Ecofans - the Ultimate test?

[Dr Bob]

Nah, not the ultimate test – more of an initial sighting shot. Do Ecofans work? 30 pages of jolly banter on Mrsmelly's Ecofan thread haven't really got very far but it keeps everyone amused. I thought I would keep this report separate so not to upset the flow on the other thread. This is long, its boring, but if you are interested in the answer then read on. In a nutshell I interpret the results as positive that these fans do work (well good fans anyway) and are significantly more than the paper weights that the unbelievers see. There, that's the answer.....for those not interested in detail, then skip to the end.......a long way down!

The only real data in Mrsmelly's thread is the paper by Waterloo University (Ontario) which did a good job of showing the temperature spread improvements with a fan (who also claimed a 15% fuel saving). This was poopooed by the unbelievers – perhaps with some basis – as there was not enough data produced. It is likely they did have the data and their results are valid, but the requirements of proof are high for CWDF. The rest of the discussion on the thread was anecdotal at best.

Trying to prove temperature differences between fan and no fan are likely impossible without a full blown lab set up. Instead an alternative way to look at fan efficacy is to study air flows around the fan – and this is the key thing most unbelievers look at – how little air the fan seems to be moving. I therefore had a play for a couple of hours with a smoker (a Christmas German nutcracker) and got some interesting results. The following is a summary. I have tried to keep it short (!!!!) so there will be some key stuff missed out.

Method:

Fan was a Baby Equaliser 5 blade, from Fluesystems (£55 – ex amazon). This fan was claimed to have a throughput of 265 cuft/m which is almost double the claims of most fans. The stove was a villager, with a top plate temp of around 200°C. All window and doors were closed but installed ventilation not touched – ie mimicking what we would have in the winter evenings. Initially the Nutcracker smoker was used to produce the smoke but this was a bit erratic in its production of smoke so just a smoker capsule in a tin was used. The test was done in the front cabin of the boat. Fig 1 shows the layout, front open area, then the dinette and behind that the kitchen. Stove was at the front on the port sided. For the first looksee, I found that at 'torso' height when sitting, 0.7m off the floor, there was no air movement without the fan but significant air movement with it, so for the first test I looked at air flow at that height around the front cabin with and without the fan. I then did a set of tests looking at the air flow at different heights around the cabin which threw up some surprises (for me – maybe not you!).

Results:

Figure 2 shows the air flow measurements taken at 0.7m off the floor at various points around the cabin with the fan running. The arrows show the direction of the smoke trail and the numbers in black show the angle the smoke was rising above the horizontal from the smoker. This angle is related to speed of the air movement ie the slower the air movement the higher the angle – but is indicative only. The number in red is the speed the smoke was moving – estimated by watching a 'perturbation' in the smoke trail and measuring how far that travelled in a 3 second period. It was surprisingly consistent once a number of measurements made. When the fan was removed – put in the cratch - and the test repeated, almost all measurements showed the smoke rising vertically from the smoker at this height of measurement. The image below shows the smoke trail at position A on figure 2, with the smoke moving quite rapidly in the direction of the stove fan which is just off picture to the right.

Discussion:

The airflow in the presence of the fan is significantly enhanced at the 0.7m height level and seems to be moving in a circular fashion to around 2.5m down the boat from the fan. Note the fan is angled at 45° to the boat line as this gives the larger space behind the fan to draw air without the flue in the way. With no fan, there was no air flow at this height. The air from the fan is hot so the circular motion of the air will transport this heat around the front open area more more than with no fan. It was surprising that there was significant movement of air towards the back of the kitchen area at 2.7m down the boat. A few of the 'unbelievers' have stated that the fan may push out a lot of air but this then slips round the side of the blades to be recirculated again. The above results seem to suggest this may not be right and significant air is pushed out and circulated in the 2.5m range.

