Re: UGF Heating Alternative

>1. PVC is a relatively good insulator.  You would not get very
>effective heat transfer from the tubing to the substrate. 

I have a similar setup using CPVC. I don't know about the insulating
properties of it but the walls are much thinner than PVC.

>2. The gravel near the "hot" end of the coil would get more heat than
>the gravel towards the outlet end of the coil as heat is slowly
>dissipated.  Depending on how it was set up, you might be heating only
>the first foot or so.

I heat the water in a reservoir and then pump it through the coils with a
powerhead. I have probed the substrate in many different places with a
digital thermometer and the temperate is about 3-4 degrees hotter than the
tank water. It seems to make no difference where the probe is places near
the inlet or the farthest point in the coil the gravel temp. is about the same.

>3. How hot does the water need to be to warm the gravel enough?  The
>Dupla coils get to about 90 F.  If the PVC acts as insulation, how
>much hotter does the water need to be?  And how will you get it that
I heat the water in the reservoir to 87 degrees using a 100W Ebo Jager
heater. I can crank it up hotter but then the tempters of the tank gets way
to high. I use the substrate heating to heat the tank with an auxiliary
heater it the tank for cold nights.

>This is not a bad idea. New people can use the newsgroup and if enough of
>them want a list they could start another one up. I also like the list but
>really don't want it getting any bigger. If too many people leave it could
>be opened up again to maintain a certain level of membership.
I agree that it is probably a good idea. Limit membership to a manageable
number, when slots open up let new members in.

Allen Sandifer