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Topic # 245036 15-Jan-2019 12:27
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Hey guys,

 

I am looking for 2x water pumps for my house. The house has 3x bathrooms (with showers, toilets and vanities), 2x kitchens (with dishwashers), 2x stand alone toilets with wash basins and 2x laundries.

 

The plan is a single tank for potable water filled by town supply for kitchen and showers/taps and another tank with rainwater for toilets and laundry. Plumbing has already been completed for this. 2x bathroom/kitchens have combined pipes going outside and the remaining bathroom also has its own pipe. All toilets and laundries are currently off the same pipe (although they could possibly be split if need be).

 

The question now is about the pumps. For potable water, I am wanting to get a pump which provides consistent pressure when using at least 2x showers, 3x taps and say a dishwasher. I understand I probably need a pressure tank on the water pump and a flow rate of >60 litres per minute for this.

 

For the toilets and laundries I don't really care as people don't feel pressure changes like they would in a shower.

 

There seem to be wildly different pricing. E.g. for the potable water I see 2x options:

 

  • $2,673 Grundfos CMBE 3-62

     

    • 69 litres per minute
    • Integral VSD speed drive
    • 2 year warranty
  • $449 Aquatanks ECO MXA 404 PC

     

    • 120 litres per minute
    • 2 year warranty

 

 

Grundfos:

 

Image result for cmbe 3-62

 

Aquatanks:

 

 

 

 

For the toilets/laundry the Grundfos JPR4 is $791.20 and the Aquatanks Ecojet 500PC is $299.

 

 

 

These are massive differences. Is it really just brand name or am I missing something?






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  Reply # 2161575 15-Jan-2019 14:52
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how big is the water tank? and why 2 pumps?

 

could just run the whole house of one tank if its big enough, just take off for the toilet and laundry before any fine filtering/UV filters for the rest of the house




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  Reply # 2161590 15-Jan-2019 15:28
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Jase2985:

 

how big is the water tank? and why 2 pumps?

 

could just run the whole house of one tank if its big enough, just take off for the toilet and laundry before any fine filtering/UV filters for the rest of the house

 

 

One tank is for potable water that is currently being bought from Watercare. This tank is 900L. Probably will put a float valve in there for now. Maybe in the future this can be filled from rainwater tank transfer if get a filter/UV steriliser.

 

The other tank is for rainwater and that is 3000L. This one is to feed toilets, laundry (and also garden hose).






 
 
 
 


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  Reply # 2161593 15-Jan-2019 15:38
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why the 900L tank? if its just council water anyways?




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  Reply # 2161600 15-Jan-2019 15:50
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Jase2985:

 

why the 900L tank? if its just council water anyways?

 

 

A number of reasons:

 

  • WaterCare don't provide sufficient flow rate with the existing meter size. There is a cost to upgrade this size of the meter.
  • We can re-use rain water once we get a UV/filter system. By having a separate "good" water tank to transfer to from the rainwater tank, we don't need these with a high flow rate which seems to push the price up a lot. Considering that you are only charged for wastewater volume based on the water you buy, there could be some cost advantages here (albeit will take time to recover)
  • Off-the grid living/have water should there be an issue with town supply etc. etc.





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  Reply # 2161603 15-Jan-2019 15:57
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Davey or Wallace pumps......... the others tend to fail a lot more. 


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  Reply # 2161605 15-Jan-2019 15:57
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Different situation  here (bore) but we had a Grundfos JP Rain 3 with a pressure controller & pressure tank installed a year or so ago, works very well, nice and quiet and pressure is pretty stable, other than the initial drop before it kicks in once a tap or whatever is first turned on. 

I think you sort of get what you pay for with pumps. 


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  Reply # 2161606 15-Jan-2019 15:58
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The difference in pricing of the two pumps is because one is VSD driven and the other is direct online.

The vsd driven pump will speed up or down to maintain pressure, the DOL pump will run at a fixed speed switched on by the pressure switch.



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  Reply # 2161610 15-Jan-2019 16:00
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Handle9: The difference in pricing of the two pumps is because one is VSD driven and the other is direct online.

The vsd driven pump will speed up or down to maintain pressure, the DOL pump will run at a fixed speed switched on by the pressure switch.

 

I was guessing this may play a role. But with a pressure tank shouldn't the pressure be consistent without a VSD?






