[Ian Sheppard]

With the recent Cold Snap and temperatures below freezing. Any Ice forming in the hose line or Pump can create higher than usual back pressure in turn this will activate the pump pressure switch with the controller displaying PS. So along with the usual checks please bear in Mind ice as a factor.

[Ian Sheppard]

PS is Displayed ( RED LED on Analogue Controller)
If PS is displayed, this means that the pump's pressure switch has been operated due to a high build up of pressure in your system. The controller is set to work with a 5.2 litre per minute pump up to 100psi, although it will work at higher ranges. It is worth pointing out that the control does not activate the pump pressure switch. The control is simply telling you the PS has opened. This will happen in one of two case,s

A. High pressure build up in your system. The control does not create or have impact on system pressure, once calibrated it can monitor pressure. Please see the following pressure dynamics link (new link)
B. The Pump has become disconnected. Please see our wiring diagram in the user guide for correct connections. The Control does check for electrical current to a pump, If the pump can not detect a pump in circuit the default message is PS. (see note 6)
Common causes for the pressure switch operating are:

1. A restriction to the water flow, i.e. from a twisted hose.
2. Blocked or small water jets. (We recommended that the jets are no smaller than 2mm).
3. Grit or dirt trapped in the system. For example a blocked pump pre filter
4. Air trapped in the system.
5. Prolonged shut off of the water flow.

6. Check the wiring connections between the pump and controller. If there is a break or damaged connection the control can not see the pump. Replace corroded or damaged connectors including the fuse and holder.

7. In some case finding the restriction that has caused high pressure is a process of elimination. Start by removing the brush and jets does this clear the restriction? No then remove the pole hose and so on until you are back to the delivery pump outlet. Bear in mind some hose reels have a non return valve in some cases these can Jam causing high back pressure.
Check that Connectors are the same ID and are not blocked or have stuck no return valves

8. Ensure the tank breather hole is not blocked.
Blocking the tank breather hole can result in high pressure build up. As the tank empties the Pump will also draw air from the tank which is now effectively air tight. As air is drawn through the pump a Vacuum is created in your tank this will cause the tank contract ( Like a kids drink carton ) and high pressure in yours system.

9.  During very cold periods Ice can form in the Pump or hose line. Ice will obstruct the line and cause high back pressure build up. In turn this will activate the pump pressure switch.

Note: as B above:
Note: The controller carries out an electrical test to ensure the pump and pressure switch are in the circuit. If the pump can not detect the pump due to damaged cable/connectors the control will display PS (pressure switch) as a default message. This is one of the crucial protections we put in place. The control no longer passes any current to the pump but instead retests the condition every few seconds. This prevents a dangerous condition occurring for example ( a loose moving or damaged connection touching ground (Van panels) because the controller is now limiting the energy.
Connectors and terminal blocks can also be a source of volt drop for this reason regularly inspecting your connectors replacing any that are worn or damaged is a good idea. Also check connections are secure with good contact to the copper core.
Check for any damaged cable where insulation has been chaffed exposing the copper core not only is there a risk of a short knocking out the fuse the exposed core can be a source of volt drop and become very hot in some circumstance,s this heat can be sufficient to melt insulation and fuse increasing the risk of fire.
An Issue with old connectors is corrosion something that is difficult to avoid in a wet environment such as WFP so keeping connections as dry as possible by placing cable into conduit is a good idea. Corrosion will increase the resistance of the connector and in turn volt drop across the connector.

A badly worn or corroded connector can become an energy wasting resistor. If your connectors are excessively hot they either need replacing or tightening, as your are wasting precious battery power.
The harder the pump works, the more current will be drawn. With poor connections in a system this will increase the energy lost in heat. Because Power = I*I*R (current squared multiplied by the connector's resistance). So the power lost in a bad connector is actually increasing exponentially. Compared to the energy consumed by the pump this is small. But every little helps!
A good connector should only feel warm to the touch in normal use.

[Spruce]

Hi Ian

That is such an interesting read. Thanks for taking the trouble to post this.

