Has anyone made their own solar roof-mounted heater for their Spa/pool ?

Found some plans onthe net wanting cash but no free links yet. am keen to raise the water 10 or so degrees to lessen water heating costs.

Am thinking of making one out of 19mm (0.75") black ag pipe on my roof. This stuff is cheap, watertight and has all fittings (elbows, joiners, etc) available in the home watering section of any hardware store.

Not sure at this stage if the 900w spa pump will have enough grunt to circulate to the height of the roof hence my query.

TIA

this sort of set up can work but you need to consider these points:
your climate does not lend itself to effective performance for any reasonable period
you need 4 x the surface area of the spa in roof solar matting/pipe to heat to spa temperatures in a more moderate climate of Sydney and north
you need a solar controller to prevent operation when the roof temperature is cooler than water temp, or it will cool down as fast as you heated it.
basically in your situation, i feel its not worthwile - in a warmer climate of Queensland, as long as the above points are considered it can work efficiently.
in your case stick to electric or gas heating only, supplementary solar installation costs to set it up properly will outway the advantages received for the short period of the year it would work
contact me directly if you want further local support or parts

Hi alacy thanks for the info.

Funny you don't think it's worth it as a I know of someone who put together a DIY kit total cost about $50 in parts to add 10deg C to a 28000L pool in Canberra. This is where I got the idea for my spa.

I figure a roof-sized heater should give not too bad performance for a much smaller application like my 6 person spa.

FYI we experience plenty of nice warm days in winter/autumn just the nights get bloody cold so a manual diversion system (two switchable valves near the spa so I could disconnect the main supply from the roof solar heater when it turns cold.

This would also allow the system to gravity drain back to the spa to empty before night time turns it into a tubular ice-making device

Will let you know how I go and post some pics up when it's done...

not that simple, but anyway go for it

It wont work, as your describing it. The problem is that solar gets less and less efficient as the desired temperature goes up. The hot tub is quite a bit hotter than a pool.

As a general rule, if you want to heat something to about above 85 degrees F you have to have pannels that are boxed in and glazed. This keeps the wind off and creates a greenhouse effect. Without this, it's unlikely you'll heat anything over 85f

As I understand it the solar heater is *supplementing* the electric heater during it's warm cycle whilst not being used during the day to decrease the amount it has to work & save some $.

Theoretically already warmed/ing water flowing through 50-100m (164-328ft) of hot black plastic piping on a roof with uninterupted (ie no trees/buildings) access to sunlight for about 8 hours a day will give enough benefit to make it worthwhile. Thankfully the home is situated in a usually non-windy area.

As a mate said it's a $50 experiment so if it doesn't work as well as expected (or at all !) I've got my new garden watering system piping with LOTS of bends

I appreciate the info, thanks !

fyi - I picked up the parts last night for $60: 50mx 19mm tubing, 20x 19mm right-angled bayonet fittings and two 3-way valves with standard hose fittings.

The roof length is 15m but not sure of width yet (est 5m) so may get as much as 90-100m up there in 6-7 runs.

It'll be stuck to tiles with liquid nails making for easy removal if required without any drilling.

you miss the point - this is not an efficient setup and will not save you money - additional pump running time, automatic cooling without the solar controller, freezing pipes without a roof mounted solar vacuum break valve, etc.

stick to your existing heating system to maintain practical performance unless you take the above points into consideration
sunlight does not always equal heat - if the roof is cooler than the spa and you run this setup, your spa will cool down.

just the humble opinion of an experienced spa tech. however, i'm often proven wrong - maybe this is one of those times

how 'bout
nome alaska?
Santa cruz ca? (Me)
death valley?