Alternative Heat For Tank (experiment)

I've been thinking about an alternative to electric resistance heat
for
my tank, in case of extended power loss or whatever. I'm thinking of
using heat from my gas water heater, or perhaps a small alcohol stove.
Today I played with a heat exchanger. Hope my notes aren't too
confusing.

Any input, thoughts, experiences, critique, would be appreciated.

Paul

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Alternative Heat For Tank (experiment)

Aquarium set up:

Tank:
-All Glass 75 gal
-Glass top
-one T-12 gro-lite

Filter:
-DIY trickle sump; 18 gal sweater box, and 5 gal bucket
filled with bio media
-Mag 5 pump with 1 in smooth bore flex hose, no elbows.
300
GPH or better, I'm guessing.

Overflow:
-DIY HOT; Two large specimen boxes, with two 1 inch OD
'U' siphons

Existing heat:
-Two 150 watt EBO's in sump, controlled by external t-stat
(Ranco ETC 111000)

Other:
-no plants
-no power heads
-total water column approx 78 gal us

Residentsin stanard length)
-Clown loaches 5 2.5 to 3.5 inches
-Rainbows 7 2.5 to 3.5 in
-SAE's 5 3 to 3.25 inches
-Skirt tetras 8 full grown
-Runny noses 14
-Oto's 6
-Platies 2
-And a Rubber nose Pl*co-sarus 2.25 in
(Very peaceful playful tank)

Makeshift Alternate Heat:

Heat exchanger:
-48 inch corrugated flexible stainless steel gas
connector,
intended for hookup of gas dryer.
-ID nom 1/4in
-OD, 1/2 inch'ish
-Supplied with connectors for use with 1/2in standard pipe
thread
-Cleaned and flushed

Brand: Brass Craft
With: Pro Coat protective coating (thin Powder Coat)
Available: Home Depot
Cheap: $10 us

Note: This item is pretty much the key component of the
test
It was selected for its cost, availability and its
(hopefully) chemically inert properties.
And with the hope that its heat transfer properties would
be suitable.

Heat source (for testing):
-6 qt elec cooker with temp control

Pump
-Rio 800
-12 watts rated
-211 gph @ 0 ft lift, 100gph @ 3ft lift
-probably running 100 to 150 gph with heat exch and
tubing(no lift)


Set up:

Heat exchanger:
-Form the stainless steel flex into a coil. It easily
coiled
down to a 1.5 in radius, for an
-overall dim: under 4 in dia coil by 2 in tall (easily
fit in a
four quart pot)
-adapt exchanger's 1/2 in pipe fittings with plastic (or
stainless) adapters, for plastic tubing

Hook up:
-Connect discharge of pump to the heat exchanger coil with
2
or 3 ft of plastic 1/2 ID tubing
-Connect 2 or 3 ft of tubing to outlet of coil, to return
water to sump.

Install:
-submerge pump and the open return tubing into sump
-place connected heat exchanger into cooker filled with
preheated
water


Run test:
Init temp:
-Room temp 59.2 deg (burrr)
-Tank initial temp 78.5.
-Cooker water init temp 110 deg
-The two 150 watt tank heaters were cycled on

Operation:
-Start pump
-Elec heaters cycle off within one minute.
-Tank temp climbed from 78.6 to 79.2 in approx 15 min
-Cooker temp dropped to 100 deg

-during the subsequent 3 hours, The tank temp rose, very
slowly to, and stabilized at, 80.2 deg
-source water (cooker) temp dropped to, and stabilized at,
91 deg

-Eight hours later;
Tank temp 80.0 deg
cooker temp 90 deg
room temp 60 deg

Conclusion:
Heat transfer capability of makeshift heat exchanger,
Impressively adequate