I’ve seen quite a few people, and some fan manufacturers, talking about using axial fans (esp PC type) for active radiator ventilation.
I’m wondering about the use of tangential fans, which are, of course, the norm in fancoil emitters, air curtains etc. A priori, they seem to be a better fit to the requirements.
Have any of you folk the benefit of practical experience?
New Jaga Briza line uses these as well. Single motor, more fan to motor surface. Seems to be a better tech. Allows more output at a slimmer radiator.
Can you buy tangential fans as retrofits for existing radiators? The beauty of the PC fans is that they can fit basically any radiator.
I can’t buy a great value mass produced low noice tangential fan that is easy fit on existing radiators. I can’t see how someone can get the required scale to produce such a product.
So unless Octopus brings out a axial fans that converts 60c flow radators into 50c flow for their Cosy Heatpump at a lower cost then a radator upgrade…
But such a system integrated into their Cosy Hub could be great, giving per room temperature control and recommending radators to rebalance while running the fans to minimise electricity usage taking into effect on flow temperature.
There are some consumer products that sit on top of radiators and blow air out with tangential fans, with RadFan being one brand that seems quite widespread. I’ve not tried one myself.
This is actually a pretty good idea, I was thinking about it too. On average, tangential fans should be quieter than axial ones and create higher pressure (although in this case, I’m not sure if that’s relevant). They will require slightly more space than axial ones (possibly needing to be placed on top) and most likely need some distance on the discharge side to stabilize the vortex flow inside the fan.
I haven’t looked for ready-made solutions and don’t know of any, but as a concept, it’s interesting—you can buy a fan on AliExpress (they come in different lengths) and make the housing yourself.
By the way, I already bought one out of curiosity. It runs on 6-12 volts (BLDC motor), and I can say that it’s still quite noisy for a bedroom, even at low voltage. For other rooms, it might be a viable option.
If anyone needs, I can measure the air flow at different voltages.
Do they also come with PWM capability such as axial PC fans? If so, they could interface with my controller. In theory I guess the voltage itself could be PWM driven so there’d be some form of speed control. Is there any way you could test it with a 12V PWM modulated signal?
A 12-volt fan requires that the output voltage of the PWM controller also be 12 volts, and the maximum allowable output current of the controller must be higher than the fan’s consumption. Most likely, this is not the case with your controller (both the voltage and current are lower). In this case, the fan is connected through a powerful transistor, so the PWM signal from the controller is applied to the transistor, which is connected to 12V and controls the fan.
My controller is 12V, and in addition to the typical PWM control line (5V), I can also switch the 12V line directly with a PWM signal. Peak current is not really an issue. It’s not very advisable from an EMI perspective and if the switching frequency isn’t high enough you can hear it as well. So if the fans can take it, it might work. Do they make these fans also as 3/4 wire versions tor a better speed control?
Then again, you say they are audible even at low voltages, so that’s unfortunately a no-go for me. Good axial 140mm PC fans are essentially inaudible below 400rpm.
My fan model features an integrated BLDC control driver, so it only has two DC wires for power (although inside the motor it most likely uses three-phase control). I agree with you—noise is a crucial factor. I would also be interested in trying something like this sometime (most likely with very low airflow and some unclear quirks). https://www.youtube.com/watch?v=LvckweOqjdk
