Solar Hot Water

[echnidna]

I'm considering finding a grant to fit Solar hot water to 2 of the halls in the district scout camp.

A friend had a solahart HW unit on his house that rusted out so I'm going to avoid that brand of heater.

So I'm looking for info and advice about long lasting and reliable hot water heaters.

Or would I get a better quality unit by making them myself?

[SilentButDeadly]

Avoiding Solahart could be quite difficult........it's a brand owned by Rheem whom also have associations with other brands such as Dux....

The reasons behind rusting out are many and varied and it really isn't totally fair to blame the unit alone.....the quality of the water that went in it is another contributing factor.

Given that you plan to use this on a public building.......then I wouldn't recommend solar for your hot water. Basically it'll be lying idle for much of the time and then frantically busy for the odd day. For which it isn't suited. Plus most SHW systems (unless you have a thermo siphon system) need power and some sort of booster (gas or electric) to ensure the water is actually hot plus they also need management to protect them from damage from getting too hot or too cold.......so they aren't entirely low maintenance.

In my book, for your purpose, you'd be better served by instaneous gas (natural or propane) which have no operating costs when they are sitting there idle - these days they have flow triggered piezo electric ignitors, not pilot lights. And they are way cheaper than SHW.

[Sprog]

Check the warranty for each HWS that you consider to see just what is covered and the length of time.

Some solar (and non solar) HWS have a sacrificial anode that needs replacing periodically, it is a service item.

All closed stored HWS will have a pressure relief valve, which is again a service item.

Solar HWS only need booster power for periods of full cloud cover which is not very often in Australia. The Sun heats the water to much higher than you would need for a domestic supply. Hot water is stored in an insulated tank and just sits there until required and being reheated by the Sun. The tanks size is based on your estimated usage so there should always be plenty of hot water.

In my experience, instantaneous water heaters, while reasonably cheap do not have a very long life.

[echnidna]

Its all rainwater so its only impurities will be parrot and magpie poop.
(the one that rusted out was on rainwater too)

I proposed instant (LP) gas and it got poo-hooed at committee level

It gets heavy usage every weekend but not much use midweek
(unless we get a crowd of the great unwashed in)

[Barry_White]

I have had a SHW system for 28 years. When I bought it was a Rheem mains pressure system with three solar panels. It operated with a recirculating pump. I first installed it on my garage which I lived in for a few years and the pump could not cope with the -3 to - 6 degrees C during the winter and the water would freeze in the panels at night and not get hot enough anyway so we always had to boost it with the electricity.

It was designed supposedly to turn the pump on with a thermostat to circulate the water when the temperature dropped down to 4 degrees C to stop it freezing but that didn't happen so what was happening was the sun was heating the water during the day and the frost was cooling it down during the night. A great system eh.

When I bought the unit I asked the guy if I could connect it to a slow combustion stove which he said was fine but that was a load of crap.

When I moved into the house I transferred the panels and sold the mains pressure tank and bought a Braemar tank designed to operate with Solar, Slow Combustion and Electricity.

It operates on the thermo syphon principle and in the winter time I drain and cover the panels and run the hot water with the slow combustion stove which is alight 24/7 during the winter. I installed isolating valves on the pipes at the tank so I can shut the water off to the panels.

I would be asking will it cope in the winter time especially in frosty weather.

As far as corrosion is concerned I have not had any problems and I am on tank water but I am using a copper tank and have 1" copper pipes from the tank to the solar panels as well as the stove.

And there was no government subsidies 28 years ago.

Just as an interesting side note rainwater coming off a Colorbond or Tile roof will quickly corrode a galvanised tank and Rheem have a habit of making steel hot water tanks using that glass coat system which has a life of about 6 -10 years

[David L]

We have had a Solarhart for 23yrs with no problems, it is serviced every 5yrs and the sacrificial anode replaced as necessary.

I was tending to agree with SBD but when I read your last post I am not so sure. If it is used regular it would probably be OK But the water does get very hot so would need a temp regulator fitted. Also it would be best wired in for backup just in case of those rainy days we may get.
I can't understand why more people don't have them.
O and don't forget to make sure the orientation is correct, no point having it facing the wrong way, and clean the glass occasionally.