Bad design?
- From: "Paul Hovnanian P.E." <paul@xxxxxxxxxxxxx>
- Date: Wed, 19 Dec 2007 18:56:32 -0800
I recently extracted a floor heating thermostat that had probably been
mis-installed and (as far as we can tell) never worked. The story about
the electrician who did the job and left before testing the system is
another sad and long one for some other thread.
The unit is (as far as I can tell) a triac that controls 120 VAC to an
electric mat installed under a bathroom floor. It incorporates a ground
fault sensing circuit so as not to electrocute one stepping out of the
shower. Because of this, the unit has two line input wires (black and
white) and two output wires to the mat (also black and white). See
crummy ASCII art below. We suspect that the electrician initially mixed
up the line and load connections (due to the way he left quickly without
testing the system). I'm trying to figure out how one could damage a
triac by swapping the Line/Load wiring. Due to the crappy color coding,
this seems to be the most probable wiring error.
System (properly wired) as I envision the
thermostat innards:
triac
black |\| black
----o-------+-----|/|---MMM-o---------+
| /|/| | |
| / |GF CT |
| | | |
Line +------+ | Load
|brains|------+ |
+------+ | |
| | |
----o----------+--------WWW-o---------+
white white
Most of the likely errors I can envision would simply prevent the unit
from operating. Am I
missing something?
--
Paul Hovnanian mailto:Paul@xxxxxxxxxxxxx
------------------------------------------------------------------
c (velocity of light in a vacuum) = 1.8x10^12 furlongs per fortnight
.
- Follow-Ups:
- Re: Bad design?
- From: Ross Herbert
- Re: Bad design?
- From: Robert Baer
- Re: Bad design?
- Prev by Date: Re: 8051 question
- Next by Date: Re: 8051 question
- Previous by thread: Re: darryl lalonde
- Next by thread: Re: Bad design?
- Index(es):
Relevant Pages
|
