We had a faultless installation by Doug Misson heating engineers in Jun'10. They were recommended by Worcester Bosch and installation came with a 5-YEAR manufacturer's guarantee and they were all done in 1-day. We had quotes from several installers around Cambridge - some didn't even bother to submit a quote: we stated that we can buy the SAME Vaillant boiler for about £1,000 including flu and delivered - so "what's the extra £1,500 for?" Most objected to this questioning - presumably as it's exposing them charging £1,500+ for some copper piping and a day's work. Doug Misson are a reasonable-sized company with enough engineers that we saw three different vans and four different people to help during the day. Doug Misson were more than £700 cheaper than "one man band" installers we also asked to quote ... and Doug Misson also fitted a top-end Worcester Bosch 27CDi boiler with a 5-YEAR guarantee. A similar-sized company, based-in Babraham wanted over £1,000 more AND had lots of caveats for opportunities to charge extra; Doug Misson gave us an "all inclusive" price and that's EXACTLY what we paid even though they had to fit a new gas pipe - we expect we'd have been charged £100's extra by the other company with these caveats - beware! We had already suffered with a Vokera for a few years: every engineer claimed it was difficult to work on and proved very expensive to service and repair. So we ONLY took quotes for Worcester Bosch and Vaillant as parts and engineers appeared more readily available. Worcester Bosch's 5-YEAR guarantee was a deal clincher for us; I'm sure Vaillant is great too. After dealing with so many different heating engineers in recent years with our troublesome Vokera boiler - Doug Misson were like a breath of fresh air: keen to do the work, competitive and did EXACTLY what they promised and with NO hidden extra costs. In our experience: faultless.