Need Help Whitening / Wiring Yellowed Detector

I recently go a BRK 2824TH smoke detector and need help whitening it, as the yellow doesn’t look good.

I would also like to wire the detector up. Help with that would be also appreciated. Thanks!

The yellowing is caused by a chemical change within the plastic due to sunlight exposure. This makes it very difficult to remove. You can try disassembling the detector and soaking the housing in a 1:1 Bleach/Water mixture, but this can cause the plastic to become brittle.

The wiring diagram can be found on page 3 of this manual: System Sensor | Honeywell Building Technologies. You can ignore the markings for the “Class A Return Loop,” this would only be wired up if you were installing the detector on a Class A system.

My detector is a thermal unit as well. Do they have a ring around the center of the metal button for that or not?

I would just spray paint the thing. Get some matte finish (not glossy) spray paint, take the guts out, and lightly go over it. Obviously you wouldn’t want to do that on a real system, but for what you’re using it for, it’s not going to matter. Just don’t go crazy with it and it will look decent. Also, if you want a test card I might have some lying around. Let me know.

Before I go through all that work, is the detector missing the thermal ring… thingy, or does it not come with one?

Also, thanks for the D.S., Nick.

I’m going to say no. Look at the picture in this cut sheet:

If I read the data sheet that Nick linked correctly, then contacts 1 (+) and 4 (-) would be for the supply voltage, and contacts 9 and 10 would be used like a pull station?

Also, Lambda, I would like the test card, please.

It isn’t missing anything. That’s how it’s supposed to look.

Exactly. 9 & 10 are just dry contacts, they close on alarm. To hook it up right you should utilize an end of line relay as shown in the wiring diagram to cause an open on the circuit when power is loss to the detector.

I’ll let you know when I find them, haven’t used them in years but I’m sure I’ve got a couple around here somewhere!

Can you get a better illustration for the relay? The image has a low resolution, and is kinda hard to decipher.

Here’s a better wiring diagram I found on the internet showing the end of line relay wired to a 4-wire smoke

The idea is that if you lose 24V power (either the power supply dies or wire gets disconnected) the zone will go into trouble because the end of line resistor will be disconnected from the circuit. At the same time, the zone circuit could still send an alarm from any device because the relay opens the circuit is at the end.

You need to use a Hydrogen Peroxide Solution.

Also, the end of line relay doesn’t have to be physically at the end of the circuit. You could wire the zone normally and at the last device return the wire back to the panel, and place the end of line relay inside the panel. The 4-wire smoke detectors in my house are wired this way. The end of line relay and resistor are inside the panel. I did this a little differently, I’m using a DPDT relay (when all you really need is a SPST relay) but it still accomplishes the same thing. The red and black wires are 12V power, the yellow and green are the zone.

Do I need a panel to wire, or will just having a key switch to cut power suffice?

If you have no “panel” any 24vdc source will work to power the detectors. To reset, power cycle the power supply.

Does the little white tab that goes in the smaller slot across from the test slot serve any purpose?

I don’t remember. It’s been years since I’ve seen one in the wild to notice.