Re: Water heater eating X-10 signal

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

In article <E9ydnWRPweMgFqnbnZ2dnUVZ_rWnnZ2d@xxxxxxx>, ROBERT_GREEN1963@xxxxxxxxx (Robert Green) writes:

| This really is a fascinating problem.  I never expected that you'd get 5
| bars at the light switch.  I'm thinking that for whatever reason, the signal
| reaching the wall switches is corrupted and that the earlier threads
| regarding interaction between the two phases was correct.

The problems with this are that (1) such interaction should cause simple
cancellation rather than corruption per se (unless the repeater is doing
something really strange like sending out of sync--that particular repeater
is known to be a bit odd) and (2) with the elements off there would have
to be a big capacitor leg-to-leg or such and I can't see why that would
be the case.  The original poster is welcome to try my spare/repaired
CR230 if he wants to rule out repeater oddness.

| The lack of low voltage feeds to the water heater suggests to me that
| there's a switching power supply capable of running from 240 volts inside
| the unit.

Traditionally 240V appliances use a 240V transformer for the control
supply (which is usually 24VAC), but then again traditionally water
heaters don't have low voltage control circuitry at all.  At this
point popping the cover of the heater seems in order.

| They are a known plague to X-10 and could be the source of the
| noise that Dan has suggested might be the problem.  If so, it might be
| possible to filter only the control circuitry inside the unit, but it
| wouldn't be a very clean fix and it would probably be impossible to get it
| inspected with such a jury rigging.

I don't know; I was thinking that that would indeed be the clean fix.
HVAC folks are always doing quasi-custom hacks to installed equipment
(some not too neatly) so maybe it isn't a big deal.

| Dan points out that might not be the case as he's seen wall switches suffer
| from interference that did not register on the ESM1 so without a scope or
| analyzer, it's very hard to say for sure.

And in fact it was pretty hard to see even on a scope.  Those switches
seem to be among the most sensitive X10 receivers.  Given the strong
signal at the switch it might be worth testing the noise theory by
connecting a 0.1uF capacitor across one of the switches.  If that makes
the problem go away it is likely noise, but you can't really leave the
capacitor there. :)  (You can desensitize the switch as I've described
elsewhere, but that's a last resort.)

				Dan Lanciani
				ddl@danlan.*com