Viessmann Vitodens 200-w - initial impressions

[larry]

Hello 

I had the Viessmann 200w installed recently and, as I wasn't able to find out loads from the forums in advance, thought I'd post a few initial impressions and 'gotchas' here that tripped up the installers a little as part of the installation.

This was the most recent version of this boiler with the colour touch-screen (B2HF/B2KF). 

 

First gotcha, it doesn't come with a 'fittings pack' - there are several types you can get and whilst it states this clearly on the Veissmann direct website, this seemed to be news to the installers, and also the merchants who supplied the boiler. So our first install left us with a boiler hung on the wall but not connected whilst we waited for the fittings pack to arrive and then be installed.

 

Second gotcha, it doesn't come with opentherm. I thought this was surprising as I believe the 100-w does, and I was hoping to use this with the Drayton Wiser system that we have installed (which I think is excellent, also).

 

Third gothcha, there are three 'modes' of operation that have to be set during the commissioning process, and if you want to change the mode you have to recommission the boiler. However, you can do this fairly easily with the app (ViStart for the installer, and ViCare for the user - you can download both from the Google Play store). The three modes are 'weather compensation' mode, 'continuous operation' mode and 'room temperature dependent' operation. The second and third modes don't seem to make any use of weather compensation - and if you set it up in weather comp mode and then connect a stat, the stat won't talk to the boiler at all (lots of head scratching here from our installer). So, to get this to work with our Drayton Wiser system we currently have it connected on 'continuous operation' mode; there is then a setting to turn off continuous pump operation when there is not a call for heat, though oddly in this mode even if there isn't a call for heat there is a minimum flow temperature setting (default at 20'c). I am going to try and switch it over to room temperature dependent operation at some point to see what this does (my guess is it'll only work with a Viessman stat), but for now it is working fine - the boiler is firing when there is a call for heat and not where there isn't. 

 

Fourth gotcha, we've got a fairly large detached house and had previously had an older Baxi boiler which clearly had the pump turned right up to maximum. The Viessman has a variable speed pump, but I found that I had to adjust the minimum pump speed setting upwards somewhat to get the far-out radiators warm at the same time as the rest of the house. 

 

Fifth gotcha, Viessmann had apparently specified not to use inhibitor with the boiler at all. Our installer thought it was something to do with rubber hoses perishing. At first I was so surprised at this (as was he) that I checked with Viessman technical who confirmed this was the case. 

 

 

Apart from this, it seems a good boiler so far - it is keeping us warm, seems pretty quiet, and the App has a few nice settings e.g. being able to see exactly how much gas (in cubic metres) you use on any given day. Quite astonishing seeing this over the recent snowy weather we've had over the last couple of weeks.  It's also nice seeing the modulation stats, as that was the main draw for us for this boiler, that it modulates very low. An interesting setting seems to  allow you to limit the amount of time the hot water runs before cutting off (and then I think set a minimum wait period).... potentially handy for anybody with teenage daughters?!!

 

 

 

 

 

 

 

 

 

 

 

[Adsibob]

@larry this is good to know; I am also considering this very boiler. Which size Vitodens 200W did you go for? Did you consider setting up with a Tado system to control it rather than the ViCare app? What other boilers were you considering and why did you go with this one? Are you still happy with your choice?

[larry]

On 26/04/2021 at 23:28, Adsibob said:

@larry this is good to know; I am also considering this very boiler. Which size Vitodens 200W did you go for? Did you consider setting up with a Tado system to control it rather than the ViCare app? What other boilers were you considering and why did you go with this one? Are you still happy with your choice?

Hi there,

 

So - it is the 35kw model, combi boiler. 

 

We use a Drayton Wiser system to control it. I had bought the Tado system but returned it when I read that it stopped working when internet connectivity dropped. I instead went for the Drayton Wiser system which I have been very happy with. It's also nice it is a UK product (the Tado system might be from a German company but it is made in PRC). I use the ViCare app though to keep an eye on the boiler, the data about gas and electricity consumption is interesting to see. 

 

In terms of other considerations I was looking at the range of Intergas boilers as these seem well regarded on the forums. I'd spent ages looking. But I'm not a plumber, tradesperson or heating expert so I suspect you can over-read into this, and everybody seems to have their favourite anyway. One of my key considerations was that the boiler modulated well (particularly with the Wiser system, where you might have heat demand from only one or two rooms), and this is by far and away as far as I can see the hands down winner on this front.  Also, practically, trying to find somebody to fit and install one over the last few months around here was a nightmare without paying silly money or just getting somebody who was only happy to put in a Baxi or similar. In the end I wasn't actually really happy with the company that installed it (a big national chain that supplies Viessmann) but I suspect I was a little unlucky with various things.  If I did it again I'd definitely want to try to get an installer who had actually seen the 200w before! 

