Low Volt Lighting for Haunted House

Hi everybody, new to the forums, but I've seen a lot of cool ideas already! I looked around for a while but couldn't find an answer. I volunteer at a local haunted house and we're thinking about updating our current theatrical lighting system.

Currently we're using small incandescent bulbs running off of a 28v system and would like to switch to LED for obvious reasons. I used the LED calculator at http://led.linear1.org/1led.wiz to figure out what resistor would be needed for our system and it came back with the correct sized, but also stated that 28v would produce excessive heat from the resistor when using a single LED. As it stands I believe every LED in the rooms will be supplied with a full 28v.

Are we trying to tackle this the wrong way? Are the resistors going to burn out and kill the LEDs prematurely? We can re-wire into series or parallel if necessary, but we were really hoping to be able to pull the old lights and swap them with LEDs.
Sorry about the length and thanks in advance for any help!

28V decent voltage which guess means volt drop on long runs isnt a problem. But does the power supply rise if lighten the load, if its its a big linear voltage might rise and you want to take that into account.

Lets take average voltage of a blue, UV, true green or white LED as 3.5V trying to drop 24.5V across the resistor is going to make it a bit hot....

1 5mm LED might not be quite bright enough for what your after, so series LEDs up in clusters, 8 would probably be pushing it slightly 6 or 7 in series and appropriate resistor gives a very useable lamp cluster possibly buildable into your current lamp base.

Cheers
Adam

If you dropped your entire system to 12 VDC, you could look at premade bulbs meant for auto LED's.

http://www.dealextreme.com/products.dx/category.708