Potterton Netaheat Electronic - turns on and off by itself

[Agile]

It may be an idea to get the pump checked before you blow another timer.

If you look on the Grundfos Facebook page then you ill see that I have posted an explanation of the problem.

Tony Glazier

 

[RobeK]

Pump is brand new. Should I check anyway?

 

[Agile]

Yes, you said it was new!

I give the advice!

But I cannot make anyone take it!

Its up to you to take it on not. I would prefer that you did not.

Tony

 

[RobeK]

Yes, you said it was new!

I give the advice!

But I cannot make anyone take it!

Its up to you to take it on not. I would prefer that you did not.

Tony

Hi Tony
I appreciate the advice. I wasn't sure if you had seen it was new. Had a look on FB but can't find your post. Could you post a link please?
Thanks

 

[Agile]

Comes up easily under Google search

Grundfos-Tony-Facebook

https://www.facebook.com/GrundfosEngineering/posts/170994886429446

 

[RobeK]

Thanks, so as the pump has now been installed and that the first visit may have fried my old timer, is it recommended that I get the guy back to install this cable?
Your post says on first powered, so as it is in place now, is there a risk it could fry it again?

 

[buck51]

Tony GlazierGrundfos Engineering
25 September at 23:48 · ..UPS 2 pumps have a problem!

They create a short high current surge when they are first powered.

This can weld the contacts on domestic timeclocks and programmers causing the system to be powered even when they are off.

As a temporary solution until the pump itself is modified Grundfos have made available a special cable with a built in resistance of 40 ohms which limits the initial surge current to a safe value which will not damage the controls.

This lead is now being included within the pump box but if you have an earlier pump supplied without one then if you contact Grundfos then they should send you one. — in United Kingdom.
.
..Grundfos Engineering Hi Tony, Thank your for your comment. I can add that we are testing different solutions and trying to find out if we can change the design, so the extra cable will no longer be necessary. Best regards, SigneLike · Reply · 26 September at 14:42..

 

[RobeK]

Tony GlazierGrundfos Engineering
25 September at 23:48 · ..UPS 2 pumps have a problem!

They create a short high current surge when they are first powered.

This can weld the contacts on domestic timeclocks and programmers causing the system to be powered even when they are off.

As a temporary solution until the pump itself is modified Grundfos have made available a special cable with a built in resistance of 40 ohms which limits the initial surge current to a safe value which will not damage the controls.

This lead is now being included within the pump box but if you have an earlier pump supplied without one then if you contact Grundfos then they should send you one. — in United Kingdom.
.
..Grundfos Engineering Hi Tony, Thank your for your comment. I can add that we are testing different solutions and trying to find out if we can change the design, so the extra cable will no longer be necessary. Best regards, SigneLike · Reply · 26 September at 14:42..

yes got that Buck51
Does not answer my query

 

[Agile]

The pump takes a high inrush current when power to it is switched on.

That's EVERY time it is turned on! ( Not just the first time! )

Tony

 

[DP]

My timer only allow HW and CH on timer together or one of the other. They are not controlled independent via a timer.

Robek, your system is fitted with a three-port valve (most likely a Honeywell V4073 midposition valve) that allows independent switching of the two zones if the programmer was to be replaced. Alternative to this is fitting a programmable room thermostat (in place of existing room thermostat) that gives you independent time and temperature control of space heating and existing timer now to take control of hot water heating HW runtime on clock will be reduced as now it will not need to cater for central heating run time (taken over by the programmable room thermostat)

Turned out to be a fault between the timer controller and the immersion tank thermostat. Both replaced and back to normal. Thank you for your input though.

Possible both were defective but a further testing would have shown where the actual fault. For HW, timer extends voltage to hot water thermostat fitted to your cylinder, which then decides if water needs to be heated, if yes, pump and boiler fire until thermostat on cylinder is satisfied.
For central heating but HW satisfied, motorized valve only sends water to radiators until room thermostat satisfied.
For HW and CH calling, valve with silver top now sends water to cylinder as well as radiators until their dedicated thermostats are satisfied.

Pump is brand new. Should I check anyway?

I would take note of pump details and contact Grundfos and see what they say. I understand there was an issue but Grundfos will be able to assist you. At the end of the day, pump is an inductive load which will cause contacts to spark and lead to undesirable contact erosion. Same would be the case when a fan or a transformer is powered up. Some contacts are designed to switch inductive loads and others are not.

Tony wrote

That's EVERY time it is turned on!

Me thinks spark will be there when pump is switched off as well- so the contacts will get thumped twice each time voltage is applied to it