Viessmann Boiler Review

November 11, 2018




Viessmann Vitodens 200

The B2KB (combi Viessmann boiler) and B2HB (system Viessmann boiler), are the latest evolution of the Viessmann Vitodens 200 Boiler range.

Not leaving any disappointment, these continue to push the boundaries of what domestic gas boilers are capable of in terms of control and efficiency.


The biggest technological leap is the Viessmann boiler's huge 1:19 modulation ratio. Which currently far outperforms any other domestic gas boiler available. Essentially, this means the boiler will run much longer and cooler than any other domestic boiler, increasing gas efficiency and comfort. Learn more about boiler modulation & cycling here.


The new range also boasts a sleek colour touch screen and inbuilt gas and electrical monitoring. Giving an excellent advanced user experience, as well as all the intelligent modulating heating control we've come to expect from this impressive boiler range.

Read the full Heat Geek review after the Vital stats below. Click orange text for full explanations.

Viessmann Boiler Review
Models/Output heating
19kW26kW30kW35kW
Minimum Heating Output
1.8kW2.6kW1.8kW1.8kW
Modulation Ratio
10:110:117:119:1
Hot water Output
19kW30.5kW31.3kW34.9kW
Combi Flow Rates
N/A10LPM12LPM14LPM
Weight
40kG40kG41.6kG41.6kG
Warranty
3 years Standard, 5 Years for Viessmann trained installer.
10 Years on the heat exchanger.
Bus Connection 
KM Bus
Heat Exchanger
Viessmann 316 Stainless steel
Hydroblock and Manifold Construction
Composite/Rubber/Copper/Brass
Expansion Vessel Size 
10L
Dimensions DxWxH
375 x 450 x 800
Clearances
-Above 300mm
-Side 1mm
-Below 100mm
-Infront servicing 700mm
-Infront operational 0m
Flue Gas Recovery
No, However will accept 3rd party manufacturers. Must check with Viessmann UK.
Nox Class
5
Internal Bypass
Yes, Adjustable with flow limiter.
Built-in weather compensation
Yes. Advanced weather compensation
App Control
Yes

Who are Viessmann?

Although a lesser-known brand in the UK, Viessmann, a family-owned company. Viessmann has just won ‘Germany’s Heating Manufacturer of the Year for the 27th year running. Questioning the UK's tendency toward German manufacturers Worcester Bosch and Vaillant. This is all on display in their €50m ‘innovation centre’ in Allendorf. A headquarters that resembles something out of a future set, utopian sci-fi movie.

Since they were founded 100 years ago, they consistently produce groundbreaking innovations in renewables and industrial heating, as well as domestic gas heating such as the Viessmann Vitodens 200 range.

The research centre, which has a €5 million a week research and development budget, conducts a host of research in heating and renewables. Which is then sold on across the industry for the benefit of all.

Viessmann Boilers

Why would I purchase a Viessmann Vitodens 200 Boiler?

There’s no denying the Viessmann 200 is an amazing boiler. With modulation up to 19:1, or, more importantly, a minimum output of 1.6KW, a stainless steel 316 (inox) radial heat exchanger, lambda pro control plus, mass flow sensor, built-in 5” colour touchscreen control with weather compensation, and an ‘Energy cockpit’ with electricity and gas meter. This is one of the most, if not the most technologically advanced boiler available, and as such deserves a long heat-geeky explanation and review.

That’s great, but what on earth does it all mean!?

Ok so breaking this down bit by bit...

The ground-breaking modulation offered by the Viessmann 200 range of boilers is unparalleled. Making it especially ideal for properties that have lower heat demands, or multi-zoned systems, as well as allowing the system to run at much lower temperatures with longer run times. Boiler modulation is a whole subject in its self, a more detailed description of this is in our article ‘why boiler modulation is important’.

The energy cockpit, along with onboard gas and electricity meters, allows you to monitor your heating systems' electricity and gas and usage, for both hot water and heating independently. Displayed in the day, week, month and year format, this data is invaluable for those wanting to minimise energy usage. As typical smart meters will also include cooking and consumption from any other gas or electrical appliances you may own this is especially helpful. Solar thermal yields are also measured and displayed separately on the interface. All of this gives both users and engineers exact data to work from, and tweak the system for maximum efficiency gains should they wish.


If this isn’t of interest, the whole system really is fire and go, and very simple to set up for such an advanced control. No complicated wiring, and due to the advanced weather compensation very little interaction is needed from the user. Certainly much less than users should be used to from conventional controls if the weather compensation is correctly utilised.

Viessmann Vitodens 200 display shows the cylinder stratification and amount of solar energy gained (subject to install type).
Individual gas usage for hot water and heating.
Energie cockpit showing solar yield
Viessmann Vitovent mechanical ventilation can now be controlled by the boiler ensuring there no heat that is generated is wasted.

 

The Viessmann 200 is the only domestic boiler with a ‘Lambda combustion control system’. This measures the combustion quality and adjusts the fuel/air mixture. This accounts for the natural variation in incoming gas quality, giving the perfect combustion and maximising efficiency.

