Rainwater Pump Advice

[remi]

I'm after some advice regarding rainwater tank pumps. We've recently moved and now have a 2500L rainwater tank in our back yard. The tank has no pump at this stage, so watering the garden with it takes agesue to the low pressure. I also plan to use the tank water for cooling when I brew (I use a plate chiller- and will recirculate the water back into the tank). This leads to 2 questions..

First- assuming the tank is half full, will it be feasible to recirculate the cooling water back into the tank and not lose cooling efficiency. Back when I collected cooling water in buckets, I would collect 100L or so for a single batch, and maybe 120-140L or so for a double batch. I'm tipping that means that I would be able to achieve reasonable cooling with my rainwater (assuming the water in the tank wasn't too warm to begin with).

Second- I have been looking at various pumps on ebay, and wonder which flow rate to go for. Living in Brunswick in Melbourne, our tap water pressure seems quite high- and that is what I have been using for cooling with my plate chiller up until now. The pumps I have seen vary in flow rate from about 2100L/hr up to 3600L/hr. Which of these will most closely match what we get out of our tap? Also, with these sorts of pumps, is it still feasible to use a trigger hose for watering at this pressure without damaging the garden?

Thanks for any tips...

Remi

 

[Screwtop]

I'm after some advice regarding rainwater tank pumps. We've recently moved and now have a 2500L rainwater tank in our back yard. The tank has no pump at this stage, so watering the garden with it takes agesue to the low pressure. I also plan to use the tank water for cooling when I brew (I use a plate chiller- and will recirculate the water back into the tank). This leads to 2 questions..

First- assuming the tank is half full, will it be feasible to recirculate the cooling water back into the tank and not lose cooling efficiency. Back when I collected cooling water in buckets, I would collect 100L or so for a single batch, and maybe 120-140L or so for a double batch. I'm tipping that means that I would be able to achieve reasonable cooling with my rainwater (assuming the water in the tank wasn't too warm to begin with).

Second- I have been looking at various pumps on ebay, and wonder which flow rate to go for. Living in Brunswick in Melbourne, our tap water pressure seems quite high- and that is what I have been using for cooling with my plate chiller up until now. The pumps I have seen vary in flow rate from about 2100L/hr up to 3600L/hr. Which of these will most closely match what we get out of our tap? Also, with these sorts of pumps, is it still feasible to use a trigger hose for watering at this pressure without damaging the garden?

Thanks for any tips...

Remi

I have 2 x 2500L tanks for house (laundry and toilets) and a 24000L for the yard gardens.

1. Cheap Option. $80.00 odd transfer pump from Aldi. Connect it up to your tank tap then run hoses to the chiller and back to the tank. Run an extension lead to the pump, open the hosecock and then turn on power to the transfer pump.

2. More expensive option, permanent and will give good pressure for garden tap. Constant pressure pump around $350 - $450 from a tank or water shop with pressure sensor and auto cut off (so you don't burn out the pump if the tank runs dry, leak etc.). More $$ for an outdoor/weatherproof power outlet mounted near enough to the tank/pump. Then just hook up hoses and turn on the tap.

Screwy

 

[therook]

Remi,

Try Nightingales in Spencer street if you ever get into the city...they have good pumps at good prices

Rook

 

[ramu_gupta]

+1 for Screwy's cheap option - works well. Hot water entering the top of the tank doesn't readily mix with the cooler water beneath.

 

[Airgead]

I recirc cooling water through my 5000l tank all the time. Works like a charm

We had a high capacity pump put in when the tank went in. Can't remember the rating but it will happily run the drip irrigation across the whole garden plus run my chiller at the same time.

We went the high capacity option as it gives us some extra flexibility in what we do with the water. If we want to hook it up to the showers one day we can do it without needing a new pump. I'd say get the biggest pump your budget will allow. It gives you a bunch more options later on.

Cheers
Dave

 

[Cortez The Killer]

With the pumps are you able to restrict the flow or will a pump only pump at it's stated capacity

Cheers

 

[Frank]

Most domestic water supplies are around 1L/sec, which is a fair bit of water.
If you go for the cheap constant flow manual switch pump, you can set up a bypass hose returning back to the tank to control your pressures and flows, this may be required if you want to run a drip system.

 

[remi]

Thanks for the tips- I think I'll go for one capable of 3600L/hr with run-dry protection. Can always use a bypass as suggested if this is too powerful to water the garden with.

Thanks for your replies...

Remi

 

[drsmurto]

Thanks for the tips- I think I'll go for one capable of 3600L/hr with run-dry protection. Can always use a bypass as suggested if this is too powerful to water the garden with.

Thanks for your replies...

Remi

Not sure i understand this. :huh:

You do realise that by only turning the tap on a little bit the pressure is lower?

Or i have completely missed something (which is entirely possible due to dangerously low caffeine and ethanol levels)?

EDIT - to add something positive (due to the caffeine slowly working) i use 2 x 8000L rainwater tanks for my chilling water. Onga pump powers it (see here). Runs through a plate chiller and then back into a downpipe. My tanks are down to 5 cm above the inlets so i have stopped using it and havent brewed since. Hopefully the rains come so i can break my brewing drought.

 

[remi]

Not sure i understand this. :huh:

You do realise that by only turning the tap on a little bit the pressure is lower?

Or i have completely missed something (which is entirely possible due to dangerously low caffeine and ethanol levels)?

EDIT - to add something positive (due to the caffeine slowly working) i use 2 x 8000L rainwater tanks for my chilling water. Onga pump powers it (see here. Runs through a plate chiller and then back into a downpipe. My tanks are down to 5 cm above the inlets so i have stopped using it and havent brewed since. Hopefully the rains come so i can break my brewing drought.

I understand that turning the tap on less lowers the flow/and therefore pressure in a fixed dimension and length of hose- but I was wondering what the pump does in that situation, as a lot of them say that they will automatically adjust to flow conditions to keep the pressure constant.

 

[daemon]

I just have one of the cheap Aldi units, back when they first came out. It's been going strong for two years without any real problems and puts out enough pressure.

I intend to upgrade to a good pump one day but considering I've already had two years worth of use from it I think it's good value!

 

[drsmurto]

I understand that turning the tap on less lowers the flow/and therefore pressure in a fixed dimension and length of hose- but I was wondering what the pump does in that situation, as a lot of them say that they will automatically adjust to flow conditions to keep the pressure constant.

The pump equalises the pressure between the pump and the tap. This means that the pressure remains the same even though the pump cycles on and off.

Between the tap and the hose outlet its all up to you.

 

[Frank]

Depends on the type of pump, on the best way to go. Some pumps can handle back pressure therefore throttle valve on the discharge of pump can control the flow (as most do with March pumps in brewing) or just control at the tap. If the pump does not like having back pressure, a bypass hose etc may be required, this will also avoid high pressure blow outs if the taps are turned off and the pump does not have a high pressure cut out.
Controlling the pressure and flow is normally only required when using low flow emitters such as drippers or micro sprays, which are designed for low pressure.

Edit:
Dr S you are correct if using a pressure controlled pump. I was under the impressure that the OP was intending to use a straight transfer pump that is either on or off manually, which could lead to high pressure spikes and blow outs if not controlled properly.

 

[Screwtop]

With the pumps are you able to restrict the flow or will a pump only pump at it's stated capacity

Cheers

They installed a gate valve in my system, so I can up the pressure (open it up a bit) if I add extra garden taps.

Screwy