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If you were me... in Tassie - Solar panels or Solar Hot water?

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  1. #1
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    Default If you were me... in Tassie - Solar panels or Solar Hot water?

    Hoping someone can give me good advice about getting the best value and outcome.

    I have a very small shack in the bush in Southern Tas. The roof is not a good option for solar panels apparently, however we have a large shed with a suitable roof and good (Western) orientation, according to solar consultant. My water is gravity fed from a tank up the hill. The pressure is reasonably good.

    My problem is that our hot water system, a smallish standard electric tank system is failing (no pressure at all) and ancient. It needs replacing, or maybe a repair is possible. Out electricity bill is HUGE for a tiny, one-bedroom shack. I suspect it is all hot water heating, as the rest of the house runs lights at night, the kitchen oven/stove, occasionally a small oil heater in the bathroom, washing machine 2, or 3 times a week. Being on tank water, we are pretty frugal with showers and water. Heating is a wood combustion stove which runs all night in Winter.

    The worst thing is paying such a huge bill and getting absolutely woeful showers - not hot enough, no pressure.

    The plan is to eventually build a bigger house further up the hill, and an investment in solar will be part of the build, potentially going off grid. Current shack will become a granny flat/rental.

    So if you were me, would you;


    1. Invest about $9,000 plus on 10 solar panels and an inverter on shed roof, which could also be used to power future house as well as cutting current bill by 60%. These are figures provided by solar salesman. (Repayments will make this cost slightly MORE than currently paying on power bill until payed off). Feed-in tariff is currently 6 cents.



    1. Install solar hot water on roof of shack boosted by wetback on wood combustion heater in Winter. This was suggested by previous solar consultant. No idea how much this will cost. Roof is Western orientation but very low pitch. Scrap solar panel idea, at least until battery technology improves for new build in a few years. This SHOULD cut our power bill, and hopefully give us decent showers.


    OR any other suggestions? Research suggests that heat pump hot water that will be effective in Tassie costs a bomb, more than I would like to spend on our shack and gas isnít really something Iíd consider for ideological reasons.

    Any suggestions of brands or contractors in Tassie? I just want a decent shower and reasonable bills.

    Thanks for your input!

  2. #2
    Slow but rough Uncle Bob's Avatar
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    3) Get the current hot water system looked at. It sounds like something isn't right with it and it's continuously heating and could be venting it's hot water out.
    Can you post some pictures of the system and valves?

  3. #3
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    After getting your current system checked for probs as suggested, (this should be your first port of call) and if it is indeed OK I think FWIW you'd be best off with the SHWS
    Install solar hot water on roof of shack boosted by wetback on wood combustion heater in Winter. This was suggested by previous solar consultant. No idea how much this will cost. Roof is Western orientation but very low pitch. Scrap solar panel idea, at least until battery technology improves for new build in a few years. This SHOULD cut our power bill, and hopefully give us decent showers.


    Solar HWS should be $4000ish + few hundred for the wetback and plumbing.... We just had our old SHWS replaced after 17 years. Bought a stainless one..Old one needed a part no longer available..

    My neighbour and I both did our original SHWS 17 years ago. I sourced one for us both that heated water by running the cold through a copper pipe in a tank of hot water that was heated by the sun...WTF that called again?
    These are perfect for wetbacks as the mains pressure water is not running through the wetback, and allows wetbacks therefore.
    Her (the neighbour) SHWS could be hooked up with the WB and get thermosiphon. Ours, not so with our cathedral ceilings. I did however get a timer into the meterbox connected to the thermostat on the HWS so if it's not hot enough at 4am it heats the water till 5am ready for showers...
    Hers is still going strong, and as you say this time of year her Slow Combustion Heater runs day and night, (like ours) And she has never used her booster.

    Batteries are getting better and cheaper all the time, so putting that off does make sense..
    And.....your point is.....what exactly?

  4. #4
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    Can we get an idea of how huge the huge electricity bill is? What/who are you comparing to?

