Viessmann wiring. Is this right? Seems wrong

Xavier Breath

Firstly, from a long time lurker, a big thanks to all who

contribute to these threads.  The real-world insight provided is something

unobtainable from manufacturers' help lines.

Install:

     Viessmann 100 WB1B

     No external hot water storage or Viessmann Combi-plus

     (2) Taco Zone valves

     (2) Grundfos circulators                                                                                                     

     Taco ZVC 403-4 controller

     Watts expansion tank, spirovent, CPVC exhaust (~3 feet),

     Viessmann LLH

     Divertech condensate pump



The wiring instructions attached to the inside of my Viessmann boiler detail

the power wiring from the power pump module to the heating circuit pump

OR the boiler circuit pump for a low-loss header application.  I have done the

latter.  That leaves the only option for a power feed to the heating

circuit pump at the Taco controller pump end switch, which I have done.   The Zone 3 contacts at the Taco controller are not jumped and the priority zone is off.  The heating circuit circulator is energized correctly when either zone valve calls for heat and the zone valves respond correctly.   The boiler circuit circulator (off the LLH) runs constantly as the boiler maintains water temp between 160 and 180.  The outdoor sensor has no impact on the boiler's behavior relative to water temperature.  The boiler will not power up when the TT contacts on the Taco unit are connected to the RT contacts at the boiler.  Initial boiler start up was smooth with no faults.  However I was able to produce a fault when I disconnected the outdoor sensor, a fault that disappeared on subsequent on/off's even though the sensor was not connected.      The boiler has been running for about a week now under the above scenario with no problems.  So, can anybody tell me what I did wrong?  I can't believe I've done the wiring correctly since the boiler is ignoring the outdoor sensor and the TT calls for heat.  Snide remarks welcome as long as they're helpful.

Thanks

Dave

R Mannino

What Happens

when you jumper RT?

Robert O'Brien

100WB1B

Boiler only runs on a demand to either RH or DHW terminals. It doesn't maintain temp or run the system pump without a demand present

R Mannino

They Come

from the factory with a test jumper installed, that's why I asked.

CMadatMe

Wiring

Boiler pump is wired to Pump on the Viessmann, End switch from ZVC to RT, System circ should be wired to the Taco Zone control as shown on the inside cover of the zone control. Boilers built in WWSD is 70 degrees. What curve (number) do you have the boier set for?



Are you sure that system pump is wired correctly? Did you OHM the sensor to make sure its not the problem?

Xavier Breath

Thanks for the responses

R Manning: Nothing happens when RT is jumped out, only when the DHW is jumped out (as I have done)



Chris: Boilers built in WWSD is 70 degrees. What curve (number) do you have the boier set for?  I have the boiler set at factory defaults.  If by system pump you mean the hating circuit pump then yes, I believe it is wired correctly as it energizes and stops as demand is called for and satisfied.  If you mean the LLH pump all I can verify is that it runs.  I did not ohm the sensor.

Robert O'Brien

Primary/Secondary

To avoid confusion,the system pump is also known as the primary pump,all others are secondary whether they service DHW,heat etc.

Xavier Breath

Gotcha

Thanks

CMadatMe

How About Some Pics

Specifically boiler piping. The boiler pump should be wired to Pump on the Vitodens 100 Power Pump Module. That pump will only run on call from RT or DHW. Disconnect your wiring to RT. If the boiler pump is on before you do that it will continue to run for 1-1/2 minutes before shutting down. The boiler logic has a 1-1/2 minute post purge feature. Does the boiler pump still run?



By the way, the dot (factory set) tells the boiler to maintain 140 degree set point when the Outdoor sensor is not connected. Your high water temps have me intrigued as to the piping. What speed do you have that boiler circulator set on.

Xavier Breath

When there is a call for heat, a connection to the RT has no

results from the boiler - whether it is connected to the TT at the zone control (while the t'stats are calling for heat) or even if RT is simply jumped out.  The boiler will not energize.  I should say that the zones valves open even if the boiler is not energized.  



I'll try & get some pix.

Xavier Breath

The DHW is jumped out. That's the only way I could get the boiler to run

The boiler circuit is set on the lowest speed and the heating circuit is set on the highest speed.

CMadatMe

Are You Sure

You have a good connection at RT. I know it can be a pain sometimes getting that Thermostat wire up in those terminals.

Xavier Breath

I think the Tstat wire is good,

 Thinking that was the case, I tried two different runs.

R Mannino

And I Thought

it was just me, Thanks Chris

CMadatMe

Not The Wire

The actual connection into RT. Been called many a time over that and have experienced it myself a few times..

R Mannino

You Can

Use the DHW terminals, but you will lose the ODR feature, that's what RT is for.

R Mannino

Done It

once or twice myself, opps

CMadatMe

Actually

By using RT he is loosing the setpoint curve the boiler will ride. That is why he is seeing the 20 degree constsnt delta..

