Any window manufacturer that I've ever contacted doesn't have any problem with adding contacts to a windows as long as the integrity of the window is maintained, and that usually means don't mess with the weather stripping.
If you really want to be sure, call the manufacturer.
One problem with vinyl windows is seating a recessed magnet. Most vinyl windows have too narrow a space at the bottom of the sash. Certainteed's "Devon" line is an exception. There's a hollow chamber in the bottom rail deep enough to fit a "stubby" magnet. Unfortunately, the upper rail's chamber is too short for a recessed magnet. Even a stubby model probably won't fit.
Better yet, there's a recessed space deep enough to cement a "rare earth" magnet in place without even drilling the sash. That approach minimizes warranty concerns. The space is on both the upper and lower rails.
Certainteed replacement windows come with vinyl frames which fit into the pre-existing window opening. The frames have a hollow space which is deep enough to fit the recessed magnetic switch. Sometimes the switch can work loose if it's not seated in something thicker than the vinyl frame. To prevent this, smooth a tiny dab of RTV (silicone caulk) around the switch before seating it in the hole. This will also prevent water seepage, though most such window frames have weep holes to allow any water that does get in to run out.
Note that Certainteed's warranty does provide an out for them if they believe your work has contributed to any damage. They state, "CertainTeed shall have no liability under this warranty for: A. Defects or failure caused by improper handling or storage or by installation not in strict adherence with CertainTeed's written instructions." That would certainly include damage caused by drilling the sash since they make no mention of it in their installation instructions.
will make much difference but I will look into the
You're most welcome. Looking at the brochure on the Bryn Mr II, it appears you have enough room to fit a rare earth magnet on the bottom. I can't tell for sure about the top rail though because the image isn't clear enough. If you send me your address I'll mail you a couple of sample magnets. Try it out -- CAREFULLY -- and if both sashes will close without being forced you're in business.
Thanks for the offer. I already have some of the rare earths. That is not a problem. My challenge is that the customer is 55 miles away and need to make one trip. I have to go there after the windows are installed minus the trim and be loaded for all possibilities. My biggest fear is that the contractor will rip the wires out and cause me major grief.
No problem. I suspect you'll be ok on this, Les. Given the round trip distance involved, I'd call Certainteed and get exact dimensions. They might even fax you a schematic if you ask. Her'e's their number. 800-233-8990.
Damage from other tradesmen is always an issue. If the home already belongs to your customer, you're in a better position to deal with it though. In future consider including in your agreement a statement that the customer is liable for any additional, labor, materials, etc., required to complete the job should anyone not working for you damage your work. This works especially well if you have the client agree to notify you when your work can be done -- that is, when he expects the framing and other rough-n work to be completed but before the insuilation goes in. This puts the onus of choosing the right timing on the clint and since it's his project that is a unreasonable burden.
I've prewired countless homes over the years and though the insulators can occasionally cause problems I've found that by doing my work the day before they arrive I avoid a lot of cut wires. I got out of it six+ years ago when I sold the installing company. Now I just do online sales to DIYers. Though I enjoyed it for many years, I don't miss it. Selling online and by phone is fun and it gives me the freedom to do a lot of things with my family that I never could before.
BTW, the worst prewire I ever had to work on actually was a free job I did for my sister. She was building a new home and I prewired her security system for her. It was a long drive from my home so I took a weekend off to prewire and test everything, including installing the switches (I always preferred doing that during the prewire). After checking everything I left.
A few weeks later I came back to finish up and nothing worked. I pulled out one recessed contact after another and found every wire had been cut and, worse, the service loops had been cut off. I had to retrofit the whole system. It turned out that her next door neighbor was PO'd because the builder had sold the lot to my sister rather than him. He wanted to keep it vacant because the new home would block his view! He apparently got into some trouble for vandalizing the property, taking construction materials or some such thing. I had known he was a problem neighbor but it never occured to me how much of one. The weird thing is this was an educated guy, en electrical engineer.