Viessman Boiler No workee

Linden

OK as a preamble, I installed this Viessmann Vitola horicel Bifferal Nat Gas boiler about 27 years ago in the house I physically built in the Denver Metro area, Hooked up to radiant heat system on two floors it has worked very well for about 26 years of them.

At the end of last winter, it refused to fire on auto settings but flip on override and away it would go.—-HEAT.

Being the end of the season, I just shut it down. with the intention of having a go at it later on after some medical attention.

Recently I came back to it to do service work and find out what is going on with this fine old bird.

Firstly flip it on as before in override and this time the Tjernaland vent fan is operative, the Viesseman control box goes live/active, but the Riello burner head unit is inoperative. NO HEAT nothing—Unit dead.

Not my usual fare HVAC as a tradesman, mine in Auto Repair Sprinter vans mostly!

So basic diag.

Taking a no contact volt tester, I have power when switched on in override mode to the control panel, and the internal circuit board goes live. I have power out to the black, brown multi pin connector but after that nothing nor feedback voltage flow on the other connector.

Opening up the connector that is live and doing a pin out with a Snap On DVOM I have system voltage at the plug but that is all, no flow to the burner head.

So at this stage I question whether the control panel is down or there is a fault on the Riello unit. Some additional pointers might be useful if anyone has any ideas

BTW all the sensors are intact, no rodent damage plus being below floors there is no water level sensor, so the troubleshooting guide is less than helpful in this case.

Lastly PARTS, do parts exist for this old gal these days.

Especially a replacement control panel (if defective or even a Riello burner unit having run for 27 years?

Dennis

Jamie Hall

Got a circuit diagram?

GGross

I'm assuming the override you are talking about is the little toggle switch that you would use for a flue test, overrides control settings and just runs the boiler? If that is the case, and the flue test function will not fire the boiler you need to look first at all of your safety devices that could block burner operation, if any of them are tripped you will need to remedy that first (either they trip for a good reason, or are broken replace if needed) Beyond that, the Riello burner almost certainly needs service, parts are generally still available for those, or entire new burners available, it is definitely not unheard of to have a few parts fail due to wear and tear over 27 years. The boiler itself really just consists of the heat exchanger, boiler cabinet, and control. The old control is probably not available, they do offer retrofit controls for your boiler that are modern controls designed to replace yours, pretty expensive but thus far nothing pointing to the viessmann control imo. If the control can be ruled out I would not mess with it much, assuming it was well setup on install you don't want someone messing with the settings, not many still around are familiar with them my knowledge of the old controls is extremely limited as well. Hopefully someone more familiar with Riello burners can chime in.

Linden

Thanks for the response.

Yes, only today I mentioned in passing that the unit boiled down consists of a CI box for making heat, a burner and a control unit to a van customer (HVAC contractor)

It's funny but the word is out that I might junk this Viessman and I am getting calls on the unit as first dibs if I junk it.

If I can source a new Riello burner, it did cross my mind to try to adapt another boiler control into it by adaption.

Another Viessman old sweat is looking for a wiring diagram tonight for me as he is familiar with these older units.

Thanks for some of the comments & suggestions.

Linden

Well, it's working, belting out heat and nothing better than hot socks on a radiant floor after having been working outside or in a cold workshop fixing HVAC contractors Sprinter vans ,

The problem?

The Jermeland flue vent micro switch.

Since I have a slew of new parts, 30 minutes of diag & fixing had the old girl running like new.

Good for another 27 years???

Thanks for the input & comments

Cheers Dennis

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