Surflo pump issue

[Baz85]

Hi, newbie to this site.

I've just had to completely drain my system before moving into a new van. Since I have, I'm having a slight issue with one of my pumps. Anytime I start the water via my uni valve, I get the initial burst of built up pressure, then the pressure drops quite low and then works as normal. I'm just wondering if anyone has any idea what can be causing the initial loss in pressure?

It's doing it each time I stop the water flow but then works perfectly after that and whilst it's not stopping me from working, it is annoying. I've tried recalibrating the pump but doesn't seem to make a difference.

Cheers in advance.

 

[Philip Hardy]

The pressure switch will be getting past its best, or there's low voltage to the pump, either way it's dead ending (usually at 100psi), when you stop the flow with the univalve, then when the initial burst of pressure clears the system failing to recognise that it needs to fire up again.
First, check your wiring and connectors to the pump only.
Then if you are remotely handy you can buy new pressure switches on Ebay for around £8, swap this out and my betting is you are back to normal.

 

[ched999uk]

If you have a V11 or V16 controller then the pressure switch shouldn't be an issue as the controller monitors current (pressure) and shuts off before the pressure switch would get triggered by pressure.
My guess would be an air lock, i.e. air is compressible, water isn't, so when the univalve switches off the pump keeps pumping till it's calibrated current is reached then shuts off. When the univalve is opened the air lock pushes the water out faster as it's been compressed, the controller doesn't 'see' the opening of the univalve as the air lock 'fools' it, then the water flow falls as the air is no longer compressed so the pump kicks in.

Basically I think air in the system is causing your burst of flow then low flow till the pump fires up again.

You need to eliminate the air lock, disconnect the pump outlet and run at max speed, reconnect pump, disconnect pole hose, run pump at max, then try the pole hose and univalve. Recalibrate and you should be good.

 

[Deleted member 7446]

Hi, newbie to this site.

I've just had to completely drain my system before moving into a new van. Since I have, I'm having a slight issue with one of my pumps. Anytime I start the water via my uni valve, I get the initial burst of built up pressure, then the pressure drops quite low and then works as normal. I'm just wondering if anyone has any idea what can be causing the initial loss in pressure?

It's doing it each time I stop the water flow but then works perfectly after that and whilst it's not stopping me from working, it is annoying. I've tried recalibrating the pump but doesn't seem to make a difference.

Cheers in advance.

Check the microswitch for continuity. Check that you are not sucking in air and have you tried to calibrate your controller?

 

[WindyinNorfolk]

Sounds more like calibration to me - set to high so when you use the univalve you get an initial surge from the build up but then a small dwell until the pump cuts back in.

best way is to run the with a good flow and operate the univalve and listen to the pump and how long it runs before stopping - should be about 4 seconds and the same when starting up again

 

[spruce]

It sounds like the way controllers work. Once the controller dead ends, power (current) from the controller to the pump is switched off. Then the controller pulses current to the motor to see if the pressure has dropped. This pulse occurs every 3 to 4 seconds. If you operate your Univalve a split second after the current pulse has finished, then the pressure in the hose is going to fade away until the next pulse. That 3 to 4 seconds can seem like a lifetime.

If we have the diesel heater switched on, the hot water under pressure expands the hose a little, creating a 'reservoir' of water. Opening the univalve then bleeds this water off as the hose shrinks back. We never notice this pump lag then.

We have 2 Varistream controllers. When the pump is running, a green LED lights up. When the controller dead ends, the green light turns red. If we stand at the van with the Univalve off, we can see the process in action when we open and close the Univalve.

We have 1 hose reel with microbore hose and another with minibore. This lag time is much more noticeable when using microbore hose.

 

[Baz85]

Thanks for all your replies, I will try a few of the different options over the next day or so