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Firing rate and turndown

Trying to wrap my head around "turndown" and "firing rates."
I think I understand that a 5:1 turndown ratio means that a boiler's burner can run at 20% when the demand is low. Any lower than that and the burner will then cycle off.
However, when the burner is running at 20%, does it mean that the actual flame is lowered or does it mean that it will cycle on and off to maintain a lowered amount of input throughout a given time lapse. If that is the case, is that what firing rate means?
This is where I am confused. What exactly is the difference between firing rate and turndown?
Thank you all for your help!
I think I understand that a 5:1 turndown ratio means that a boiler's burner can run at 20% when the demand is low. Any lower than that and the burner will then cycle off.
However, when the burner is running at 20%, does it mean that the actual flame is lowered or does it mean that it will cycle on and off to maintain a lowered amount of input throughout a given time lapse. If that is the case, is that what firing rate means?
This is where I am confused. What exactly is the difference between firing rate and turndown?
Thank you all for your help!
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Comments
Turndown is manipulating that firing rate to a lower rate based on the need of the system to meet the building's heat loss.
PHC News Columnist
Minnich Hydronic Consulting & Design, LLC
https://heatinghelp.com/find-a-contractor/detail/minnich-hydronic-consulting-and-design
So will the burner have the ability to adjust its flame?
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
Every work on a Quadrajet carburetor? Never mind an SU?
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
As far as boiler turndown controls go...do any of the mod/con manufacturers utilize an oxygen (lambda) sensor for fine tuning the mixture? It seems like it would be the optimum application for overall control of combustion.
But maybe I'm wrong, too...as I said, I'm more knowledgeable on bimmers than boilers.
Police & Fire Equipment Lead Mechanic, NW WI
Lover of Old Homes & Gravity Hot Water Systems
Qjets are easy if you follow the rules.
Same as installing boilers.
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
Also glad to hear veissmann is doing that with lambda sensors...I'm kind of surprised that everyone isn't, considering the control ability and fine-tuning possibilities. If we're going to have so much complexity in modern boilers anyway (relative to a conventional cast iron unit), might as well take that extra step.
Police & Fire Equipment Lead Mechanic, NW WI
Lover of Old Homes & Gravity Hot Water Systems
Basically, a one size fits all.
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
Currently it has a Edelbrock Thunder and I'll probably go back to the quad.
The big problem with quads is the lead seals in the bottom go and leak gas into the engine, you have to clean them up and epoxy them on a rebuild.
They only made 6 Ram Air convertibles in 67 and none survive so I made a tribute, it's as accurate as I could get down to the cam and the ram air package, so be careful if you see one advertised for sale, even Hemmings lists them in value sheets but they do not exist, PHS confirms it.
The real joke of the day was the hp claims, way under because GM had a 1hp per 10lb rule and if you check your cars weight you'll find the hp was similar, hmmm, now let's look at the Ram Air II, 400, 10.75-1 comp, 320 510 lift cam, 366 hp??? with the standard 400 at 360??? there's no way.
Ram Air IV was the same engine with 1.65 lifters, I & III are basically the same with the inlet valve difference, the II & IV were pretty radical, wouldn't idle below 1000, they were 2500rpm and up motors, a lot of people that got the IV switched the rockers back 1.5, it was just too radical. My buddy had a 69 Camaro 427 Motion that was wild, one scary car.
http://www.musclecarfilms.com/1969_Firebird_Ram_Air_setups.html
The nailhead was an interesting engine -- it didn't get no respect, as Rodney used to say. Mine was officially rated at 325 horsepower (there's your 10 to 1 rule!). I never did put it on a dynamometer, but there's no way that number was right. It also had buckets of torque -- which led to the other oddity on those Buicks: a three speed stick shift (Hurst). Why? Because there was too much torque, and the intermediate shaft on the only four speed that would fit in the chassis wasn't big enough...
The comment on rarity is right -- to the best of my recollection, there was less than 1,000 '66 Buick GS's made, and of that perhaps 300 had the stage II mods -- and perhaps 20 of those were convertibles. Mine is in California, now, on the show circuit. I'd love to see it again...
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
one other thing, there's only one Octane Booster that really works Lucas, but don't over add it , like every other fill is enough
My parents car was a 67 Ford Galaxie 500 fastback with the 390, what a fast car, wanted it for my first car but dad said no, he sold it to a guy that worked at a station in town, THEN almost everyday on the bus going to HS I saw the car heading to town with aluminum slots all jacked up, I was dying, a few months later I saw the car on the side of the station totaled.
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
He got chased by the cops a few times but they never caught him. That was a dangerous car.
Bob
Vaporstat with a 12oz cut-out and 4oz cut-in
3PSI gauge
The only problem with them was that they were not a Holley 4150. The 4150 had the ability to deluge fuel accurately at WOT and when that was your MO that seemed to be your carb.