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  Reply # 2161612 15-Jan-2019 16:03
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The Grundfos are good units, and the one you have highlighted is a variable speed model, whereas the other is either "pump as fast as I can no matter if a single tap or all taps are open" or "off" :-) 

 

I used to have a VSD Grundfos and it worked great, but when it died I cheaped out and got a single speed .. wish I had stumped the extra as it was only a few hundred more.

 

You might want to shop around, the price you have there seems really high, I think I was quoted $900 for the VSD, ring a few rural plumbers who handle farms and lifestyle properties rather than a shop in a city.


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  Reply # 2161740 15-Jan-2019 19:53
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Zeon:

Handle9: The difference in pricing of the two pumps is because one is VSD driven and the other is direct online.

The vsd driven pump will speed up or down to maintain pressure, the DOL pump will run at a fixed speed switched on by the pressure switch.


I was guessing this may play a role. But with a pressure tank shouldn't the pressure be consistent without a VSD?



As already said You need a VSD if you want constant pressure even when the flow rate changes.

Also pump flow rates are quoted based on ”open outlet”. You need to look at the hydraulic curves to determine what pump you need. Even a cheap pump would be able to provide 60L per min at say 0.5 bar outlet pressure. But you will need a much larger pump to get the same 60L per min at 5 bar outlet pressure.

Also have a look at the DAB E.sy box pump. I have one on my own house and have installed 2 of them on customers houses. They are much quieter than most other pumps as they have a VSD combined with a water cooled motor. You can also set the cut in pressure separately from the run pressure, and change PID settings on it.






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  Reply # 2161744 15-Jan-2019 19:59
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You need to specify a flow rate, a delivery pressure that needs to be maintained at that flow rate, and the location where those 2 are to be provided at.

So your plumber can calculate what size pumps you need. Including allowances for static head and friction losses in your pipes.

VSD pumps have lower motor starting in rush current, and typically use less power. Which is important if the pump needs to run from an off grid power system.





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  Reply # 2161757 15-Jan-2019 20:23
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Aredwood:

As already said You need a VSD if you want constant pressure even when the flow rate changes.

 

 

 

This.

 

 

 

I have 4 water pumps (and 3 tanks totaling 50,000L+). 2 for house supply--- one from the rainwater tank, one the riverwater tank (also runs irrigation), then there's a transfer pump, and a large river water pump.

 

Main rainwater pump is a Davey. Do yourself a favour if you're using a pump on a daily basis and buy a Davey.

 

River tank to house is an Onga. About to rebuild the POS as the bearings have failed (not the first time). Transfer pump is an Onga but transfer pumps hardly get used so should last a long while yet. 

 

Then there's the beast. 950 metres away, sucking 100m out of the river, then to a tank 65m higher than itself. Through 40mm blue line poly. A DAB jet pump.

 

I'll say it again though.  Do yourself a favour if you're using a pump on a daily basis and buy a Davey.


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  Reply # 2161811 16-Jan-2019 00:21
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blakamin:

Aredwood:

As already said You need a VSD if you want constant pressure even when the flow rate changes.


 


This.


 


I have 4 water pumps (and 3 tanks totaling 50,000L+). 2 for house supply--- one from the rainwater tank, one the riverwater tank (also runs irrigation), then there's a transfer pump, and a large river water pump.


Main rainwater pump is a Davey. Do yourself a favour if you're using a pump on a daily basis and buy a Davey.


River tank to house is an Onga. About to rebuild the POS as the bearings have failed (not the first time). Transfer pump is an Onga but transfer pumps hardly get used so should last a long while yet. 


Then there's the beast. 950 metres away, sucking 100m out of the river, then to a tank 65m higher than itself. Through 40mm blue line poly. A DAB jet pump.


I'll say it again though.  Do yourself a favour if you're using a pump on a daily basis and buy a Davey.



holy heck at the number of pump(s) you got there! +1 for Davey.

btw, i was thinking about uv filter for our rain water tank (used for cooking/drinking etc), i read around it and it looks like a 'scam'. we just have the simple cheapie water filter. no problem lol.





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  Reply # 2161813 16-Jan-2019 01:04
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I have 3 pumps as part of my main rainwater system. Plus various other pumps for secondary tasks. And this is all on an suburban property.





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  Reply # 2161873 16-Jan-2019 08:55
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Our local water system contractors, who do all the dairy and domestic work out here, swear by Lowara pumps.





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