"Zak" wrote in message
...
I had always lived in the belief that a 15W soldering iron ran cooler
than a 35W iron but recently I read something which said they both
run at the same temp.

Presumably the real difference is the speed at which the iron reheats
once the thermostat kicks in to say the iron is too cool.
You are assuming the iron has a thermostat. Basic units don't. Just like a
basic electric 'bar' fire, they heat up and stabilise at the point where
the heat loss from the iron, matches the input power.

I'm in the Uk and I currently use a 25W Antex. It seems to "run out
of heat" all too often when I am soldering undemanding things like a
fine wires to small tag.
If you are doing a lot of joints in succession, with an unregulated iron,
then the tip will get cooler with each one. Also, you must be careful to
be using the right solder. The iron will have a 'design' temperature, and
some solders will require less heat than this, while others require more.

If the temp is the same then would I be ok using something like a 35W
iron even for working on electronics components.
Get the smallest shafted temperature controlled iron you can find. Two
basic designs, 'single temperature' units, like the Antex TCS50 (trimmable
with a screwdriver), or fully adjustable units, like the 660TC, with the
TC50.
Antex irons give better heat transfer to the joint (I also use a 100W
Weller TC iron, and the Antex 50W will out solder it on some jobs), than
many competing designs, and I like the weight.

Best Wishes