Alternative Technology Assn Forums

1. 

   munter
   Member

   Hi all,
   I'm getting close to installing a water pump for the new rainwater tanks that I've been installing and am looking to get some advice about pumps. What are the good brands and models to look out for? Our house is single level at the moment but might grow upwards in the future. The tanks are located with their base at about 1.5 m below the existing floor level. I want to use the water for toilet flushing, laundry and two external taps for garden watering. What would people recommend? What brands should I stay away from?

   Thanks for the help.

   Posted Friday 12 Feb 2010 @ 1:20:38 am from IP #
2. 

   Russell Moore
   Member

   munter, I chose an Onga pump when I had my tank installed, over four years ago.

   It was made in Australia, and had a good reputation, and they are used extensively around Australia in rural areas. I have had no problems with it, but then again I only use it for irrigating the garden and occasionly washing the car.

   I would seek some advice from a company that supplies rural areas, as the people on farms, etc, have to rely on their pumps 24/7, and don't have the luxury of a fallback onto city supplies. There should be such companies out around the Windsor area.

   Good luck, Russell

   Posted Friday 12 Feb 2010 @ 1:43:12 am from IP #
3. 

   whatcouldyoubesaving
   Member

   My take on that would be besides looking at just the manufacturer. Find out the water displacement requirements and the minimum flow rate required then investigate the different makes and then choose the one with the lowest wattage. Just because its 1.5kw doesn't make it any better than a 550 watt unit. Just cost more to run. Also look at having the largest possible;e pressure tank installed and I mean LARGE 20 to 50 ltrs this will reduce the need for the pump to fire up when smaller amounts of water have been consumed.

   Posted Friday 12 Feb 2010 @ 2:28:01 am from IP #
4. 

   munter
   Member

   Thanks for the advice.
   Energy efficiency is an important point for me and I feel like I would take a slight reduction in capacity or reserve if it meant a meaningful reduction in power usage could be achieved. I'll probably size it to suit the operation of one of the end uses at a time rather than having sufficient capacity to supply all taps at once. Refilling the cistern will be the primary use and given that it is small in size (a water efficient toilet) and not time critical (we would rarely flush more than once every 20 minutes) I think a relatively small system would be adequate. I'll need to find out what the flow rate of the garden hose is though - I don't want to have to double the time it takes to water the garden just because the water is coming out slowly!

   Retamal, M.L. at UTS has written a couple of interesting papers covering distributed vs centralised water supply including one covering the relative energy intensity of the systems. From memory, and I'll now go back and check, that paper found that no particular configuration stood out as being the most energy efficient in terms of their energy intensity (kwhrs/kL) suggesting that we haven't captured the variables (equipment type, usage patterns, plumbing configuration etc) that determine the end power consumption properly yet. Starting with a pump on the smaller side rather than the larger side would probably be a good starting point though.

   Posted Friday 12 Feb 2010 @ 6:01:29 am from IP #
5. 

   swanning_it
   Member

   Quick question if I may Munter....I see you state the cistern refill as being the primary use. Are you not supplying the whole house because of tank size, or because of local council regulation?

   I ask this as I've installed enough tank capacity to supply my entire house. Plumbers are dead set against it saying the local council have notifyed them to say it is against their policy guidelines (in fact illegal until just recently) and the plumber will be liable for any future "health" impact as a result. As I grew up on tank water, I have no such concerns and in fact, just a few km's away, are properties that rely only on tank water as there's no reticulated supply. I can't figure out the council logic as to why it is unsafe for me, but perfectly OK for others just a stones throw away, though I do wonder if their water sales budget may have a lot to do with it.

   Posted Friday 12 Feb 2010 @ 8:25:04 pm from IP #
6. 

   munter
   Member

   It is neither tank size nor regulation stopping me from connecting the whole house. Instead I am looking to stage the installation so that we can get an operating system in place quickly, maximize rebates and generally test it out before considering using the water for other uses. We're considering renovating and I think we will assess the success of the system at that point and work out whether it is good to roll out tank water to more locations. Our tank size is 7500 L in total. If only it was all in place already it would have filled significantly just last night!!!

