[imautoparts]

I'm diagnosing an open fault on an overhead radiant heat system. 240V, 20A circuit, SPST thermostat. I've already opened up a small hole and have full access to the overhead system.

I'm getting an infinity reading on ohms, but I located a break with my toner and repaired it, and STILL no connectivity.

I'm using my toner, and I can tell there is some kind of connection between the t-stat drop and where I found the break (loud LOUD tone, same as if I touch the toner to the other end of the wire), but when I use my long lead to test DVOM continuity at that point I'm still getting infinity.

So - with the wire exposed I get 100% tone continuity to this spot, but when I use my ohmmeter I still show infinite. Frustrating.

Help!

 

[NiNe O]

Will the unit run if the thermostat is jumped out at the unit itself? If so replace all the tstat wire since you already found one break.

 

[imautoparts]

No, I'm just not getting continuity. The t-stat is working fine. I think I may have isolated another break point near the wall-"up" line on side b

My plan is to slowly identify any breaks using side A, till I get right near the t-stat. I'll post back after fixing this break #2

 

[imautoparts]

Done and done. I'm sure I wasn't the most efficient finder of broken spots, but after three cuts into the ceiling I got a good solid tone from the whole grid.

Checked continuity - 70 ohms of resistance, plugged in the breaker, drawing 7 amps from dead cold. Good deal - and thanks to DIY Chatroom!

Drinks for everyone!!