Dimmers are useful when you have a lamp that overheats easily
It controls the flow so you have proper movement of Lava
Also if the lamps have placement near heat source
Next to other lamps, etc
Hi from across the pond! Claude has answered you in technical terms better than I can, maybe it's worth adding some lava fills (eg - I believe - Goo-Kit) need less heat than originally-installed lavas, so a dimmer comes in handy there
Also big lamps - Lunars etc over here, (maybe Grandes and Giants I guess over your way, and certainly Colossus), need ages to warm up and, because of their size/volume etc, exhibit individual characteristics in lava flow that make tight control of power/incandescent heat useful to prolong the flow... so dimmers are factory fitted.
I'm now retro-fitting them to some of my smaller lamps over here - Astros - and really like the results, as many of the older Brit lamps have needed Goo-kitting.
I believe - Goo-Kit) need less heat than originally-installed lavas, so a dimmer comes in handy there
the paraffin blend uses less heat to make the goo rise
Andy, I've been thinking about attempting the refurb but my Century lamps aren't quite at that point. I have a lamps from the 80's, Midnight and Silver Streak I think, that are short a few inches of water each so I may attempt to add some water. Do you have reference for instructions on the retro-fit?I have seen a lot of "how-to's" online but don't know if there's a favorite or definitive source for it.
For small quantities missing, just add distilled water to the desired level
If flotation is an issue afterward, use Propelyene glycol.
It is best to invest in a bottle capper
Jim, it's entirely dependent on what dimmers you buy... they are fitted like an inline switch, a comfortable/convenient distance from the base, obviously... though the Colossus ones were built into the base (and not very good by some accounts)
The ones I use are Relco, made by the Italian firm that made the dimmers fitted to Mathmos Lunars - they do a small one for less powerful bulbs (40-100w I think) as the model for Lunars is OK up to 300w but doesn't operate below ??30w.
If they make them for US voltage I can certainly recommend them, but I know Claude has experience in this area and can guide you for US dimmers if not. They can be quite tricky to fit, a fiddly wiring job.
Btw, one thought - I'm increasingly playing with lower wattage bulbs to overcome the problem of overheating, especially on wall lamps where you can't fit a dimmer... eg a Mathmos Jet (original spec was 40w golfball, with older formulation wax, then down to 30w reflector) I'm successfully running without dimmer on 25w reflectors - it's a fine line, as 25w golfballs weren't sufficiently powerful. The key issue is get the mix dead right first, obviously - but it's worth remembering that the correct bulb on the original spec may no longer be right with your new mix...
its a simple formula
less wattage = More propylene glycol for flotation
There is a midline where the wax will not melt properly so it's usually best to stick with basics.
And, there is a 12VDC dimmer available. https://www.ebay.com/itm/Brand-New-Inline-PWM-12-Volt-2-Amp-Dimmer-...
Some dimmers even have remote controls