Their new 'LPro Control Plus' has taken things a step further in terms of accuracy, this now means the boiler can automatically adjust to work on LPG. Not only that, but the boiler will also run on E-gas, H-gas, shale, LNG, hydrogen generated from wind energy and PV energy, synthetic methane and upgraded biogas, all without any manual adjustment. Meaning although this boiler is sold as a fossil fuel burning appliance, it's ready for many future developments in the renewable sector.

Of course, none of this means much to the average Uk buyer, but it does show the forward-thinking nature of Viessmann as we try to incorporate new energy sources into our lives. But talking from a geeks perspective, it’s just pretty darn cool!

The new mass flow sensor is embedded into the fan. It constantly measures and adapts to the varying pressure drop through different flue installations, installation heights, air pressures, and prevailing wind conditions. Then modulates the fan speed. This further refines the perfect fuel-air mixture 100% of the time, ensuring the highest efficiency of combustion available.

Viessmann are most known for their Inox Radial Heat exchanger.

Inox essentially means the heat exchanger is made from corrosion-resistant stainless steel. There are various types of stainless steel quality available, this uses 316 which additionally infuses titanium and gives the highest resistance to corrosion.

The ‘Radial’ part refers to its physical shape and design. It consists of a singular continuous loop of large bore pipework. There is a couple of advantages of this over the typical multi-pathway heat exchangers used elsewhere (where the flow splits off into multiple smaller coils

Viessmann Boiler Burner


If one pathway were to block you would be none the wiser, and lose efficiency due to the reduced surface area, meaning a hotter heat exchanger and flue gases, less condensing, and more wear and tear. The other advantage is that if it were to develop a blockage it would be easy to clear. Multi pathways can be much more difficult as water takes that path of least resistance when flushing.


They are particularly proud of their heat exchanger and often refer to its precision-made 0.8mm gap within the spiralled design. This is designed to prevent 'core flows' of gas, where you have a hotter core that doesn't get the chance to make contact with the heat exchanger. This maximises condensing of the flue gases, and in turn, improves efficiency.

The easiest way to explain this would be to say the heat exchanger is like a strainer for the heat, leaving no gases that haven't had a chance to come in contact with the heat exchanger to condense. Larger flue pathways would be akin to larger holes in your strainer.

Viessmann heat exchanger with condensatio droplets

Viessmann Controls

Although the 200 range boiler is not Open therm as standard, there is an Opentherm module available opening it up to third-party controls. However, this module is hard to obtain in the UK and is not supported by Viessmann UK. Regardless, Viessmann totally flexes their muscles once again here and manufacture some of the best domestic controls available.

As mentioned above, the boiler comes with a Vitotronic 200 (AKA HO2B) built into the front of the boiler. This control has a 5” colour touchscreen with hot water, hot water circulation, and weather compensated heating times and temperatures all programmable here.


We find the control very sleek, intuitive and simple to use. Additionally, to, they also offer external controls and room sensors in the form of the Vitotrol 200 and Vitotrol 300. These both give the optimum solution of placing a room influence % on your weather compensated control.


This gives your property and lifestyle the optimum efficiency and responsiveness. This sounds quite complex but really isn't... More on that subject here.


Furthermore, this boiler also accepts 0-10V signalling, as well as 240-volt signal commands, which you can assign to a multitude of tasks. Also, 240-volt relay outputs with various other input/output modules are available.


The optionalVitoconnect 100 will give direct app control of your boiler. This logs your boiler onto any local wifi you have available, rather than plugging it into your router. It gives full control of your heating system/hot water and boiler. Its also supposed to give diagnostic access to installers to reduce call out charges and any unnecessary visits, however, this is not yet available.


Their VitoCom unit has also been available for a fair number of years now which gives similar control with diagnostics. However, it's slightly more expensive, less accessible, and more ‘clunky for the installer end.

Viessmann control panel

Other benefits of the Viessmann Vitodens 200

Because of the boilers size and physical empty space inside, all components can be worked on and replaced very easily from the front. An Asubmounting kit is available, which connects beneath the boiler and gives dual temperatures with an optional full plate or partial plate separation (max 5KW circ). This essentially gives two separate weather compensated circuits and saves heaps of space, and assembly time.

Push-fit type design makes installation quick. The boiler has a push-fit installation system.
Plug and play extensions and controls mean more complex systems that require no faffing or complex wiring.
Although priced at the higher end of the market, the boiler comes with integral modulating controls as standard with diverter, meaning practically no wiring is needed or zone valves. Making advanced efficient installation very cost-effective.
Of the 2000 odd adjustable parameters, one of the most useful is the pump control. This enables separate pump control at both maximum output and minimum and ensures no excessive flow or lack of flow throughout its extensive output. Lack of flow control can lead to many issues, but in the main can save a notable amount of electrical consumption.

Viessmann Vitodens 200 Combi boiler Version

Unfortunately, the latest Viessmann 200 Combi boiler has downsized its plate heat exchanger to one resembling what you would find in most domestic boilers. An advantage of the last plate heat exchanger was its physical size, this gave more condensing and less chance to block up on dirty systems. However, they have made this incredibly easy to remove, which involves one forward-facing screw and the plate pulls forward.


