can't figure correct resistance for teflon coated copper wire

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I didn't have much luck with Biddeford either. I tried one of their heated mattress pads. It didn't last a season. Hopefully, you'll have better luck with their blankets.

I never did go with the nichrome wire. I have some, but used it three years ago to make some telescope dew heaters. The idea was to wrap the front of the telescope with nichrome embedded in a fabric with just enough wattage to keep dew away. Works great at 5 to 10 watts. For that I believe I crimped it to the supply wires. When I started on the blanket, there was no way I was going to try using nichrome for something that large and went with some 22 ga Teflon coated wire I had around for years. So far, it has been working out well. I can get up to 80 watts, but I will mostly be running at half that or a little over as there's much less heating to deal with. Today, the dimmer arrived and I tried out a jacket I also wired. It too reaches 80 watts but again I will only need about 50. 80 watts seems a bit too much even in a cold house.

Initially, to hold the Teflon wiring in place, I used hot glue. However, when 80 watts passed through, some of it began to not only outgas but melt so I removed all of it and went with nylon ties. I first tested the nylon and a bit of blanket fabric by heating in the oven at 90 C for several hours and both came out fine. I was a bit concerned as nylon seems advertised to hold well up to like 85 C, but I don't see any issues.

Only other issue was temperature. The longer the blanket is on at the max, the warmer it slowly creeps up. So, I have to either run it at less power, which I will normally do, or have a duty cycle using a timer. I have since incorporated a timer for when it gets colder in here. I'm going to try for a 33% time on and 2/3 time off and see how it goes. Someone has suggested a thermostat, but not sure how other than maybe using a probe attached to the blanket wires and then a relay turns the blanket on and off as needed.

Sunbeam blankets don't flat out quit, they slowly get colder over time. No t sure why that is. It's like they're programmed to do so. Too bad because their controllers are great. I switched to their mattress pads and they g et inert over two or three seasons. Looking for another option right now.

Exactly right, don't just quit but lose warmth over time. Out of the three Sunbeam blankets I owned and two heated throws, they all did this. This was my main inspiration for my DIY revamping. There's actually a fair amount of online info on the Sunbeams if you do a patent number search. A circuit block will come up along with at least one schematic. I thought the culprit might have been a small SMD voltage sampling transistor inside the little box where the cord plugs into the blanket, but replaced that and still no heating. I also swapped out controllers for a different one to no avail. So, that left the blanket itself. I suspect the changing of wire resistance from repeated heating is what does it and of course there's no solution without either a revamping as I have done, or a new blanket.

Patent numbers show that someone definitely designed their latest circuitry. IMHO, probably due to lawsuits and other worries from the past, it was overdesigned and thus now stops working after short order. There is no easy solution unless one wants to try other brands and take a chance that you might come across one that actually keeps working.

I don't get it. We purchased two Sunbeam extra-large heating pads with five (5) year warranties. One failed in short order and was replaced in short o rder. The other is going strong after four (4) years. We purchased through Amazon so there would be no nonsense with losing receipts. From what has be en discussed here, they seem to fail on an hourly basis and no one invokes the warranty??

Peter Wieck Melrose Park, PA

Three of my Sunbeam blankets failed within the five year warranty period. I returned and exchanged each for replacements direct from Sunbeam. However, the big catch is with the shipping. Even with blankets that fail, Sunbeam does not pay shipping cost to ship the defective blanket to them, and when paying $15 for insured shipping, this almost defeats the entire process when the blankets were purchased on sale for around $20 to $25. Besides, by the third time, Sunbeam had become far less responsive and I had to contact them a lot more to get them moving on the final blanket. And, yes, they were strict about receipts, blanket tags, and such so don't forget anything and keep copies of all.

Why all this and not have a blanket that simply works? Not for a single season, but for years like they once had. Beats me.

It is, unfortunately, "the race to the bottom". Price and features drive sales; long-term reliability does not.

Sunbeam (and most other brands) thus have an incentive to "buy cheap", from companies which are skilled at building stuff which will last _just_ long enough. They count on most of the devices being out of warranty by the time they fail, and on most consumers being unwilling to go to the trouble and expense of keeping receipts and asserting their warranty rights. That way, they get to sell you cheap things every couple years, and collect a small profit each time, rather than sell you something once every 10 years for only a slightly higher profit.

Sadly, it shows the truth of an old rule of thumb. "When somebody asks 'Why X, it doesn't seem to make sense', the answer is most probably 'Money'."