One for the know it alls lol

Good evening chaps

Probably something obvious, but up until I recalibrated my pump on Saturday, the pressure would build up while I had the univalve closed, then when I’d switch it back on you’d get a nice burst of built up pressure to rinse with.

But now after calibrating it, it’s the opposite. Nothing comes out for 2 seconds, then it goes from dribble to normal pressure. Just wondering why? 

You'll find it's the cold. Takes a while for the pressure to build back up. There's been posts on this before very technical tho. But trust me as soon as it warms back up again you won't get the 2 or 3 second delay between turning on the univalve. I allways used to think my pump was knackered but it's 100% the cold. Bit like ourselves takes us a while to warm up lol 

RWCleaning said:

Good evening chaps

Probably something obvious, but up until I recalibrated my pump on Saturday, the pressure would build up while I had the univalve closed, then when I’d switch it back on you’d get a nice burst of built up pressure to rinse with.

But now after calibrating it, it’s the opposite. Nothing comes out for 2 seconds, then it goes from dribble to normal pressure. Just wondering why? 

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As @GSS Window Cleaning. In the summer your water is warmer. Warmer water will make the hose a little more flexible (elastic). In winter our hose is rather stiff and more difficult to manage whereas in summer its much easier to manage as its 'softer,' more plyable. When you switch the Univalve off the pressure builds until the controller dead ends the pump. In summer that more flexible hose expands fractionally with the increased pressure so there will be more water in the hose. This is like a reservoir under pressure. When you switch the Univalve back on that extra volume of water in the hose under pressure will shoot out as the hose contracts.

With colder water that less flexible hose doesn't expand, hence the symptoms you describe.

Our Varistream controllers pulse the pump every 4 secs to see if there is still pressure in the hose. Sometimes you will switch your Univalve on frationally before the next pulse. The controller will then identify that the pressure has dropped and starts the pump. This gives you the impression that the pump has started the moment you opened your valve. But if you open your Univalve fractionally after that pulse then the pump will only start a few seconds later. In summer we never notice that delay, but winter it sometimes seems we have to wait forever before the pump restarts.

spruce said:

As @GSS Window Cleaning. In the summer your water is warmer. Warmer water will make the hose a little more flexible (elastic). In winter our hose is rather stiff and more difficult to manage whereas in summer its much easier to manage as its 'softer,' more plyable. When you switch the Univalve off the pressure builds until the controller dead ends the pump. In summer that more flexible hose expands fractionally with the increased pressure so there will be more water in the hose. This is like a reservoir under pressure. When you switch the Univalve back on that extra volume of water in the hose under pressure will shoot out as the hose contracts.

With colder water that less flexible hose doesn't expand, hence the symptoms you describe.

Our Varistream controllers pulse the pump every 4 secs to see if there is still pressure in the hose. Sometimes you will switch your Univalve on frationally before the next pulse. The controller will then identify that the pressure has dropped and starts the pump. This gives you the impression that the pump has started the moment you opened your valve. But if you open your Univalve fractionally after that pulse then the pump will only start a few seconds later. In summer we never notice that delay, but winter it sometimes seems we have to wait forever before the pump restarts.

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I know what you mean about hose more flexible in summer, I tried coiling some garden transfer hose up yesterday, as it was a mess and it just snapped. Mind you, this particular hose has lived outside for as long as I can remember.

The OP also mentioned the issue started after recallibrating the controller. If it is now switching the pump off at a lower pressure that could also explain it as the pump is switching off before the hose is becoming highly pressurised. Though this saves battery power it can be frustrating waiting for the controller to go through that 4 sec cycle as spruce describes.

When my new PF trolley arrived with one of these digital controllers fitted I had to remove it as I found this really annoying due to using a short length of PU hose which isn’t very flexible anyway. I now use a plain PWM controller which doesn’t have the calibration feature. 

Marko067 said:

The OP also mentioned the issue started after recallibrating the controller. If it is now switching the pump off at a lower pressure that could also explain it as the pump is switching off before the hose is becoming highly pressurised. Though this saves battery power but can be frustrating whilst waiting for the controller to kick in as spruce describes.

When my new PF trolley arrived with one of these digital controllers fitted I had to remove it as I found this really annoying due to using a short length of PU hose which isn’t very flexible anyway. I now use a plain PWM controller which doesn’t have the calibration feature. 

Click to expand...

Yeh I’ve only noticed it after calibrating the pump on the weekend 

If you prefer it the way it was you could try recalibrating the controller manually to a higher setting.

Marko is right Calibrate it manually.

I never auto calibrate mine anymore as I think its way too low. The higher you calibrate it the higher the pressure of your system will be

Ok thanks I’ll have a look today