please define Modulation

[Deleted User]

ME

jp_2

in your own words.

define Modulation?

no analogies, just a definition.

mine is simple: something that can vary, automatically adjustable.

Mike T., Swampeast MO

something that can automatically vary to achieve a goal

ALH_4

AM/FM

But where is the boundary between "staged" and "modulating"? Is there a difference? Should modulating refer only to something that is continuously variable? Probably not.

Modulating = Changing

J.C.A._3

I think...

The ability of an appliance to adapt to the delta T, according to the needed heatloss of the system, and to permit heating at a comfortable level with the lowest possible water temperatures. Just my take...JCA

GW

good answers. But when I think of "staged", I think of a two stage gas burner such as gas furnaces. So, I would say the two words are not the same

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EBEBRATT-Ed

When I think modulation I think of a honeywell series 90 controller. It will control a damper motor at any postion between open and closed/high/low etc.

How about infanitly variable?????????

Two stage is two position high/lo...open/closed.

The europeans call modulating burners "expanding flame burners" something got lost in the translation.

ED

Mark Hunt

Good point


In a staged, multiple boiler situation, we do modulate the fuel consumption. Four 40k btu/hr boilers staged as opposed to one 160k/hr boiler. Modulating total input/output. This all seems a bit excessive considering the technology we have available to us these days. IMHO.

I like JP's definition. Mike adds a caveat that is also true. No point in modulating anything if full linear bore will do!

I was speaking to a rep from a boiler company the other day and asked if we could ever expect to see a modulating NON-CONDENSING boiler. Probably not going to happen. Apparently MOD/CON is/are the buzz word(s) of the future.

Thanks JP for starting this thread. It is a good question!

Mark H

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Christian Egli_2

? - What you get when fiddling with a module

Modulating an output means wiggling it and jiggling it in order to follow some kind of input signal. It's the way of tailoring heat use to heat need and the opposite of modulation is keeping the fire up, on full blast and at all times.

With a gas burner it is thus possible to modulate either the gas throughput (by fiddling with the valve) or modulate burn time (by cycling the fire on-off) or do any combination of the two, such as hi-lo stuff.

In my book, modulation is anything else besides keeping the burner on full power at all times - and don't laugh, this is done very often, without blinking. For the rest, whether you achieve modulation by chopping the time line or by varying the fire size is all the same, boiler wise.

For example, electric boilers are perfectly functional with a simply crude full on / off cycle tailored down to the second; you easily get super steady - modulated - boiler outputs. Of course, not all gas trains work particularly well under such regimes, and so, it is preferable to go easy on the flip switch while gently tapering the gas flow. In their days, coal boilers had it all already.

Lastly, electronic gadgetry allows for phenomenal modulation. All the possibilities that come with modern equipment. So much so, it might even seem modulation is the attribute of only the newest stuff, but I rather see it as the continual great improvements on the old concept. All this, thanks to electronics - the rest is all marketing.

There are yet further distinctions between step wise and infinitely variable modulation, neither of which is particularly new, but, there are many ways to skin an opossum.

Your words? My words?

Maine Doug_59

I think that

is what my prostate does when I am trying to pee.

Christian Egli_2

New terminology

Cool observation Ed, about the expanding flame wording. More of the bigger words for more effect...

Weezbo

Accelerating and decelerating ..

within a parameter about a fixed point.

Vs Moderating, gradual momentum within a desired set of parameters avoiding extremes...

jp_2

thanks all

i was curious, in a recent thread there seemed to be confusion as to what modulation actually meant.

Mike T., Swampeast MO

Andrew: You asked, "Where is the boundary between staged and modulating?"

When you modulate you move continuously between levels (actually a dictionary definition). When staged, you "jump" from one level to another.

John Ketterman

But many mod/con boilers are actually multistage boilers. Many more stages than a two-stage furnace, but still, not continuous.

Brad White_167

Mod versus Stage

I agree with Mike and others who posted that modulation is an infinitely adjustable process whereas stages is in distinct steps at fixed levels.

Further, as applied to the real world, modulation to me is the direct and continuous adjustment of an input or output to control a variable.

Good thread. Had to be asked.

Scott Denny

Accelerating and decelerating

Like cruse control on a car...

Mike T., Swampeast MO

One of my books regarding modern (yes, I do own and study some modern books) control of HVAC systems repeats three general forms of control over and over and over: digital, staged and proportional.

Each system in the book regardless of heating or cooling, production or distribution shows graphs of each control theory.

Digital graphs are spikes.

Staged graphs are stairsteps.

Proportional graphs are waves.

S Ebels

\"Fiddiling with a module\"

I love it!!!

S Ebels

Modulation

Speaking as the term would apply to boilers: Modulation is the abiilty of burner and control to constantly adjust input to meet a specific output demand. No steps, no bumps, just seamless, automatic and constant adjustment of the firing rate.

AFA analogies: See Vitodens