Backyard Aquaponics
A place to discuss aquaponics

VB - how did you go with your stainless steel heat exchanger?

Lot of work in this heat exchanger and black pipe ( only heats in daytime).

AHHH,why not just normal aquarium heaters , majority of heating needed at night and the new deal in our area see's off-peak (8:00pm-8:00am) Electricity rates at near give-away prices.
Eitherway , good insulation around and especially on top of the tank will be very important and NOT havingthe tank "in-ground" will be necessary.

Think we have been through this with KE, however the system I will probably go with is as follows.
Solar panel (scrap price) Rheem storage heater (roadside pickup). HT pump (out of a heat exchanger aircon) temp sensors to relays (still checking on the ones I have pulled out of things).
Solar panel heats storage heater which is in an insulated box. Part feed from sump pump goes round storage heater poly pipe coil and returns to FT.
Haven't picked up a storage heater yet so am unsure of the heat bleed at the moment (may need some mods).
Poly pipe to FT will not get hot, only warm so no leaching problems.

When I started my hort. degree I visited a rose farm in Wagga Wagga that had computer controlled heating to grow roses for the cut flower market all year round. What they did was run a network of steel pipes (looked about 70mm diametre) through the greenhouse, about 10cm above a gravel bed, and pumped hot water through it that was heated by an oil furnace. The oil they used was free because they had a deal with all the local mechanics that they would pick up their waste oil to use in their oil burner. Several DIY solar water heating strategies I've looked at seem to be very efficient producing water of near boiling point temperatures and this pumped around a greenhouse-covered network designed to heat the air and not the water would raise the ambient temperature which would also help maintain high water temps and the thermal properties of water mean it would act like a heat bank. I particularly like this idea: DIY Solar Thermal - Hawaii Addition - hooked up so the hot water form the coil indirectly heats the water... what I want to know is will conventional water pumps handle hot water like this?

I think we all have the wrong idea anyway... this guy has the right idea Beer + sunshine

- bought the stainless steel pipe, picked up the old pool heating shit from the old man (is in pretty bad nick, with a lot of broken connectors) and did nothing else. Is a project to be completed by next winter I'm affraid (ie 2009), as I have a fair few other things that the boss (wife) has determined need to be done as a priority

I take it there's a list stuck on the fridge VB

More like tattood to my brain

My year 10 daughter just did an experiment...

looped black pipe .... solar heating..

Low flow rate pond pump ... flow is constant..

looking at temperature rise per metre ... from a massive constant temp water supply. Cut off a metre each time. One hour each way from solar noon in a clear sky!

Most of this stuff can be calculated

BUT ..

She is not a chemical engineer ...

maybe interesting to see her results and report...

I will post when it is marked by her teacher!

There are possibilities using black pipe.

Timers, temperature sensors and flow control are essential.
"Smart" flow control and timing would make this efficient... but expensive!

However .. big / commercial scale ... computer control software becomes relatively cheap.

Na, just a simple quad op-amp a couple thermistors and a triac or relay. Not expensive to control flow by temps.

Just another thought,,not trying to wreck the thread. Temperature shock!!,water in fish tank say 27C , pump turns on , waterflows out to several tons of blue metal sitting at around 0C and flows back to fish, could be down as low as 10C in a matter of minutes,,,result floating Barra.

If the bed is at 0C theres not much point sending it any water as nothing is likely to grow much. The bacteria will (hopefully) be dormant and not dead
Re-route the tank flow to a mechanical filter, FBF and finally lots of NFT gutters or perhaps dwc buckets.

The answer to this is that the heater could be in the return from the GBs, so that the water is warm enough to return to the FT.
Alternatively, a heat exchanger could be placed between the water to the GBs and the water returning to the FT. This would warm up the water returning to the FT by cooling the water going to the GBs.

Tony

400 metres of poly tube to be 'green" ? possible chemical leaching , inefficient pump required due to length of rise and resistance of flow on 400 metres,with elbows ETC,, i.e total head.. System only makes heat on sunny days when least needed .
Damn ,, trying to be overly green can really mess up being practicably green.
Ok, time to stop with the scarcasm bull and get to the point.
We are looking for an efficient practicle and cost effective way to heat water. Agreed?
Ok , I can go all green and chase the local dogs , collect their poo and build a methane powered heater ..... NO ,, we said PRACTICLE / cost effective ( time equals money ).
time chasing the dogs ,, time building the methane heater etc etc makes this unrealistic.
There is a product called a Solar heat pump ,, misleading name because it ain't got nothing to do with the sun,,, best way to think how is works , is as a refrigerator in reverse.They use VERY little electricity ( buy your power from green suppliers if that makes you feel better) , it will produce efficiently day or night ,, rain or shine. Ok , the down side ,, they are about $3,000 ,, AHHHHHHHHHHH ,, yep agreed expensive. can this cost be off-set? Well other people have suggested that having their normal house Hot water system replaced with one of these sees near $2,000 in rebates , if one was to 'replace ones HWS and then after recieving said rebates ,, this "solar" heat exchanger was to suddenly , inexplicably be re replaced with your original heater and the efficient heater was to find its way to an Aquaponics system ,, well , well ,, things like this do happen:)

For most systems Sydney and North , heating is most criticval at night, off peak electric rates are super cheap.

Hey Chappo, check out this thread:

viewtopic.php?f=8&t=1366

Smiles ,, haven't read the whole thread but obviously people are thinking.

These Solar pumps ( bad name) are for now the obvious answer , running costs are very low , start up costs high if you cannot get the governemnt rebates ( more accurately if you are unwilling to recieve same and moove the system, not that I would ever suggest that idea)

i am costing smaller units , but scale of economy will of cause be a factor.

An aside note ,, i am also sourcing stainless steel grow tanks , amazingly I may be able to get these at less than most are paying for fibre-glass.

I LOVE Whales ,, they taste great .....,,
await nextg weeks NON politically correct Chappo comment.