Viessman WB2B 26 stuck in stand by

Puckahuck

HELP! Ok so I started getting an F4 fault about a month ago. We changed the ignitor, ion rod, ignitor transformer to no avail. The gas valve was then changed and the boiler fired on startup but once the initial demand was satisfied the boiler has been stuck in standby with no fault code. Flow switch seems to be making continuity when boiler pump starts. Viessmann had me check code 38 which indicated 33 so they told me to change the control board. Well I did that last night and the boiler is doing the same exact thing, starts up, no error code and sits doing nothing. I have a low loss header and an indirect superstore off the boiler. Any ideas??

Robert O'Brien

Seems to be? Confirm the flow switch and fixed high limit are closed, either of those will do this.

GW

Chimney mode and you have flow and it’s not trying to light? Two boards ? Must be something basic I would think 

Derheatmeister

Couple things...
1.Gap on rods..You will need to remove the burner for this..We use a metric Allen whrench set as a gauge for the gap..
2 Clean the Burner with compressed air.
3.Clean HX ?
4.Gas type are you on Nat Gas or propane and is the gas valve/Programming adjusted ?
5.Do you have a pressure regulator prior to the Viessmann and how far away is it installed ?
6. What is your static and running gas pressure?
7. Do you have a concentric venting system...and if so have you observed if it is regurgitating it's own exhaust ?
8. Do you have any indications that some condensation may be dripping from the bottom circumference of the Heat exchanger and onto the Gasvalve plug ? if so, do you have corrosion on the plug to the gasvalve ? If you do you will need a new wiring harness,possibly a new gas valve followed by a new control board and i would recommend a shield over the Gas valve..
9. Is sensor # 15 in the vent hole.
10. Propper grounding ?

Yes Viessmann is correct a value of 33 on Code 38 calls for a new board
>>>BUT <<<DO NOT install or power up a new board until you check you wiring harness to the gasvalve for corrosion unless you want to purchase additional boards.
Some pictures of the install and the boilers innerts may help..

Puckahuck

Flow switch and high limit switch show continuity. Everything was just cleaned. There was a small pile of white powder underneath the fan when I took the outer cover off initially, you can see in the one picture the stain on the cabinet where it was. Natural gas system that had been running for about 11 years, venting had seemed to be working fine. I’m thinking it’s something basic too but just can’t figure it out! I’m in Western MA are c

EBEBRATT-Ed

If you kill the power and reset it does it come back up and run at all?

Puckahuck

It turns back on and sits here. After power off/on fan cycles and that’s it .

Alan (California Radiant) Forbes

I had one that was doing the same thing. The pressure was fine, but somehow, air had gotten into to system and stopped flow. 

Embarrassing that it took so long to figure it out. Pump, flow switch all checked out. I would just look at it and scratch my head. 

GW

press these two at the same time, nothing?

Puckahuck

I hear one of the relays pickup in the power pump module and that’s it. 

sunlight33

Did you check the fuse?
nvm, if your board has been changed then the fuse should be fine
This may describe your symptom: https://www.viessmann-us.com/en/services/tsb/tsb-006.html

Derheatmeister

I assume that you do not have hot water as well ?
Not that it matters but the circulating pump from the Low loss header is installed in the wrong position( The head should be in the horizontal position)
It seems that you may not be calling for anything...Are you operating on WWSD or TT demand ? Did you check your Programing ?
Did you try DWH only and does the DHW circ work ?
Can you do a Relay test ?

Puckahuck

Correct no hot water and operating on WWSB . Programming as far as I can tell Is correct - not familiar with the relay test.

Derheatmeister

Do you have voltage on the "Radial fan" plug when you first power it up ?
Are all of the plugs on the board inserted correctly ?
Did you ohm out the Gas valve/ check the wiring harness ?

On one of our service calls we had to reset parameter #38..After that everything worked..

If parameter 38 keeps reverting back to the dredded # 33 you will need a new board and possibly other components that are causing the "Control console"/Board to go bad in the first place i.e coding card,wiring harness,Gasvalve.Radial Fan..
I would start Ohming out components
I know that it is very frustrating but if you plug in a new "Control Console" to a faulty device such as a gasvalve/wiring harness it will damage the new Control Console.
The Service tech/you will have to change ALL of the Faulty Component as a Group at the same time and it needs to happen before power is applied..
(Gas valve,Wiring Harness,Control Console,Coding card,Radial fan..


Or as Viessmann states it:

Boiler is not responding to a call for heat
Applies to: Vitodens 200, WB2B Series (all models)

Symptoms:
Boiler is not responding to a call for heat (the burner does not fire at all), no fault is displayed on the boiler control, and coding address "38" has a value of "33".



Cause:
The internal, non-replaceable fuse in the boiler control console has failed.

This can be caused by:

1. An electrical short at the gas valve terminals, if they have become wet. Burning or discoloration of the terminals will usually accompany this failure.

2. A faulty gas valve or radial fan.

3. An internal fault within the control.


Resolution:
Viessmann recommends that the control console, coding card and gas valve be replaced as a group, to prevent one faulty component from damaging others.

In addition:
1. If there was an electrical short at the gas valve terminals, then the gas valve wiring harness must be replaced.

2. Check if the radial fan is faulty, and replace it if necessary.

3. Check if any other outside influences are negatively affecting the control.