 

 

Am I still happy with my choice? So far, yes... at least until.... two weeks ago we have had our first problem. It had been working absolutely fine. It then started essentially not turning off even  when there is no call for heat/DHW. It runs down to 6% modulation so the burner is right down but it essentially seems to think there is DHW demand when there is not. Pump keeps running, burner keeps running. It turns off when you turn off the system in the ViCare app. Have tried various things and in the end contacted the company who installed it who (very quickly) sent a Viessmann rep. They spent all morning fiddling about with it and it seems to have been fixed - but I'm not hugely confident, since clearly the installer didn't know what was wrong or why it was doing this; he just explained he reset all the boards and settings. I'm always sceptical when the 'mechanism of action'  for the failure isn't clearly identified and 'oh now it seems to be working'.   If this turns into a longer term problem I guess my answer is 'no, I'm not happy', but if it it's a one off then 'yes'. However, the engineer's approach did make me think whether these boilers are just a little too complex for their own good.... 

 

I'll update on here whether we have other problems and try to give some longer term updates in any case. 

 

 

[Nickfromwales]

Thanks for the heads up, that is very valuable information for the masses  

For me a relatively complex, not cheap boiler which dictates that the rest of the system can just literally sit there and rot away minus the presence of an inhibitor chemical......? Not a chance!!! After 5 or so years the primary water will be like gravy, and then comes the likelihood that the subsequent high concentration of waterborne debris start to cause other early fatigue.....? Again, not exactly a strong selling point, sorry.

Have you asked if there is a consequence of putting an inhibitor into the system? Warranty void etc / other? 

[Onoff]

6 minutes ago, Nickfromwales said:

Thanks for the heads up, that is very valuable information for the masses  

For me a relatively complex, not cheap boiler which dictates that the rest of the system can just literally sit there and rot away minus the presence of an inhibitor chemical......? Not a chance!!! After 5 or so years the primary water will be like gravy, and then comes the likelihood that the subsequent high concentration of waterborne debris start to cause other early fatigue.....? Again, not exactly a strong selling point, sorry.

Have you asked if there is a consequence of putting an inhibitor into the system? Warranty void etc / other? 

 

I understand the advice from Viessmann is to fit an air seperator to exclude air from the system as in no air no corrosion. Read that somewhere.

[PeterW]

Alpha e-Tec and Protec boilers are good for the price. They have also brought out one with a thermal store add on which is a combi with a gas saver and buffer if you can’t site a cylinder and still want large flow rates. 

[Nickfromwales]

12 minutes ago, Onoff said:

 

I understand the advice from Viessmann is to fit an air seperator to exclude air from the system as in no air no corrosion. Read that somewhere.

It's a problem when you first introduce oxygen rich 'fresh' water into the system, and the problems escalate from there. No air ever 'gets into' a system, it's nitrogen that gets generated by the corrosion process that usually needs 'venting off' hence the air release valves at all high points vs an air separator per-se. Wasn't aware you could get an AS for a sealed system? 

[SimonD]

1 hour ago, PeterW said:

Alpha e-Tec and Protec boilers are good for the price. They have also brought out one with a thermal store add on which is a combi with a gas saver and buffer if you can’t site a cylinder and still want large flow rates. 

Great stuff, thanks for the heads up on that. I've been looking for boiler and thermal store setups for a while now and this looks ideal.

[PeterW]

@SimonD I’ve not looked at it but does the Alpha thermal store have an immersion available for backup or PV dump load...?

[SimonD]

2 minutes ago, PeterW said:

@SimonD I’ve not looked at it but does the Alpha thermal store have an immersion available for backup or PV dump load...?

I've just been scanning brochure and installation docs and it does have immersion available. They also sell a PV kit. I haven't read in detail but remains promising.

[Adsibob]

@larry I was also attracted to the Veissman because of its superior modulating abilities. We need to heat a largish 5 bed house with 3 bathrooms (although only two bathrooms will be in use regularly). Hot water demand is going to be HIGH because I just bought a ridiculously large bath from Lusso Stone and plan to use it regularly, so a Combi Boiler is not feasible. All the boilers I've ever had have been Vaillant Combis. They are okay, but they do fail. It's a shame Veissman is that much more complicated. I did originally go through a Veissman approved company to get the whole heating and hot water system designed, but I was put off by the sales tactics and they were also unreliable. 

