To Dim or not to Dim

[aLf]

I am in the process of changing out 30+ dimmers due to paddle problems. I am surveying my network and I'm giving thought to changing some (mainly wife) "always on or off" dimmers to relays. I know the difference (as far as using them), but I wonder if I'm making a mistake tying my hands with a relay when the dimmer is so much more usable? Is there any "mechanical" reliability issue that makes the relay better, or is the dimmer always out ahead with its flexability? Also does anyone else have any history with SH as to the REV#'s that are covered in warranty?

 

Thanks,

 

aLf

[Sub-Routine]

In my own undocumented experience setting ramp rates and using less than 100% levels greatly extends the life of incandescent bulbs. Bulbs last for years rather than months.

 

I really think the ramp rate makes most of the difference.

 

Rand

[IndyMike]

Hello Alf,

 

To add a bit to Rand's comments (that I totally agree with), much of the life of an incandescent bulb is used during initial turn-on when the filament is cold. When the filament is cold it will exhibit a much lower resistance than in it's normal operating state. When used with a relay, this produces inrush current that can be 10 to 20 times the steady state current draw of the bulb. This creates and incredible thermal shock in the bulb filament. A typical bulb that is rapidly cycled will not last nearly as long as a bulb that is left on continuously.

 

When an incandescent is use with a "soft start" dimmer, this inrush is greatly reduced and the bulb life greatly extended. I've never seen any estimates on how limiting inrush can improve bulb life. However, there are documented relationships for applied voltage and bulb life - a 5% reduction in applied voltage can double an incandescent life. A typical dimmer at 100% output does not supply 100% voltage (more like 98%). Dimming down further will further increase the life of the filament (again I don't have number - this is not a linear relationship).

 

I have used both Insteon relay and dimmer units in my home since 2005. I have not noticed a reliability difference between the two. The big question is what type of load you intend to use. If you plan to convert to CFL in the future, you will need either a dimmer/dimmable CFL or a relay/standard CFL. Beware that the relay units are only rated for 480W Incandescent because of the current inrush. If you have large incandescent loads (chandeliers) you may not be able to use them.

 

Since we mentioned CFLs (well I did anyway), be careful in calculating the payback on these units. My experience has been the the life of a CFL is overstated, while the life of an incandescent on a "soft start" dimmer is greatly understated. Since the cost of the incandescent bulb is a factor in the payback, consider that your bulbs will last much longer on a dimmer than advertised.

 

IM

[paulw]

SH will replace any v35's. From my experience if you have any of them, replace them all whether they are causing issues or not.