What is going on in Tulum

Oh I see you're talking about heaters that maintain a permanent storage of hot water at a certain temperature. Those are quite old fashioned with "hot water on demand" heaters being the popular choice.

LOL, you have made some very funny/odd comments over the years.
No need to switch hot water tanks on and off. In fact that is not advised.

When living in Europe I really disliked having ice cold water to wash my hands, for example, in a restaurant. All the children in the school were forced to wash their hands in ice water, too, seemed extremely un-hygienic. Or having to turn on a water heater before I could do the dishes. It just seemed like it was the turn of the century over there, a 100 years ago.

Can't imagine the sort of places you picked to live in, were you on a very low budget ?. Here in Europe the hot water on demand heaters have been the norm for as long as I can remember. Known as combi-boilers they also heat the central-heating radiators in the Winter months. They are never switched off but obviously only heat water when you turn the tap on. Don't personally see what is funny about that but no accounting for taste. If you are asleep and not using hot water clearly there is no risk of carbon monoxide poisoning.

But there have been several recalls of tankless hot water heaters because of the risk of carbon monoxide poisoning.

Here in Europe the hot water on demand heaters have been the norm for as long as I can remember.

My family in Ireland have used on-demand electric water heaters for a very long time now.

LW

The few times I've read about tourist carbon monoxide poisoning, it's been the fitting of the appliances that has been found to be at fault rather than the appliances themselves.

The few times I've read about tourist carbon monoxide poisoning, it's been the fitting of the appliances that has been found to be at fault rather than the appliances themselves.

If you look at the photos I linked @14, above, you'll see one of the hot water heater ... and what appears to be it's worn condition ("fittings").

LW

A combi boiler is not what I call an on demand hot water system. Yes, our house had that oil fired boiler over there (it was a new modern house) and I found it very strange to have to keep the heat turned on in the summer in order to have hot water. It was really weird, but I was told that was the only way to have the water warm, unless I wanted to turn the electic immersion heater on and remember to turn it off again (water would get to a unsafe temperature). Schools and restaurants just didn't have warm water at all in the washrooms and in the cold weather (which was most of the time) it was painful to wash hands.

The on demand tankless hot water systems are completely different.
They only supply hot water for a very small area, so are not feasible for the typical sized houses in Canada, as you would have to have 4 or more of them and they are too expensive.

I see that retailers are selling portable CO detectors online for as little as 33 CAD.

Update:

TULUM, Mexico — The Iowa family who died during their spring break vacation here was asphyxiated by gas from a faulty water heater that had rusted in the humid Caribbean climate, Mexican police told the Des Moines Register. ... The initial autopsies, conducted in nearby Playa del Carmen, show the four Iowans died of asphyxiation from propane inhalation ...

Source:

https://www.desmoinesregister.com/story/news/investigations/2018/04/04/creston-iowa-sharp-family-dead-mexico-water-heater-gas-asphyxiation/486239002/

LW

I found this statement interesting: "When police took apart the water heater, they discovered rust had corrupted the device, a common problem for appliances in this part of the Caribbean, police said." (bold added)

It also raises the question of whether a noxious smell was added to the propane (or not), and whether the closed windows (a/c) added to the risk of asphyxiation.