Re: Water heater eating X-10 signal

[ddl@danlan.*com (Dan Lanciani)]

In article <1177611333.772049.118620@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>, graftonfot@xxxxxxxxx writes:
| On Apr 25, 12:56 am, ddl@danlan.*com (Dan Lanciani) wrote:
| > In article <1177470203.376066.127...@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>, grafton...@xxxxxxxxx writes:
| >
| > | Sorry for the delay, finally got time to do a little data gathering on
| > | this issue.
| > |
| > | I find my measurement results a bit confusing.
| > |
| > | In my breaker panel I have a Leviton HCA02-10E coupler/repeater.  It's
| > | wired via an existing 2-pole 30A breaker feeding a dryer, and was part
| > | of my working configuration before this problem started.
| > |
| > | To do some measurements, I wrote a small HomeSeer script consisting of
| > | a loop which sends "B1" "ON", waits 3 seconds, sends "B1" "OFF", waits
| > | another 3 seconds, then repeats.
| > |
| > | With this script running I measured signal levels in the breaker panel
| > | using an ESM-1 connected via alligator clip leads.
| >
| > Where did you connect the clips in the panel?
|
| I connected one lead to the neutral bus bar, then alternated the other
| lead between the phase buses (the metal tabs that the breakers stake
| onto.)

You might want to try hooking on to the "output" of the breaker feeding
the yard light circuit.

| >
| > | Here are my (somewhat puzzling) results.  I've arbitrarily labeled the
| > | phases "A" and "B", and expressed the observed signal strengths in
| > | terms of number of bars lit on the ESM-1:
| > |
| > | Condition: HCA02 breaker OFF, water heater breaker OFF
| > |     Phase A: approx 1.5 bars
| > |     Phase B: 0 bars
| > |
| > | Condition HCA02 breaker OFF, water heater breaker ON
| > |     Phase A: approx 1.5 bars
| > |     Phase B: 0 bars
| > |
| > | Condition HCA02 breaker ON, water heater breaker OFF
| > |     Phase A: 5 bars
| > |     Phase B: 4 bars
| > |
| > | Condition HCA02 breaker ON, water heater breaker ON
| > |     Phase A: 5 bars
| > |     Phase B: 4 bars
| > |
| > | Apparently the HCA02 is performing its repeater function quite well.
| > | But what's puzzling is that with the coupler in-circuit, closing the
| > | breaker for the water heater apparently has no visible effect on the
| > | signal coupling as shown by the ESM-1 at the breaker panel, even
| > | though I've repeatedly confirmed that it debilitates my control of my
| > | front yard lighting.
| > |
| > | Shouldn't I expect to see a big drop in Phase B signal with the water
| > | heater circuit connected?
| >
| > Are you sure that one or both elements in the water heater come(s) on when
| > you enable its breaker?  Alternately, do you know that the yard lighting
| > control is debilitated even when no elements are on?  Or maybe simplest of
| > all:  were you checking that the yard lighting control came and went as you
| > closed and opened the breaker during your above tests?
| >
| >                                 Dan Lanciani
|
| Actually, I'm more sure that the elements *aren't* on for all these
| tests.  I'll need to figure out a reasonable way to confirm this,
| though (I don't have a clamp-on ammeter.)

Turn the thermostat way down?

| All of the phenomena/tests I've described have occurred during times
| of no water usage.  I realize this doesn't absolutely guarantee that
| one of the heater's elements is not in-circuit during the test, but it
| makes it much more unlikely.  As I said I'll try to confirm this.

As long as you are sure that both the measurements and the debilitation
happen under the same circumstances it should be fine.

| I'm not familiar with water heater circuitry - are they as simply as
| an SPST switch controlled by a heat sensor?

I think you will find two DPST switches (one for each element) plus an
additional high-limit cutout feeding both of them.

| I'm wondering if they
| typically include some sort of spark-suppression RC stuff to preserve
| the thermostat contacts...perhaps that's doing something weird to the
| X-10 signals.

It's certainly possible.  Whatever the exact mechanism I'm interested in
this type of effect where one circuit causes impairment of another without
having any observable effect at the repeater.  We shouldn't ignore the
possibility of a noise source (rather than attenuation).  What type of
X10 modules are controlling the yard lights?

				Dan Lanciani
				ddl@danlan.*com