Constant Circulation article for customer needed

ScottMP

A link to an article I can send a customer on Constant Circulation ? I have explained it to him but it would be nice to send him something detailed.

Maybe Robert Bean ??

Scott

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Paul Pollets

Article by J Friedrick

here ya go Scott: From Rich Trethewey's site

http://www.comfortableheat.net/pdfs/continuous.pdf

All contractors should read this...it's the very basis for modern HW heating.

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jp_2

single statement.

the house constantly looses heat 'a little at a time', with constant circ you replace that lost heat, 'a little at a time.' keep it simple.

lower water temps: i think anyone can understand it take more 'heat' to boil a pot of water compared to heating it to 130F.

keep it simple

Brad White_9

I second Joe Fiedrich's article

That is the first thing that comes to mind. Good call, Paul.

ScottMP

Thanks Paul

Thats what I needed.

J.P. I allready gave him the simple answer and he agree'd I just wanted to follow up with some info.

Thanks Guys.



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D107

Less electricity consumption?

the report says: "...Elimination of circulator startups prolongs the life of the motor, while decreasing electricity consumption..."

I can see the prolonging of motor life, but less electric consumption doesn't seem right. ???

David

Uni R_2

David I hear ya...

Unless they are talking peak startup wattage, consumption can't decrease. Likewise, isn’t it completely disingenuous to say that you are prolonging the life of the circulator without mentioning that it requires a more expensive, more complex circulator that may not last as long as the other circulator would have before constant circ?

I can never figure out why you can’t sell something on comfort alone?

D107

Interesting--I never heard special circs are required--

Wouldn't they use standard circs like Taco 007s and the Grundfos Brutes?

Thanks,

David

adambuild

Diagram / Schematic

I'm planning on putting a new Ultra in my own home shortly and had toyed with the idea on constant circ. Anyone have diagram and/or schematic? I'm blanking out! Can it be found in any of Dan's books?

Dave_4

They could...

I actually should have said "motorized device". The standard circ stays (and stays on), but then you need either an injection pump or a motorized valve actuator (unless it is a single heating zone system). These cost more than a small circ.

J. Cricket_3

> lower water temps: i think anyone can

> understand it take more 'heat' to boil a pot of

> water compared to heating it to 130F.


It may be simple but it's misleading. How much energy it takes to heat the water is irrelevant. It's a matter of how much energy it takes to heat the house and keep it warm---that's a much bigger number.

Condensing boilers are more efficient at 130F, but that' because of condensing, not because it takes more energy to heat water to 180F.

It's never a good idea to insult the HO's intelligence. Foe every stupid HO you'll meet a smart one who will resent being given BS.

jp_2

wow cricket?

boy you are way off.....where to begin, maybe 8th grade science class, you must have been sleeping?

plus this thread wasn't about condensing boilers. by the way they will only get you another 10% efficiency.

i won;t try to correct your statements cause they are all wrong, sorry, read some books on basic science , a high school physics book is a good start. try high school chemistry too.

i leave you to your studies

ScottMP

" not because it takes more energy to heat water to 180F. "

I'm with J.P., that just dosn't make sence ????

Scott


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John Ketterman

Perhaps I could explain.

Water is the the medium used to carry heat from the boiler to the house. The boiler puts heat in the water, then the water releases the heat to the house. So while it takes extra energy to heat the water to a higher temperature, that energy is released in the radiators or returns as warm water to the boiler. It is never lost.

Only heat that is lost from the house (goes up the flue or out through the walls) affects efficiency. Energy that never leaves the house has no bearing on efficiency.

I am assuming, of course, that whether you use short bursts of 180deg water or long cycles of 130deg water, the house is being heated to the same temperature (say 70deg).

Now if you were constantly heating fresh cold water and then running the return water down the drain, that would be very inefficient. But in a closed system, it doesn't matter.

Of course long cycles are more comfortable, but they are not significantly more efficient (unless you have a condensing boiler and are able to operate below 140deg; you also save a bit if your flue gases are cooler).

jp_2

point to add.

if you were to measure the flue gas temp in any heating(fuel burning) appliance, you'll find as you want to heat(water) hotter and hotter, you'll find the flue gas temp increasing, so efficiency will decrease, heat going outside (waste).

it also follows Newtons Law of Cooling, so as an example, to increase the water temp 10% takes more than 10% energy. sorry but i do not know the exact numbers.

also higher water temps mean higher losses everywhere throughout the system, pipes, radiant floors & ceilings, radiators, yep think of the part of the radiator thats against the outside wall, the higher the rad temp, the more losses go directly outside.
higher delta T toward the outside!

lowest water temp to heat the house will win everytime.

John Ketterman

> if you were to measure the flue gas temp in any

> heating(fuel burning) appliance, you'll find as

> you want to heat(water) hotter and hotter, you'll

> find the flue gas temp increasing, so efficiency

> will decrease, heat going outside (waste).


True.

> also follows Newtons Law of Cooling, so as an

> example, to increase the water temp 10% takes

> more than 10% energy. sorry but i do not know the

> exact numbers.


What you are saying is that at higher temperatures there are higher heat losses, the water loses more heat more quickly. But this heat loss goes (mostly) to heat the rest of the house, so it is not inefficient. There is higher net heat loss (to the outside) only if the house as a whole is warmer, or in the situations you describe below.

