, why not make the diameter greater too?

Guys (I am including Tony in the post after yours as well). Can  you not read graphs/data properly? The script clearly says the temp is rising during the test - with and without the fan.  On purpose. There are two key sets of data.

1) the mantlepiece thermocouple is showing a significant decrease when the fan is on showing that the 'convection' upwards is disturbed - therefore likely breaking the stratification (good) and the 'lost' heat must be going somewhere else other than the ceiling. Of course there is no detail on where the probe was so we are guessing - but it looks like the fan is having a significant effect.

2) On the other 2 thermocouples, we are not looking at temperature with time, we are looking at the rate of temperature change with time, dT/dt, or integrate the area under the curves when the fan is on. The only problem here is we dont know what the rise (or rate of rise ) would have been without the fan. You can only guess. However to me in the first and last fan periods on, dT/dt looks significantly higher in the 6 mins the fan was on. In the second period, it is impossible to know (but dT/dt is certainly no worse). They needed to repeat the experiment a number of times to get more convincing statitistics. However, this snapshot convinces me that the fan is having a useful effect on changing the stratification when coupled to the other paper/video.

The writers say the rise in temp with the fan on is "around half to one degree Celcius over where it would otherwise have been." Maybe they did some further runs.

If you are both saying that one or two degrees is insignificant - then that is were the problem lies. One or two degrees is significant for my 'thermal comfort' which is why I see the fan as beneficial for disturbing the stratification. It sounds similar to the experiences of a few others here. It seems likely that neither of you feel the difference of one or two degrees.

That is now 2 papers and one video showing distrubance of the stratifcation in front of a stove with a stove fan. All with faults but all showing the positive benefits. Any papers/videos showing the opposite? If not we are doing a Liverpool........(wining 3-0)

 

Edited November 20, 2017 by Dr Bob
speeelin

[mross]

Look at minute 55.  The rate of temperature rise does not change when the fan is started!  Nor does it change at minute 94.

There is a lovely (but unexplained rise) at minute 82 but the fan is off!  What causes the sudden drops at minute 46?

I think there are some drafts or a door was opened. The fire was probably adjusted at minute 94 but this is just a guess.

As I said, this experiment needs to be done with a heat source that gives a steady output, such as an electric heater.  The fan also needs to run at a constant speed, so it should be supplied from a bench supply.

[Dr Bob]

48 minutes ago, mross said:

 

Look at minute 55.  The rate of temperature rise does not change when the fan is started!  Nor does it change at minute 94.

There is a lovely (but unexplained rise) at minute 82 but the fan is off!  What causes the sudden drops at minute 46?

I think there are some drafts or a door was opened. The fire was probably adjusted at minute 94 but this is just a guess.

As I said, this experiment needs to be done with a heat source that gives a steady output, such as an electric heater.  The fan also needs to run at a constant speed, so it should be supplied from a bench supply.

Good challenge!

To take you last point first, I am not sure I agree. I think the speed of the fan needs to be at the speed you would get on the top of a typical stove so there will always be a criticism if it was done artificially. Also the heat source is best as the stove itself so you get the same convection/radiant heat as what we want to prove. Maybe heating the steel via an electric heater would work. The authors of this work though used the strategy of measuring the fan during a rising temperature - which is quite clever - and it is a good way of showing the effect of the fan on the 'rate' of rise. However they did a poor job of keeping a steadily rising temp.

In every case where they put the fan on, (3 times), there was a 'blip' in the rate of rise of temp (dT/dt) in the minute before the fan was turned on. Why? In the first instance, in minute 35m the dT/dt was increasing (ie the rate of rise of temp was increasing) but then there is a blip level at 36 min, so it is diffult to draw conclusive info on what would have happend at minute 37 onwards. It looks like in the 6 mins with the fan on after min  37 that the dT/dt was higher than the previous 15 mins but not conclusive. At minute 54 the dT/dt goes negative, so it is impossible to know if that trend line goes up, down or constant in the 6 mins after that. Similarly at min 93, the dT/dt has gone negative but in the following 6 mins does seem to go up with the fan. If I was doing this test, I would have spent a lot longer trying to stabilise to a constant dT/dt with no fan before turning the fan on - or repeating the work 10 times and used some sort of statistical analysis to show that the increased dT/dt with the fan was real. I certainly would not have put the fan on after a blip. Like you, I guess they had too many drafts or people going in/out of the room to move the fans. I am also surprised that the temp probes picked up temp swings so quickly and maybe actual temp swings were higher.

So, yes the test is far from pefect but for me does show that the  fan is breaking the stratification (at least from the mantlepiece data). I dont think you are right in saying 'conclusive proof that they are useless', but neither is it right to say 'conclusive proof that they work'. However coupled with the previous paper and the video, I am happy that the fan (decent fans that is!) do break the stratification so increase thermal comfort...for me.

[mross]

8 minutes ago, Dr Bob said:

breaking the stratification

How do you conclude this?  I think you are merely 'assuming'.  I was reading about convection and radiation.  I see that the Morso Squirrel is a convection design.  As far as I know, this is unusual in narrowboat stoves.

If a stove is designed for convection it will have a double case, or at least an air passage to collect heat from the 'furnace'.  I wonder if the top casing is significantly cooler than that of a radiant stove like my Aga Little Wenlock Classic?  Maybe stove fans are less effective than on radiation stoves?  ( and by that I mean 3/10's of SFA)

Your ball, sir!

Edited November 20, 2017 by mross

[Dr Bob]

18 minutes ago, mross said:

How do you conclude this?  I think you are merely 'assuming'.  I was reading about convection and radiation.  I see that the Morso Squirrel is a convection design.  As far as I know, this is unusual in narrowboat stoves.

If a stove is designed for convection it will have a double case, or at least an air passage to collect heat from the 'furnace'.  I wonder if the top casing is significantly cooler than that of a radiant stove like my Aga Little Wenlock Classic?  Maybe stove fans are less effective than on radiation stoves?  ( and by that I mean 3/10's of SFA)

Your ball, sir!

Breaking the stratification: I think I am more than assuming based on

1) the mantlepiece temps shown in this paper

2) the heat diagrams in the Waterloo paper (but with the assumption that the heat diagram were created using real data - which they should have been) and the thermal comfort graph.

3) the video above which shows a clear air flow blowing the tissue at 1 meter away (it doesnt take much air flow to spoil the stratification)

4) the 'feel' in our boat when sat 10ft from the stove, where you can feel the fan, and that fact that my feet have been a lot warmer since we got the fan (totally subjective and other variables could be in play)

Certainly in 1-3 there is clear evidence that there is an effect on the stratification. There is not enough evidence to say how big that effect is.

What is clear here - and the only thing clear, is that some people are adamant the fans have no effect and some people are adamant that they do. I dont believe it is a placebo effect. There are other things at play. I think it is partly down to the individuals sensitivity to temperature. Our stove is a villager puffin and has been lit on our boat 24/7 while we have been on it. Havent a clue if it is radiant or convective as although I understand the terms, I dont have the experience to make any comments either way.

[mross]

Dr Bob, yours is a radiation design of stove.  It will produce some convection currents in the boat but it is primarily designed to spread heat by radiation.

A convection type has outlets that discharge hot air.  They may or may not be clearly visible.  Morso Squirrel is such a stove.