hot water heater elements

[altereddezignz]

I have kinda a crazy question. I am needing to heat about 200 cal of water to between 80-90 degrees. the tanks right now are the plastic poly tanks like farmers keep chemicals in. I have an old hot water heater with electric elements but i curious do the thread on the elements get hot. I would like to drill a hole in the side of the tank and buy a nut and use a gasket on the inside and outside of the elements to seal it. But i am afraid that it might melt the plastic. I will probable end up having to run 3-4 4500 watt elements b/c this water will not stay hot over night just during the day so it would have to be heated up daily or if i knew i was going to use it over a day or 2 span i could leave it on. The tanks will be very well insulated on the outside with a cover for when not in use? Any ideas..
Thank you very much.
Oh and this is for nothing illegal lol making some temporary hydro graphics dipping tanks lol..

[jadnashua]

There are some WH that have plastic tanks. I do not know if they use special heating elements, but it's probably possible. Having the element surrounded by water would limit the temperature rise. Now, I'm not sure a standard WH thermostat can go that low, so that may complicate things.

[Terry]

Any heating of a closed system or tank is going to need thermostats, and pressure relief at the least. As water is heated, it expands. I'm not liking the idea.

[altereddezignz]

I guess i need to put a little more info up here. the tank will not have a top. It would be only for heating. Doing some testing with hydrographics and need a dipping tank. Want to test before i spend 4-5k on a stainless tank.

[altereddezignz]

Yes it will also be thermostatically controlled

[hj]

The typical water heater elements do NOT have sufficient thread length to accomodate a lock nut on the inside of the tank. You would need some type of 1" female "boss", or "bulkhead fitting", attached to the tank, then the element screwed into it.

[LLigetfa]

I guess i need to put a little more info up here. the tank will not have a top...

If it is open, why not just hang an immersion heater?

[altereddezignz]

The reason for not using a submersion heater is i really need to heat the water from the bottom with circulating water so it is more efficient. If i have a submersion heater then i have to heat the top an push the water down to the bottom.
I dont have anything against using a submersion heater since i was in the begging looking at using 4 300 watt fish tank heaters but it would take forever to heat up.
One more reason i am trying not to use submersible heaters is b/c whatever heater element i use now i would like to be able to transfer it over to my stainless steel tank when ever i build it.
I have even been thinking about running 4-6 4500 watt elements and making them all kick on with initial heat but only 1-2 run when just keeping the water warm. Since this tank will not be used everyday i would be able to heat the water within a very short time since the ambient air temp would hardly ever be below 50 even in the winter and it needs to only be heater to 90 degrees.

I guess i could always use one of the 4 bolt water heater elements.

[altereddezignz]

Also on the subject of heating the water would anyone be able to help me on trying to figure out how long it would take to heat the water to a specific temp at a specific start temp with a specific amount of wattage for a required gallon?

I can figure how many watts needed to heat it in an hour using this

KW= Gal X Temp Rise F
------------------------
375 x heat time HR

KW= 200 X 50
----------------
375 x 1

KW= 10000
-----
375

KW= 26.66
1 kw= 1000Watts need 26600 watts