Viessmann Vitodens 100-W Boilers

Viessmann Vitodens 100-W Boiler Overview

The Viessmann Vitodens 100-W is a gas-fired, wall-mounted condensing boiler. The Vitodens 100-W is Energy Star rated with an efficiency of 94.0% AFUE. It has a stainless steel heat exchanger, and a low-emission modulating stainless steel cylinder burner which is factory calibrated to eliminate field adjustments. The unit has built-in automatic frost protection and multiple venting options with vent length of up to 200 feet. Pipe connections are located at the bottom with serviceable components in the front, allowing for easy installation and maintenance. The Vitodens 100-W is suitable for altitudes of up to 10,000 feet.

Questions about this model?

Consumer Reviews of Viessmann Vitodens 100-W


  • Very Satisfied
  • Somewhat Satisfied
  • Neutral
  • Somewhat Unsatisfied
  • Very Unsatisfied
  • #2 of 6 Viessmann Boiler
  • 28.57% of customers recommended

Read Reviews of Other Viessmann Products

Find ratings and reviews for Viessmann Boilers and more

Read Reviews

Top 10 Boilers

See who made our list of the best Boilers of 2021.

See the Top Products

Find a Certified Heating & Cooling Professional In Your Area

Contact a top-rated local expert to help with all of your home's HVAC needs.

Viessmann Vitodens 100-W Boiler Reviews

Showing 6-10 of 14 reviews

"Reports of satisfaction and efficiency greatly exaggerated"

1.0 rating
Very Unsatisfied

Unit installed in October in under 1500 sq foot, 130 year old home. Promoting this type of unit for this type of dwelling, approaches fraudulent representation. Even if quality installers "should" know, and speak up, if they are sold a bill of goods by a company, and cold is descending hard and fast and there is no heat, then, consumers can't fully blame them – not fully, at least. Never has so much fuel – propane, now – been used in 12 years. There is also the issue of the outside venting, which vents toxins onto such things as plants and side wall shingles. Neither things are good. The fellow who commented that he has these boilers installed on three of his properties? I'd like to hear from his tenants. I don't buy it. As I don't buy other glowing comments. Either they have different units, or properly made units, or their dwellings approach near-laboratory conditions for these boilers, or ? At last, the regional sales rep showed up today. He hit the floor saying that everything looks great, without doing a full check. The boiler generates heat when it wants to. You can't adjust thermostats, and, here, there is one downstairs, and one upstairs, without the unit taking 6 hours to readjust, so, you leave them set. Period. And that's what's been done here. Consumers can do all the research available, but how these units work is so locked in, so computerized, so dependent on having the perfect conditions under which they might work, that they should be avoided unless you dwell in a Viessmann-level laboratory-like environment. An oil burner may have its problems, but if there is any way you can stick with one, I assure you that given age, conditions, etc, of site, you can count on an oil burner, and for far less money. Greater comfort — and you can even adjust the thermostat and have it respond.


Coastal Maine

"Mine works great"

5.0 rating
Very Satisfied

Mine has been working well for 5 years now, and has entirely paid for itself in saved electricity costs. It is supplying hot water to an air handler to heat the house, and to a small hot water storage tank for domestic hot water. Right now it needs a replacement gasket, but it is still working and I don't expect it to be expensive.


Ontario, Canada

"Convinced Viessmann product is a lemon"

1.0 rating
Very Unsatisfied

We've had a Viessmann vitodens 100 for eight years and every year it has been giving us problems. This year it's constantly registering an f9 fault. My plumbing-heating contractor has been in three times this season, and he has even contacted Viessmann technical support for help even the technical help couldn't figure out what is wrong. I'm convinced we have a lemon. We used to have a Burham boiler for 20 years with never a problem, just maintenance once every year; and I miss it.

Richard Williams

Toronto, Canada

"Horrific waste of money."

1.0 rating
Very Unsatisfied

Five days into installation, replacing an oil-fired boiler. There's the notion that it is the consumer that "doesn't get it." Not the case here. Day five on Vitacon 100 condensing boiler. I hate it. I am cold. Some component is running almost constantly, without any benefit of heat. I have not altered the thermostat temperature. The heat is not dry heat. The unit came with a defect – a missing "wire"? The hot water – flapper? (And there should be a deep manufacturer's discount for that). I would not have switched from an oil-fired boiler to this, if the oil guys had worked harder to find some way of getting a new boiler into the basement, and placement for a new oil tank. (Also they have now lost all business from me that they've had for 11 years). This old house needed the dry heat that the oil furnace supplied. You could tell me that I am imagining that it is now humid (and cold), but I swear I'm not.This took all my savings. The installers, who are "highly qualified" explained nothing about the function of the thermostat, but I asked. If there is an outside sensor to this piece of crap, I'd like to know where it is and if it is working.Sure. The installers will be called back, but what are the chances of any correction. And, if improperly installed, (and I wonder how they could have mounted this thing on a piece of 1 inch plywood sitting on a damp basement floor, and the plywood will rot), there is nothing to do about it. Also, there is the cost of the lease of the propane tanks. The oil tank was "owned." Today, the tanks, delivered with less than 80% full for delivery, were topped off. At a thermostat setting – there are two thermostat's – one upstairs, and one down – of 64 degrees, one person in the house. Electric stove, refrigerator, washer and dryer, I'd like to know how it is that the tanks took 163.1 gallons of propane in under 5 full days.The old oil-fired furnace cracked. But until then, the heating was consistent, efficient like crazy, and provided safe comfort, without those blasted tanks looming outside. Entire savings gone, and cold. And it takes a full 25 seconds for hot water to come out of the kitchen faucet, which is located not 30 feet from the boiler. Either I capture that water in a pan so that I can add hot water to it to use for washing dishes, or I am wasting water. I'm betting the water meter is having a field day. Until now, the water and electric uses had been way below the standards. What a blasted waste of everything. If this is also an installer's failure, just what does anyone think the chances are of them owning it. If there is any way you can avoid replacing your trusty oil-fired furnace, (and the one here also heated water), do it. Take off the side of your house if you have to get a new furnace to fit. PS Why did that woman from Maine give this thing 5 stars when she hates the noise – which I hate, too.




1.0 rating
Very Unsatisfied

Do not buy their crap, total waste of money. Demand hot water had to be replaced with electric hot water tank. Furnace had 3 major failures in 4 years. No support from company.

Dave Savage

Ontario, Canada

Other Vitodens 100-W Reviews

The Vitodens 100-W is considered an excellent boiler on online forums. A professional on states that Viessmann was the first to make a stainless steel heat exchanger and the Vitodens 100-W has the best heat exchanger of any boiler. A comparison between the Vitodens 100-W and a similar Peerless unit on found most people choosing the Vitodens 100-W, with many saying that they don’t compare and one member stating that it is like comparing a Volkswagen to a Cadillac.

Vitodens 100-W Warranty

The warranty for the Viessman Vitodens 100-W boiler is comprised of the following:

  • 2-year warranty on the enclosure, combustion chamber, burner, controls and other parts
  • Limited lifetime warranty on the pressure vessel of the boiler. The warranty is prorated after the tenth year

The warranty covers only the original owner at the original site of installation. Labor costs are not included in the warranty.

HVAC Brands

Learn more about your home's heating and cooling system with our guides, how-to's, FAQ's, tips and more.

Ready to get a quote from an HVAC contractor?

Let us know what type of service you need and we can connect you with a certified local HVAC contractor.

Please enter a valid name

Please enter a valid phone number

Please enter a valid zip code

There are no dealers in this zip code.

Please enter a valid email address

Please select repair or replace

Please select heating, cooling or both