Running thermostat in bunde of 120v?

Ironlight · 01-10-2012, 02:17 PM

I'm cleaning up my unfinished basement ceiling and one target is the ancient thermostat wire that meanders drunkenly from joist to joist from the front of the house to the boiler back near the rear. I ran a bunch of new home runs to my circuit panel when I did my kitchen renovation which are neatly bundled and follow 90% of the same path, and ideally I'd like to run the thermostat wire in that bundle or close to it for neatness sake. Are there any potential electrical interference issues that would render this a Bad Idea?

Thanks in advance.

biggles · 01-10-2012, 02:29 PM

might make a wierd field along the lenght that stat run and disrupt the 24Vs. putting the 24V line in scrap lenght of empty BX won't hurt

harleyrider · 01-10-2012, 02:30 PM

Quote:

Originally Posted by Ironlight

I'm cleaning up my unfinished basement ceiling and one target is the ancient thermostat wire that meanders drunkenly from joist to joist from the front of the house to the boiler back near the rear. I ran a bunch of new home runs to my circuit panel when I did my kitchen renovation which are neatly bundled and follow 90% of the same path, and ideally I'd like to run the thermostat wire in that bundle or close to it for neatness sake. Are there any potential electrical interference issues that would render this a Bad Idea?

Thanks in advance.

Its not recommended, but if you use a shielded wire, it will be OK.

yuri · 01-10-2012, 02:48 PM

run a new 18/3 or 18/4 LVT wire from HDepot and then you can use a programmable thermostat w/o batteries dying and needing changing. keep it a few inches away and you should be okay. I see it strapped to 120 volt BX cable dropping to the older furnaces all the time and nothing happens BUT the newer furnaces and boilers and circuit boards don't like any interference. What brand and model of boiler is it? If it is an antique millivolt conversion gas burner then 2 wires is all you will need.

Ironlight · 01-10-2012, 04:19 PM

Yuri it's a Carrier PWB-5D, a couple of years old. The thermostat is a programmable Honeywell that I installed a few months ago and it's working well. The wire between them is ancient, as I stated, and only two wires.

So the Honeywell can pull power from the furnace if I run the right wire? Cool. I'll have to figure that out

And I can find another route for the wire that does not run with with the 120v.

yuri · 01-10-2012, 04:28 PM

If the tstat has a C terminal / not their el cheapo model then yes a 3rd wire can go to it and C on the terminal board of the boiler or C on the transformer and run off the 24v supply.