Hydor in-line heater - what's inside? - The Planted Tank Forum
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post #1 of 6 (permalink) Old 04-22-2013, 07:00 PM Thread Starter
Planted Tank Obsessed
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Hydor in-line heater - what's inside?

Has anyone ever disassembled a Hydor heater? I would like to know where exactly the heating element is located and where the temperature sensor is located with relation to the inner chamber and the water flow. Is the heating element evenly distributed across the entire inner chamber wall, or is it localized in some narrow[-ish] band?

The reason I'm asking is that I'm doing some aquarium plumbing in a tight stand space. One of the consequences of that is that I will install a Hydor heater in a vertical segment where water actually flows straight down, not up. This results in a dilemma: what is the best way to orient the heater in such installation?

If I install it "top side up", the water will flow against the intended direction indicated on the heater body by an arrow. The water flowing "backwards" might affect the sensor operation, since it might effectively swap the relative positions of the heating element and the temperature sensor. Does this consideration apply to Hydor heaters or not?

If I install it "upside down", the water flow will agree with the arrow on the body, but if the heating element is localized somewhere around the temperature adjusting wheel (the original bottom end of the heater), I might increase the risk of air pocket forming right next to the heating element (for example, if the heater is not primed properly).

At this point I tend to choose the latter approach, i.e. obey the suggested water flow direction. But I might be missing something important. I would appreciate any advice.

Last edited by AndreyT; 04-22-2013 at 08:29 PM. Reason: typos
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post #2 of 6 (permalink) Old 04-22-2013, 08:01 PM
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They have been looked into....once....

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post #3 of 6 (permalink) Old 04-22-2013, 09:05 PM
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I was faced with the same dilemma, and chose correct flow direction, upside down. Haven't had any problems. They do make it awkward to mount like that, though - puts the one and only "hanging" loop at the bottom. Wonder if that's on purpose.
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post #4 of 6 (permalink) Old 04-22-2013, 10:56 PM
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Look through it. It's just a smooth-walled plastic chamber (no stars, here!). As long as you don't have any air caught in there (which would be tough to do), water will be in full contact with all surfaces and it doesn't really matter which way you orient it.
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post #5 of 6 (permalink) Old 05-25-2013, 05:53 AM Thread Starter
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Found this page, in case anyone's interested to see what's inside


The chamber wall is apparently glass, not plastic.
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post #6 of 6 (permalink) Old 05-25-2013, 03:37 PM
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Good find. I've been wanting to get these myself, but I worry about flow loss.
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