Double Hung Window Sensors

I have Pella, all wood, double hung windows and I am doing pre-wire. What is the preferred contact for these and where on the window? If anyone could supply a pic, I'd appreciate it as well.

Pella is a very hard one to narrow down, they tend to change window designs and like almost every couple of years.

If warranty is not a concern, 3/8" recessed contacts and rare earth donut mags would be my suggestion.


Typically the choice of contact comes down to wire routing path and asthetics, balanced with any window warranty concerns, as most manufacturers will void a warranty on a window if the window is modified from "factory". Some will only void the warranty on the affected component (ie: sill) while others would void the entire unit. If you're going to ask Pella, I would ask about using small screws to mount a magnet on the sash and if that is going to affect coverage on the thermal seal/sash. I wouldn't worry too much about the sill, provided you drill "inside" of the weatherstripping.

I used Honeywell 944T contacts that I think you recommended, DEL! Mine are all-wood, double-hung windows installed in new construction and these worked well. I ran 22/4 wire (only used two of the four on these) to both top and bottom sashes, daisy-chaining groups of windows (e.g., both windows in the office) onto single circuits. I drilled "inside" the weatherstripping as well. The fit of the contact in the 3/8" hole is quite tight so I'm comfortable that once painted I won't have any leaking issues.

I was a little nervous drilling in the sash toward the glass, but with some caution I didn't have any problems.

I took a bunch of pictures with the intention of putting together a retrospective when I'm done, which should be the end of January if all goes well.

I took a slightly different approach. I didn't want to drill my windows. I used the larger, wide-gap bar-magnet style sensors (I forget which one exactly, but I can look it up) designed to span longer distances (~1.5-2", I believe). I put the sensor bar underneath the bottom sill. I then super-glued the magnet bar underneath the bottom sash.

I'm not 100% sure, but this may have been the sensor I used: http://www.mcmelectronics.com/product/82-3322&utm_source=ExactTarget&utm_medium=email&utm_campaign=ConfirmEmail

I took same approach than tadr. It is too much of a risk drilling new windows. Pella windows have different styles. They have builder grade and the Architect series. The Architect have a deeper sash to allow for recessing. The builder series are super shallow and it would be a huge risk drilling those. Second problem is that with were you locate them. To do it right you need two magnets, one for each sash. But most thieves would just move the bottom sash, triggering the alarm.

Securitystore has tiny little magnets that are about 1/8" thick and a hole in the middle to take a screw. Good option for new windows with shallow sashes.

tadr, when you say you put the sensor bar underneath the bottom sill, are you saying that the sensor is buried in the wall? Is the sensor sensing through the window sill? What material is the sill made of?

I am looking at building a house in a year, and I know I too will face this issue.

rockinarmadillo said:

tadr, when you say you put the sensor bar underneath the bottom sill, are you saying that the sensor is buried in the wall? Is the sensor sensing through the window sill? What material is the sill made of?

I am looking at building a house in a year, and I know I too will face this issue.

Click to expand...

The sensor is buried behind the casing, yes. If something went wrong with the sensor, I would have to pull off the window casing (which is a less than ideal compromise, but one I was willing to make).

Yes, the extra-wide gap sensor allows it to work through the window sill. The sill is wood and fibrex cladding. The windows are Andersen Woodwright 400. I don't know if this would work with other windows -- I went to a store that stocked the same type of windows ahead of time to test it out.

I have attached an annotated diagram of the cross section of my window that will hopefully be helpful to you and others. The distance between the sensor and magnet ultimately depends on the angle of your sill - mine isn't quite as steep as what's shown in this diagram, but you get the idea.

[sharedmedia=gallery:images:520]

The picture makes it very clear. A very innovative approach. Thank you for sharing this!

I have been reading on some home inspection sites about the problems that water encroachment through security sensors can cause. This solves the problem without drilling holes. Good idea.

tadr said:

I took a slightly different approach. I didn't want to drill my windows. I used the larger, wide-gap bar-magnet style sensors (I forget which one exactly, but I can look it up) designed to span longer distances (~1.5-2", I believe). I put the sensor bar underneath the bottom sill. I then super-glued the magnet bar underneath the bottom sash.

I'm not 100% sure, but this may have been the sensor I used: http://www.mcmelectr...gn=ConfirmEmail

Click to expand...

Can't see your pictures, but casement window?

Part of the "trick of the trade" for Andersen's for years.

DELInstallations said:

Pella is a very hard one to narrow down, they tend to change window designs and like almost every couple of years.

If warranty is not a concern, 3/8" recessed contacts and rare earth donut mags would be my suggestion.

Click to expand...

Can you provide a model # or link for those rare earth donut magnets? How deep are they?

ETA: nevermind, I see honeywell (ademco) offers a model with the magnet included.

Do you glue this in or is it snug it will not fall out? I like this idea alot.

You need to consider how much space the bottom of the window has and how it closes to determine if the rare earth mags need to be recessed/flush with the bottom of the sash or if surface mounting is acceptable and doesn't cause issues with the window closing and latching. Typically, they're held in with either screws or silicone instead of the double sided tape that come with them, which really is only suitable to hold them until silicone dries.

The thickness of them is typically about 1/8" but you should always check your manufacturer's dimensions if you're in doubt.