   Posted Saturday 13 Feb 2010 @ 3:17:08 am from IP #
7. 

   munter
   Member

   Btw, I'm thinking about a grundfos CH2 pump. The power use seems quite low at around 400 watts but the pump curves seem adequate based on my limited knowledge of this topic. They aren't cheap though at over 600 for a pressure controlled unit.

   Posted Saturday 13 Feb 2010 @ 3:20:48 am from IP #
8. 

   Solgen
   Member

   Like swanning_it I have most of my house in Sydney running off a tank and I also had the plumber advising against and that it was illegal, etc. He even required me to sign a waver that I not sue him if we get sick. City plumbers!

   I have 10kL tank connected to a 1kW, 150l/m pump (Orange). We have had no pressure problems but the big mistake was not to specify a pump that had a pressure tank as now every time a tap is turned on even for cleaning teeth the pump starts.
   The other problem we have only just discovered is that the changeover point from tank to mains should be as close to the tank/filter as possible. Ours unfortunately, is about 10m from the tank. We have just had blockage problems due to algae blocked up the filter in the tempering valve on the hot water system. We think the algae was growing in the pipe between the filter and the changeover point while the tank was turned off recently because of low water.
   While the pump was off the water stagnated in this pipe and as it also exposed to the sun it would have had perfect conditions to for algae to grow. Then, when we got rain last week and turned the pump back on, the sudden flow of high pressure water would have disturbed the algae and transported to the rest of the system. Things you learn with experience!!

   Best of luck finding a good plumber who knows about water tanks, don't rely on Green awarded plumbers, I would not recommend mine.

   Finally, Munter, our 10kL is not big enough for our 2 person household even though we have nearly 100m2 of roof feeding the tank and theoretically our rainfall is more than adequate it is the long dry spells in spring and summer that show up the inadequacy of our system. I would recommend a min of 15kL for a 2 person house in Sydney.

   Posted Saturday 13 Feb 2010 @ 5:10:05 am from IP #
9. 

   TomC
   Member

   Munter,

   We have a Grundfos CH2 pump on our 47kl tanks which was installed about 18 months ago.
   Our property is quite steep and the pump has to lift about 10m to the highest tap.
   The pump was recommended by my plumber and by the local pump supply dealer.
   As far as I was concerned it ticked all the boxes, had run dry and overheating protection and stainless components, but it wasn't all that cheap.
   After 18 months of operation (and I guess about 6okl of water pumped) there has been no problems which is more than I can say about several of my neighbors who bought cheaper pumps and have much smaller tanks and lower lift requirements.
   I am a happy customer.
   Tom

   Posted Sunday 14 Feb 2010 @ 10:57:10 am from IP #
10. 

    whatcouldyoubesaving
    Member

    Pressure Tank Pressure Tank Pressure Tank... BIG BIG Bigger the Better

    Posted Monday 15 Feb 2010 @ 5:52:27 am from IP #
11. 

    munter
    Member

    As I understand it pressure tanks allow you to draw down several litres of water before the pump starts up again. I can see how this would be important when a user might just want little quantities at a time without wanting to trouble the pump. Would it still be important in my application where the smallest quantity of draw down is likely to be a 3 L half flush of the toilet?
    The additional cost seems to be about $140 for a grundfos tank with 7L draw down capacity.

    Posted Monday 15 Feb 2010 @ 7:08:57 am from IP #
12. 

    munter
    Member

    Update: I have gone with a grundfos CH-2 30 PC15 pump from a retailer in Ballarat. Their price was $75 better than any other I could find. The PC models are said not to need a pressure tank due to the way the pressure controller works. We will see how that works in practice and possibly retrofit a tank later if required.

    Posted Wednesday 17 Feb 2010 @ 10:21:26 pm from IP #
13. 

    ghostgum
    Member

    My Davey pump doesn't need a pressure tank either, but if you add one the pump runs less often, will use less power and will hopefully last longer. With a pressure vessel you can flush a toilet without the pump having to turn on.