> also higher water temps mean

> higher losses everywhere throughout the system,

> pipes, radiant floors & ceilings, radiators, yep

> think of the part of the radiator thats against

> the outside wall, the higher the rad temp, the

> more losses go directly outside. higher delta T

> toward the outside!


True.

But this is a lot more complex than "anyone can understand it take more heat to boil a pot of water compared to heating it to 130F".

jp_2

newton

sorry Rkalia, close, but the cooling law goes both directions equally well!

if it take 10 btu's to heat something, when cooled back to orignal temp, you'll find it lost 10 btu's!

John Ketterman

[deleted]

jp_2

mod & temp

i GIVE UP!!!!

I'll say this much, if you modulate the burner your output temp will change from the input temperature! they will "follow" each other.

EDIT: kalia, instead of this true/false/true stuff, why don't you explain a little and give an example of why I am wrong? who knows I might agree! otherwise I think you just want to....I don't know what you want to do?

by the way, sometimes I find it easier to give a simple example of a comlex system than a complex desciption to person with limited knowledge of the subject......thus the heating water example, please tell me why I'm wrong here.

jp_2

R Kalia, question

i've read copied my message down here:

kalia, instead of this true/false/true stuff, why don't you explain a little and give an example of why I am wrong? who knows I might agree! otherwise I think you just want to....I don't know what you want to do?

by the way, sometimes I find it easier to give a simple example of a comlex system than a complex desciption to person with limited knowledge of the subject......thus the heating water example, please tell me why I'm wrong here.

also, if newtons cooling law does not work for heating, what does? if cooling is nonlinear, is heating linear?

curious minds want to know!

pipefitter#51

Hydronics Institute Div. of GAMA, www.gamanet.org Technical Topic #7A, "Continuous Ciculation". if this helps any.

Mike T., Swampeast MO

If you're modulating the burner to achieve some output (target) temperature and add load but do not change the target temperature, the input and output temperatures do not "follow" each other.

After an inevitable dip in the output temperature (time for the controller to respond and make changes to the modulation rate), the output temp will go right back to where it began. The input temperature however will drop directly proportionate to the amount of added load.

As the added load becomes more and more satisifed, the input temperature will increase. Once fully satisfied the input temperature will be somewhat lower than before and the burner output somewhat higher than before--both again proportionate to the amount of added load.

jp_2

right mike,

wrong or unclear wording.

this arguement stems from a comment that supply temps and modulation were not really related. my orignal post was that they were related and dependant on each other. supply temp correlated with modulation, this also takes into concideration the return temp.

so a better statement above : water temps(bolier) follow modulation.

Is that any better?

remember, modulation, the ability to vary.

DanHolohan

Gentlemen,

are you able to have this discussion in a respectful way, without insulting each other.

I don't allow people to treat others with disrespect here. You may not have realized that. Thank you.

Mike T., Swampeast MO

You can however modulate to any temperature sufficient to meet the load and such temperature does not have to be variable.

John Ketterman

> by the way, sometimes I find it easier to give a

> simple example of a comlex system than a complex

> desciption to person with limited knowledge of

> the subject......thus the heating water example,

> please tell me why I'm wrong here.


I've already told you why, but I'll repeat. Indeed it takes more heat to heat water to 180 than 130, but that extra heat is 99% used to heat the house, it is not wasted.

You are correct about 1% level increased losses due to the higher flue temp and any hot pipes in the outside walls, but that's not discussed anywhere in your "simple example". So it is misleading.

> also, if

> newtons cooling law does not work for heating,

> what does? if cooling is nonlinear, is heating

> linear?


Newton's Law says that the rate of flow of heat (from hot to cold) is proportional to the temperature difference (linear, as you said). But this has little to do with efficiency, since the heat thus lost mostly stays in the house. (I'm sorry, I previously confused Newton's Law of Cooling with a different law. But it is still not very relevant.)

jp_2

where do you get

your data from? this 99% and 1% ?

as you said: """You are correct about 1% level increased losses due to the higher flue temp and any hot pipes in the outside walls, but that's not discussed anywhere in your "simple example". So it is misleading."""

a simple example is just that, not sure why you do not it see.

by the way newton Law is not Linear, not sure why you did rub that in?

jp_2

where does this come from?

you wrote:

I've already told you why, but I'll repeat. Indeed it takes more heat to heat water to 180 than 130, but that extra heat is 99% used to heat the house, it is not wasted.

You are correct about 1% level increased losses due to the higher flue temp and any hot pipes in the outside walls....."""

where does this 1% increase in loses come from? why only 1% and not a variable dependant on temperature?

how newton talks about efficiency? you answered you own question.

as delta T between pipes/radiators vs surroundings increase, especially surfaces facing outside walls, so does the rate of heat flow increase out of the house.

by the way heatloss and rate of cooling are not linear, thought you'd get me on that? they can be approximated as linear, as in heatloss calcs.

michael malsbury

"lower water temps: i think anyone can understand it take more 'heat' to boil a pot of water compared to heating it to 130F.

keep it simple "


Sure, but that doesn't explain why lower water temperatures are more efficient.