I switched off the washer about a half hour ago. The beep just happened as I was writing this.

Isn't the drama.... mildly irritating?

You'll prolly have to burn the house.

Sump or septic alarm?

Nope, no sump, and if there was an alarm for the septic it should have burnt out by now.

Keep the ideas comin'!

With my smoke detectors, it may initially be 10-15 minutes between "chirps" indicating a low battery. It can be a nuisance waiting for the next chirp to tell which detector it is; so, I twist them off their base mountings as I would to change the battery and I put them all next to me for awhile, some to my left and others to my right until one of them chirps again. If it continues to do the same with a fresh battery, the life of the unit's sensor is probably up and the detector needs to be replaced. Battery backup units beep intermittently when the electricity is out; but, some will also beep when their rechargeable battery is no longer holding a sufficient charge and needs to be replaced. If you have something like an APC battery backup for your cable modem and Wi-Fi router and those are in another part of the house, you might check that too.

I have ruled out two smoke detectors. I have also ruled out the entry room.

This time I made a note of when the beeps occurred

6:17

6:32

6:47

Aha. At 7:02 I hope to have another data point.

I have ruled out upstairs.

I have ruled out the tablet.

Hearing aid?

I have spent an entire weekend ruling out alarms as a beep resounded through the house every 120 seconds. I disconnected every smoke and CO alarm and the beeps continued. In the end it was a fading rechargeable battery, as sexobon suggests.

My sympathy.

Suspicions have moved to the UPS right under my feet

Ruled out. Now under suspicion is the smoke detector that was right above my head and I didn't notice it.

That's ruled out and the beep came a minute early this time.

FOUND IT. Verizon FIOS battery.

It's $50 to replace this battery. Now you have to understand what the battery is for, because this is part of this. I'm mildly annoyed, so YOU will be mildly annoyed.

In the olden days, the phone company had batteries in their central offices which would provide voltage to your phone. If your phone could ring, it had power coming to it.

But if you have FIOS coming to your house, it's fiber. It's not copper. It doesn't conduct electricity. It only carries data.

Lucky your voice can be converted to data, and it only takes a fraction of a percentage of a high speed FIOS connection to transmit the voice part. So that's what they do now, they do the conversion in a box somewhere in your house.

However this means that your old phones will no longer work, because they don't get power from the central office. The solution: put a battery in your house to provide power to your phones.

Sneakily the phone company puts a 1 year warranty on these batteries and so you will eventually have to pay that $50 for voltage these assholes used to provide gratis.

Now me, I ordered phone service and never used it, so I will cancel my phone service and remove the need for this battery. But I'll bet they won't come out to remove it. No, that would be a service call. It's too much.

I have found a youtube procedure for disconnecting the battery temporarily, and this is supposed to stop the beep for about a month.

Something just beeped in my kitchen while I was cooking. I blame you, Undertoad.