Destratification Fan

[awemawson]

I have the luxury of central heating in my workshop. It's oil fired and runs three fan assisted radiators mounted at about eight foot high on convenient steel truss beams. However there is a further about eight foot to the apex of the roof. Recently climbing on top of my Traub lathe to stash some spares away I was amazed how much heat there was up there under the spray foam insulated corrugated fibre reinforced cement roof sheets.

In an ideal world the fan assisted radiators would have been up at the apex, but they are not, and I'm not moving them now so how about a 'downdraught fan' . Apparently these are called 'Destratification fans' in the industry, and the fancy name comes with a fancy price tag.

As an experiment I've rigged up an old 45 watt desk fan dangling from the apex, and initial findings are that it works. It's crude, it looks odd, but it may stay there for quite a while 

[Pete.]

Often I have to work at high level in tall spaces like plant rooms and I've been stifling hot where it was merely comfortable at floor level. If you wanted directional heat at floor level you could get hold of some space tube ducts and fix the end up high, leaving the fan at floor lever so you can direct warm air where you want it.

[awemawson]

Just done some measurements with an infra-red point type thermometer. Before the fan was turned on I was getting 26 degrees C on the roof insulation for a thermostat setting of 17 degrees C at 5'6". Now with the fan running the roof insulation temperature is 19 degrees C. That must be quite a large saving in heat losses through the 3" of sprayed insulation. Also I suspect that it is not fully airtight at the apex.

Andrew

[Joules]

 Andrew,
            We had ceiling fans in a high ceiling workshop that got used in the winter, just to get the heat down from the ceiling.  We also tried grey pvc drain pipe with fans at the base to draw down the warm air to floor level and get the building warmed.

[awemawson]

Well it seems to be working well   

The boiler has only fired up once in the time since I fitted the fan and the workshop has stayed at the programmed 17 degrees C - ceiling temperature seems to be staying fairly constant at 19 degrees along the full length of the apex so the fan is obviously drawing warm air along the apex and then downwards.

Far more effective than I was expecting - I suppose really I should put a thermostat up in the gods and control the fan off that but access is a pain

Andrew

[lordedmond]

Andrew

you need a couple of the large Dia. slow speed fans that you have in these posh conservatories should be able to source some on the bay  get the biggest you can get run them slow as not to set up a circulation current

http://www.ebay.co.uk/itm/Ceiling-Fan-48-Inch-Conservatory-Ventilation-Cooling-Home-Office-/121077227708?pt=UK_Home_Garden_Ceiling_Fans&hash=item1c30c3e0bc

bit pricey but you get the idea

Stuart

[awemawson]

Stuart,

I had looked at one or too of the combined light & fan arrangements - but they are amazingly tacky ! Wicker work blades and gold anodised aluminium - ugh ! Those conservatory ones at least look reasonable so thank you for the suggestion.

Andrew

[John Stevenson]

Pity you are down sarff.

Up ere in the industrial nurth you can get a Punkawalla for 3 rupees a day.

[75Plus]

Andrew, you might check the power consumption as you look at the ceiling fans. Some models are extremely efficient. For example a 52 inch Hunter (the inventor of the ceiling fan BTW)  specs.

67 Watts HIGH, 26 Watts MED, 9 Watts LOW
Airflow Cubic Feet Per Minute (CFM): 4827 (High Rating)
Airflow Efficiency: 72 CFM Per Watt (High Rating)

Joe

[awemawson]

Thanks For that Joe - sounds like you've been down this route before 

John : I hate to dis-illusion you but Long Eaton isn't North as far as us native Yorkshiremen are concerned - you're practically Midlands 

Andrew

[John Stevenson]

Yabut once you get past Watford gap and get your passport stamped and changed your money the area's get a bit blurred 

[Meldonmech]

           The hottest part of my home is the loft conversion, I would like to pipe some of the heat down to ground level, but the practicalities are overwhelming.
                                                         Cheers David

[awemawson]

Time division multiplex down the soil stack 

Andrew