How Waterproof are Fish Tank Heaters?

[Andrew Mawson]

I am making a cylindrical nickel plating tank as I find that the bucket I usually use often isn't deep enough - currently need to plate some 27" shafts. So I've made up a 30" length of 160 mm underground drain with a stop end at the lower end. Shape is ideal as I can drop a tank bubbler in the bottom for agitation and the entire length of the shaft will be agitated. However although I've been using fish tank heaters in a plastic bucket, and they've survived the occasional 'total immersion', in this tank they will be well under the surface. It occurs to me that they might not stand up to this treatment - any opinions?

(I have a fall back plan to slip a suitable diameter plastic tube over the cable and top 1" of the 'test tube' that they are built in, secured with a plastic clip but I'd like to avoid it as the plastic tube will be relatively inflexible and tend to knock over the vessel)

These are the heaters I'm using:

Andrew

[newshound]

I'd expect them to be OK. Although the ad talks about not lying them on the floor of an aquarium because of the pressure, I'd be surprised if they couldn't take a couple of psi, which is all they will see even at the bottom.

You will have RCD/RCBO protection presumably?

[Dave Plowman (News)]

The cable entry doesn't look waterproof to me. Nor does the temperature adjustment.

[Graham.]

My aquaeium heater is over 30 years old and although I try to keep the top above the surface it must have spent a good while totally submerged with no ill effects.

[tabbypurr]

Standard aquarium heaters are totally waterproof, but I doubt those ebay ones are.

NT

[James Wilkinson]

You only need that if there's fish in it.

[whisky-dave]

I'd have thought they;d be alright as the are designed to be submurged mine was almost always under the water.

I;d be very worried by a heater that looked as though adjusting teh tempera ture with wet hands looked dangerous as it's difficult to adjust these thin gs without getting yuor hand went and even your arm while adjusting such th ings.

I wouldn;t worry if buying from a shop but buying these cheap ones from eba y I might be more careful.

Regarding not letting them sink to the bottom I don;t think it's the PSI, i t's that if it was in left on the gravel over time it could create a hot sp ot on teh glass as normally the heater relies on water passing over it to c ool the outer glass which can get pretty hot if not underwater. So if it's resting on teh bottom it could cause problems as the glass wouldn;t call as expected, again with a cheap ebay item I'd be more worried.

[alan_m]

It's probably more to do with overheating. Aquarium heaters need a free flow of water around all of the heater. Rest a side on the bottom of a tank and that side of the heater will 'cook' the glass envelope.

In 30+ years, the aquarium heaters I have owed could have, and did, survive full immersion in water.

[newshound]

Plating fluid has high conductivity (of course). You don't want to zap yourself or the DC supply with mains.

[newshound]

In the old days, the far east used to make cheap clones of quality western stuff. These days, I suspect most of that sort of stuff, even when sold with nice packaging in pet shops, comes out of the same far eastern factories. They have recognised that they make more money from good quality products.

You are quite right about hot spots, though.

[dennis]

They should be fine, I have had similar submerged for years.

However why not use an immersion heater and run it at reduced power. They are about the correct length and more robust.

[Graham.]

Aquariums are amongst the things that are often recommended not to be RCD protected

[James Wilkinson]

On what grounds?

[James Wilkinson]

I'll give you the DC supply, but being scared of mains is pathetic.

[Andrew Mawson]

Because:

a/ they are metallic so would contaminate the plating

b/ too high power - these are 100's watts not kW

c/too bulky

...otherwise ideal, but thanks for the suggestion :)

Andrew

[Andrew Gabriel]

As a life support system, they shouldn't share an RCD with anything else, but it's a good idea to have dedicated RCD protection.

[dennis]

plate it first?

240V 3kW immersion on a 24V supply is about 30W if my mental arithmetic is correct. Just use a dimmer (a big dimmer?) its a resistive load so it doesn't need any fancy electronics.

a tube about 10-12 mm dia and 27" long is too bulky?

OK.

[tabbypurr]

no, they haven't. I buy Chinese products as part of my work.

NT

[tabbypurr]

a lighting dimmer on minimum would give around 1.5kW on a 3kW element. Perhaps you'd recommend tossing in the potatoes first.

Feeding mains to a nonwaterproofed element in water is not a sane idea. If you do install it waterproofed, DHW elements routinely split open near end of life & pass mains through the water.

Oh... and some are copper alloy plated, which is lethal to fish. Other than those points a great idea! Dennis strikes again.

NT

[dennis]

A modern dimmer should give a much lower limit than that or it won't work with LEDS or CF lamps. These are proportional to the current through rather than needing to be hot to get any light.

You feed mains into an immersion heat all the time. Don't forget the earth.

What have fish got to do with it? I wouldn't have recommended one if fish were involved.