This installation started as a phone enquiry relating to a house in the Kensington area of London in early 2021.

The story, relayed by owner’s son in law, was that his parents had a light commercial boiler that had failed some months earlier, and they had found it difficult locating a contractor prepared to consider utilising the existing chimney for a new boiler.

Snow on the ground, it’s February 2021 in Kensington and Chelsea

As we are based in Kent, Kensington is a bit of a schlep to drive for a quotation. We have done a fair bit of work in Kensington during 2020, much of it that would make really interesting reading on this blog – but unfortunately we are not able to use this material.

We do make a charge for quotations outside our normal working area, this varies on the value of the job and the distance travelled. The owners were in their 80s, and had been without heating for months when we got involved. Being made of strong stuff, they had battled through winter regardless with very little complaint.

Dealing with the owners, and their son in law, was an absolute pleasure. Nothing was too much trouble for them, we had the family reserving pay and display spaces with their cars each morning.

The property was 4 stories tall and faced onto a major road, with a typical rendered Georgian frontage. At the rear of the property was a square, effectively a huge private garden for all the surrounding properties.

The large pipes top right are asbestos lagged. We left them alone, the lagging was in good condition and sealed.

It was believed that there was a local bylaw forbidding boiler flues from exiting in the garden direction, although one rather ambitious kitchen extension seemed to have flouted this rule.

Ideal Concord CX60 and hot water cylinders

At the front of the house, a flue coming horizontally out of the cellar would have shrouded the front of the building with steam, thus their desire to have a lined chimney solution.

Light well passage at the front of the property, often used for flue outlets

Their local Gas Safe company had said they could fit new burner bars to make their old boiler work, but my survey showed that this would have resulted in a dangerous situation. Their Ideal Concord 60Kw CX open flue boiler had a cracked iron section, dropping system water onto the burners.

Burners are under water
Gas burners were full of heating water
Cracked iron sections inside boiler mean it is the end of the road

Lining a chimney for a new boiler is always more expensive than bashing a flue horizontally though a wall, but given the circumstances they knew what they preferred and entrusted us to make it happen. Fortunately the building had a predominantly flat roof making chimney top access relatively straightforward.

Finishing touches
Flue terminal had to be metal version due to proximity to others – 7 day lead time from Germany!

We specified a Viessmann 200W 60KW boiler, which we wall hung within the existing hearth. Using open flue mode, like the Concord CX, we drilled ventilation high and low vents – because, amazingly, there had been no permanent ventilation.

The house had two hot water cylinders, and considering the boiler was replaced as recently as 2000, there was no way of separating heating and hot water without turning every radiator off individually in the summer.

Clearly, this couldn’t continue.

The Viessmann 200W was fitted with a low loss header and the old ‘one pipe’ heating circuit was attached by zone valves, and the hot water similarly.

One pipe heating systems have delivered good service in buildings for many years, and while the ‘2 pipe’ method used over the last 60 years delivers better results, the former will still make a good job of heating a house. Therefore unless significant alterations are needed, the one pipe can usually be repurposed on a modern condensing boiler, and that is what we did here, meaning virtually no work had to be done outside the cellar area.

One thing we did have to change was the feed and expansion tank, this was located in a box on the flat roof, and linked to the heating system by a pipe loosely insulated with hessian wrap running 4m horizontally across the roof. It was considered likely that at some point this had frozen solid and caused excess pressure from the expansion of heated water to crack the boiler.

Combined cold feed and vent outside? Yep. There was another 4m of pipe up out here

We removed the header tank from the circuit and provided a Mikrofill AFD (automatic filling device) in the cellar boiler room. Because of the height of the property, the pressure in most of the house under a sealed system is little different to before. And as we hoped, there were no significant issues resulting.

The system has a target fill pressure of 1.3Bar. This unit keeps it topped up, but disconnects in the event of a significant water loss from the radiators
Ricky adding inhibitor to the finished system, dual Magnaclean 28XP filters were fitted to protect the boiler

Our customers were relieved to get their heating working again, a Nest Generation 3 heating controller was fitted to control heating and hot water from a room upstairs, and via the Nest app.

Nearly finished, group shot with our customers, new boiler takes up less room too…

The Viessmann 60Kw 200W was commissioned by us and supplied with a manufacturer 10 year parts and labour warranty.