Good post above. Needs to go in the Carbon Price thread.
Evacuated Tubes SHW - Cost / Benefit Analysis
(39 posts) (17 voices)-
cnheu
MemberMine? If so thanks mate. What most people don't understand is this is EXACTLY what carbon tax is supposed to do. It increases tax, sure, but it encourages people to implement carbon reducing technologies, AND THEN it still reimburses people with the money it originally spent to convince them to go green.
So whether that's an industry level, investing in energy efficient design of their buildings/work processes, making a profit in savings, THEN getting reimbursed, or the householder, getting taxed with higher electricity rates, investing in green energy PV/SWH THEN, getting reimbursed.
Everyone wins, if they're willing to adapt and take up low carbon technologies.
Posted Friday 3 Jun 2011 @ 6:34:24 am from IP # -
adrian.gab
Member@cnheu
Yes 3% is unrealistic but even if I plug in 10% (ACT announced a rise of 6.4% starting 1 July) into calculations it is still a long way off.
And my sums assume that my energy is being reduced by 30% as a result of the SHWS. If this is off then the pay back times are even more.
One thing I forgot was that in the event of my electric HWS dying, I need to also factor in what the cost of another system would have been. I have rough quotes of $1500 for gas continuous hot water system so I should really only be looking at the difference between it and a SHWS. Factoring this in makes the pay back times shorter.
Another thing which I am not going to try and calculate but needs to be kept in mind is that a gas continuous hot water system obviously uses gas and there would be an ongoing cost every time you turn the hot water on.
So as you can see there is a lot to factor in when making your mind up.
Posted Monday 20 Jun 2011 @ 11:53:32 pm from IP # -
mick_queensland
MemberHi all,
Sorry if this is off topic but I want to help katy.
to Katy, if you are still trying to figure out where your KwHrs are going to. I am in Qld, I have a large pool, up until recently, I didnt even care about the electricity bills, and then came the financial crunch, anyway, I took a very long and careful look at my whole situation. I have an advantage in that I have an electronics degree so I have a head start. Anyways, my bills were in the order of $1200-$1300 per quarter! Ergon were kind enough to point out on the bill that I was using about 280% of the average user... Yikes! Anyway, I did some research on swimming pools and found that my pool installer, while a nice guy, is clueless about pump and filter timing. They want your pool to look perfect, and therefore set your pump to run for 8 hours per day. I had a 1500watt pump so I was using 12 KwHrs for filtering and another few KwHrs for the solar heating pump. Check what the pump flows in litres/min, it will be on the name plate on the pump. Find out how big your pool is in litres, then divide the pool size by the pump flow. You then have how many minutes it will take your pump to turn over the whole of the water in your pool. Add 50% (half the time) again and then set your timer to turn on/off to match the amount of time your calculated. If you have a automatic salt chlorinator you will need to increase it by about 30%, just take a guess, and for the first month you will need to monitor your pool more closely and adjusting the chlorinator until you are confident it is working fine, but you will be saving heaps. I dropped from 8 hours a day to 3.5 hrs, which is saving me about $100 per quarter. I also replaced the pump which conveniently blew up while I was doing this. I used a smaller pump and installed it properly so that it flows the full amount, also the original pump was sized larger than the sand filter would flow. The new pump cost $300 delivered (Aussie Onga) and uses 30% less power, so I save another $30 per quarter by having the right pump installed properly. After a few months you can even start to reduce the pumping further until you are not cleaning your pool enough or your chlorinator is 100%, then it will start to go green. Increase it again so it is good. I would not go below the time it take to turn over all the water once in your pool. Example: 45,000 litres / 200 Lt/min = 225 minutes (3h 45m) If you dont know how big the pool is estimate. Example 1 cubic metre of water is 1000 ltires. if the pool is 8m x 4m and 1.5m deep you have 48,000 litres. (subtract any steps etc)
Hope this helps you as much as it did for me.
cheers, MickPosted Wednesday 22 Jun 2011 @ 8:15:31 pm from IP # -
mick_queensland
MemberHi All,
back on Topic, I did the same kind of calculations as Adrian but my numbers were much different. I calculated that I am using about 15-18 KwHrs per dayof Off-peak Tarriff 33 to heat my hot water. I think it is absolutely worth changing my old elec HWS over to solar. I think a very important thing here is to have that solar HWS installed properly or you will not see all the benefits it could produce, I would also suggest to size it correctly so you dont feel like you are ripped off if you have to boost. I am deep in the research and planning stage for my Solar HWS right now. I plan to install very soon.
