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When we purchased our house, it had an existing off-peak electric
hot water unit in the roof. We disconnected this as part of the initial
renovations and replaced it with a gas-fired external unit. After
around 15 years, this unit died, and we replaced it with another
gas-fired unit with a capacity of 300 litres. This was on the basis
that this would be our only source of hot water, and we had two teenage
boys. Fortunately, Dawn decided to get a unit with a stainless steel
boiler (rather than a mild steel one with a coating) as it would cope
with the higher inlet temperatures if we decided to go solar later.
Around 2004 we decided to move to solar. We got a three panel unit on
the roof (with its own storage tank, but no booster) and plumbed it
into the cold water line to preheat it before it gets to the existing
gas unit. In practice, this means the gas unit runs on a pilot light
only for much of the year - it still comes on during winter, as the
solar doesn't heat the water sufficiently. This summer (2008) we
actually switched the gas unit out of the system and let it go out.
This didn't cause any problems, and we will now follow this practice
The solar hot water unit (we went with an Edwards unit) has
been one of the most trouble-free pieces of green technology we have
ever fitted. We essentially never think about it, and it just does its
thing, providing us with free hot water.
With the benefit of hindsight, it would have made more sense to
purchase a small instant gas hot water unit when our first large gas
unit died. That would have cost more and probably have been more
Had we known that the rebates would have got more attractive we
might have waited to get the solar unit. But at the time we thought it
was a good decision. The payback time on our unit was under ten years,
and it came with a fifteen year warranty, so it was a relatively
When the current large gas unit dies, we will probably replace it with a small instant unit. When the solar unit finally dies, we will definitely replace it with whatever is the best technology at the time.
©Andrew Treloar, 2015. W: http://andrew.treloar.net/ E: firstname.lastname@example.org
Last modified:Wednesday, 11-Nov-2009 10:34:00 MST