Re: Water heater eating X-10 signal

[nobody@xxxxxxxxxxxx (Dave Houston)]

ddl@danlan.*com (Dan Lanciani) wrote:

>In article <1177821975.289731.89000@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>, graftonfot@xxxxxxxxx (Mr. Land) writes:
>
>| Through trial and error I identified the breaker which feeds the
>| lights in question.  I re-ran my looping test script and used the ESM1
>| to measure the signal at the screw connection to that breaker.  I saw
>| a the 5-bar signal level there, along with the green X-10 light on the
>| ESM1.  Next I removed one of the troublesome WS467's (the pole lamp)
>| from the wall near the front door.  I disconnected it and tested from
>| ground to each wire there at the box - on the line side wire I saw the
>| same "healthy" 5 bar signal level there.  Really confused at this
>| point, I rewired the WS467 into the circuit, and tested again - I
>| still saw the 5 bar signal level!  Yet the WS467 does not respond to
>| it.
>
>Sounds more and more like a noise problem.  Perhaps it's time to
>look at the control circuit for the water heater.  It might have
>some "helpful" electronics...
>
>| Could this be some sort of minor garbling and/or ringing that the ESM1
>| can handle well enough to show a green X-10 indicator, yet be enough
>| to foul up the WS467's?  Could two phase wires in the 70-odd feet of
>| 10/2 feeding the heater be causing some sort of weird ringing?
>
>The WS467 has a very sensitive receiver and you can get some surprisingly
>complicated transmission line effects in the wiring network, but I'd keep
>looking for simpler explanations for a while.  I know from personal
>experience that the ESM1 will not show noise that can incapacitate a WS467.

I agree that it's likely noise. The ESM1 also doesn't do anything
sophisticated for the "X10 Good" indicator. Paul Beam, who designed it, told
me he just looked to see if there were the expected number of 1 and 0 bits
following 1110. I'm not sure whether it even rejects sequences like 1100 but
did not ask that specifically.

The gain bandwidth product of the opamp used in the ESM1 is not very high
which limits its response to higher frequencies.

I tried, unsuccessfully, to find specs on newer GE water heaters. If there
are any electronics, the lack of a neutral suggests that they use a switch
mode power supply connected phase-to-phase.