DIY Heated RO Drum

[Daniel 123]

Hi All,

Figured Id share a new project I'm going to be working on.
Tired of waiting for that 55 gal drum to heat up to temperature? I always need it sooner rather than later too...

The reason it takes forever to get to temperature is because of the relatively small surface area used to dissipate the heat from the heater as shown above.


What if we used the whole plastic drum to dissipate heat?
Efficiency...

We'll use an industrial vat heating blanket, a resistive wire element sealed in a silicone type blanket, one side has a very strong adhesive backing, this unit I believe is 180W. Like so...

To control this heating element and our drum temperature well need a temperature control relay and temperature sensor...
Here we go.

Ranco SPDT relay Electronic Temperature Control with sensor this particular unit is a dual stage for heating and cooling typically used in HVAC/refridgeration a single stage would suffice.

Well wire the 120VAC cord from the blanket to the internal relay of the Ranco above, then wire a typical 120VAC power cord to the ranco unit, that way we can just plug it in and were heating.

Well probably glue the ranco to the drum and well stick the adhesive blanket on, stick the temp sensor in the drum and we have our plug and play DIY heated drum. This is how some of industry typically heats chemical drums, and should have our water at temperature in no time!

Project starts tomorrow, if anyone is interested, needs more information or any other photos let me know, otherwise I just thought Id share an idea I had.

 

[boneone]

hope you don´t melt your plastic bucket^^

 

[Daniel 123]

hope you don´t melt your plastic bucket^^

You are right.

I have a variable transformer to limit the current/heat this would not be a viable solution for everyone, it would be easier to use a resistive component dissipating a ratio of current to heat of the 1.5amp draw 180w heating element. The blanket is currently capable of heating up to 450*F. I have contacted the manufacturer Brisk heat to find out if they have a chart which shows power resistor ratings and their direct correlation to the max heat the blanket will then reach. I think a good starting point is around 100-150*F. Hopefully this is no problem for them. In the meantime I will also reach out to global industrial and find out the max temperature rating for their trash can at 140mm thick.

 

[boneone]

1.5amp thats a real beast of a heater^^
i read about silicone heater 800W taking only a few seconds to heat 45x45cm MIC6 alu plate ~100°C (4 3d printing) ...

HDPE is a bit heat resistand ~100°C
but the thermoconductivity of HDPE ~0.42 - 0.51 W/(m · K)
a big metall pot would be mutch better alu(99,5 %) 236 W/(m · K)
https://en.wikipedia.org/wiki/List_of_thermal_conductivities
https://de.wikipedia.org/wiki/Wärmeleitfähigkeit

 

[Daniel 123]

There is no need for anything more thermally conductive than your standard HDPE plastic trash can which I think many use to fill with RO water. The heat exchange alone based on the surface area of a large cylinder like the trash can will heat up your RO water in no time, and at a relatively low temperature.


1.5amps is an estimate of draw based on a 120VAC source and a wattage of 180 on the blanket. The blanket is rated to 450*F so it is not known If inside the blanket there is a thermal fuse that would open given whatever time it takes to reach that said temperature, with a draw of 1.5amps.

Without really getting too indept with it we would use Fourier's law to calculate the conductive heat transfer q = (k / s) A dT . While the we lack proper material and material thickness on our standard fish tank heater we would have to make a couple of estimates, versus the heating blanket whose measurements would be more straight forward. With that said heating the HDPE trash can will produce exponentially more heat transfer even with its slightly lower thermal conductivity than an equivalent 180W common glass(thermal conductivity = 0.91W/mk) "fish tank" heating element with an extremely small surface area. I quickly calculated with some estimations to make sure Im providing the community with good data, of course I am missing some data points like the heat transfer laterally from a point source of heat ie the blanket area given the total surface area of the can but for a project such as this I am fairly confident, and will certainly time temperature rise to a stable 78*F of the blanket vs ordinary heaters, or should I say how many Watts of heaters it would take to match the blanket.

If you want to help me or have other ideas by all means Im open to your suggestions.

 

[boneone]

i was thinking of min 230V AC we have @ austria/europe, sorry my mistake.

the only other idea i got would be an isolation on the outside...