One fan or two

[agricontract]

Any one cleaver than me on here that can answer this we have a one meg heat exchanger with one large fan on it that uses 60 Kw a hour for our drying floors would it be more efficient on electric to have two smaller fans producing the same air flow as the one big one we currently have ?
Thanks in advance

 

[akaPABLO01]

Any one cleaver than me on here that can answer this we have a one meg heat exchanger with one large fan on it that uses 60 Kw a hour for our drying floors would it be more efficient on electric to have two smaller fans producing the same air flow as the one big one we currently have ?
Thanks in advance

Attach a picture of the vim plate for the fan ol

 

[Exfarmer]

I know little about pushing air, but certain pumps for water will use as much power as water they push. Presumably you are concerned that when the fans are not used to full capacity that they are not drawing the amps. I think the fan manufacturers would be the ones to answer that.

 

[sjt01]

Download the pdf of "Woods Practical Guide to Fan Engineering". Google shows lots of sites offering it free. It is the classic. You will probably find your fan is a BCC or a multi-stage axial, and you will be able to find the fan curve, and compare with alternatives

 

[Doing it for the kids]

I looked at fitting invertors, reduce power consumption hugely but not in relation to air speed. Was too expensive though

It’s a complex area though

 

[rollestonpark]

If you fit a vfd, (variable frequency drive) you can reduce the speed and the power savings im told can be quite large. Need to talk to an experienced electrician

 

[Doing it for the kids]

Something like 80% drop in juice use for 20% loss in fan speed I think

 

[rollestonpark]

Something like 80% drop in juice use for 20% loss in fan speed I think

Yeah I think your right.

 

[sjt01]

Yeah I think your right.

Just look at the fan curves in the Woods book. I can never remember whether it is square law or cube law, but a minute drop in speed has a dramatic effect on output and consumption. It will depend on the design of fan, you really need the fan curves to know what is going on.

 

[scotston]

Errm. Are you not asking the wrong initial question- what's the required minimum airflow to dry with? Then spec a fan for that flowrate. I wouldn't worry about running two smaller ones as there's always more losses in two compared to one. Unless... your load requirements are not always even? ie do you sometimes use only one floor and therefore require half the airflow.

 

[agricontract]

Yes but I have inverter on current fan and can speed it up and down but should I have to half the size and would that save me any electricity

 

[sjt01]

Yes but I have inverter on current fan and can speed it up and down but should I have to half the size and would that save me any electricity

Unless you can get the fan curves, you cannot say. See if they are available on the web.

 

[scotston]

How much air do you need?