Heater resistor

[Bongolia]

I am fitting a taxi cab rear heater unit it has two speed settings achieved by using a wire wound ceramic resistor. My question,is there a more efficient way of achieving this other than using a resistor?

[mikeonb4c]

I am fitting a taxi cab rear heater unit it has two speed settings achieved by using a wire wound ceramic resistor. My question,is there a more efficient way of achieving this other than using a resistor?

There's some interesting reading material out there, such as this:

http://www.orientalmotor.com/technology ... 66-1e.html

.....or we could wait for Geoff to turn up. Suspect it might be tricky unless the motor winds are set up for multi speed operation

[g8dhe]

Given that it is a HEATER you adding then generating a little more heat from a resistor, makes very little difference to the outcome!
The only other route is using even more technology to use modern motor technology, which basically means an AC driven motor - yes DC brushless motors are actually AC motors internally!

[Bongolia]

Thanks.
It wasn't the heat I was thinking of it was the energy consumption. Would I be right in thinking that the energy used would be the same whether the fan was running at high or low speed?

[mikeonb4c]

Thanks.
It wasn't the heat I was thinking of it was the energy consumption. Would I be right in thinking that the energy used would be the same whether the fan was running at high or low speed?

You would (i think but geoff might correct). Then again, are you relying on a running engine to generate the heat (in which case electricity there will be in abundance) or are you using a diesel heater, in which case the implication is you're resting in the van and you might then find that by making a suitable installation convection alone could be used to provide air circulation without the noise of a blower.

[g8dhe]

The electrical energy consumption will be a less possibly around 50-60% of running the motor at full speed depending on how much lower speed it is. Not sure what the source of the actual heating is with those heaters, hopefully it taps into the exhaust heat ?

[Bongolia]

Thanks.
It wasn't the heat I was thinking of it was the energy consumption. Would I be right in thinking that the energy used would be the same whether the fan was running at high or low speed?

You would (i think but geoff might correct). Then again, are you relying on a running engine to generate the heat (in which case electricity there will be in abundance) or are you using a diesel heater, in which case the implication is you're resting in the van and you might then find that by making a suitable installation convection alone could be used to provide air circulation without the noise of a blower.

Just looking for ways I can cut down on electrical energy consumption with the van engine off really.
I have a Webasto Thermo Top that I am in the process of fitting. The down stairs would be in the main get heated by convection but i was considering ducting heated air into the AFT I would need to use a blower as the ducting would be quite small in diameter 2.5" max to run it through the D pillar this would come from the taxi heater which would also be used to boost the circulation of warmed air downstairs like first thing in the morning or from a cold start.
All in the preliminary stage at the moment so any input would be useful. I did PM the BF guy who fitted one but as yet have heard nothing back, I remember he was a keen skier so probably on the piste somewhere.

[Bongolia]

The electrical energy consumption will be a less possibly around 50-60% of running the motor at full speed depending on how much lower speed it is. Not sure what the source of the actual heating is with those heaters, hopefully it taps into the exhaust heat ?

Thats good to know thanks.
The heater is a Webasto Thermo Top bit like a diesel fueled boiler and links into the Bongos cooling system pipework. The Webasto runs independent of the engine. The Taxi heater uses a water filled matrix.
Images here.

https://goo.gl/photos/kzuxPV176afcB87p7

[mikeonb4c]

The electrical energy consumption will be a less possibly around 50-60% of running the motor at full speed depending on how much lower speed it is. Not sure what the source of the actual heating is with those heaters, hopefully it taps into the exhaust heat ?

Thats good to know thanks.
The heater is a Webasto Thermo Top bit like a diesel fueled boiler and links into the Bongos cooling system pipework. The Webasto runs independent of the engine. The Taxi heater uses a water filled matrix.
Images here.

https://goo.gl/photos/kzuxPV176afcB87p7

I wonder what the power consumption of computer cooling fans is. I was reading the other day about a device that sits on top of a radiator and disperses the rising air around the room. It used computer cooling fans and was v quiet.

[Bongolia]

Yes I had thought of that, but not sure if they have the oomph to push the air over that distance.
The thinking was to put the blown outlet at the hinged end of the roof.
However an alternative could be to utilise the existing B pillar duct that feeds the over head vents and extend that into the roof space to exit alongside the tent the air could be directed by a flap to switch between over head vents or upstairs.
That would mean I could use convected air from the taxi matrix and be boosted by its fan if needed.
Another benefit of using that method would be more space behind the trim panels.
The problem is the upstairs outlet could be masked by the bedding so some kind of riser would be needed that would automatically close when the roof was lowered. This method does seem a more elegant solution.
I need to get on the net and do some Goolgling I would expect there is something out there to solve the riser vent issue.

[g8dhe]

Typical Antec cooling fan; spec.
Speed Input current airflow noise input power
High 1200 RPM
0.20A 1.91m³ / min (67.5 CFM) 23.8 dBA 2.4 W
Medium 900 RPM
0.15A 1.43m³ / min (17.41 CFM) 17.41 dBA 1.8 W
Low 600 RPM
0.10A 0.8m³ / min (28.3 CFM) 8.9 dBA 1.2 W

Dimensions 120 mm x 120 mm x 25 mm / 4.7” x 4.7“ x 1.0”

[Bongolia]

Typical Antec cooling fan; spec.
Speed Input current airflow noise input power
High 1200 RPM
0.20A 1.91m³ / min (67.5 CFM) 23.8 dBA 2.4 W
Medium 900 RPM
0.15A 1.43m³ / min (17.41 CFM) 17.41 dBA 1.8 W
Low 600 RPM
0.10A 0.8m³ / min (28.3 CFM) 8.9 dBA 1.2 W

Dimensions 120 mm x 120 mm x 25 mm / 4.7” x 4.7“ x 1.0”

That is quite impressive and reasonably priced.
Set me thinking whether to make an enclosure for the Bongo matrix and mount the fan to that. It would give a good space saving in that area that could be put to good use.

[mikeonb4c]

Happy to have sowed a seed - Bongo ingenuity strikes again

[Bongolia]

Looked into the computer fan option and I think its a probably a non starter, speaking to our local computer parts seller and he is doubtful it will have enough pressure or shift enough air but I was more concerned with the vibration from being jolted about in a van.
So going back to the taxi blower I think. That is rated ae 125CFM on full where as the computer HP ones are around 65-75 CFM
I ran the taxi blower and it pulls 3 amps, after a bit of a spike, on the low setting and 6 amps when on full pelt, higher than I was hoping for so I will investigate the convection side in a bit more depth.
Thought I might check the Bongo OE front and found that pulled 13 amps when on full.
Does that sound on the high side?
The motor spins freely by hand so no sign of seizure.

[mikeonb4c]

But do you really need forced air distribution. I'd have thought assisted convection might be sufficient (it is in narrowboats and they use fans powered simply by heat from the fire they're sitting on). And quietness and low power consumption are big attractions. I'd have thought also that robustness would be adequate, especially if mounted with vibration isolators. I'd be inclined to try it as tbey can be got pretty cheap. If the cheap one looks promising, you could upgrade to a better one. If the experiment fails its cost v little to try.