RIMS Element question - Distance and Low vs Ultra Low Density

Here is my setup-

operating on 120v, PID controlled RIMS
pre-owned BobbyM/Brewhardware.com pre-triclover setup
4inch rtd

previous owner had a short 1500W ultra low density element - it's rusted a bit

i was thinking of putting in a 4500W LOW (instead of ultra low) density element. this will run at 120 - for a small amp. this one is quite a bit longer - 10 inches instead of 4.5 on the old one. this would be slower ramp up time, but would give me a little more room when operating on a 15 amp circuit.

Some of my thoughts about using this different element was based on what I read in this thread:
http://www.homebrewtalk.com/f51/electric-heating-element-rust-prevention-172928/index5.html

See post 46 and 48

that the camco LOW density elements have a different coating that may be more rust resistant.

when i stick in a tape measure down the element side of the pipe, there's 14 inches before i hit the RTD.

Would it be ok to have a 4 inch gap between element and RTD vs the ~9 inch gap with the old element?

Thanks for the help!

 

I have approximately 1" between the end of the element and the probe and have no problems. Flow through the tube is not laminar, so there is plenty of mixing to make the flow over the probe representative of the entire wort flow. Personally, I would remove the 1" - 1 1/2" reducing bushing and fit it to the element, coat the end of the element and the exposed 1" ID threads on the bushing with silicone and then put the bushing back in the RIMS tube. That will help reduce the rusting on the element base. Mine has been that way for a couple of years now and shows no signs of rust. It does require that any disassembly of the element be by removing the bushing from the tube rather than the element from the bushing.

 

Thanks for the reply. That makes sense.

Do you use normal home depot bath kitchen silicon?

 

No, most of that type of silicon has an anti-fungal in it. I use some designed for repairing aquariums, once it has cured there is no problem. There are NSF listed food safe silicons, but I can't find them around here.

 

This is the silicone I bought and it seems to work out just fine food grade and all. http://www.ebay.com/itm/281059384089?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649 I built a spot on my brew stand so my rims tube can sit in vertical and when i'm done using and rinsing it I just lay it on it's side and the electrical enclosure box on the end keeps it at an angle so the water never sits on the element end and has yet to rust. Never thought about using the silicone at the end of the element.