  5. #5
    4K Club Member Marc's Avatar
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    With 6c feed back tariff you need not 10 but 30 panels to reduce your bill by 60%.
    Hot water solar works well but if you have off peak tariff like we do in NSW, it's not worth it. I went from $30 a quarter down to $6 for hot water. Whoppidoo.
    Whenever you find yourself on the side of the majority, it is time to pause and reflect
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  6. #6
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    Thanks for replying Uncle Bob.
    Doesn't seem to be continually heating. The main problem is no pressure, although cold water pressure is fine. Have tried to in vain to release pressure and look for a filter to clean. I imagine dirt and silt from the tank water could occasionally clog up the system. Second prob is that it has a safety switch installed recently to meet council plumbing certification. The water hitting the cast iron bath in the freezing bathroom is so lukewarm that you cannot ever have a bath without adding copious instalments of kettle water. Not the safest option!

    Here's some pics.
    thumb_img_1837_1024.jpgthumb_img_1838_1024.jpgthumb_img_1839_1024.jpg

    Option 4 - Hydronic/wood heater powered stand alone hot water. We are running our combustion heater all Winter anyway

    Option 5 - Maybe heat pumps aren't that bad? There's a new interest free finance available for low-emission appliances.

  7. #7
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    Looking at those pics I don't think it's that ancient...I'd punt on something amiss with that, ie: not doing it's job properly,,,
    And.....your point is.....what exactly?

  8. #8
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    Hi r3nov8or
    Electricity bill is way over $600 in Winter, not much cheaper in Summer.
    Maybe I'm in denial, but seems a lot for a tiny one-bedroom 63m2 house considering all our heating is wood combustion.
    Comparing to previous house, when renting, 4 bedrooms, heat pump heating for whole house, many more HOT and longer showers per week (on mains water), lighting, washing machine, etc. 150m2 house. Winter bill was about $1000 and that includes heating during Tassie Winter.

    As far as I can tell current usage is;

    - 160 litre electric hot water heater used for 10 x 10 min showers per week. 1 small sink-full of hot water per day to wash dishes.
    - 2 to 3 loads of washing per week, cold water. (Sticker says 71kw )
    - Energy efficient lights at night for 63m2 house.
    - Column heater in bathroom used for 10/15 mins during shower, so 2.5 hours per week max.
    - Electric stovetop and oven in kitchen.
    - New-ish fridge (428 kw/year).
    - The usual kettle, toaster, computer, wifi modem, small tv.

    No one is home weekdays.

    Also spoke to SHW sales people. Apparently if the pitch of the roof is too low for panels, then same goes for SHW. Unless you spend $1000s on roof engineering to angle it....

    Heat Pump HW sales say that Sanden work fine in Tassie (not according to some forums) and will save 40% of my bill....

  9. #9
    Slow but rough Uncle Bob's Avatar
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    Quote Originally Posted by David.Elliott View Post
    Looking at those pics I don't think it's that ancient...I'd punt on something amiss with that, ie: not doing it's job properly,,,
    I agree. It looks like it may have a water tempering valve on it. Those things are the work of the devil if you like hot water. And really, the hot water pressure should be about the same as the cold water pressure, since it looks like a mains pressure cylinder.

    Hopefully one of our member plumbers will comment.
    Smurf, I think would have good input on this discussion too.

  10. #10
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    Is a water tempering valve what the plumber would have had to put on to pass council plumbing certificate? The one that makes the water not too hot to burn? We had to have that done to get a belated completion certificate a few years ago.
    Makes me mad having the council tell you how hot you need your water. We have already had accidents filling the bath with kettle water to compensate. Poor kids (and mum) can never have a bath now, only lukewarm trickle showers in the dead of Tassie Winter.

    Also, the pressure gets way worse after we have run the top tank dry accidentally, then improves slowly over weeks. That's why I think it's a problem with air in the tank, or a clogged filter or something, but there doesn't seem to be anyway of clearing blockages. Have tried releasing pressure and water from valve but nothing changed.

    The reason I can never call the plumber is that I am spending all my money on electricity bills!

    But, yeah, before spending $1,000s on new appliances I should check it out.

  11. #11
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    Hot water has a problem that will not be solved by solar panels. Find out what the problem is ( and 50degree s is too hot to stand under).

    more important is whether you are on time of use charges or flat with hot water/heating tariffs for costs, it could be that your hot water system is playing up and it's also not on a reduced tariff which it should be (should be connected to a timer for instance if you are on TOU

  12. #12
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    I'd go with solar hot water (evacuated tubes) and a wet back back up.

