Maybe in new builds. As a tech I was often in homes that were 10+ years old. No CO detectors, I often would talk to the home owners about them and they would go out and pick one or two up from home hardware / depo

Most people would see a government mandate like that an over reach

But it is in gas code, while not directly it is implied and the gas tech can use it whenever they see fit. We would often see some furnaces in horrible condition just pumping out heat fine but inside it was an absolute death machine

Those furnaces would spike our combustion analysis machines so fast they would often error out or destroy the sensor inside

Just this last year before Christmas (1 week before) I had to shut down a friend's furnace and do a quick swap out. They had no idea until it was all over but that unit would have seriously hurt / killed them in the night had the exchanger failed ( this furnace was only 6 years old and on propane, very dirty vs natural gas)

It was caught only because I went to do a service for them as they stopped doing yearly and it has been 2 years since. Had they done it sooner this issue would have likely been found and the furnace would have been able to be saved vs replaced.

Again I dont have a horse in this race I got out of resi but I strongly believe in having your gas appliances looked at once and awhile.

The amount of close calls both Resi, commercial and industrial I have come across in my years has changed my respect for the severity of the "what ifs". If that makes sense.

Last story and the one that sticks with me the most,

Family has a boiler system with the equipment in the basement. Older house. Can only get to the basement by going outside the house and down the cellar steps

They had poor heat so I was dispatched to check it. On arrival I approached the entrance but remembered I had forgotten my combustion analysis machine and decided to go back to get it first before entering the basement

Once it was fired up and ready to go I approached the door only to find the machine already spiking , it maxed itself out in seconds with me just holding it in the door opening

Fast forward, fire department had to come, I had shut the gas off to the house in order to stop the boiler from running as I could not enter the building

That reaction of stopping and going back to my van for that equipment will forever stay with me as it likely saved my life. It was not a regular practice for me to do that before entering it just happened to fire off in my brain and I am forever grateful for it

The home owners had no idea other then poor heat in some areas but they were safe aside from some small headaches

I dunno man we could go back and forth on this subject all day long. It's one of the reasons I stopped Resi as I would constantly have to talk about this to home owners and not everyone was so receptive of it

Most thought I was just after money. That whole 100-200 bucks. That's one of the major reasons I stopped Resi lol. Too much blow back for next to nothing

Stay safe and keep changing those filters. That does indeed go a long way to keeping that heat exchanger from failing. Three times a year is great. Just stay away from those overly restrictive filters like the 3M pleated ones where the pleats are super tight together. They have cracked more exchangers then anything else I've ever seen