Where do I put outdoor reset (besides outdoors)?

JeffGuy

My Alpine mod/con install is nearing the home stretch. Gas meter will be installed tomorrow. One remaining question before starting it up- where should the outdoor reset sensor be located?



Putting it right next to the vent/air inlet would be the easiest, but how far away should it be to avoid interference with the vent output?

furnacefigher15

North side

Ideally the sensor would be located on the north side of the building above the snow line.



If north is a no go, west is next best.

Tim McElwain

It should be on the

North side of the building away from sun and any other heat sources. It should be measuring actual outdoor temperature so anything that would affect that should be avoided.



When you run the wire from it avoid all other wires and voltage sources.

JeffGuy

It will be on the North - but where?

The North wall is also the wall that the Alpine is venting out of. Vents are seven feet high (went through a first floor closet), so that is where I would like to locate the sensor.



But how far away from the vents should I place the sensor?

Tim McElwain

As far away as you

can and still be on the North wall, that way there is no chance for interference.

JeffGuy

How far is that?

Thanks for the answers. But "as far away as possible" isn't realistic since I only have one closet that allows me to come out more than a foot above ground level.. How many feet away MUST it be?

furnacefigher15

3 feet from discharge

at least 3 feet if not more, but not directly below discharge as icicles may form

Rich_L

Where to locate

Put it near the intake and you'll be good. 6" away will work fine. The intake is dealing with the air at the temp you wish to sense, ambient outdoor temp. I've even seen installers, when having trouble getting the sensor wire outside, mount the sensor inside the intake line since it's pulling in outdoor air and not changing it's temp. I don't recommend this method if possible since it should accurately measure the temp when the boilers running but not necessarily when the boilers off.

Bob Vennerbeck

reset sensor near air intake COULD be problematic

Putting the outdoor reset sensor near or in the air intake could be problematic on SOME modcons - I have a Triangle Tube Prestige Excellence installed with 3" PVC inlet and exhaust - each a total of 6' with 2 each 90* elbows indoors, and recommended exterior T on exhaust, and 45* elbow down on intake, both with provided 'bird screens' - I observed gentle but noticeable warm air flow OUT of the intake on occasion, and after triple checking that the boiler cabinet was properly closed and tight, I finally sussed out that the integral potable tank in the cabinet, although well insulated, clearly looses some heat to the cabinet, and the intake is open to the cabinet - so when boiler is idle, air starts thermosiphoning both in and back out the fairly short unconstricted intake - I added a 90* elbow down, and a 18" vertical to provide a heat trap, and the thermosiphoning stopped. I still have 4' above snow line, and am monitoring performance - and would not make ANY such modifications to the recommended exhaust routing.



But I'm glad I put my outdoor sensor 6' away...



I don't know how many other modcon models pull intake air from inlet dumping into sealed cabinet, but even without the potable reservoir, I suspect they could be susceptible to similar air movements - the actual amount of heat lost might be minor, but you wouldn't want it to bugger up carefully calculated reset curves....



Vbob

JeffGuy

Thanks for help

I ended up finding a good location for the sensor; its a dozen or so feet from the intake and vents. Instead of using the closet as I originally intended, I put it several feet above a doorbell switch on an open back porch. I was able to use the doorbell wire plus a snake to pull my wire into position. That took almost as much time as connecting the boiler and circulators (I did my own electrical).



Man, it's nice to have heat!!!