    Posted Wednesday 17 Feb 2010 @ 10:32:15 pm from IP #
14. 

    whatcouldyoubesaving
    Member

    Pressure Tank...............PRESSURE TANK... Big BIG BIGGEST... HUGEST YOU CAN FIND/ afford.....................

    Posted Saturday 20 Feb 2010 @ 9:08:33 am from IP #
15. 

    munter
    Member

    wcybs - your post would be more useful to me if you could verbalise the reasons for your suggestion. Through the internet I can't tell if you're deranged or rational and so its hard to know how to assess your brief recommendations.

    Posted Tuesday 23 Feb 2010 @ 2:25:25 am from IP #
16. 

    ghostgum
    Member

    munter, see my posting above for an explanation. Mine is an 18 litre tank with 8 litre draw down.

    Posted Tuesday 23 Feb 2010 @ 2:38:41 am from IP #
17. 

    munter
    Member

    Thanks Ghostgum. I guess I'm trying to work out whether my application is the same as those who strongly recommend a pressure tank. The smallest quantity I anticipate drawing off is 3 L at a time (half flush toilet). If I always drew this much down I then an 8L drawdown tank will mean pump starts are approximately halved due to the tank reserve and that sounds like a good result and I'm sure that would save energy and pump motor wear. The thing is, I think most of my draw downs will be much larger than 3 L (say 10-20L) and so its likely that the pump will start on each of these draw downs anyway which, to my current understanding, means that the pressure tank is not really beneficial. I'm not absolutely confident that that logic is right though hence my request for more detail. Is the usage pattern the same? If not, then different conclusions might be reached. Apologies if it sounded shirty - perhaps I'm having trouble communicating myself!

    Posted Tuesday 23 Feb 2010 @ 3:38:34 am from IP #
18. 

    ghostgum
    Member

    If the draw downs are 10-20 litres, then with my pump the tank I've got would probably not help. It would just delay the start up time for the pump.

    A pressure tank would help if you had a slow filling cistern. In this situation, my pump without the tank would switch on and off a few times, then realise it was a slow flow and then stay on. The tank prevents this.

    If you go for an even larger tank, then you could have 20l draw down. The brand of pump I have support 8l, 18l, 35l, 50l and 105l sizes. Draw down is a bit less than half of these volumes. The bigger ones are probably quite expensive.

    What needs a draw down of 10-20l ?

    Posted Tuesday 23 Feb 2010 @ 4:28:53 am from IP #
19. 

    munter
    Member

    I was thinking the washing machine would be about that volume and that use of the hose in the garden for veggies would be considerably more.

    The pump won't be connected to internal taps other than the cistern and the laundry. I think I understand your point about the cistern filling slowly and the possibility for cycling to arise. I'll time the filling time to see what the average fill rate is. The pressure controller is supposed to keep the pump on down to a low flow rate so I'm hoping there won't be any cycling as the cistern fills.
    At this stage I think the best thing to do would be to install the system as currently specified and to monitor the pump starts to see how it operates in practice.

    Posted Tuesday 23 Feb 2010 @ 5:54:33 am from IP #
20. 

    Russell Moore
    Member

    Probably not applicable in suburban areas, but don't country people use a tower tank to provide water pressure?

    This is where you pump water up to a small(200lt?)tank on a stand high enough to provide sufficient pressure in the house, when the tank draws down to a low level the pump comes on and refills the tank, or a windmill does the same thing and water is pumped up using the free cost of wind.

    This is basically what the city water supply companies do for the water supplies to their city customers, water is pumped up to large tanks on top of hills overnight using cheap offpeak electricity, and gravity supplies us with water under pressure.

    Posted Wednesday 24 Feb 2010 @ 4:25:40 am from IP #
21. 

    munter
    Member

    Got a spare tower and header tank Russell? I like the idea of doing that as it would probably be the most energy efficient and best for the pump but the logistics, approvals and explanations to the neighbours probably all make it impossible in my circumstances.