@Nickfromwales are your negative comments about the Veissman based on real world experience of it, or is it just a theoretical aversion to it based on what you've read about it?

I have just googled Protec following on from @PeterW's recommendation and they seem focused on Wakefield and the surrounding areas. No good for me as I'm London. The Alpha E Tec seems to be a combi boiler, so that won't work for me either as I need a system boiler really.

My builder has recommended Keston, but my father in law has had bad experiences. Obviously this is all subjective opinions formed on anecdotal evidence. Which magazine purports to provide more independent and scientific views, but actually much of their "best buy" recommendations is based on limited survey data as opposed to thorough tests.

 

Any further thoughts welcome, anecdotal or not.  

[Nickfromwales]

4 minutes ago, Adsibob said:

@Nickfromwales are your negative comments about the Veissman based on real world experience of it, or is it just a theoretical aversion to it based on what you've read about it?

My negative comment wasn’t about the boiler it was about a boiler manufacturer telling me I can’t protect the rest of my system by banning the use of inhibitor. A first for me, and I’ve been installing heating systems for over 25 years. 
The Veissman boilers have a good reputation, but this latest nonsense with controls / boiler type selection / aversion to inhibitors etc would put me right off. Plus they’re asking a lot for it too. 
Give me a good old Baxi or Vaillant every day of the week. 

[Adsibob]

8 minutes ago, Nickfromwales said:

Give me a good old Baxi or Vaillant every day of the week. 

So which Vaillant and Baxis do you recommend to supply hot water to a 300L tank, heat 5 towel radiators across the three bathrooms and a couple of rads on the loft floor and do about 100m2 of underfloor heating? Modulation abilities and efficiency are key, as heating and hot water demand is variable in our house. 

Edited April 28, 2021 by Adsibob

[PeterW]

Like @Nickfromwales I would never specify a system without inhibitor. The boiler is one component. You can get galvanic corrosion from a mix of materials and there are far too many in a heating and hot water system to remove what has become a core component of a heating system. 
 

14 minutes ago, Adsibob said:

have just googled Protec following on from @PeterW's recommendation and they seem focused on Wakefield and the surrounding areas. No good for me as I'm London. The Alpha E Tec seems to be a combi boiler, so that won't work for me either as I need a system boiler really.

Have you googled the right thing ..? Alpha make the e-tec S which is a system boiler. 

 

https://www.alpha-innovation.co.uk/products/Boilers/System+Boilers/E-Tec+S/793038486

And it’s UK wide distribution and installation - this is the London map

 

[Adsibob]

Thanks, that's helpful @PeterW. The website I was finding was this one: https://protecboilers.com/.

 

I note the Alpha E Tec S only gives you a 10 year warranty if you install their "Alpha Premier Pack Extra". Didn't know what that was, but digging around their website I found this:

 

The Alpha Premier Pack Extra is only suitable for use with Alpha boilers originally supplied with threaded type isolation valves. It must be installed in accordance with these instructions and the installation instructions supplied with the boiler. The kit comprises of a wall jig fitted with a magnetic cyclone and pipe clips, wall template, flow and return split tails, bottom tray, screw pack and wall spacers. The wall jig has been designed to be fitted to the wall before the boiler, allowing the pipework to be pre-fitted. The pipework can be installed vertically upwards and downwards using the flow and return connections supplied on the jig.

 

Apart from the magnetic cyclone - which I presume is something equivalent to a magnaclean - how does this prolong the life of the boiler?

 

Also, anyone know why the specs don't reveal the flow rates its capable of? Isn't that important in terms of knowing how quickly it can fill the hot water tank and supply the rads?

[PeterW]

9 minutes ago, Adsibob said:

Also, anyone know why the specs don't reveal the flow rates its capable of? Isn't that important in terms of knowing how quickly it can fill the hot water tank and supply the rads?

Flow rates normally only refer to combi boilers. For a system boiler they are unknown unknowns ..?? Cylinder recovery rate is based on cylinder size, coil surface area, pump speed and boiler temperature. Radiators are just rads - it supplies the rated kW at 70°C to the heating system. 
 

Who’s done the M&E design for the build ..?

[larry]

2 hours ago, Nickfromwales said:

My negative comment wasn’t about the boiler it was about a boiler manufacturer telling me I can’t protect the rest of my system by banning the use of inhibitor. A first for me, and I’ve been installing heating systems for over 25 years. 
The Veissman boilers have a good reputation, but this latest nonsense with controls / boiler type selection / aversion to inhibitors etc would put me right off. Plus they’re asking a lot for it too. 
Give me a good old Baxi or Vaillant every day of the week. 

