PTC Heater - reduce power

Thread Starter

DaveOB

Joined Apr 11, 2013
4
Hi. Question about PTC heater.
I have a small desktop heater that I want to use in an enclosure that needs heating.
The heater is 220V and advertised as 400W.
The heater is heating up the enclosure too fast and I want to reduce the energy produced.
Terminals A and C are Live.
Terminal B is Neutral.
( the pcb at the end is only for converting to 12VDC to run the fan behind the PTC heater )
Can I disconnect terminals A or C to have only half the heater working ?
I am a little confused with the 5 rows in the heater - would it be 2 separate elements ( 1x3 rows & 1x2 rows ) or would one row be shared ?
My multimeter over terminals A & B reads 0.83 ohm. Same for terminals B & C.
 

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Thread Starter

DaveOB

Joined Apr 11, 2013
4
Sorry...NA is North America.

If the fan PC is driven by 220 then you must disconnect one of the elements without disconnecting the fan PC.
sorry. SA ( south africa )
The PCB for the 12VDC for the fan is a separate wire directly from the switch so not affected by the heater terminals.

Just been reading up on the PTC heaters, and it appears the heater is the white ceramic strips, and the concertina fins are only there as a heatsink so the fan can convert the heat to the airflow.

So appears that I can disconnect either terminal A or C and have the PTC heater produce around 50% of it's 400W capacity.
 

ElectricSpidey

Joined Dec 2, 2017
2,177
Sounds correct...but I'm not familiar with the AC system in South Africa...be very sure the neutral can carry current before doing any modifications.

And you are also correct about the fins and the elements.

Post is EDITED.
 

Thread Starter

DaveOB

Joined Apr 11, 2013
4
Sounds correct...but I'm not familiar with the AC system in South Africa...be very sure the neutral can carry current before doing any modifications.

And you are also correct about the fins and the elements.

Post is EDITED.
Thank You. Our local grid is 220V and this mini desktop heater works 100% out the box from the store.
 

Ian0

Joined Aug 7, 2020
6,663
The PTC element heats up to a certain temperature, above that temperature a phase transition takes place and the material changes to a high resistance state.
Switching it on and off will not be effective, because when it is switched back on it will run at a higher power until it reaches the PTC transistion temperature.
So, you can either reduce the size of the element, or reduce the air-flow.
If you reduce the airflow, the element will continue to regulate its own temperature but the amount of energy that is transferred will be reduced, as it is the air that transfers the heat.
 
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