TV Interference From CH Boiler

[drlabman]

I've been noticing for a while that our TV goes blank for a split second periodically. This is while watching Freesat via the Humax HB-1100S. I'd put it down to poor signal and the age of our LNB. But it's now dawned on me that it happens when someone turns on a hot water tap in the house. This obviously causes our (recently installed) combi boiler to activate. What sort of interference is this likely to be - RF, mains? And what could I do about it? Thanks.

 

[Channel Hopper]

There used to be issues with thermostats over the air interference, though you might find putting the Humax on a filtered extension lead.

Does the boiler play up when you switch the receiver on ?

 

[drlabman]

There used to be issues with thermostats over the air interference, though you might find putting the Humax on a filtered extension lead.

Does the boiler play up when you switch the receiver on ?

The Humax is on a surge protected extension lead. Is that what you mean?

My thermostat is a Hive, but I don't see how that comes into it. The Hive doesn't control the hot water, and it's the hot water tap being turned on that causes the problem. I'm no expert though so I may be missing something.

It's hard to tell whether the interference is affecting the TV or the Humax, or both. It just happened a couple of minutes ago when someone turned the tap on. The screen went black, the TV showed "Wide" in the top left and then it went back to normal - as if it lost connection to the Humax. It's very strange.

 

[Channel Hopper]

By thermostat I mean the mechanical device with some electrical things inside for closing the circuit for hot water.

Does a hive have that ?

 

[Analoguesat]

Its probably a pump kicking in on the hot water supply side. We had an odd issue here for ages where when one of the many pumps on the communal heating system kicked on at 1830 our broadband router reset. All the pumps were changed a few months back & the problem has gone away.

 

[drlabman]

By thermostat I mean the mechanical device with some electrical things inside for closing the circuit for hot water.

Does a hive have that ?

No, it just controls the heating.

 

[drlabman]

Its probably a pump kicking in on the hot water supply side. We had an odd issue here for ages where when one of the many pumps on the communal heating system kicked on at 1830 our broadband router reset. All the pumps were changed a few months back & the problem has gone away.

I don't believe there is a pump on the hot water supply. Being a combi boiler the hot water is at mains pressure. However, I imagine there are other parts of the boiler that become active when hot water is drawn

 

[Terryl]

This problem could have several possibility's, one could be a bad or corroded ground on the satellite system, thus allowing external interference to get into the system, another could that one of the pumps is connected to same AC power leg that the TV/Humx is on, when the hot water system comes on there could be a high frequency surge on that AC power leg, what ever is controlling that system is causing this spike/surge.

One thing to look at is the boiler electric or gas fired? If electric is it on a single phase or both sides of the AC mains? (connected to both sides of the AC main) If dual phase connection then the following test may not be performed.

If it's electric and single phase then you need to see if it's on the same AC phase as the TV/Humax system, this would require an Volt meter to measure the AC voltage and a long extension cord, long enough to reach the location of the boiler.

You plug the extension cord into where the TV/Humax AC power surge protector is located, the other end of the extension cord is used to test the voltage at the boiler, if the voltage reads zero volts then you have a possible spike problem on that side of the AC, one way to possible eliminate this spike is you use some ferrite beads on the AC line at the boiler, this may require an electrician to do this job.

If you get a voltage reading then your TV/Humax system is on the other phase of the AC main supply, and the problem may be at the TV/Humax side.

Note: if you are not comfortable working with AC mains voltage then a electrician should be contacted to do the test.

If the tests prove out that the TV is on the same leg as the boiler then try find a AC socket that is on the other phase, us the extension cord and plug the TV/Humax system into this side of the phase, try the hot water, if the problem goes away you may need to run a cord to the other plug.


Sorry long winded too much coffee this morning.....

 

[drlabman]

This problem could have several possibility's, one could be a bad or corroded ground on the satellite system, thus allowing external interference to get into the system, another could that one of the pumps is connected to same AC power leg that the TV/Humx is on, when the hot water system comes on there could be a high frequency surge on that AC power leg, what ever is controlling that system is causing this spike/surge.

One thing to look at is the boiler electric or gas fired? If electric is it on a single phase or both sides of the AC mains? (connected to both sides of the AC main) If dual phase connection then the following test may not be performed.

If it's electric and single phase then you need to see if it's on the same AC phase as the TV/Humax system, this would require an Volt meter to measure the AC voltage and a long extension cord, long enough to reach the location of the boiler.

You plug the extension cord into where the TV/Humax AC power surge protector is located, the other end of the extension cord is used to test the voltage at the boiler, if the voltage reads zero volts then you have a possible spike problem on that side of the AC, one way to possible eliminate this spike is you use some ferrite beads on the AC line at the boiler, this may require an electrician to do this job.

If you get a voltage reading then your TV/Humax system is on the other phase of the AC main supply, and the problem may be at the TV/Humax side.

Note: if you are not comfortable working with AC mains voltage then a electrician should be contacted to do the test.

If the tests prove out that the TV is on the same leg as the boiler then try find a AC socket that is on the other phase, us the extension cord and plug the TV/Humax system into this side of the phase, try the hot water, if the problem goes away you may need to run a cord to the other plug.