Xavier Breath

Not The Wire

When the RT was utilized, the connections to he wires were secure

CMadatMe

If That

Is the case, then you have a bad board. Would be the first one I've seen with this issue since the introduction of this version and the last version of Vitodens 100 but anything is possible.. That's a lot of boilers, so please double and triple check yourself..

Xavier Breath

Gonna call it a night & try some stuff tomorrow

Thanks to all

CMadatMe

The Outcome

Curious minds would like to know how you made out?

Xavier Breath

Outcome

I took your advice and went through all the wiring once more.  I just cannot get any response from the boiler when utilizing the RT contacts, either through the Taco controller or simply jumped out.  However the DHW contacts work like a charm in that the burner will go through all the proper sequence of operation (as published) and the factory-set 160 - 180 default DHW high limit is maintained.  Thinking it may be bad flow, I wired the LLH circulator to run independently of any Taco/Viessmann controls and wired the heating circuit pump to the PPM, removed any DHW jumps and wired the Taco isolated end switch (TT) to the Viessmann RT.  I then had all zones call for heat.  All zone valves opened correctly but the circulator would not energize and the boiler would not energize.  After I let that setup run for 3 hours the boiler water temp equaled the ambient house temp.  I'm at wits end and am proceeding to get a new PPM card.  Sounds funny but I was really hoping it was something I wired wrong.  The controls were the last item to finish before standing back and looking at my install as a job well done.  Now, not so much.  Guess I'll have to go back dating old women for money.

Thanks your input Chris and I'll update once the new card is in.  If I don't spill coffee on it first.

Thanks to all.

CMadatMe

Flow Switch

Try this...Jump RT and the flow switch. If it runs need to see some pics of the boiler piping before I say you may have a bad board or flow switch..

Xavier Breath

Bad flow -

OK, I'll try that tonight after I get home from work. 



When you say bad piping, what would you be looking for? 

CMadatMe

Didn't Say

You had bad piping. Want the pic to eliminate any possible piping/flow issues.

veissman_Bob

I don't think you've got a problem

I have a vitodens 200 WB2B-45 with a similar set up and noticed the same problem - boiler pump runs continuously to circulate water in the LLH loop.  Viessmann verified that that's the way the system is designed to operate and offered to send me a new wiring diagram to have it engage only when needed, i.e. when a heating zone is calling for heat (via its respective thermostat) or DHW call.  They never sent that wiring diagram, but I have been working directly with Taco and their suggestion is to swap out my current ZVC with their newer ZVC-404-EXP that has two end switches (instead of one) - one is for the primary (system) pump like you've got wired, and the other end switch can control the secondary (boiler LLH) pump.  Using this controller, the secondary pump comes on only when there is a call for heat. 

The only part I'm confused about with the new controller is the DHW connection.  I presently have it wired from the Viessmann PPM.  If I leave it as is, I think I could run into a situation where the DHW could be running without the boiler pump being on, i.e. if none of the thermostats were calling, I don't see how the boiler pump would run.



So I think this is an "all or none" situation.  You either accept the fact that the Viessmann boiler pump will run nearly continuously (and spike your electric bill), or you wire all the pumps - system (primary), boiler (secondary) and DHW - to the new Taco controller and allow it to control everything.  And then you'd "add back" the Viessmann control features you "lost" - DHW priority, post purge, pump exercise,etc.  



If anyone else has any other opinions or options, I'd love to hear them.  Thanks. 

Xavier Breath

ZVC-404-EXP

Bob - Can you control the LLH loop water temperature? 

If you jump out the RT on your boiler, does the boiler energize?



Thanks for your interest

CMadatMe

No No

The Vitodens 200 and Vitodens 100 are two different animals with different control and burner logic platforms.



In Viessman Bob's case, there is no RT on the boiler. No the 143 plug is not RT/TT Bob nor do we ever use the 20Aplug for the system pump unless I was running a constant circulation system like they do across the pond. Your system pump should be wired into the Taco Zone control so when a valve opens the pump runs. The boiler will fire if it needs to based on the feedback from the LLH sensor.



In the Vitodens 100 there is a TT (RT) to activate the boiler. Still waiting to see thos pics. Could you also draw and post how you have the boiler wired.



Bob in coding 2 you can get rid of the LLH sensor and then utilize the 143 plug if you want to run the boiler llike a traditional boiler with a TT. You then have to program the boiler via External Demand to tell it what you want it to do on that call.

Xavier Breath

Have had to work late this week

so I apologize for no updated info.  I'll post the info as soon as I can.

Thanks

Xavier Breath

Update

I put a warranty claim in for a new power pump board  and received it Tuesday (took four business days - came from Canada, eh).  Viessmann sent the entire module, which was nice, but the new replacement board inside the module did not match the old board item-for-item.  Not sure what electronic components they changed but it's definitely different.  All the connections in the new module/board are the same as the previous module/board.  Anyway, long story short, the new board is in and the controls work flawlessly. Couldn't be more happy with this boiler now. 



I can't believe I'm looking forward to winter. 



Thanks to all who gave me their time. 



Dave