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Viessman Vitola Boiler

Hi Folks
I have a 25-year-old boiler in my house running on natural gas feeding radiant sub floor system on two levels and domestic hot water through a hot water tank.
Recently it has developed a fault of not tripping back in correctly after reaching cut out temperature.
It seems that the boiler temperature decay is not being seen because after about 5 minutes of cut out, the boiler control demand heat, but since the temperature is already at peak temp it shuts off shortly after re-ignition creating a redlight trip out on the Reillo burner control,
As an experiment, I pulled the thermo couple from the front of the boiler carcass leaving it connected but reading basement temp but that made little difference to its performance nor cut it /cut out temperature control delay.
Any thoughts and where could I get a shop manual of sorts on this boiler and setting?


    EBEBRATT-Ed Member Posts: 15,329
    edited December 2021
    Not famallier with the boiler.

    There are a bunch of different Vitolas, I don't know what you have. Here is the link

    EBEBRATT-Ed Member Posts: 15,329
    That link doesn't seem to work. Google: Viessmann Historic boiler manuals ..............it will come up
  • GW
    GW Member Posts: 4,678
    hmmm never seen a riello cut out on temperature. It cuts out on flame loss (unless the primary control is getting wonky). I would need to stare at it a bit
    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
    [email protected]
  • hot_rod
    hot_rod Member Posts: 21,863
    A Vitola biferral by chance? That was a beast of a boiler, Uber German engineering. It should last 50 years if cared for. Rich Trethewy made that boiler a big seller back in the day.

    Plenty of info if you Google that full name
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Linden
    Linden Member Posts: 2
    edited December 2021
    Yes you have it !
    A Vitola Biferral
    Essentially, I built the house in Denver myself about 25 years ago and used this boiler making up the hydronic heating system using PEX alum tube to heat two floors of 3500 sq fit property.
    I have a HVAC license, but I am a diesel vehicle tech and repair shop owner so it a bit off "topic' for me.

    Some of my HVAC Sprinter/Ram van customers stated that it was probably on its last legs but over the 25 years it's been pretty reliable only needing a flame/burner adjustment for 6000 ft altitude. I have every so often run a gallon of white vinegar through it and flushed it out.
    Earlier this year I installed a new Tjernland exhaust vent blower --worn out!

    Suspecting It was getting furred up and overheating internally although the cut-out point was 160 F, I was tempted to use some Fernox but was advised against it by my HVAC experts. (customers)
    So, as a Hail Mary approach and ran a gallon of CLR through it for several days which after having run it flat out for 24 hours with the house like an oven, it appears to be behaving itself.

    So now do I run a dose of Fernox F1 through it or leave it as is?

    As for the manuals etc. I had them originally for the set up and commissioning, but the missus tossed then in the trash as dust collectors! Married life normal!
    Rich & topic contributors' thanks for the response and any opinions on the Fernox purge /system maintenance liquid .

    I do need to find a 4 way 1,25 inches Viessman mixer valve its showing signs of corrosion on the fabricated steel structure but in Denver boilers are rare birds in houses it's all forced hot air.
    Can any you folks recommend a good Viessmann part supplier in the US ?
    Again, thanks for the responses & Happy New Year.
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 3,938
    edited December 2021
    There were a few models of their Vitola-biferral. Here are the installation and service instructs for the VBC model. Instructions for other biferral models are on their website.

    We installed four of them in the late 90's, early 00's. I've only had a call to service one of them when the reset tripped. Opened the firebox and it was as clean as the day we installed it. Fantastic boiler.

    Viessmann ONLY recommends CitriSurf for cleaning their HX, not CLR. Don't know why.

    Viessmann offers rebuild kits for their mixing valves. You should be able to call your local rep. for that part number. I've been buying Viessmann parts online from Boston Heating Supply, but they don't have everything. Your local supplier can buy them directly from Viessmann.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • Derheatmeister
    Derheatmeister Member Posts: 1,515
    Coming from Dillon CO we get our Viessmann Parts from Low Energy in Denver ..
    Talk to Seth 1 800 873 3507
    BTW I serviced a couple of these boiler over the Years... The biferral boiler is the Bomb.

  • 8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • Derheatmeister
    Derheatmeister Member Posts: 1,515

    Ohhh you have what i call " Das Glockenspiel" control..
  • Das kann sein. 
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • Derheatmeister
    Derheatmeister Member Posts: 1,515
    As for system fluid:
    Back when this boiler was manufactured >>I think<< the instructions stated that the fluid used to fill the system with should be of "Drinking Water Quality"
    The Fernox Makes a good product and F1 will not hurt your boiler..

    The New North American ANSI Standard H 1001.1 (Which i was involved with) States that in order to maintain proper Inhibitors one shall maintain at least 20% glycol (Chemicals)... OR... Use high purity water(Deionized Water).

    For Various reason personaly i try to stay away from chemicals as much as possible and adhere to the what i call German "Reinheitsgebot" for Hydronic heating systems >>>VDI 2035<<< :)

    If you want some easier reading of SOME of the things mentioned in the VDI the Caleffi Idronics #18 is very good.

    I you are interessed in making sure that your system fluid is OK
    some of the main things to watch for are PH,EC,TDS,SAL

    IMO and since the occurrence in Flint Michigan in order to prevent loosing the "Patina" on the pipes most of the Water Companies (Incl. Denver Water) have been maintaing a higher PH :)
    One of the issues that arrises from a High PH Water is that when this now "safe water" is being used in Modern Hydronic heating systems it deposits on the Heat Exchanger and equipment.. :(
    Not only does it deposit on the HX, It also increases the Electrical Conductivity (EC) of the System Fluid which allows different materials to react to each other. (Galvanic Reaction).
    This Galvanic reaction surfaces as what most technicans call "Sludge"
    "Sludge" Consists of a bunch of things incl. Magnetite
    Magnetite is Ferrous and any Magnetic field incl. a wet rotor pumps field will attract it causing premature Failures of the system Circulating Pumps..

    You should sample some of your System fluid,Send it to either Low Energy or Innovative Hydronic Solutions for Analysis
    Just make sure that the Sample does not Freeze..But if you are in Denver you could also just drop of a sample at Low Energy.
    Hope this helps and Happy New Year.