[RD]

Radio Frequency Interference.

Electric motors can be strong sources of RFI.

[Seany (OP)]

Hmm. Our wireless router is about 4 metres away from the motor thing.(I think)
Can you specify where the motor may be located?

[RD]

I don't suggest that you attempt to replace a central heating pump yourself,
 you could end up with an unintentional indoor swimming pool, or electrocuted.

If the pump is knackered it's a job for a central heating engineer.

You could try making sure that all the radiators have been bled.

[Seany (OP)]

I know I know.. I'm not that dumb []

[Madidus_Scientia]

Is the pump in between your router and your computer?

[Seany (OP)]

The positioning of the computer doesn't matter, as all computers in our house fail to connect to the internet when the clanging takes place.
It must just be the wireless router being interfered in some way..

[RD]

Central heating pumps run for several minutes,
 if the pump motor was the source of the RFI your Wi-Fi link would also be down for several minutes.

There is an electro-mechanical valve which is only activated momentarily (seconds) when the pump motor starts.
So a faulty electro-mechanical valve could be the source of RFI and your momentary loss of Wi-Fi, (and the banging).

[lyner]

Radio Frequency Interference.

Electric motors can be strong sources of RFI.

Yebbut not an induction motor like they have in water pumps. There are no brushes to cause sparks.

The rotor in the pump could be clanking on a loose bearing. Or your room thermostat could be arcing. Or the CIA may be bugging you due to suspect postings on this forum.

My fan-blown condensing state of the art boiler is sounding like an old diesel engine at the mo. The fan bearing has gone, I'm sure, but I can't dive in and look or the British Gas man will rap my knuckles and say the maintenance contract is void.

[RD]

What about the motors in the electro-mechanical valves ?


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photo source

[lyner]

Induction motors, too.
They have to work for years and years with no maintenance and they only need low power.

[lyner]

I think you'll find that the only possible possibly arcing contacts are in the room and tank thermostats. They don't break a lot of current either and the interference usually drops off above VHF frequencies. Also, unless you get noticeable interference on analogue TV reception I very much doubt that WiFi signals would be affected all over the house; in a marginal situation possibly but not everywhere. If the incoming line to the router is affected or even the router / modem's power supply run near some of the C/H equipment, there could be some affect - even physical rattling of a poor contact.
I'd be only too pleased to come for an all expenses paid holiday visit to investigate. That's two eggs with the full English, please.

[Andrew K Fletcher]

Most earthing from the mains relies on hooking up to copper pipes. Maybe an electrical surge or even badly earthed tubing? caused by a failing boiler / pump Only thing I can think of that would link both together.

[Andrew K Fletcher]

One other possibility is that your boiler may be kettleing or boiling the water, possibly due to poor pump function or if a gravity flow and return system, there may be an air lock due to poor plumbing design. This can cause a hammer effect in the pipes that may sound like your boiler is defective. If a cable to your electrical equipment has a loose connection, the vibration from the pipes banging could disrupt the supply to your computer.

[Seany (OP)]

Central heating pumps run for several minutes,
 if the pump motor was the source of the RFI your Wi-Fi link would also be down for several minutes.

There is an electro-mechanical valve which is only activated momentarily (seconds) when the pump motor starts.
So a faulty electro-mechanical valve could be the source of RFI and your momentary loss of Wi-Fi, (and the banging).

OK, so electro-mechanical valve noted..

[lyner]

But they are very unlikely to cause RFI because there are breaking contacts in a simple induction motor.
The same goes for the pump and fan (if the boiler has one). They are all 'shaded pole' type motors; inefficient and low powered but very reliable.

There is another possibility and that is both effects are due to a common cause - such as a poor electrical contact in the electricity supply itself. That could make the pump work in bursts and produce banging.
Does your HIFI make any odd sounds whilst this is happening?

[neilep]

Seany,

Listen to me. Ignore all the above this is the real deal !

Your central heating system has been infested by some Carribean Kettle Drum Plumbing Fairies !!

As soon as the heating comes on they think it's time to partayyyyy !!!

The way to cure this problem is to open up a radiator valve and play some Bob Marley...The Fairies will seek out the rhythmic notation and fly out. If ewe have a jar ready they will fly into it, ready for depositing through your neighbours letterbox !!

Ewe won't see them because they are invisible but some rice and peas and a piece of coconut in the jar will keep them happy whilst in transport. You'll know when they have all arrived because if ewe put your ear close to the jar you should be able to hear them Jamming !

It's worth knowing that for most people, they welcome this introuduction to the wonderful Jamaican culture as a welcome gift...and they soon enjoy the musicality and soothing laid back sounds that their central heating creates.

[RD]

But they are very unlikely to cause RFI because there are breaking contacts in a simple induction motor.
The same goes for the pump and fan (if the boiler has one). They are all 'shaded pole' type motors; inefficient and low powered but very reliable.

What if the valve driven by the motor was sticking (e.g. due to limescale) the motor would draw excessive current or could even burn out as a result.

Does your HIFI make any odd sounds whilst this is happening?

An analogue radio or analogue TV would be a better RFI detector than the new digital types.
You could tune an FM radio to the hiss between radio stations listen for any signal which occurs when the central heating starts. By moving the FM radio you may be able to find the source by the signal getting stronger of weaker.

[Re: pipes as earth connectors. EMI can travel along earth connectors, so a faulty motor (pump or valve) could introduce electrical noise into the earth circuit, my money is still on RFI due to faulty motor thought].

[Seany (OP)]

Seany,

Listen to me. Ignore all the above this is the real deal !

Your central heating system has been infested by some Carribean Kettle Drum Plumbing Fairies !!

As soon as the heating comes on they think it's time to partayyyyy !!!

The way to cure this problem is to open up a radiator valve and play some Bob Marley...The Fairies will seek out the rhythmic notation and fly out. If ewe have a jar ready they will fly into it, ready for depositing through your neighbours letterbox !!

Ewe won't see them because they are invisible but some rice and peas and a piece of coconut in the jar will keep them happy whilst in transport. You'll know when they have all arrived because if ewe put your ear close to the jar you should be able to hear them Jamming !

It's worth knowing that for most people, they welcome this introuduction to the wonderful Jamaican culture as a welcome gift...and they soon enjoy the musicality and soothing laid back sounds that their central heating creates.

Neil! I've done all you've told me to do, but it doesn't seem to work!
Maybe I've missed out a step?

Maybe I need to stand on one leg and hop 20 times, spin around and say "cuckoo"?

[]

[Karen W.]

I think you have it now but mae sure you bleat too.... Radiators love Sheep!

[lyner]

What if the valve driven by the motor was sticking (e.g. due to limescale) the motor would draw excessive current or could even burn out as a result.

'fraid not; a shaded pole motor is designed not to take much current, even when stalled. The current is limited by its winding resistance and self inductance. They run quite hot because there is a thick wire turn wrapped around one pole of the motor (a shorted turn) to give the phase shift in the magnetic field.
The only arcing that can take place in a normal system, unless there is an actual loose connection somewhere, is a thermostat. They are nearly all very shoddy in construction and more than capable of making zzzuzzzing noises.  And, in any case, the whole system uses only low current for everything so it couldn't be more than an amp or two in any arc.

I could suggest running and turning off the C/H as soon as the WiFi starts to misbehave and see if it stops with no C/H. That would confirm / eliminate it.

I think neilep's solution is the best one, in any case.