Wicked old two pipe, no traps

Jamie Hall

Well you are quite correct to the limited applicability of the analogy between cars and boilers, at least in residential sizes (power boilers are, in almost all cases, fully adjustable between no net output and full song). The analogy with the World War I aircraft with all or nothing engines is much more exact (and they are a blast to fly, once you get the hang of blipping the ignition -- I have!). Old timer gasoline engines from the same era worked the same way -- the governor allowed fuel and spark only often enough to keep the average rpm constant over a very wide range of loads.

Interestingly, both of those applications above had very large flywheels -- rotating inertia -- in comparison to the total power output, so could be remarkably smooth in operation. In small boilers one gets exactly the same effect from a boiler with a large thermal inertia (the metal of the boiler plus the water), so the output is also remarkably even over time. This is not true either of engines in the one case with small (relatively speaking) flywheels -- which may stop under load in only one or two revolutions -- or boilers with low thermal inertia (think a typical mod/con which one man can pick up and move).

So, as I agreed, cars are not a very good analogy -- but better than nothing, sometimes. And you are certainly correct that driving a significantly overpowered car (I had one once) with on/off throttle, while it can be done with finesse and skill, is difficult. For what it's worth, I also had a 1955 VW beetle convertible for a while, too -- and while it was a lot of fun (and occasionally a handful -- oversteered badly) on back roads, it was a hazard both to me and all those around me on a freeway. Yes it could go all day at full throttle -- but tootling up a hill on the Mass. Turnpike at 30, wide open, in the breakdown lane to avoid being squashed by an errant semi was not much fun.

Voyager

Yes, adding substantial energy storage to a system, either mechanical via a flywheel or thermally, helps tremendously, but at the cost of efficiency and system responsiveness. Much better are computer controlled power sources that can be set to exactly match the power demands, but that adds cost.

I’ve never flown an airplane with the ignition based power control, but it probably is a lot of fun, but a lot of work. Wouldn’t want to have to fly an ILS that way.

I always had a chuckle when reading my VW Beetle owner’s manual as they listed:
Top speed: 81 MPH (or the km/h equivalent)
Cruise speed: 81 MPH

Jamie Hall

No, flying an ILS with a blip throttle would not be much fun... even if you had a canopy.... I'll take autothrottles any day of the week! When they work, that is...

My sister who lived in Texas had a VW campervan for a while. They used to drive from Houston to Big Bend to camp -- a bit of a trip -- and most of the trip was with wide open throttle all the way. The thing never missed a beat.

REDD

"Danger Signs" with asbestos flaked off onto the floor? Maybe best left alone until it becomes unrepairable?

delcrossv

mattmia2 said:

Here is the original moline brochure:
https://heatinghelp.com/assets/documents/27.pdf

The building at Malden and Wilson in Chicago shown in the brochure is still there- couple of blocks from my MIL's. Picture doesn't show it was done in yellow brick. That was a ritzy neighborhood back in the 'teens of the last century.