Vitodens 100-W temp setting question

markt

I have a 100-W (WB1B) and the temp setting dial doesn't make sense to me. It has a dial with positions 1 thru 6, and the manual says position 1 == 81°F and position 6 == 178°F. Presumably, it's linear, so that works out to 19.4° per increment. However, two facts don't jive with this.



First, the manual also says the factory default, a dot on the dial at about 4.75, is 140°, but that position would be 154°.



Second, position 3 should be 120°, but I get ~132° at position 3. To get 120°, I have to dial back to a hair less than position 2, which should be ~100°.



Am I missing something here?



Attached is screenshot of manual page, with a table of the interpolated dial temps drawn in by me.

CMadatMe

Do You Have

The outdoor sensor hooked up or are you running the boiler without it? Are you piped pri/sec or have the LLH? When you run the boiler what is calling and what is the flow/gpm of what's calling? What's the return temp at the boiler?

markt

Outdoor reset off..

Let me preface by noting I am not HVAC professional. I am homeowner, with just installed hydronic floor system. I am trying to better understand the system, both out of general curiosity, and practical application (not 100% sure it's all OK)



I disconnected outdoor reset. My immediate reason for this was to force heat on, because I just had hardwood flooring installed, and flooring guy suggested I run heat before sanding and finishing, even though climate doesn't need heat at the moment (55° nights, 70° day).



Flooring people say floor temp should not exceed 80-85°, and radiant installer said boiler temp should not exceed 120° to keep floors to under 85 (based on his experience, not theory). So I picked #3 on dial, which corresponds to 120°. I then watched and saw it go to ~135°.



I have two zones calling. Pri/sec, not LLH. Grundfos Alpha "smart" pump. Initially, it was running in mode II, reporting 2gpm. I switched to mode III (tinkering), and it goes to 4 gpm. It makes no difference in the boiler temp however. Return temp is 90° at the moment.



I have some questions about outdoor reset, and various other things, but I thought I'd start a separate thread on that.

CMadatMe

Sounds To Me

Like the Radiant installer didn't do a heat loss and the flooring guys are giving you the industry standard for floor surface temp. Both are not giving you the answer to your home and application.



Without knowing the heat loss of the home, water temp requirement at designed based on the heat loss cannot help ya out. I can tell you that don't try to decipher the Viessmann world because it never makes sense until you can appreciate the entire thought process behind the control process.

markt

Installer did do heat loss

And yes, flooring people are citing industry standard, and manufacturer's specs.



My question was simply if anyone can explain why the boiler water temp does not correspond to what the manual says it will be at a given point on the dial.

Jean-David Beyer

if anyone can explain why the boiler water temp does not correspond to what the manual says it will be

If your boiler is anything like mine, if you disconnect the outdoor reset, the boiler will go up to maximum allowed firing rate, ignoring the outdoor temperature. In other words, it will assume outdoor temperature is as cold as it can possibly get. That will make it put out water as hot as it can.

markt

That's definitely not the answer

If you look at the manual in the attachment on my first post, you can see it states:



"With no outdoor reset installed, the dial will provide a temperature constant set-point based on the dial positon selected. Setting the dial between 1 and 6 will provide a set-point of 81° to 178° respectively."



I verified that the dial controls the set-point. Eg, position 2 has max temp of ~120°, position 3 has a max of ~135°.



So the dial controls max set-point, but set-point VALUES don't correspond to spec.

CMadatMe

The Boiler

Will still follow the curve for the setting you chose. It just rides it through modulation until it gets to set point. The boiler slowly or creeps from the bottom to the top of the curve.



Is this a WB1B10-26 or a 35? What is the boiler pump and what speed is it set on? I would also hope he installed a mixing valve for the radiant. If not what protects the floors

markt

Follow the curve?

Note sure what you mean. Per manual, it just targets a set-point. Perhaps it follows a designed curve to reach that, but that seems beside the point. The question is why it over-shoots the set-point by 10-15°. Note this is not transient. It rises from ~75° to 120° in about 2 minutes and will run at 120 for 10 minutes. In dial position 3, same thing except it reaches peak of ~135°. To the lay engineer, it just seems like dial and burner not closely calibrated.



This is perhaps moot, since I don't plan to run without outdoor reset. But it's curious.



