Fault finding AC heater

[rthorntn]

Hi

Any advice would be much appreciated.

The mains AC powered heater in our house stopped working after 2 years, it was expensive, I would like to safely figure out if its the 10V AC transformer that appears to power the control board inside that's failed?

I was looking at a variac as a way to supply the 10V AC to the control board to see if that brings it to life.

I have a DMM and oscilloscope, obviously I am totally aware that beginners shouldn't be playing about with AC, that why I am asking for advice before doing anything other than taking a peek with it all unplugged.

Thanks for looking.

Cheers
Richard

[CompElitePC]

pictures?

[IanB]

What kind of heater is it?

The most common fault with an electric heater is that the heating element has failed. Usually replacement elements are available as spare parts. You would check for this fault by disconnecting the heater from the mains and then measuring continuity through the heating element with a DMM.

[G7PSK]

Check the fuses first, then power to the appliance and power out of appliance, I have seen many cases of people using a power detector (volt stick or neon) and finding that power was going to the equipment and then blaming said equipment for being faulty and all the time it was the neutral wire that was at fault. Then if all that is good check the thermostat before pulling anything apart.

[807]

I would advise against using a variac.

Why not power up the heater & check out the secondary side of the transformer?

[SeanB]

Just use another 9VAC transformer to check, it will tell you. Simpler is to disconnect the transformer from the board and measure primary and secondary resistance. Primary will be anything from 1k to 20k resistance, secondary anything from 0.1R to 50R. If it is open circuit on the primary ( most likely) then there is a thermal fuse under the first layer of insulation that needs replacing with another 110C thermal cutout.

[rthorntn]

Thanks everyone, we have heat!

As an FYI it's a Delonghi SDH2000 heater.

I opened up the belly of the beast and was just about to take a photo when I thought let me just try and bypass the tip over switch so I just went directly from the power switch to the power board PCB, I will replace the switch as it's clearly faulty.

Cheers
Richard