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Thermostat interference problems

« on 08/05/2007, 23:33 »
Hi, came across a mention of thermostat interference problems in another post and I'm convinced I have the problem. I have an extension cable going to an internal adsl modem. Connection disconnects when thermostat fires up on either gas boiler or more likely the fridge,(watching TV and I hear the fridge thermostat clicking causes interference on TV). Really annoying  obviously when playing online games etc. Was wondering if you have any suggestions to solve problem because a solution would  I believe just not cure my disconnect problems but might also increase speed on the line. Thanks in advance, Danglese
« Reply #1 on 09/05/2007, 10:51 »
Try and rule out as many causes of interference at your premises as possible.

I'd start by removing the extension cable if possible as these are probably the worst cause of interference and move the router away from the thermostat.

I appreciate that this may be difficult but I would be surprised if you did not see an improvement afterwards.
Chris Cotterill
Business Marketing Manager
« Reply #2 on 09/05/2007, 17:14 »
Hi, appreciate the reply but as posted I don't have a router, only an extension lead going to an internal adsl pci modem.
« Reply #3 on 09/05/2007, 17:25 »
Couple of questions.
Is the extension lead before or after the filter.
How long is the extension lead and what type is it.
Just to add - if you can hear the fridge thermostat clicking it is almost certainly faulty and should be replaced. The clicking is usually due to faulty contacts causing arcing which creates interference.
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Old Harry Rocks
« Reply #4 on 09/05/2007, 22:33 »
Hi,the telephone extension lead comes after the filter, I think its around 10 meters looks pretty cheap..still don't know if you can buy better quality ones.Will get that fridge contact sorted out. BTW, how much superior are adsl router modems than an internal adsl pci modem?
« Reply #5 on 09/05/2007, 22:49 »
If you can I would change to a router and locate it near the phone socket. You can then run a network cable from the router to your PC.
Alternatively you could go wireless.
If you stay with your present system I don't know which is better - a high quality RJ11 cable or a twisted pair BT quality cable with the filter next to the computer.
I certainly wouldn't go for a flat type cable for either option.
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Old Harry Rocks
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« Reply #6 on 09/05/2007, 23:57 »
Probably the best thing about a router is that it's completely seperate from the PC which means that you aren't limited by where you position it (or have crazy long extension cables) and that it isn't reliant on the PC's power, CPU time, etc.

My wireless router just sits on the windowsill next to the master socket out of the way and only gets touched to reboot it once every few weeks (or when the cat tries to attack it). Makes life a lot easier with wiring, apart from the wire between router and phone socket and the ethernet lead to my desktop everything else is wireless.
Dave Tomlinson
PlusNet Network Services
« Reply #7 on 10/05/2007, 16:17 »
Thanks for your help guys, Danglese
« Reply #8 on 11/05/2007, 13:11 »
Room or Fridge themostats can give EMI (Electro-magnetic Interference).  Generally through age.  These mains spikes will travel through electrical mains cable in the house.  It *could* also get picked up by any telephone cable passing close to the faulty device.

Below are suggestions, in the order of least expensive first.  If the telephone cable passes VERY close to the suspected faulty themostat, try temporarily routing it away from the faulty device.  Preferably at a right-angle to its current travel past the device.  Here, the telephone cable could be acting as a antenna.

The above is unlikely.  You say that your ADSL modem is built into the PC.  More likely is that the PC's PSU (Power Supply Unit) is letting mains bourne EMI in.  In severe cases, mains spike will result in the PC suddenly rebooting on its on.  Here though, it could be that mains spike are getting to the PC's audio components, such as the modem.  Cheapest solution would be to plug the PC into a mains extension lead (4-way mains bank) that has a spike (EMI) filter built-in.  These can be got for under 10 ukp.  A better PC PSU is more costly at 30 to 40 ukp.  So, the filtered mains lead is more desirable.

If anyone is experiencing the same problem but, have an external modem or router.  It is always a cheaper solution to try and plug it into a mains (EMI) spike filtered extension lead.

« Reply #9 on 11/05/2007, 13:20 »
In principle I agree but as the OP said he is also seeing interference on the TV screen from the same source.
To me that implies or more serious problem which I had assumed was due to arcing creating an em field.
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Old Harry Rocks
« Reply #10 on 11/05/2007, 16:15 »
I must admit that I missed the observation of interference to the TV.  That's what happens when you try to review the forums whilst forcing a sandwich down your throat during a short lunch!  ;-)

Tends to make me think it is a room thermostat.  The basic ones, just a knob, contain two metal sprung discs.  That come together , as a switch, passing the electrical current.  Through dust, wear and tear, these do arch.  Can be bought from a DIY store for 10 ukp.  Not a job for the inexperienced though.

I had to replace the thermal sensor in my fridge recently.  The only time that I have looked at a fridge thermostat, so not sure how the designs differ.  Mine, the sensor was at the back of the fridge, connected to the control on the side.  Here switching is being done by a relay.  In this design I wouldn't expect the relay to arch much though.  Not compared to a room thermostat.

Still, my earlier offering is sound advise.  Agreed that, if the problem is so noticeable on your TV, the problem needs locating and fixing.  You can prove if it is the room thermostat or not by - Temporarily turning off the fridge.  Turn the room thermostat near to the current room temperature and then wait for it to come on.

You can do a simular test with the fridge if you like.

« Reply #11 on 11/05/2007, 23:19 »
It is an old fridge, was in the house when I moved in about 4 years ago, and looks pretty old but works ok except for the interference. Decided to get a new fridge..
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