However, with reset, it also doesn't follow reset curve too closely. See attached reset curve with my overlay. The dotted line is dial 3.5, and I observed boiler peaking at 119° (for sustained periods) which corresponds to outdoor temp of ~35°. However, it was 47° at the time (I have a separate thermometer at outdoor reset sensor)



It's a -26, Grundfos UPS15-58FC pump on middle setting.



No mixing valve. According to installed, floor protection is to not exceed 3.5 on the dial. Gives me a little pause, given the $50K I just spent on floors...

CMadatMe

Set Point Is

The same curve as the ODR. The boiler just follows it. So if the coldest day of the year is 0 Degrees then you would be set on Setting #2. Have you taken an OHMs reading of the outdoor sensor to make sure it's not the cause? Page 78 of the install manual..

Paul48

Chris

How can it follow a curve, with no outdoor reference? I believe he is reading it this way....In the absence of an outdoor sensor, it should operate at a fixed temperature, as it states. His is not accurate to the dial setting.

markt

And the curve is pointless anyway

As you note, it cannot follow the ODR curve without the ODR sensor, but it's completely beside the point.



It raises temp to set-point, and then settles there. The curve from cold to set-point is of no consequence whatsoever --- at least in this application, I'm not saying that's never important. I can see how the rate of rise is potentially important with a high delta T, given certain materials, stresses from thermal expansion, etc. But as I noted, it goes from 75 to 120 in under 2 mintes and stays at 120 for ~10 minutes. The exact curve in the first 2 minutes is not terribly important, and it surely has no bearing on why the peak temp does not correspond to what the manual says it would be for a given dial setting.

SWEI

accurate analog dials

were common up through about the mid-1970s.

RobG

Photos

Can you post photos of the boiler and boiler piping? It will help in ensuring piping / pumping issues are not at fault. The more photos the better.

Rob

Paul48

Someone

has to verify the inputs are correct. If they are, there is something wrong with how they are being used by the equipment, i.e. not properly calibrated.

markt

What inputs?

Do you mean the outdoor temp sensor? I will measure that tomorrow.



But of course that has no bearing when in fixed set-point mode (no reset). Are you referring to any other inputs?

markt

Yes

I can post some photos tomorrow.

Paul48

Dial

The dial provides fixed inputs, and would have to be checked by a tech.

markt

Pic

Here's a pic. I measured outdoor sensor resistance and it's right on the curve in the manual.

CMadatMe

What Size

Is that near boiler piping?

markt

Size

All 1", until the tees to the manifolds, which are 3/4"

forabunny

Vitodens 100-W temp factory setting question

Vitodens 100-W temp factory setting question...

I have a 100-W (WB1B) and the temp setting dial doesn't do anything... I have tried to lower the temp of the boiler, and it is way too high for the house... reading between 170-180 degrees... I have it set between 2 and 3 to get it to 135... but it continues to stay at the higher temp...



does anyone know the way to reset this dial?



btw I don't have the outdoor sensor connected...

CMadatMe

No Sensor

Means no reset, means no turning down. Boiler is just riding the curve at that dial setting.

forabunny

Vitodens 100-W temp setting question

so to reduce the boiler temp to 140° i need to do what?

CMadatMe

Install

The outdoor sensor and set a curve.

thus

Hi,

I know it's an old thread, but anyways, the question is on point.

I've got a Vitodens 100 WB1B (i would say it doesn't have an outside sensor), when water for heating starts heating, the power is always on MAX (it doesn't matter which one is set 1-6). And the water is always heated to the MAX temperature (80°C)

I even tried to do the Set maximum heating input. I can get it to the high-fire test, but when I rotate the water temperature selector, the screen does the water heating - not the icon -.-.-

GW

might be good to start a new thread

Your boiler must have some sensor or board issue

jasonscorvairs

Hi 

jasonscorvairs

Hi
I'm having the same problem with my Vitodens 100-w and was wondering how you corrected this situation with the knob not responding to any positions. I also have a Vertroniks controller hooked up. I can't find anywhere to get an outdoor reset controller. 

Any help would be much appreciated 

Jason

learningcurve

I can confirm that the instructions in the attached worked like a treat. The flame intensity on boiler was stuck at its lowest setting but now flame intensity goes up and down as you rotate the CH dial.