# bkf11

• Nov 7, 2006

### Orangeboard

bocaboy8 years ago
Benjamin,
You seem to be knowledgeable with regard to the use of transformers for wiring alternative projects like the styrofoam cutter.
I want to use the same type of low voltage unit to make a heated toilet seat. I plan to rout out the bottom of the seat and then use a heavily insulated wire sealed in place with silicon caulk. My question is what type of wire should I use that generate enough heat to warm the seat without generating enough to burn my butt?
I have a variety of transformers to choose from (I think they have been multiplying while in my desk drawers.)
I know it can be done. They sell them at http://www.sani-soft.com/heated.html , I just want to do it myself.
Any input would be appreciated.
Thanks,
Michael

bkf11 (author)  bocaboy8 years ago
Hi Michael. There have been many cold winter mornings that I have wished for just such a thing! I'd say the most important thing would be to keep the heating voltage at a safe level (below 40V is considered safe to touch I believe). 12V would be good, maybe 24V. This is so that if anything goes wrong, you don't electrocute anyone while flushing the toilet and water splashes up to the seat which might have just been broken, torn or whatever. How much total power you need depends on how you operate the seat. If left on all the time maybe only a few watts would be OK. Given that our heated towel rail is 60W and gets pretty hot and is twice the length of a toilet seat, maybe 1/4 of the power would be ok - 15W or less I guess. In that case do the math using the calculations above to figure out what length of wire will suck that amount of power. So for 15W using nichrome wire & 12V you want twice the length of what I calculated - 60cm. For 10W, use 1m of wire. For 5W, 2m. If you use a computer power supply you could use the 5V rail instead of 12V. If you intend to turn on the heater only when people flick a switch or when a sensor detects the door opening then you may need a higher power output like 50W but ony for a minute or a few seconds. If you used a microcontroller you could get pretty fancy with people sensors, temperature sensors, PWM temperature control and timers. I'd love to know how you get on. Keep me informed or discuss further at benjamin.franzmayr at agresearch.co.nz Good luck Benjamin