May I ask you a question off topic please?

We have used Varistream controllers since day one. I have 2 of the first Varistream digital controllers on the van.

These controllers are set to dead end at C and designed around the 5.2 lpm Shurflo pump. (If memory serves me the dead end settings are from 1 - 9 and then A - F)

At the moment we have both controllers set down at DE of 6. At one time C was good for summer and D was good for winter. On those setting I couldn't run the pump speed at 7 without the DE limit being reached.

Could this be due to component deterioration or could it be caused by other factors? Its odd that both controllers are acting the same way.
I've opened one of the controllers and there is no moisture in the inside at all and the PC board is perfectly clean with no corrosion on any component at all.

We got a brand new leisure battery about 2 years ago, but I can't say the situation with the controllers is linked to that change at all. I also changed the VSR about 2 years ago, but again I can't see that being related either.
We probably run a controller with the van's engine running once every blue moon tbh.

Any comments would be appreciated even although they aren't 'your' controllers'.

Thanks

[Ian Sheppard]

Hi Ian

That is such an interesting read. Thanks for taking the trouble to post this.

May I ask you a question off topic please?

We have used Varistream controllers since day one. I have 2 of the first Varistream digital controllers on the van.

These controllers are set to dead end at C and designed around the 5.2 lpm Shurflo pump. (If memory serves me the dead end settings are from 1 - 9 and then A - F)

At the moment we have both controllers set down at DE of 6. At one time C was good for summer and D was good for winter. On those setting I couldn't run the pump speed at 7 without the DE limit being reached.

Could this be due to component deterioration or could it be caused by other factors? Its odd that both controllers are acting the same way.
I've opened one of the controllers and there is no moisture in the inside at all and the PC board is perfectly clean with no corrosion on any component at all.

We got a brand new leisure battery about 2 years ago, but I can't say the situation with the controllers is linked to that change at all. I also changed the VSR about 2 years ago, but again I can't see that being related either.
We probably run a controller with the van's engine running once every blue moon tbh.

Any comments would be appreciated even although they aren't 'your' controllers'.

Thanks

Hi Spruce

You have a well designed and well maintained system and this care pays off with a long lasting system. It shows a little regular maintenance goes a long way.

Interesting question and while over time electronic components will suffer some wear through repeated heating and cooling ( As you know over time this reduces the components ability to manage heat/current effectively ) I suspect it is not a major factor here.

I am tending to lean toward environmental factors in particular ambient and ground temperature. As temperatures fall this has impacts on the Viscosity of the water and the hose line expansion rates. The colder the water the thinker it becomes as the molecules clump together bit like a slush puppy. This means the water actually moves slower through the line and the pump must work harder.

The cold ground will also impact on the ability of the hose wall to expand as fast as it would during warmer periods. As the hose does not expand as well this creates an additional restriction in the hose line.

The two factors of lower viscosity and hose restriction mean the pump must work harder to move the water down the line. In turn we see increased pressure and increased current draw by the pump . The varistream and V11 use similar means of detecting DE

When setting the calibration  we are telling the control what the base line pressure is and the base line current draw is by the pump during open flow. setting your controller to 6  or 7 the pump is drawing some where between 3 - 5 amps in open flow.
Shutting the flow off increases both pressure and current draw the control detects this change and drops the pump into DE. Now the higher your calibration setting the slower the controller is to DE the pump because it allows the pressure/current to build for slightly longer

If we work on the basis that due to lower temperatures the pump is working a little harder in open flow  The base Pressure and current are higher. We can expect that Calibration will need to be set higher during low temperatures possible even using F rather than C
This may allow you to run at the higher flow rate or you may find due to the increase pressue in system flow rate has to be tweeked down slightly.

The test will be if when the weather warms up again that you experience the same issue.

Cheers

ian

[Dave Willis]

Maybe it is Rocket Science after all!

[Spruce]

Hi Ian

That is such an interesting read. Thanks for taking the trouble to post this.

May I ask you a question off topic please?