    Posted Wednesday 24 Feb 2010 @ 4:30:57 am from IP #
22. 

    Russell Moore
    Member

    So how high does a header tank need to be to give you sufficent pressure?, I'll see what Google can give us.

    Sorry, we gave our header tanks away (that we used on our poultry farm), when we sold our farm many years ago.

    Posted Wednesday 24 Feb 2010 @ 4:40:17 am from IP #
23. 

    Russell Moore
    Member

    Munter, there seems to be two schools of thought on header height. If you need some reasonable pressure you will need about 5m of difference from outlet to inlet, but if you only need to fill something slowly, such as a toilet cistern, than only a small height difference appears to be needed, although a reasonable pipe diameter is needed, such as 25mm minimum.

    If you are working to eventually feed the whole house, remember that if you are using a header tank, the highest outlet in the house is the shower rose, so your tank would need to be about 5m above that.

    Posted Wednesday 24 Feb 2010 @ 5:08:28 am from IP #
24. 

    munter
    Member

    Thansk Russell - so you could potentially put a header tank in the ceiling space above a second story and have it feed cisterns reasonably well? You could use a short run of large diameter pipe to the second story cistern and a longer run from greater height difference to the lower cistern. I wonder though whether the extra engineering and build cost required to allow a tank so high up in the ceiling space would ever be less than the cost of the energy saved in using such a set-up? I suppose it depends on the future price of electricity and how much you value the broken sleep from the pump coming on in the middle of the night when someone has taken a whizzer...

    Posted Wednesday 24 Feb 2010 @ 5:41:18 am from IP #
25. 

    Solgen
    Member

    For those of you that can remember or still use a roof mounted gravity feed HWS, pressure is not great. Good installations used larger pipe diameters to reduce pressure loss. Obviously, if you are using to feed a toilet, etc. then pressure is probably not a problem but to avoid flooding your ceiling I would suggest that you have good controls for the pump!

    Posted Wednesday 24 Feb 2010 @ 7:02:26 am from IP #
26. 

    tonyjas1
    Member

    Here's another consideration. In the event of a prolonged power failure a large pressure tank can still give you a minimal amount of water for that "final flush" or emergency drinking rations. I have installed a 100Lt pressure tank and it works just fine in our rural setting. The pump had to be positioned under the bedrooms, so not having the thing cut in during the early hours is another bonus.

    Posted Wednesday 14 Apr 2010 @ 6:40:57 am from IP #
27. 

    Diver
    Member

    As already noted by others, suitably sized pressure tanks will reduce pump use and resultant high start up energy demands whenever small amounts of water are drawn.
    WELS ratings are soon to be introduced for pool pumps and significant pump design improvements are on the way!
    For watering, connect an 18mm hose to the tap, then a shorter length of 12mm hose off that if needed. If your pump can maintain 20 litres per minute through a 15 metre 12mm hose, its friction loss will be about 8 times greater than a 15 metre 18mm hose.

    Posted Wednesday 14 Apr 2010 @ 11:50:46 pm from IP #
28. 

    Diver
    Member

    The last post mentioned new high efficiency pool and spa pumps being developed and on their way.

    http://www.supastelthpumps.com/index.htm

    Posted Wednesday 28 Jul 2010 @ 1:30:57 pm from IP #
29. 

    munter
    Member

    Thanks for the link. The manufacturer is pretty strong on hype - I hope the pumps deliver to expectations. It might be too early to call conventional pumps obsolete but if the technology does indeed make it so then that's an exciting development.

    Posted Thursday 29 Jul 2010 @ 2:43:24 am from IP #
30. 

    Diver
    Member

    Munter,
    Being an engineer, the following links may be of further interest to you. As you would be aware, the flow characteristics of air and water are essentially the same.

    http://www.linux-host.org/energy/scoanda.htm

    http://www.newfluidtechnology.com.au/THE_COANDA_EFFECT_AND_LIFT.pdf

    Posted Thursday 29 Jul 2010 @ 3:19:29 am from IP #

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