I installed an Alpha during the summer and, now the CH is on, I've noticed that whenever the Suprima re-fires after the boiler stat has shut it down, then the Alpha speeds up before gradually settling down again. This means that, contrary to the way it's supposed to work, the noise through our TRV's is quite loud, and all the more noticeable because it comes & goes. The Alpha is set at the lowest point on its variable scale.I *think* that what's happening is that the Suprima is momentarily disconnecting the pump as the boiler fires? If this is true, then the pump is acting correctly.Is this (disconnecting the pump) a known *bug* with the Suprima?ThanksRory

In message , Rory writesWhen a Suprima comes on, it momentarily energises the pump, this is normal. It should also energise the pump on a daily basis to prevent it seizing up during the summerThe information contained in this postmay not be published in, or used by

In message , Rory writesDefinitely,but it would still contain the same software

Grudfos Alpha & Potterton Suprima 'bug'?

Oct 20, 2004 28 Replies

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IMM 21 years ago

This will momentarily de-energise the pump as the stat switches over from a switched live to a permanent live. This is what he doesn't want as it effects the pump operation.

It is best to have the switched live energise the pump as per normal. Then a permanent live through the stat to the pump. When cold the switched live switches on the pump. The flow gets over 65C and the stat switches in the permanent live to the pump too. It doesn't matter as the pump is already energised. The switched live de-energises, but the stat is still above 65C so the permanent live keeps the pump energised and running until the flow is cooled. Simple.

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Rory 21 years ago

What I think will happen here is that when the pipe stat switches in the permanent live then this will connect to the boilers switched live and cause the boiler to run continuously (limited by the boiler stat). That is what I almost achieved when I shorted Pump Live to Switch Live - if the boiler control hadn't sensed it and locked out the boiler then the overrun timer would have kept the boiler firing.

I reckon it *has* to have a relay - simples solution I can think of is coil wired to pump live and n/o contacts in parallel with n/o on pipe stat, supplied by permanent live. Any other offers?

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raden 21 years ago

That's not what I was on about

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Rory 21 years ago

Sorry. What were you on about?

I understand about pulsing the pump every 24hrs and on initial power up, the question that's bugging me (which you may know the answer to) is; When the boiler is going through it's relighting procedure after pausing having satisfied the boiler stat (but not the CH or HW stat) does the controller deliberately momentarily disconnect the pump?

If, perhaps, the controller shouldn't do this, or the firmware has been upgraded, then it would be worth me changing the PCB to cure the annoyance this causes.

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raden 21 years ago

DIMM was talking about running his pump from his programmer

They all do the same, your £150+ would be wasted.

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IMM 21 years ago

Maxie,are you asking DIm Lin the far eastern luscious lovely about this? My oh my....

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Rory 21 years ago

Do many boilers do this? If so, would seem to negate one of the benefits of choosing the Alpha.

I wouldn't dream of spending £150 - if/when I need to change the PCB I'll buy one off you. Hopefully it will be soldered better than the original.

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raden 21 years ago

Definitely,

but it would still contain the same software

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raden 21 years ago

I refer the learned gentleman back to insurance liability

If you modify the pcb in any way, then it is no longer correct for the boiler. This may seem a trivial point to you atm, but you leave yourself open.

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