Flow rates are just OK, although they could be higher. If you look at the specs they offer higher than stated kW output to hot water. However, the 26kw, 30kw, and 35kw models are fitted with 10lpm, 12lpm, and 14lpm flow restrictors retrospectively. Although not advised by the manufacturer, these can be interchanged. They have also told us it will not work without a flow restrictor but will comment no further on that. If flow rates are a concern Viessmann also sell the industry-leading 111 and 222 boilers.


As stated above there is no built-in flue gas recovery which is a shame but 3rd party flue gas recoveries are accepted although these will need checking with Viessmann technical first. Also worth noting the combination boiler version has full rubber flow and return hoses, whereas its system boiler counterpart is practically all copper.

Viessmann Vitodens 200 System boiler Version

As always, the Viessmann Vitodens 200 has an internal diverter valve. This has given them exemption from part of the G3 regulations which requires a cut-off valve and cylinder overheat thermostat if installed with one of their own cylinders and cylinder sensor. Its Also makes wiring the wiring of systems (particularly weather compensated) incredibly easy and fast.

This can also be assigned to sit in one position should you have difficulty installing a 4 pipe design, and the boiler configured to control external valves.


The flow and return on this boiler are nearly all copper. as opposed to its combi version which some see as a positive.
All in all, one of, if not the best system boiler available

Any Viessmann Vitodens 200 negatives?

The main negative of this boiler, depending on your priorities, is its size. It's literally the perfect product for flats and smaller homes due to its modulation ratio, but its physical dimensions, although making it very spacious and easy to work on, means finding a location for it can be more difficult than other boilers. However, in typical houses, this isn’t as much of an issue.

The dreaded ‘crunchy hoses’. There’s a rather big discussion between installers about the fact the boiler has rubber hoses. Rubber hoses seem to attract dirt particles through what we assume is the positive static charge of the rubber, binding with the negatively charged iron from corrosion in steel radiators (basically static charge).

The advocates of rubber hoses say it reduces noise, gives a natural filter which is easily cleaned on servicing if needed and gives ‘a window into the system’ (engineers squeeze the hoses to check for levels of deposits within the boiler). They also say this shouldn’t be an issue provided heating systems are appropriately flushed on installation and water quality is checked and adjusted if necessary during annual boiler servicing. Those not so fond talk about an unnecessary weak point, and boilers blocking up if not serviced for long periods of time.

Due to all the extra functionality, the PCB can be expensive as a spare, ranging from £300 to £450. All other spares are comparable in price to other brands.

The only other negative talked about is the availability of spares, however, due to internet stores this wasn't really ever a problem but more lack of installer awareness and now seems to have been addressed. Additionally, two main suppliers have started stocking parts on the shelf.

Modulating controls

That work with the Viessmann 200...

Tado
This image has an empty alt attribute; its file name is tado-smart-thermostat-starter-kit-smart-radiator-thermostat-vertical.jpg
Multiple Zones?
3, 2 mixed 1 unmixed, untested with smart valves.
Hot Water Control
Time and temp
Weather Compensation
Yes, local sensor
Internal Influence
Yes, adjustable
App Control
Yes
Wireless
Yes, Optional
Geofencing
Yes
Installer Portal
Coming soon, still, however available with Vitocom extension
Smart Integration
Alexa, Google Home, Apple Home Kit
Smart Power
Built into boiler controller
Known Issues
None
Vitotrol 300RF
This image has an empty alt attribute; its file name is vitotrol-300rf.jpg
Multiple Zones?
Room sensor and temp control only.
Hot Water Control
No
Weather Compensation
Yes, local sensor
Internal Influence
Yes, adjustable
App Control
Yes
Wireless
Yes, Optional
Geofencing
No
Installer Portal
Coming soon, still, however available with Vitocom extension
Smart Integration
Alexa, Google Home, Apple Home Kit
Smart Power
Built into boiler controller
Known Issues
None
Vitotrol 200A and 200RF

This image has an empty alt attribute; its file name is vitotrol200a.jpg
Multiple Zones?
Room sensor and temp control only.
​​​​​​​
Hot Water Control
No
Weather Compensation
Yes, local sensor
Internal Influence
Yes, adjustable
App Control
Yes
Wireless
Yes, Optional
Geofencing
No
Installer Portal
Coming soon, still, however available with Vitocom extension
Smart Integration
Alexa, Google Home, Apple Home Kit
Smart Power
Built into boiler controller
Known Issues
None
Vitotrol 300A
This image has an empty alt attribute; its file name is vitotrol-300a.jpg

Multiple Zones?
3, 2 mixed 1 unmixed
Hot Water Control
Yes, time temperature and HW secondary circulation
Weather Compensation
Yes, local sensor
Internal Influence
Yes, adjustable
App Control
Yes
Wireless
Nol
Geofencing
No
Installer Portal
Coming soon, still, however available with Vitocom extension
Smart Integration
Alexa, Google Home, Apple Home Kit
Smart Power
Built into boiler controller
Known Issues
None

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November 11, 2018
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Vat number: 364541984
Company number: 11887015
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