As the airflows suggested significant air being blown towards the back of the kitchen at the 2.7m range across the entire width of the boat at 0.7m high, I decided to look at airflows at different heights – ie if all the air is going backwards, how can that air being replaced? With the fan off, I therefore looked at air movement in the open cabin and dinette. Whilst it may be open knowledge to many – it wasnt to me – that there was a constant flow of air around 0.1m/s going to the back of the boat at 1.5m off the floor and a constant flow of air going to the front of the boat at 0.3m off the floor. This is shown in figure 1. This circulating air flow is significant and shows how heat is transferred towards the back of the boat via convection. It was surprisingly efficient without the fan. Interestingly the flows were similar across the boat at high and low level but at the 0.7m height there was no flow and no air movement. Another point to add was the reverse flow to bring air back to the stove, was slightly faster – maybe 0.15m/s due to restrictions to flow, ie chairs, dinette etc. With the fan on, the high and low level flows were pretty similar across the width of the boat once 1m down the boat except that they were faster! At 1.5m high the flow was 0.2m/s (vs 0.1m/s with no fan) and slightly faster at the lower level.

Whilst it was clear from the two sets of tests that airflow is increased with the fan, the airflow at height information is interesting. I have always assumed that the hot air 'stratified' in the cabin – and hence there were static layers of air at different temperatures from floor to ceiling in the position where I normally sit. I assumed the fan would disrupt these static layers. This test has shown that it is not stratified (well at least not static) and in the absence of a fan, there is a high level down the boat warm air flow with a cooler return flow at just above floor level – with zero movement at torso level. With the fan, these high and low level flows are enhanced and more importantly, air flow at torso level is created which covers the open cabin where our chairs are. This is not about disrupting the stratification, its about moving warm air from the fan towards the living area.

That was just a 2 hour play with a smoker. It would be useful to look further at smoke flow at all points in the front cabin and quantify the speed of air flow more. It would be useful to look at flows back in the kitchen. It would be useful to have a better smoker – but the downside is being able to breath.

I'm convinced. So is the Duck who witnessed it all.

ecofan diag fig 1.pdf

ecofan diagfig 2.pdf

Edited January 8, 2018 by Dr Bob

[rusty69]

7 minutes ago, Dr Bob said:

I'm convinced. So is the Duck who witnessed it all.

Roll on Spring

 

What from the bog?

Edited January 8, 2018 by rusty69

[Tony Brooks]

Thanks Dr Bob. Nice to get some measurement based figures instead of gut feeling based.

[Dr Bob]

39 minutes ago, rusty69 said:

Roll on Spring

 

What from the bog?

No he had come out by then. Can't we talk about ecofans after April?

[rusty69]

2 minutes ago, Dr Bob said:

No he had come out by then. Can't we talk about ecofans after April?

Nope, too busy doing outside boaty stuff.

Edited January 8, 2018 by rusty69

[mrsmelly]

Dr Bob...you do know the world is flat dont you?

[1agos]

I was always a believer.....thanks for posting your findings.

[Dr Bob]

2 minutes ago, mrsmelly said:

Dr Bob...you do know the world is flat dont you?

It's certainly flat in this marina. I can prove that because if it wasnt flat, all the water would run out.

[mrsmelly]

Could dveryone please see the original Eco fan thread re this spoof thread. This is an account by hackers and has been reported.

[Dr Bob]

28 minutes ago, rusty69 said:

Nope, too busy doing outside boaty stuff.

Does it get warm enough in April to do outside boaty stuff?

[Dartagnan]

Well that’s good enough for me!  Off to Amazon I go for when we get onboard.  Grateful for your efforts.

[rusty69]

Just now, Dr Bob said:

Does it get warm enough in April to do outside boaty stuff?

Only if your a hardened boater like what me and mrsmelly are

[Dr Bob]

1 minute ago, Dartagnan said:

Well that’s good enough for me!  Off to Amazon I go for when we get onboard.  Grateful for your efforts.

