tt solo

tim smith

If they do a deep setback and mild temps outside, it will boost the temp up to max design setting and overtemp floors and cause separation and dispair. I wish they had a way to adjust the amount it goes up per time segment to help prevent this. I tried it at my house but did not like the way it responded in our mild temps here. Tim

[Deleted User]

mcba solo

we installed our first mod con triangle tube heater, the install went well, problem is we are not sure how to enter mcba controll to change parameters, we did set max temp to 186 for a 0 deg day but when outdoor temps are around 28 deg home owner cannot get rooms to go above 62 deg with 102deg water temp, we were hoping to downland a manual to let us change settings,, thanks ...

TimS

Prestige Control Application Supplement

is what you need for specific info/instructions
try to get one from the local rep.
For temporary fix disconnect the outdoor sensor.

Derheatmeister

What kind of heat emitters do you have? and are you using the internal Circ only? what is the buildings heat loss and what size boiler?and where did you locate the out door sensor?.

Unknown

Call the factory

They usually dont give out the control sheet without factory training but if you assure them your a professional I think they will email you a PDF. Have the serial number off th mcba control ready. They recently added new parameters and in doing so completely changed the position of all the parameters. So there are now 2 mcba control codes to get in. So make sure you get the right supplement. You cant turn on the boost without accessing the hidden parametrs.
TONY

JohnNY

Is "the boost" the parameter that allows the water temperature to rise over time as the demand is not met?

That's an elusive feature that I've never seen work.

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Unknown

It works John,

just dial-in the delay time, and after that it will rise 18F until it achieves the "cap" temp.
Had an old customer who liked deep setback, couldn`t persuade otherwise, this quieted the guy down.

Dave

scott markle_2

Boost seems like an interesting idea, But it kind of undoes the odr. A well calibrated odr will operate at close to constant circulation and this is a good thing. I would try and get the reset curve calibrated before I activated the boost feature. In a single zone system I would consider using indoor thermostat to activate the downward parallel shift as a means of indoor feedback.

It helps to see this graphed. If you have a clue what kind of water temps you need at 23 make sure you reset curve intersects 23 degrees at the appropriate temperature. Remember that it is bottom and top side of the curve that effect the slope, you probably need a steeper slope, as well as shifting the curve up.

I can't believe they don't supply the mcba supplement with the boiler, Glad I took the class, They ran out of literature binders but, the one thing I came away with was this supplement, you need it if you want to understand what this boiler can do.

Uni R_2

Something's not right.

The defaults I believe for P4 - P8 are 186, 86, 0, 64 so we get 86* water at 64* ODT and 186* water at 0* ODT.

The default slope is 1.56 which is pretty steep.

With the default curve, you'd get 142* water at 28* ODT and 102* water at a 54* ODT.

You say you have it set for 186* water at 0 and get 102* water at 28. It that were true then that slope would be 3. No place ever needs a slope like that.

Medium insulated house with a mostly fintube and some pap/plates and my slope tends to run between 0.70 and 0.85 depending...

Unknown

Boost is unfortunate for the reasons you state. I'd much rather have proper set parameters.

Worse, on the Ultra it was (maybe still is) ON by default!! Man, that still makes me shake my head.

scott markle_2

Uni, how do you convert the hi and low parameters to a slope (or reset ratio)? I'm more familiar with reset as expressed by a single number than coordinates on a graph. Your slope seems really low for the kind of emitter you describe, even seems low for radiant. perhaps this has something to do with where you are on the vertical axis (shift).

Personally I find the Viessman slope and shift, and minimum max supply temp approach to be much easer to understand and adjust. What a difference in "culture" that Viessmann makes these parameters available as part of the user interface, as opposed to concealed by installer access codes.

I was in the supply house today and got talking to a guy who had just put in the new peerless condenser. I asked him about his reset slope and what he was using as a starting point, I didn't press him but I don't think he knew what I was talking about, He understood reset and supply modulation but was just using boiler defaults, I would imagine there are a lot of instals, that are not leveraging full condensing potential, for lack custom reset adjustment. The idea of a default reset and needing to special order a supplemental literature to explain the features seems a bit lame. There are so many variables from structure to structure. I don't think many people realize the importance of tuning this adjustment.

Uni R_2

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Uni R_2

I cheat...

I use a spreadsheet to visualize it. With the MCBA, it's primarily about those 4 points so using lines really helps to see it.

The slope is merely the line going from one set of points to the other. My slope may seem low but I can hold the house at a constant indoor temp there without the t-stat (barring solar gain).

The blue line is the default. The purple line is basically what I can run, although after February it actually could be flattened a bit due to solar but then the next fall you'd be cold the first really cold day of winter.

Uni R_2

I use a spreadsheet...

Then I only have to do the harder math once. The slope is merely the slope between the 2 intersecting coordinates. My house follows that curve pretty closely save for any solar gain which the t-stat handles.

Unknown

Yes as Dave stated

it will boost your temp 18 degrees for every so many minutes up to and including 30 until the stat is satisfied, then it will go back to reset control. It will also allow you to set your max temp, so no worries about overheating floors.
Theoretically a boiler should run 24/7 just putting into the structure what is being lost, this is very hard to do because of minimal modulation abilities but with that said if you do get close to the perfect reset temp you will never be able to gain temp, just put in what is being lost at that point in time. kinda like using cruise control on your car without having the accelerate button....you could never pass. Also as metioned here you must have a thermostat for external heat gains..solar, big dogs ect. The mcba control also has a parallel shift ability, that may or may not be useful.
TONY

eluv8

Peerless Purefire

If he installed the peerless purefire its actually a very easy control to setup, it pretty much askes you the questions in english and you answer and it sets it up for you for the most part. As far as boost I do use its feature but if you cant set the increase increments and time between increases it could backfire real quick. Nothing better than a good reset curve, but leave it to a homeowner to setback a thermostat 10 degrees and expect the house to be warm in the morning when he or she takes his or her shower. got to have the boost if your going to have a chance in making those customers happy.