I also have the halogen downlights, single pane glass windows that need shade in summer, too many fridges, old A/Cs, etc etc.
One of the best things I did was when I installed my Solar PV system, I also installed a Current Cost EnviR with a current clamp on each electricity tariff and one for my solar too. Once you see how much power you are using, you start to turn things off, it really works and now everyone in the house is way more power conscientious than ever. I would recommend some kind of power meter for all homes.
Cheers, Mick
Posted Wednesday 22 Jun 2011 @ 8:30:50 pm from IP # -
BigfellaJ
MemberHi all,
First time posting! - Keeping on the topic of SHW cost/benefit analysis, is there a way to determine the benefit of adding SHW to a house that currently uses instantaneous gas HW? (Rinnini Infinity) - 4 person houshold.Thanks, John.
Posted Thursday 23 Jun 2011 @ 5:07:01 am from IP # -
Lance
Key Master
Posted Thursday 23 Jun 2011 @ 5:21:15 am from IP # -
Lance
Key MasterBigfellaJ said:
Hi all,
First time posting! - Keeping on the topic of SHW cost/benefit analysis, is there a way to determine the benefit of adding SHW to a house that currently uses instantaneous gas HW? (Rinnini Infinity) - 4 person houshold.Thanks, John.
Posted Thursday 23 Jun 2011 @ 6:30:54 am from IP # -
mick_queensland
MemberHi bigfella
yes, there is a way. How accurate an answer you want depends on how much work you want to do to figure it out. To begin with you need to consider your main goal/goals. Do you want cheaper hot water (who doesnt!) do you want to help save the planet, etc I say this because you can simply calculate costs based on cost of your gas and system or you can additionally calculate energy use and greenhouse gasses emissions as well.
using your instant gas water heater as a booster for solar hot water is the most efficient way to heat water (unless you have solar PV array as well and then your electricity is both free and zero greenhouse)
The most important step is to first analyse your hot water usage. It doesnt take much to do. You need a thermometer to sit in hot water, reasonably accurate is good but not absolutely necessary (you will use the same thermometer to calculate temperature differences. You need a measuring jug, say 2 litres and a stop watch/shower timer.
First take your thermometer and jug into the shower, get the shower running the way you like, nice and hot, just warm, whatever. Measure the temperature of the water. Now, time how long it takes to fill the jug and convert that back to litres per minute (EG if it takes 8 seconds to fill 2 litres your shower head flows 15 lt/min, 60sec/8sec x 2lt = 15lt/min) Now time your showers, dont rush, you want to see how much water you use in the shower. Now you know how much warm water you use for a shower. How many showers per day in your house?
Measure the temperature of your cold water. You can now calculate how much hot water you need to mix with cold to get your shower temperature for the whole house for a day.For the rest of the house hot water, use the online estimators but be selective, EG: they all say "X" amount for washing machine and I only use cold water in it, disregard their estimations on showers and use your calculation. You will then have a fairly good idea of how much hot water you use, and therefore how much you need to make a day.
This will tell how big a Solar Hot water tank you need.
Where you live, how good your installation will be (EG collector angles etc) and mains water temperature mainly control how many tubes you will need. Given that, you can find out how much the Solar HWS will cost.To give you a very rough idea of cost, most approved solar HWS will cost about $2000 after govt cash rebates, plus installation costs. You can get cheaper Solar HWS but they do not get govt rebates or STCs. You could install it yourself with just the plumbing connections done by a professional.
You should already know how much you pay for gas, but is that only for hot water? If not then you could calculate how much gas you use to heat your hot water based on the amount of hot water you use daily, since you already have measured that now. Search for formulae that calculate how much energy it takes to heat the amount of water you use, and how much energy is in gas.
Hope that helps you out some.
cheers n beers, MickPosted Friday 24 Jun 2011 @ 3:58:28 pm from IP #
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