    What you have there is basically a gravity operated kettle. Gravity works fine but the kettle is not suited to the conditions.
    For the air lock problems, try an air relief valve on the inlet side in the meantime...the ball style versions work a treat. Avoid the rubber flap ones.
    And when you don't need hot water, don't turn the damn thing on. Run it for a couple of hours in the morning and evening only. Say 5-6 am then again 5-7 pm. It's tiny so it'll heat fast...
    Joined RF in 2006...Resigned in 2020.

  13. #13
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    Your tempering valve has gauze filters, most likely blocked causing a pressure loss. You need to remove valve and clean the filters.

  14. #14
    4K Club Member Marc's Avatar
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    Yep I thought the problem should be the tempering valve but from that photo, that gadget does not look like one (?)
    Anyway if it is, you can vary the temperature mix.
    But my money is on silt finding it's way into the tank. Rainwater accumulates all sort of muck.
    Whenever you find yourself on the side of the majority, it is time to pause and reflect
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  15. #15
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    Quote Originally Posted by plum View Post
    Your tempering valve has gauze filters, most likely blocked causing a pressure loss. You need to remove valve and clean the filters.
    Other problem is the saxon water heater you have is a heat transfer unit which has a valve that must be opened every 3 months to top up the tank in the saxon heater, otherwise, you are heating air in heater which will give you a little hot water at the tap initially, then go cold quickly.

    Spray the lever pin on the valve with a good dose of RP7/WD40 etc before attempting to pull the lever.
    Pull the lever and leave it open until water runs out the 20 mm copper open pipe, it may take some time to fill if not done for a while, also, the hole in said valve where the cold supply runs through is approx 3 mm, so that, coupled with severe lack of pressure (not to be confused with flow) from the tank up the hill, on top of having a tempering valve, makes for severe lack of flow/supply of hot water.

    See this link to work out how much pressure you have from the tank up hill. https://www.hunker.com/12300950/how-...-head-pressure

    The valve may need cleaning out as well, or replace, but they are expensive.

  16. #16
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    Quote Originally Posted by plum View Post
    Your tempering valve has gauze filters, most likely blocked causing a pressure loss. You need to remove valve and clean the filters.
    ...and then put the valve in the shed, in a draw you'll never look in again

  17. #17
    Slow but rough Uncle Bob's Avatar
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    Quote Originally Posted by r3nov8or View Post
    ...and then put the valve in the shed, in a draw you'll never look in again

  18. #18
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    Looks like you have a tempering valve fitted and I don't know weather they are suitable for gravity fed system. Your cold pressure might look good but with large pipes it can give an illusion of high pressure when in fact it is high flow

  19. #19
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    Thanks everyone for useful ideas. Will be trying all those solutions out today. Yeah I agree, that tempering valve ruins everything, damn council. I will try and release pressure too. I think I have tried that before though.
    Had a look at the calculations for water pressure. Might take a bit of figuring out in feet and inches but will have a go. My tank is at least 40m up the hill and have been told pressure is pk.

    I have a plumber coming on Tuesday if all else fails.

  20. #20
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    Quote Originally Posted by ShonkyShack View Post
    Thanks everyone for useful ideas. Will be trying all those solutions out today. Yeah I agree, that tempering valve ruins everything, damn council. I will try and release pressure too. I think I have tried that before though.
    Had a look at the calculations for water pressure. Might take a bit of figuring out in feet and inches but will have a go. My tank is at least 40m up the hill and have been told pressure is pk.

    I have a plumber coming on Tuesday if all else fails.
    At the risk of repeating myself, you are not releasing pressure from the heater, you are topping up the tank in the water heater.
    This MUST be done every 3 months until water overflows from the 20mm copper open tube, which is the overflow tube.
    See my post # 15 above.

    As to pressure from head/height of supply tank, if the 40 metres you refer to is actual height and not run of pipe up the hill, then 40 metres x 3.28(feet in metres approx) = 131 feet divided by 2.31 = 56 pounds per square inch, which is as good as most homes get today, so there should not be a pressure problem, more so, as plum said in post 13, valves need cleaning including the lever valve on the heater.

    The tempering valve is installed to stop the risk of scalding, mostly for children or elderley/infirm, and some owners remove them in their own home, but I would never suggest you do that

  21. #21
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    At the risk of repeating myself, you are not releasing pressure from the heater, you are topping up the tank in the water heater.
    This MUST be done every 3 months until water overflows from the 20mm copper open tube, which is the overflow tube.
    See my post # 15 above.

    My old solar did this with a float valve...I now get what you were saying doh!
    And.....your point is.....what exactly?

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