A laymans explanation of a heating curve and parallel shift.

Greg_9

Hello

I was wondering if there is anyone out thre who gan give me a laymans explanation of heating curves and parallel shift.

Thanks.

Ken_8

No.

Unles you tell us "in reference to what"

"Heating Curves" is just a general term used to define the way heat moves in relationship to some factor you have not mentioned. Did you mean with regard to outdoor reset? In relationship to emitter (radiator) losses? With regard to a pump curve? We need to know in what context the term is being applied.

The first reference that comes to mind for "parallel shift" is the reset curve's reference to a calibrated setpoint - and then adjusting same to a nubmer of degrees up - or down, to make reset curves relevant to your particular system - rather than the theorhetical one in some book.

You're already lost right?

That's okay. So am I - unless you tell us the additional information we would need to help.

Why don't you just tell us what you're dealing with - and why you want to know?

We can help from there.

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Mark Eatherton1

Sounds like

he reading the Buderus Logamatic control manual.

ME

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Ken_8

Auf

Deutsch?

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Ken C.

I watched one of my coworkers set up a Buderus Logamatic control and I skimmed the manual, but it was a bit over this newbie's head. So, I would be grateful if one of you could give a layman's terms definition of "heating curve," in reference to "outdoor reset." And no, I don't speak German.

doug_16

I like SE's better

also, now that it is daytime.

S Ebels

Simply put

This is assuming you're talking about standard outdoor reset of the boiler water temp.

Most reset controls are adjustable to provide a given water temp change per degree of outdoor temp change. Example: If you pick 68* as your starting point and select a reset curve of 1.0, your boiler water temp target would go up 1 degree for every 1 degree of temp drop outside. So if the outdoor temp dropped to 18* your boiler control would add 50* to 68 (your reference point) and give you 118* boiler temp (average) If you select a heating curve of 1.5 the control will add 1 1/2* for every degree of outdoor temp drop.

Some controls have starting points independent of the warm weather shut down temp I.E. Buderus. You can select a 63* WWSD and still maintain a 70* reference point for the begining of your heating curve. Some reset controls have the two point locked together.

Shift is simply taking any given curve and "shifting" the whole thing up or down by however many degrees you desire.
You can maintain a 1.0 curve but start the water temp at a higher or lower temperature value.

Hope that helps.

Kal Row

very good SE.also..

goto http://www.tekmarcontrols.com/literature.html
and read the essays - especially
http://www.tekmarcontrols.com/acrobat/e003.pdf

Kal Row

very good SE. also Greg ...

goto http://www.tekmarcontrols.com/literature.html
and read the essays - especially
http://www.tekmarcontrols.com/acrobat/e003.pdf

S Ebels

Additional point

Most boilers are limited to a temp range of 140* and up for safe operating conditions. IE: no condensation. This means that the boiler itself is limited as to how low it can go. This is an important point to remember due to the fact that the lower any boiler runs tempwise the more efficient it becomes. This is why boilers that are able to handle condensing conditions are more efficient.

As far as I know, (someone correct me if I'm wrong) the only cast iron boiler that will operate safely at low temp is the Viessmann Vitola series.

If you use a standard boiler and wish or need to reset your water temps below 140*, a mixing device is required. This would be a motorized mixing valve or a variable speed injection type control. A standard boiler can not safely operate at a temp of <140* under most conditions as a rule.

Just a heads up lest someone decides to crank their aquastat down to 120*. (I've seen it done, hence the comments)

steve l

boilers

you can add the Buderus and the De-Deidrich from France to the low return temp boilers, and soon the smith condensing cast iron!

Weezbo

its cold outside....

so ,the boiler temps all drift upwards 10 degrees to keep up with the new "Normal" temps. clear as a bell:)easy onda brain:)

S Ebels

Buderus

Will run down to 100-110* before the pump logic will kill the pump and allow the burner to fire. I don't know anything about the D-D.

What I was refering to was a boiler that will actually hold a narrow (10-15* temp diff) and do it with the pump and burner running at low water temps. The Vitola and the various condensers will do that along with water heater type equipment not designed for heating use.

It's 52* degrees here and my Vitola is firing right now into 105* actual boiler temp with the system pump running.

doug_10

Exquisite Heat

Most of this is now obsolete with Exquisite Heat. Let your thermostat do the work.