Can central heating freeze my TV picture?

  Confab 20:46 14 Dec 2009

Over the weekend I purchased Humax 9150T digital set top box.

Picture quality is great and most of the time it works really well but yesterday I noticed that the picture occasionally froze for about a quarter of a second and then jumped, so to sort of catch up with itself (hope this makes sense).

I had a similar problem with my sky TV box on certain channels and narrowed the issue down to interference from my DECT phone. I fitted a screened wall outlet and that solved the problem.

This evening I’ve been going around the house switching things on and off and I think that my central heating is interfering with the picture. Every time the heating comes on the picture freezes (just briefly). It then freezes periodically when the heating is on and then freezes again when the heating goes off. The thing is I’ve got a combie boiler – it’s gas!

So what could be the cause of the problem? Could the boiler be interfering with the TV signal/ aerial or could it be some interference coming through the mains socket? Perhaps I should buy one of those filtered mains extension cables? I just don’t know what to try.

I live in a good signal strength area I have a roof mounted aerial and a signal booster. I have checked the signal strength on the box which shows 79% and the signal quality shows 100%.

Any ideas?


  wiz-king 06:02 15 Dec 2009

Yes it could be the boiler, or the thermostat -either can produce quite large spikes to the mains and radiated RF spikes.
If it coincides the the boiler lighting it is probably the igniter spark, if you can make it happen by altering the thermostat them it could be that.

  jack 08:59 15 Dec 2009

It is almost certainly the electrical components of the Heating system putting a 'spike' in the mains when cutting in and out these as mentioned thermostats, ignitors ,pumps.
The cure?
A surge Protected power strip - from any electrictal outlet
Price - A tenner up[depending on the number of sockets.]
You should have one of these on you computer too[preferably one with phone protection incorporated.

Add to Christmas list.

  oresome 13:56 15 Dec 2009

Further to the suggestions offered already which are worth trying...

The interference can either be mains bourne or radiated from the source and picked up by the TV aerial or down lead.

The aerial should incorporate a balun to reduce impulse pick up on the downlead and the downlead shouldn't be routed alongside mains cables. Naturally the cable should be of good quality and this includes the flyleads.

If you live in a good signal area with an outdoor aerial, why do you have a signal booster? Do you have the same problem without the booster?

It's always best to eliminate interference at source and in this case the central heating thermostat is a likely cause and should be tested by replacement.

  Confab 21:56 15 Dec 2009

wiz-king & jack - Thanks very much for your replies. It’s definitely not the thermostat because I can make the TV picture freeze by turning a hot water tap on (I never thought I would write that!) so it must be the boiler. I’ll buy one of those surge protected power strips at the weekend and hopefully it will solve the problem.

Oresome – Thanks also for your suggestions. I don’t know what a balun is/does but I’ll do some research. Perhaps I could get one in Maplins? I hope I don’t have to fit it to the aerial as it’s on top of the chimney stack so, if need be, I'll leave this to the professionals.

The reason I have a signal booster fitted is because the feed from my aerial is split between six rooms. I have by-passed the booster by plugging the aerial cable directly into my freeview box but I still get lock-ups when the boiler fires up.

Thanks again


  oresome 16:47 16 Dec 2009

The balun is an integral part of a digitally approved aerial. Prior to digital transmissions, baluns were rarely if ever incorporated in aerial design, so if you have an old aerial, chances are it won't have a balun.

Balun is short for a balanced to unbalanced transformer which is used to connect the dipole receiving element of the aerial to the downlead. It was found to be necessary with digital reception because it is prone to impulse interference as you have found out.

  Confab 13:09 22 Dec 2009

Thanks for your advice so far.

I purchased a Belkin 410UK 4 Way Surge Protector from Currys (£24.99). This offers Noise filtration to 58dB reduction (whatever that means). I plugged both the TV and Freeview box into it and turned on the hot tap. The boiler sparked up and the tv picture froze so no joy there. I went to Maplin and bought a TVI RF Filter (£10.99). I fitted this directly between the aerial and the freeview box. The RF filter made the signal strength drop from about 80% to 30% on some channels and the signal quality from 100% to 30%. Anyway I sparked the boiler up and again the tv picture froze. So no joy there either.

I’m not sure what to try next. Someone in work has offer to lend me one of these click here

I’m not sure it will work but it’s worth a try.

Can anyone think of anything else I could do other than buying a new Combi boiler?


  Confab 13:11 22 Dec 2009

Sorry I wasn't that one in my link I think its this one

click here

  theDarkness 19:21 24 Dec 2009

every time my electrical heating system switches off and on, my tv digibox will freeze for a few seconds (sometimes more or even require a switch off), or stutter! my digibox is underneath the temperature control for the heating-so it could definately be your digibox or sky box. take note of exactly when your heating goes on and off through those vents, and if there was a slight jump or freeze with your tv picture at that time! im not sure if all boxes are effected though

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