Thanks Nick, well to be honest what actually happened was the first fitter who arrived couldn't finalise the install as they didn't have all the parts. However he had helpfully installed it so the heating output was connected to a 15mm branch not the 22mm main runs. He'd also connected it so the the t into the branch leaked, but we didn't know that at the time of course until we filled it up. Next chap who came  (who seemed to know his onions a bit more) discovered the leak after filling and spent a morning trying to resolder a joint that clearly wasn't having it. It worked but then leaked after the day after left. With snow forecast, and no promise of an engineer, I ripped out the pipework myself and did it myself to my own standards (which believe me are not high) running it back to the main 22mm pipes. I only explain the drama as I actually filled it and added inhibitor when doing so which remains in the system now. When the chap came back to sort out our controller (again another morning on the phone to viessman working out how to plug it in) he explained the viessman advice about inhibitor but was not fussed about draining it down. I certainly wasn't going to drain down the system only to fill it with plain water and frankly given the risk as I understand it seems to be avoiding rubber hoses perishing rather than anything else I certainly plan on keeping it that way - and will see what a (completely different person as yet to be identified!!) makes of it when it comes to service.

Honestly, the install was a nightmare and this is only a quarter of the story. But that's not (much) the fault of the boiler itself....

Edited April 28, 2021 by larry

[Adsibob]

1 hour ago, PeterW said:

Who’s done the M&E design for the build ..?

Me. Based on research done here! It's not being installed for another 3 weeks or so, and nothing has been bought yet, so a little bit of time for changes to be made. The current plan is:

 

Veissman Vitodens 200 35kw some other system boiler!?!

"appropriately sized low loss header", whatever that means

Telford Tempest Horizontal unvented cylinder, 300L with one heating 3kw element (which is how Telford make them - do you think I need a second element as i see some come with two?

A secondary loop with a timer running 1 min every 25 or 30 minutes during the day to keep outlets providing hot water instantaneously

underfloor heating on ground and first floor (in the ground its inbedded in screed, on first floor it is routed through Cellecta XFLO extruded polysterene boards). A couple of small rads in the two bedrooms on the loft and 1 towel rad in each of the three bathrooms, except the ensuite is big enough to have two.

All pipes will be insulated.

 

I have not specified any more detail than that really. I showed it to my builder and asked if his plumber and heating engineer could confirm whether they could supply and install such a system and make sure it worked well, and ... well he's never come back to me! 

 

Originally I had designed it so everything was very close to everything pretty much, but then the MVHR design company pointed out that their Flair 400 would need much more space than I had allowed for it because of all the pipes, and so we've had to move the cylinder quite far away... but that is the subject of this other post.

 

[Nickfromwales]

9 hours ago, Adsibob said:

Veissman Vitodens 200 35kw some other system boiler!?!

Never had a days problem with Vaillant

[Adsibob]

35 minutes ago, Nickfromwales said:

Never had a days problem with Vaillant

Thanks @Nickfromwales The Vaillant Ecotec Plus looks good. 30 or 37kW heating output?

[Nickfromwales]

I’d only go to the 37 if you were doing DHW via a thermal store. 30 will be plenty. IIRC both modulate down to much the same minimum output so, as you’re heating via a buffer, there’s only so much heat you’ll be able to get from A>B anyways. 
The only time you’d ever suffer is when you’re heating from bitterly cold back to comfort temps but that’s not a regular occurrence and not worth any subsequent investment afaic. 
Vaillant are rock solid, but, same as with most, the weather comp is a total ball ache ( however you cannot fit it anyway because of the number of heating circuits plus you’re heating a buffer so deffo do not purchase WC equipment. 
I’d look at  Emmeti ( thanks to @PeterW for the link ) for controls, so you get a closer handle on hysteresis, as a stat with as much as 0.5oC can cause over / under shoot. 1oC would be a train crash. 

[Adsibob]

6 hours ago, Nickfromwales said:

I’d only go to the 37 if you were doing DHW via a thermal store. 30 will be plenty. IIRC both modulate down to much the same minimum output so, as you’re heating via a buffer, there’s only so much heat you’ll be able to get from A>B anyways. 
The only time you’d ever suffer is when you’re heating from bitterly cold back to comfort temps but that’s not a regular occurrence and not worth any subsequent investment afaic. 
Vaillant are rock solid, but, same as with most, the weather comp is a total ball ache ( however you cannot fit it anyway because of the number of heating circuits plus you’re heating a buffer so deffo do not purchase WC equipment. 
I’d look at  Emmeti ( thanks to @PeterW for the link ) for controls, so you get a closer handle on hysteresis, as a stat with as much as 0.5oC can cause over / under shoot. 1oC would be a train crash. 

