The boiler is noisy when starting up and running - the manual timer fitted to the 100 is also irritating due to the constant fast ticking noise. The manual timer does not allow for setting different times on different days. The boiler’s eco settings can cause the radiators to be warm even though the hall thermostat is set to the absolute minimum. Other reviews have mentioned this also happens with overriding individual radiator thermostats but I’ve not tested for this. The model has had issues in the past and they now recommend copper pipes being fitted on installation. Personally I’ve been unimpressed with this boiler since installation. I’ve given it three weeks since the install and I will now either sell the property or scrap this one and fit another brand that I’ll be happier with. The performance of the 100 for my 3 bed property is very poor. It has a 10 year guarantee of which one month has expired. The guarantee doesn’t seem to mean much and who knows how much longer Viessmann will be around as a company to honour it if required. Avoid. Don’t risk buying. If I see a Viessmann boiler fitted in a property I’m considering buying I’d factor in changing it to another model. Don’t waste time and energy on something that’s not worth the trouble.

Had this boiler fitted 5 weeks ago has gone off twice in two days and failed. The worst thing is the Engineers don't work weekends. Now British Gas they work 7 days a week and prioritise the elderly and disabled. This company can't even be polite when you finally get to speak to them three times I tried Sunday first numpty that answered asked me to hold them kindly cut me off,second time nobody answered guess he was busy having coffee third time took the details said someone would be in touch Monday another story. All in all a chap boiler fitted by a bunch of xxx as expected with German engineering overpriced rubbish!!!!!

We spent over $8000 installing this boiler 5years ago, called the company for installer. 3year ago it broke down, this year it did again, changed the control panel for $2600 on January 25th, it broke down twice already. It was a bad investment and it poses a potential damage to your home.

we've had a Viessmann Vitodens 100 for eight years and every year it gives us problems. This year it's constantly registering F9 fault. I had my plumbing-heating contractor/installer look into this 3 times this season. He has even called Viessmann technical support and even they couldn't figure out what is wrong. I'm convinced this product is a lemon. We used to have a Burnham boiler for 20 years and never a problem, only yearly maintenance was necessary. I miss it. anyone wanna buy a used Viessmann boiler?

We've had this boiler for nearly 9 years. First new part just after 2nd year, and even though it's serviced every year, we've had same part(bladder) renewed every two years! We have now just been quoted for a small part that has cracked so boiler leaking. The cost is over £450 plus vat and labour. So have nearly paid for this boiler twice. Time for a new one!!!

We have the misfortune to own veissman vitodens 100 and t is the worst thing we have ever owned, it constantly has problems from the clock not working through leaky taps and washers to simply just not working. It first really failed "Just after the warranty ran out" and that was 5 years ago, we have never had proper service out of the boiler and the company just wants to charge exorbitant call out fees to even come and look at it. Veissman are without a shadow of a doubt the worst boilers and company ever, we are going to replace it with a Worcester boiler next. It would have been nice to know nhow bad they were beforehand

I've installed over 30 of the Vitodens 100's and a few 200's (and viessman oil boilers) over the last 8 years. I have had very little installation issues or call back complaints. Recommend the low loss headers, and a quality air separator. Also check water quality and use cleaner/conditioners (authorized by Viessman) especially if this is a replacement. Setup or check combustion with quality certified equipment. Remember any product can have issues but many of my findings in the field come back to installation. Follow manufacturer recommendations and true of any brand, hire a company who has actually been to a class for the brand they are installing.

Bought this boiler in 2014 based on the installers recommendation and we have had more problems with it than we had in the 10years of our old boiller. In the last 6 months , this boiler has broken down 3 times due to dirt in the system. The last time we were advised to power flush the radiators which cost about £350 but guess what, we have no hot water again! Another blockage due to dirt. Engineers really need to stop recommending this product .. our installer with years of experience is as disappointed as us.. you might have a few happy customers but overall just a scrappy piece of work .. my advise is to avoid this product!

Had this boiler fitted and constantly had issues that at first were corrected under warranty. They then decided to void the warranty claiming it must be a fault in our system of radiators. We have spent £100's or repairs and now face a £500+ bill for a manifold. We have decided it's time to just rip it out. I'm disgusted with not only the poor quality of the boiler but also the customer services. Avoid at all costs is my advice.

Installed Jan 2008, So called state of the art, Has never completed one year without fault. Most years plumber called 2 or 3 times. Reading other reviews I see that we all suffered identical breakdowns and faults so, Viessmann, do not blame the fitters. Serviced annually only to be followed several weeks later by another breakdown. Was repaired,again, three weeks ago.This morning it has "died" again.Plumber advises " a new motherboard £500!! The most unreliable,costly item I have ever come accros. Absolute junk. DO NOT BUY.

I'd a 5 year g/tee. Year 6 the "bladder" failed so no heating for more than a week as the part is not held in the UK & has to be imported. Will cost me well over £300 for plumber to replace. I was sold the boiler as being "state of the art" and cheap to run: but had not reckoned it would fail after 6 years. So I am very disappointed that it hasn't lived up to my expectations. Friends who have had similar combi-boilers installed have had no problems over 10 years +. My previous Potterton boiler served me well for 30 years without problem. Why is it that Viessmann has glitches after only 6 years? Not at all happy.

Had this boiler installed winter 2008 whilst building a very large extension to my property. Services new plumbed rads (8) and underfloor heating to new build and (12) old rads to existing along with heating my hot water. Never had any problems with the boiler (professionally installed, regularly serviced). My bills are very low in relation to the size of my property. No complaints only praise as its on 24/7 365.

Had this boiler installed for my self build and have been running it for over 5 years without a single issue. It's running hot water, radiators on one floor and under floor heating on two floors. Make sure it's installed by someone truly competent and of course keep it serviced. My bills are far lower but this is probably as much due to the new house construction as to the boiler.

Not long after moving into our property we have had our boiler break down on Christmas eve, Due to the time period we were without heating till the start of Jan. The heating and hot water just stopped. No faults came on the system and our heating engineer advised a new motherboard, which was fitted. At first it still did not work again and baffled the engineer, who did in the end get it working after several phone calls. All was well for 10 days and the fault has now came back again. So cold again.

About the only thing you can rely on is that it is going to let you down. Regularly. Repeated faults, where it just refuses to flame up - and this is definitely the boiler's fault, not the thermostat or water pressure. One frequent failure is "F5", which is reputed to be due to a flap in the air circuit sticking. The flap seems to be totally unnecessary but we are not allowed to remove it. Don't buy a Viessmann - anything else must be better.

Far superior than any other boiler, if you have a Viessmann installed by an accediated Viessmann installer you will be offered an extended warranty for ten years. I have had my current boiler for three years, my gas bill reduced considerably after I had it installed. It his boiler knocks the socks off my last boiler

Three years ago I moved into a house with a Veissman boiler and have had no trouble with it whatsoever. It's easy to use, good controls and everything's very logical. I had the boiler checked and serviced before the winter really started - the maintenance guy gave it a thorough going over and replaced something small which didn't cost very much. The boiler has worked well again over the winter, keeping the house warm. This is a great boiler - compact so it doesn't take up laods of space and it runs efficiently without any problems. All in all, I'm very impressed with this boiler and would recommend it to others who are considering ahving a new boiler installed.