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Jesse

Losing network connection when HVAC cycles on....

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Jesse

Hello,

 

My network will often temporarily lose connectivity when our HVAC system cycles on.  My wife works at home, so this can sometimes be a real problem for her.

 

Let me start by telling you what I have done so far. 

 

When this started we were on DSL and were using a DIR-655 router.  I have pulled about 1000 miles of cat5e and cat6 through the house, but with all the portable devices I had the router and modem in our living room in an effort to get the widest possible wireless coverage.  When she first noticed the problem I moved the modem and router off of a surge strip and onto a small APC UPS.  As a test I fired up the browser on my workstation and pulled the plug on the UPS.  Sure enough, I was still able to browse the web just fine.  The next day she informed me that this did not fix the problem.  She was not impressed.

 

All the network cable in the house is home-runned to a patch panel in the basement, which sits next to the switch.  At this point I realized that the switch was also just plugged into a surge protector, so I moved it onto the UPS that powers the server.  Still not fixed.

 

Next, I moved the router, modem and UPS to my wife's office and plugged her laptop directly into the router.  Still not fixed.

 

I then replaced the DIR-655 with an Asus RT-N66U (very nice router, great wireless range).  Still not fixed.

 

Shortly thereafter we moved from AT&T DSL to Comcast.  It would have been a real bear to put the new cable modem (Motorola 6141) in her office, so I installed it next to the switch and plugged it into the same UPS.  I was disappointed, but not surprised, when this did not solve the problem either.  Still, 35 down beats 6 down.

 

Next I installed whole home surge protectors in both our main and sub panels.  Still not fixed.

 

A friend suggested that as the switch and all the home-runs are in the same space as our HVAC air handler, and as the problem happens when the HVAC system cycles on, that maybe it is and EMI issue. 

 

Any advice would be appreciated.

 

Jesse

Edited by Jesse

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ikon

I think a diagram of your LAN might be in order.

 

I'm also not completely clear on just which devices you had on UPS, at which times. Have you, for example, done a test where everything is on UPS at the same time. Have you done a test where everything is running on UPS (i.e. not connected to AC) while you force the HVAC to come on. If everything is running disconnected from AC, and the problem still exists, then it's not noise on the AC lines.

 

If your LAN cabling is done properly, EMI should not be an issue. Do you have a LAN tester, preferably something that does more than just a wire map check?

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schoondoggy

Are you losing connection to your home network or the internet?

Doe this happen every time the HVAC comes on?

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ikon

Good question. I took it, since he specifically mentioned DSL twice, to mean he means internet connectivity.

 

I also forget to ask another question: does this happen to every computer in the house, or just his wife's? It might be worthwhile to start up every computer in the house and start a continuous PING to a very reliable site (one that normally does not give timeouts) and cycle the HVAC -- see if any, and how many, of the computers show timeouts in the PINGs.

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KydDynoMyte

This might sound crazy, but you don't have a wireless or wifi enabled thermostat by chance? I do have a wireless audio/video transmitter that on one of it's few selectable channels will crash my wireless modem.

I should clarify, the wireless audio/video transmitter is 2.4ghz with its own receiver. It's not trying to connect to my network at all, but it will kill it requiring the router to be power cycled. I never let it sit long enough to see if it would correct itself.

Edited by KydDynoMyte

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ikon

I've had my microwave interfere with my wireless connections; basically, injecting noise into the air.

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schoondoggy

If it is the internet, I would disconnect the cable modem from the home network and connect a pc directly to the cable modem. If the problem goes away, it is your home network, if the problem remains it is an issue with the service.

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ikon

That's also a good test, but I would do it after trying the multi-computer PING test.

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FiLiNuX

I agree with Ikon on 2 points.  

 

1. He is correct that microwaves can REALLY jam up a wifi signal (I have done it intentionally and unintentionally :).  

 

2. You should Generate some traffic (ping as suggested or use a software net analyzer) and find out what equipment is troubled.  

 

As far as the problem goes I don't see this as a problem with the AC power / ups/ surge protectors  etc as none of the equipment cycles or locks up does it?  Could it be that one of the cables you ran has exposed wires in it and is in contact with something hooked to the HVAC?

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ikon

Yeah, possible cabling issues are why I asked if the OP has a proper cable tester.

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