Central heating pump affecting my subwoofer?!

[jonnywells]

Over the last couple of months i have started to notice when my central heating system switches off i sometimes get a couple of loud thumps come though my sub-woofer.

My heating system is a normal boiler (Worcester 15Ri) coupled with an unvented hot water cylinder. Both hot water and heating are pumped around with a Grundfos Alpha2L pump.

Really struggling to try and find a cure to the rumble that affects the sub-woofer? Any suggestions would be most grateful.

 

[D_Hailsham]

Has an old pump recently been replaced by the Alpha2L and the problem only arisen since then?

 

[jonnywells]

No, the pump was installed not long before i had my new boiler (just over 3 years ago)

 

[D_Hailsham]

No, the pump was installed not long before i had my new boiler (just over 3 years ago)

The pump is connected directly to the boiler, which controls pump overrun. This keeps the pump running for a few minutes after the boiler goes out. The problem therefore may not be the pump but the boiler.

It will be difficult to identify which is the culprit, so I suggest you power the sub-woofer via a lead with built-in surge protection.

 

[jonnywells]

Tried one of these but has not cured the problem.

http://www.amazon.co.uk/kenable-Sur...&keywords=surge+protection+extension+lead+rfi

 

[Gerrydelasel]

Presumably it's an active sub? How far away is it from the boiler? Just wondering if it's close enough to pick up the EMP from the solenoid/motor.

 

[Agile]

Those mains RFI filters are usually designed to remove higher frequency interference and over voltage spikes which might damage a computer or other sensitive equipment.

We have very little relevant information here so I am going to have to guess at the problem.

The CH pump is a highly inductive component and when connected or disconnected can cause disturbances to the mains supply locally and particularly if the mains supply has a higher impedance as would often be found in a rural area.

When this model of smart pump was first introduced a few years ago it took a very high inrush current and it was found that this was so high that it could damage time clocks. The immediate solution was to introduce a high resistance mains lead to limit this current but after a few months a redesign was made to the pump circuit and that seems to have solved these problems.

In your case I would have to make a guess that a noticeable variation is being made to the mains waveform and that is affecting the switched mode power supply in your audio equipment. These are cheap to build but can be very sensitive to variations in mains waveforms which is why many TV sets don't run properly on small generators.

My first check would be that the HiFi is being powered from a different MCB on the consumer unit.

If that is the case then on my house I might try adding a mains rated capacitor of about 2.6 uF to the supply at the HiFi equipment, probably on test just with a plug at the HiFi. But I would not advise that to a DIYer.

If I am correct with my guess then you may find that a replacement pump, either a current model might cure the problem. As would probably one of a different make although the Grundfos is about the best one.

But I would try the effect of a UPS designed for computer systems. I buy these very cheaply when their batteries have failed for just a few pounds. Since they are an AC to DC converter to charge the battery and then an inverter to reproduce the 230v they create a filter to remove short term disturbances on the mains supply.

But all that may be too involved in your case.

Tony Glazier

 

[TCCHeating]

Over the last couple of months i have started to notice when my central heating system switches off i sometimes get a couple of loud thumps come though my sub-woofer.

My heating system is a normal boiler (Worcester 15Ri) coupled with an unvented hot water cylinder. Both hot water and heating are pumped around with a Grundfos Alpha2L pump.

Really struggling to try and find a cure to the rumble that affects the sub-woofer? Any suggestions would be most grateful.

Does the noise happen as soon as the heating is turned off? If it does then it's not the pump causing the interference. (Presuming it is wired correctly to overun)