When did pressure relief valves become standard?

From what I had read years ago, they began use in the early nineteen hundreds after many boiler explosions. Steam ships and railroad engines were some of the first warning signs when explosions had occurred on those boilers. The use started there, and was adapted on home steam boilers sometime around that time.

That's for hot-water boilers. Steam boilers have required LWCOs for decades, almost as long as they've been made. ISTR they came out not long after oil burners for home use became available.

I think I've only seen two coal-converted steam boilers that didn't have LWCOs. One had dry-fired and cracked; I put a #67 on the other.

James Watts…first relief valve I believe. Mad Dog

Steam boilers naturally lose some amount of water and will heat possibly even after the water level is dangerously low. Steam boilers generally aren't controlled on temp so there would be nothing to stop the burner as it keeps getting hotter.

Hot water boilers don't lose water unless there is a leak and will usually stop heating because they are air bound long before they dry fire although it certainly is still possible in a few ways. Usually the aquastat will cut the burner long before they dry fire as well. I think most dry fires of hot water boilers are burner controls that get stuck on, either gas valves getting stuck open or relays on oil burners welding shut.

Ok..wrong saints name... Joseph Watts 1874 in Massachusetts..mad Dog

That can't be right, @ChrisJ ! That dude isn't even American!

What year did Hartford Insurance debut their little piping contraption? The LWCO must've been after that, right? Not sure about the relief valve, but I'm glad someone thought of it. I've seen video of a Fulton 100 psi boiler go off like a rocket.

I've got a great idea....Do a scholarly paper on it...after your other basement "experiments" are published in ASHRAE & ASME journals as the new industry standards. Mad Dog

Something wrong with being American?

There was a time, not too long ago when codes and even common sense were considered suggestions rather than law. What you chose to put in your own boiler room was between you and maybe your insurer. I've seen plenty of 1930 and 1940 installations with no more than a check valve in their returns. Some had just a solder plug to douse the fire if pressure or temperature went amiss…

I’m just saying we all know that non-American fittings, fixtures, materials, tools, and inventions are junk, as I’ve seen written here innumerable times, so I’m a little shocked and disturbed that such an important invention came from “over there”

Don't know why you'd say that. Some of the inspectors don't allow Chinese fittings,and my insurer woun't allow us to use Chinese tools, unless they're listed, but other countries manufacture many good products and appliances. America's stuff is pretty good too, if you can afford it. There's a market for cheap junk among amateurs, but most of them don't put high value on their time or pay workmens' comp.

Although it is sort of hard to tell through the asbestos, there have been some converted boilers posted here that looked like they didn't have a relief valve. Some of them were likely hot water boilers that had open expansion tanks.

Hi, About domestic water heaters, I believe it was around 1960 that it became code in the US to install T&Ps on tanks. Watts filmed "Explosion Danger Lurks" in 1942 to try and convince code people to require relief valves. It's an interesting film 🤠

Yours, Larry

Hi, Ruud made the autohot. It was the first automatic tank heater I know of. It had a light brown top and tan sides. Mine had a copper tank and was made around 1925. I did find this: https://inspectapedia.com/plumbing/Fowler-Water-Heater-Age-Manuals.php about Republic. All of my water heater files now live at the General Society… and they like it there! 😽

Yours, Larry

I recall seeing that film at a trade show in the early 80's. They also had another showing 80-100 gallon tank explosion in a school house. There was a T+P installed, but the temp sensor was cut off so the valve would fit into a 90 ell.

In the 80's and maybe early 90's I would get water heaters WO T&P's. That was the industry standard. You had to buy one as an extra cost. Eventually every WH came with a valve installed.

I recall seeing electric WH's with pressure relief only. I think they relied upon the upper T-stat with the ECO as the temp safety. Saved what? maybe 2 bucks with the pressure valve only.

Then at the trade show after the films a company rep said that he was asked that "do we still have to install these T&Ps anymore as there haven't been any explosions from WHs for the last few years" Duh??