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Comment by MrBuddyCasino | Hacker News Reader

Isn't there a temperature sensor that will shut down gas supply if heat stops?

While it could be problematic for a stove blowing out, it's slightly worse. If in your home, the most readily available airflow is through the exhaust vent of your gas water heater or HVAC unit and either are running it's possible for the whole house fan to pull the exhaust (carbon monoxide) into the house. This is why it's very important to consider where a whole house fan is placed as well as ensuring there's enough incoming air through an open window or vent. Ours will do this if we don't open a window. For an abundance of caution, I have a CO detector in the HVAC closet as well as one's elsewhere in the house.

This is true for gas heaters (actually it's usually a physical valve that opens on thermal expansion, not a sensor). This prevents a blown pilot from being a safety concern, but it's a pain to manually relight them.

I know of no gas stove that has such a feature, though.

The gas safety valves I've read about aren't physical, but are actually electric. They use a thermocouple to power an electromagnet in the (sprung) safety valve.

Presumably this allows the safety valve to be located further away from the heat source reducing the risk of thermally-induced failure modes.

Gas water heaters have this, as do older gas furnaces (any newer furnaces will have electronic ignition not a standing pilot).

For kitchen stoves, most have electronic ignition as well. For an older stove, the amount of gas released from an unlit pilot is not significant enough to pose a danger.

The issue isn't pilot lights for the oven itself; it's the stovetop. Most of the ones I've seen have individual electric lighters for each burner, which must be semi-manually activated (by turning the knob past "maximum" to a "light" setting until it catches). If you turn it to on without lighting it, or turn it off enough to put out the fire but not enough to completely cut off gas flow, you'll get a constant gas leak.

I'm in the UK and I'm pretty sure every gas stove I've ever used has had this feature.

The exception being camping stoves which I think may not have had it.

Our brand new, 2017 kitchen stove will happily dump unlit natural gas into the air without automatic shut-off, as far as I can tell. I've never had a burner go completely out during use, however. The highest area, lowest flow setting burner will flicker a bit when the oven heating element kicks on, but that's it.

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