Garden sprinkler pump, etc.

[richandjo]

Hi, all.

Not sure if this is a plumbing issue, exactly - but hoping someone can help.

Have got average pressure to the outside tap but nowhere enough to power a decent sprinkler.

I figured - simplistically - that I would just fit a (pressure) pump to boost the pressure/flow. I now realise that it isn't quite as simple as that, what with water bye-laws, break tanks, pressure, flow, etc.

It seems that I can't just connect a pump from the outside tap through to the sprinkler. Would you agree with this?

Assuming that I can't, is it a question of having to fit a storage tank (to be fed from the outside tap with perhaps a ball cock to limit fill) which then feeds the pump on to the sprinkler?

I have got the current flow rate from the tap and have the flow rates (based on x bar pressure) from Gardena who make the sprinkler, if it helps.

If anyone knows a way around this, I'd be grateful, as it's taking what seems like an eternity to sort.

In an ideal world, I'd like the pump to switch on automatically, depending on outlet demand. I need around 4 bar pressure at the outlet.

Thanks, in anticipation...

 

[simond]

A sprinkler is a static load, in other words, it is on for extended periods of time.

Your water storage would have to be suitably sized for the flow rate - which you have from Gardena but have kept to yourself(!)

Lets say it uses 20l/m. If you wanted to pump the water for 2hrs use from a tank that would need 2400 litres, not allowing for the slower refilling from the mains.

In other words, it isn't going to be cheap, because you are using the water faster than it is coming in (I assume, in the absence of the key figures).

And as you suggest, extraction from the mains by pump is not usually permitted.


So you will need a very large tank, and a Stuart Turner pump. We had a similar set up at our last warehouse; it was filled from the roof gutters and we washed our plumbing vans with rainwater, which was great because it doesn't leave streaks like tap water.

I haven't repeated it but it worked very well. It made financial sense because we have recovered the ST pumps and the water tanks from a mansion we changed over to accumulators. So we got the equipment for nothing. Recycling at its best.

 

[richandjo]

Thanks for that.

The flow rate from the tap is 12.5 litres/minute. The sprinkler would use (at 4 bar) 18 litres/minute (good guess on your part!), so I figured that the top-up requirement (deficit) would be 5.5 litres/minute. Based on the sprinkler being in use for an hour at a time, I reckoned a tank of minimum 330 litres would be required.

What I'm trying to work out really is whether there is any means of fitting a pump directly to the tap (without the hassle of a storage tank) or whether this is the only way to do it.

Haven't got a clue (yet) what a Stuart Turner pump is but I can possibly suss out the pump size. That said, that's probably more complicated than I think, too!