Good to hear you liked it.

The big surprise for me was how the air moves without the fan. I had spent the first hour testing the air flows at 0.7m from the floor (torso height when sitting) where there was no air flow without the fan. I was really surprised when I found the upper and lower level flows without the fan showing this 'stratification' is a myth, at least on my boat (other boats are available). Convection is a wonderful thing - but it is significantly enhanced with a decent fan.

[rusty69]

I have been watching amazons price on the Baby equaliser which seems to fluctuate a bit.

We have been without a stove fan for 19 years now, but given your conclusive experiment results will definitely purchase one when the price fluctuates down to 35 quid(the equivalent price of 4 bags of Newburn).

Alas you will never convince the likes of mrsmelly ,who moved onto his boat the same week as Noah did

[Mike Hurley]

In picture 1 i can clearly see the clown holding the Eco fan, was he waving it about?

[mrsmelly]

3 minutes ago, rusty69 said:

I have been watching amazons price on the Baby equaliser which seems to fluctuate a bit.

We have been without a stove fan for 19 years now, but given your conclusive experiment results will definitely purchase one when the price fluctuates down to 35 quid(the equivalent price of 4 bags of Newburn).

Alas you will never convince the likes of mrsmelly ,who moved onto his boat the same week as Noah did

[rusty69]

1 minute ago, mrsmelly said:

You can't argue with scientific data pal ,especially that provided by a Dr of thinkology, held in such high regard as Bob!

[mrsmelly]

3 minutes ago, rusty69 said:

You can't argue with scientific data pal ,especially that provided by a Dr of thinkology, held in such high regard as Bob!

Your all quackers!!

[Dr Bob]

7 minutes ago, Mike Hurley said:

In picture 1 i can clearly see the clown holding the Eco fan, was he waving it about?

No, dont be daft, that was only a handheld windmill

Just now, mrsmelly said:

Your all quackers!!

Quaaaack

[system 4-50]

Thanks Dr B. for your hard work. My todo for a ceiling to floor duct with a computer fan will be raised in priority after reading your findings.

[Col_T]

Good stuff, Dr. Bob.

I got the missus one of the Baby Equaliser 5 Blade fans for Christmas, based on your recommendation. We've only been on the boat once since, the night before New Year's Eve as it happens, so have used the fan only once. The layout of our boat looks the same as yours and both the wife and I found the warmth from our Morso Squirrel seemed to be spread more evenly vertically. Certainly there was no overly hot layer of air at head height!

The lady is more than pleased, which makes my life easier, and we're looking to using it much more in the days to come.

 

[rusty69]

Also available is the Equaliser 5 blade fan which has the same Cubic feet per minute rating, but is aimed at fans of the tv series "The equaliser" staring Ed Triple wood

http://www.fluesystems.com/shop/equaliser-stove-fan.html#SID=625

 

With free pipe thermometer if ordered direct (not through Amazon)

Edited January 8, 2018 by rusty69

[mrsmelly]

13 minutes ago, Col_T said:

Good stuff, Dr. Bob.

I got the missus one of the Baby Equaliser 5 Blade fans for Christmas, based on your recommendation. We've only been on the boat once since, the night before New Year's Eve as it happens, so have used the fan only once. The layout of our boat looks the same as yours and both the wife and I found the warmth from our Morso Squirrel seemed to be spread more evenly vertically. Certainly there was no overly hot layer of air at head height!

The lady is more than pleased, which makes my life easier, and we're looking to using it much more in the days to come.

 

Composting loo? 

[Dr Bob]

2 minutes ago, mrsmelly said:

Composting loo? 

No I only believe in things that work

[reg]

Thanks appreciate the work you have put in on this.

Any comments i have made in other threads relate to the ALDI £24 ecofan which basically is a novelty item which I believe does not have any benefits, certainly not enough to warrant taking up stove space but does warrant taking up space in the rubbish bin where it now resides.