Sorry long winded too much coffee this morning.....

Thanks for that. Not sure I fully understand but let's start with this ...
Ground on the satellite system - as far as I know, it's only the TV that has a dedicated ground. The Humax box power is supplied by an external adapter - DC or AC? not sure - but does that ground the Humax?
The boiler is gas fired.
I don't think the pump is involved in hot water delivery because it's at mains pressure.
The TV, Humax and boiler are all on the same ring main.
Does that answer some of your questions?

Update: from what I can tell the power adapter for the Humax supplies 12V DC and there's no ground PIN (it's plastic) - so the ground for the whole system is supplied by the TV only? Am I missing something?

 

[Analoguesat]

I don't believe there is a pump on the hot water supply. Being a combi boiler the hot water is at mains pressure. However, I imagine there are other parts of the boiler that become active when hot water is drawn

Doesnt need to be a pump - it could eaily be an electric on demand valve causing an rf spike

 

[drlabman]

Doesnt need to be a pump - it could eaily be an electric on demand valve causing an rf spike

Indeed - that's what I'm wondering. Although, I've also seen it mentioned that it could be an EMI (electromagnetic impulse?) on the mains circuit rather than RF. If it was RF where would that be picked up in a way that it would make the TV picture go off? Would it be via the TV aerial - which is also connected to the TV, BTW? I guess a simple test would be to remove the aerial connection from the TV and see if it still happens.

Annoyingly, the problem doesn't happen 100% of the time. But when it does happen it's definitely related to the hot water taps.

 

[ozumo]

FWIW my old Panasonic plasma telly loses picture momentarily when plugging in a Samsung TV to the same multiplug, though I am unsure if it's the television or the satellite receivers that are being affected.

 

[Terryl]

The satellite system coax and or the TV antenna coax should be grounded somewhere before it enters the house, a good ground on the coax will keep unwanted outside interference to a minimum.

Question: is the hot water heater hard wired or does it plug into a wall socket? If it hard wired then a ferrite choke (or two) can be installed on the hot water heater AC side, this will cut down on any RF interference caused by the hot water controls. This can be done on the TV/Humax side.

Example of a ferrite choke..https://www.mouser.com/ProductDetail/Fair-Rite/0431173551?qs=KmHvPbTOE4ReAQmf8DAXyQ%3D%3D&mgh=1&srsltid=AfmBOorfypi7T-QjG8T_znWK99Qh_svBErRyeZODCxXmqlLEoSj-UJyfUfM

You can google for one at your location.

 

[drlabman]

The satellite system coax and or the TV antenna coax should be grounded somewhere before it enters the house, a good ground on the coax will keep unwanted outside interference to a minimum.

Question: is the hot water heater hard wired or does it plug into a wall socket? If it hard wired then a ferrite choke (or two) can be installed on the hot water heater AC side, this will cut down on any RF interference caused by the hot water controls. This can be done on the TV/Humax side.

Example of a ferrite choke..https://www.mouser.com/ProductDetail/Fair-Rite/0431173551?qs=KmHvPbTOE4ReAQmf8DAXyQ%3D%3D&mgh=1&srsltid=AfmBOorfypi7T-QjG8T_znWK99Qh_svBErRyeZODCxXmqlLEoSj-UJyfUfM

You can google for one at your location.

Where would the sat coax be grounded? Ours comes straight from the LNB into the Humax (as does everyone's else's in the area as far as I can tell).

The combi boiler is powered from a fused spur on the downstairs ring main.

 

[Channel Hopper]

Temporarily run an extension lead to the Humax from - for example - the upstairs circuit.

 

[a33]

Indeed - that's what I'm wondering. Although, I've also seen it mentioned that it could be an EMI (electromagnetic impulse?) on the mains circuit rather than RF. If it was RF where would that be picked up in a way that it would make the TV picture go off? Would it be via the TV aerial - which is also connected to the TV, BTW? I guess a simple test would be to remove the aerial connection from the TV and see if it still happens.

Annoyingly, the problem doesn't happen 100% of the time. But when it does happen it's definitely related to the hot water taps.

It could even be different for 22kHz channels, or 0kHz channels.

Greetz,
A33

 

[Terryl]

I don't know about your local codes but here all TV, Cable TV and satellite TV system coax have to be grounded in some way.

 

[drlabman]

Temporarily run an extension lead to the Humax from - for example - the upstairs circuit.

Yes, I'll do that ... but first I need to double check whether the upstairs is on its own ring!

 

[Miika]

The boiler is gas fired.

Has it pilot flame or high voltage spark starter? If latter, then you have the culprit.

 

[drlabman]

Has it pilot flame or high voltage spark starter? If latter, then you have the culprit.

I'm pretty sure it doesn't have a pilot flame ... haven't seen one anyway ... but now you've got me thinking ... nah, it can't have. So, it must be a high voltage spark starter. I'd say it must be that then, except I don't have a problem when the heating comes on, and I presume the heating uses the same ignition method. Or is it different for heating/hot water?

And when you say "the culprit" is that because it would be generating RF, EMI or dropping the mains ring voltage?