View Full Version : Solar hot water. Cost? Reccomended suppliers in Tasmania?
17th Jan 2011, 10:19 AM
We just bought a house and found out it only has a 60 litre hot water cylinder, I don't know much about these things but am under the impression that 60 litres is VERY small.
So we are most likely going to need a knew hot water system and thinking if we have to buy one we may as well go solar, depending on the cost.
I am aware of the long term cost/enviromental benifits of solar hot water but the initial cost is also an issue for us as we do not have a great deal of money having just bought the house.
Does anyone know how much a much more in dolllar terms a solar hot water(electrical) v's normal eletrical hot water cylinder? And are the goverment rebates still in place?
Thanks any advise would be greatly appriciated.:)
17th Jan 2011, 07:50 PM
First let's see if you really do need a new hot water system.
Are you sure it's 60 litres? You don't mean 160 litres? I ask because 60 isn't a common size. Common sizes near that are 50 or 80 litre. Others are 125, 160, 250, 315 and 400. So 60 seems a bit odd.
But if it is only 60 litre then yes, that's pretty small. Most common size in Tas is 160 litre, with most of the rest being 250. Tanks in the other states are generally larger, but they also generally run them on off-peak (sometimes only on for 6 hours a day) so they need the larger tank to store more water. Most homes in Tas don't use off-peak for hot water (though you can if you want to and yes it will save a few $ on power bills).
Do you know what the element size is? This will determine how quickly the tank heats up. If the element is big enough and there's a bit of a gap between showers then the small tank size may not be an issue at all (unless you like deep baths rather than showers). And it's no big deal to install a larger element if it's presently a small one - the tanks are designed to fit various element sizes and there's nothing wrong with having a big element in a small tank (indeed that's common practice in some states anyway). Aurora has recently changed the rules and now allows this in Tasmania (and yes, you still get the discount hot water rate).
Also, how many people in the house? This is a key factor.
As for a new electric HWS - they're approaching $1000 for the tank, plus a bit for a plumber to install it. Solar - it varies a lot depending on brand and type of system but expect to end up paying somewhere in the order of $2500. Costs will vary depending on the situation however.
18th Jan 2011, 10:40 AM
I am about 95% sure it is 60 litres, we haven't moved in yet but that is what they have writen on the information sheet the real eastate gave us on the house. Maybe it is a typo and meant to be 160 litres like you say, I hope so, altough when she showed us through the house I remember thinking it looked like a small cylinder (short). We are going to wait until we move in and just see how it goes for a couple of weeks and then if we are constanly running out of hot water we will get a new one.
I wouldn't have a clue about the element..
Anyway just doing some reserch incase we do need a new one so we can plan for how much money we might need.
We have two adults and a child and do enjoy deep baths and long showers.
Thanks heaps for your advise.
18th Jan 2011, 08:16 PM
Whether the HWS is 60L or 160L, if you like baths and long showers as you say then you will probably soon be running out of hot water!
Whichever you get you'll need to have Off Peak power available to minimise cost, whether OP HWS or solar with OP booster. I suspect you probably don't already have a separate OP meter in the meter box, so you will need to get a sparkie in to do this. Meters are usually free and sparkies normally only charge about $300 to fit one.
Here's how you calculate your HW needs.
Firstly, check if you have a 3-star WELS-rated showerhead - if not - get one! THese flow at 9L/min which is IMHO the lowest flow rate that can be called a 'shower' - anything less is a drizzle!
So, then you need to time your normal shower. If 10mins, that's 90L of water, of which probably 50L is HW. A bath will probably use almost double that, so from an energy efficiency perspective baths are bad!!! But nice as a change, every now and then. :)
So that means you will probably be using 3 X 50L/day = 150L
(I'm assuming shallow bath for child)
Add 50L for washing hands and washing up, say 200L/day.
So a 250L OP HWS would be okay for you as it would reheat overnight. You might need to have shorter showers if you have family or friends visiting.
BUT....if you decide to go solar HWS, to save the cost of power by getting some of your hot water free from the sun, you will need a bigger tank. The whole point of solar HW is to get *most* of the heat from the sun most of the time, so you need to allow enough HW for at least two days usage, to allow for rain days. Hmmm. Maybe in Tassie that should be 3 days???
Therfore, first thing to do is minimise the usage, so cut the shower time back to, say, 7mins (this IS do-able without being ridiculous), and go easy on the hand washing and dishes only once a day, which gives you:
3 X 35L + 25L X 3 days = 390L
Therefore a 400L tank should be enough.
The soalr collector is sized according to the tank and local climate, but it is a well-known fact that the evacuated-tube-type solar HWS are somewhat more efficient in higher latitudes and or cooler climates, so I'd be looking at those.
As this is a big tank it will have to be a split system, with the tank on ground, or better still, in the laundry or a large cupboard which can double as a drying room. Helps insulate the tank in colder months.
Try to get a stainless steel tank as this will last longer, especially if you check and replace the sacrificial anode every 8years.
You will still need to boost a lot more in winter, so Off peak is virtually a necessity.
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