Thanks @Nickfromwales. I think the 30kw unit is a bit shallower in terms of how much space it will occupy in our utility room, so if we can make that work that would be a bonus. Controlwise, I was planning on all the thermostats in the house being tado ones. They can be calibrated to 0.1C and I found they worked very well at my last place. I know they rely in part on internet connection, but I think that's less of an issue for me and they mostly have a backup manual override that can be used if ever the internet is down.

[Adsibob]

2 hours ago, Adsibob said:

Thanks @Nickfromwales. I think the 30kw unit is a bit shallower in terms of how much space it will occupy in our utility room, so if we can make that work that would be a bonus. Controlwise, I was planning on all the thermostats in the house being tado ones. They can be calibrated to 0.1C and I found they worked very well at my last place. I know they rely in part on internet connection, but I think that's less of an issue for me and they mostly have a backup manual override that can be used if ever the internet is down.

 

So turns out the 30kw model is 2dB louder than the 37kw model. I wonder if it's a bit like MVHR in that by oversizing one strains the system less. Or maybe it's the additional housing that comes from that extra couple of cm.

 

If i go for the 37kw model, do you know whether i need the 28mm boiler protection kit or the 22mm boiler protection kit which Vaillant insist on to get their 10 year warranty?

[markocosic]

Have a read up on VDI 2035 water treatment standards.

 

Inhibitor isn't required on a tight (airtight) all-iron system willed with decent water. There will be some initial corrosion, which will use up all the oxygen and raise the pH of the system, then it stops and all is good.

 

You get problems if there is a continuous supply of oxygen into the system. (systems with leaks and lots of top-up action; cheap underfloor heating pipe without an oxygen barrier) You MUST use an inhibitor with these (and keep replenishing it in the case of leaks)

 

You get problems in mixed metal systems. High pH destroys (cheap) aluminium alloy heat exchangers. Low pH destroys steel. You MUST use a buffered inhibitor with mixed metal systems.

 

Quality boilers will either have stainless heat exchangers or stainless-lined-alloy / copper-lined-alloy. Perfectly normal NOT use use inhibitors on these. You might dose them to get the pH up quickly if they're a large system. Else just leave well alone and if it's tight it won't rot as there's no supply of oxygen to drive the reaction. No chemicals down the drain. No chemicals attaching your plastic/rubber components.

 

Fernox, Adey, Worcester and co all have massive marketing budgets. Systems are often leaky old rubbish (and you don't notice with open header tanks). Cheap boilers (Worcester et all) are all make of case hardened recycled coke cans and plastic. They will fall to bits without treatment. All the premium stuff usually calls for water quality to VDI 2035 instead.

[Adsibob]

4 minutes ago, markocosic said:

Have a read up on VDI 2035 water treatment standards.

 

Inhibitor isn't required on a tight (airtight) all-iron system willed with decent water. There will be some initial corrosion, which will use up all the oxygen and raise the pH of the system, then it stops and all is good.

 

You get problems if there is a continuous supply of oxygen into the system. (systems with leaks and lots of top-up action; cheap underfloor heating pipe without an oxygen barrier) You MUST use an inhibitor with these (and keep replenishing it in the case of leaks)

 

You get problems in mixed metal systems. High pH destroys (cheap) aluminium alloy heat exchangers. Low pH destroys steel. You MUST use a buffered inhibitor with mixed metal systems.

 

Quality boilers will either have stainless heat exchangers or stainless-lined-alloy / copper-lined-alloy. Perfectly normal NOT use use inhibitors on these. You might dose them to get the pH up quickly if they're a large system. Else just leave well alone and if it's tight it won't rot as there's no supply of oxygen to drive the reaction. No chemicals down the drain. No chemicals attaching your plastic/rubber components.

 

Fernox, Adey, Worcester and co all have massive marketing budgets. Systems are often leaky old rubbish (and you don't notice with open header tanks). Cheap boilers (Worcester et all) are all make of case hardened recycled coke cans and plastic. They will fall to bits without treatment. All the premium stuff usually calls for water quality to VDI 2035 instead.

@markocosic thanks for that, which makes sense as I always thought Veissman was a quality brand. You've really put the cat amongst the pigeons now!