We have used Varistream controllers since day one. I have 2 of the first Varistream digital controllers on the van.

These controllers are set to dead end at C and designed around the 5.2 lpm Shurflo pump. (If memory serves me the dead end settings are from 1 - 9 and then A - F)

At the moment we have both controllers set down at DE of 6. At one time C was good for summer and D was good for winter. On those setting I couldn't run the pump speed at 7 without the DE limit being reached.

Could this be due to component deterioration or could it be caused by other factors? Its odd that both controllers are acting the same way.
I've opened one of the controllers and there is no moisture in the inside at all and the PC board is perfectly clean with no corrosion on any component at all.

We got a brand new leisure battery about 2 years ago, but I can't say the situation with the controllers is linked to that change at all. I also changed the VSR about 2 years ago, but again I can't see that being related either.
We probably run a controller with the van's engine running once every blue moon tbh.

Any comments would be appreciated even although they aren't 'your' controllers'.

Thanks

Hi Spruce

You have a well designed and well maintained system and this care pays off with a long lasting system. It shows a little regular maintenance goes a long way.

Interesting question and while over time electronic components will suffer some wear through repeated heating and cooling ( As you know over time this reduces the components ability to manage heat/current effectively ) I suspect it is not a major factor here.

I am tending to lean toward environmental factors in particular ambient and ground temperature. As temperatures fall this has impacts on the Viscosity of the water and the hose line expansion rates. The colder the water the thinker it becomes as the molecules clump together bit like a slush puppy. This means the water actually moves slower through the line and the pump must work harder.

The cold ground will also impact on the ability of the hose wall to expand as fast as it would during warmer periods. As the hose does not expand as well this creates an additional restriction in the hose line.

The two factors of lower viscosity and hose restriction mean the pump must work harder to move the water down the line. In turn we see increased pressure and increased current draw by the pump . The varistream and V11 use similar means of detecting DE

When setting the calibration  we are telling the control what the base line pressure is and the base line current draw is by the pump during open flow. setting your controller to 6  or 7 the pump is drawing some where between 3 - 5 amps in open flow.
Shutting the flow off increases both pressure and current draw the control detects this change and drops the pump into DE. Now the higher your calibration setting the slower the controller is to DE the pump because it allows the pressure/current to build for slightly longer

If we work on the basis that due to lower temperatures the pump is working a little harder in open flow  The base Pressure and current are higher. We can expect that Calibration will need to be set higher during low temperatures possible even using F rather than C
This may allow you to run at the higher flow rate or you may find due to the increase pressue in system flow rate has to be tweeked down slightly.

The test will be if when the weather warms up again that you experience the same issue.

Cheers

ian

Thanks for the detailed reply.

I appreciate the time you spent answering that.

I realise that calibration is linked to current draw of the the pump which 'translates' into pressure.

So if C  = 5.0 amp draw and D slightly higher, then my 'logic' would tell me that 6 is down in the 3.0 amp area, probably a little lower.

Knowing that the pump requires more energy to drive colder water - water at zero is theoretically a solid, then it seems logical that the calibrating setting must be higher, not lower.

Had it just happened to 1 controller and not the other, then I would have automatically concluded that one of them is on its way out.  It could also be that both are on their way out.

My knowledge and understanding of electronic components is virtually zero, hence the reason for asking. I know what a diode does, I know what a capacitor does, but that's about the limit of my capabilities.

We will see what the summer and warmer weather brings.

.

[Ian Sheppard]

Hi Spruce

No problem I think the combination of higher calibration EG D means the control expects a higher base current draw and by reducing flow rate we are balancing out the current draw. In theory with the higher calibration the system should run at your usual flow rate. But the restricted hose wall expansion is a bit of an unknown.

When it comes to Fluid dynamics you could spend a lifetime trying to get your head round it. My explanation barely scratches the surface. I am very fortunate to have some very clever people behind me in the workshop. So hopefully not to much rocket science Dave.

I also think as it is both that are effected that its not a control issue and all the time they work all the better.