Today we are in a house in a beautiful part of the Garden of England, in other words, Kent.
The house is in a small village reminiscent of the one filmed many years ago for a Hovis advert, with cobbled streets and high pavements.
Our customer had bought a house with an old Potterton Osprey light commercial in the cellar, and British Gas had said that many parts were no longer available.
Other contractors had suggested the only options involved siting a new boiler on an external wall; this would have resulted in lots of unwanted visible pipework but also would have required approval due to the change to the facade of the building.
Our survey was confusing, because although there were many pipes in the cellar, none of them seemed to specifically relate to the hot water cylinder sited on the second floor.
Many of the rooms were large and had a plethora of 1960s era radiators in them. It was a difficult house to heat as many of the walls were very thin, rendered with lime plaster on timber lathes with tiling on the outside. In fact, if they put heat inside, the owners found it soon disappeared.
Our brief was to replace the boiler system, make the system more efficient, whilst not affecting the external appearance and thus upsetting the conservation officer.
It turned out that the hot water was indeed uncontrollable – you had to physically walk around the house and turn off 20 radiators individually when the summer months came by!
Not sure this system would have met building regulations even when the Osprey was new, but there you go. It was clear that the installers 25 years ago had decided that threading new pipework through the property to the hot water cylinder was just too difficult.
So, what to do?
Our proposal was centered around upgrading the boiler plant, giving the latest modern control, reducing running costs, whilst increasing comfort, and getting the new boiler in without affecting the external appearance of the building.
We specified a Viessmann 100W 35Kw open vent boiler in the basement; although the outgoing Osprey was considerably more powerful (around 50Kw) it was apparent that this was oversized.
Scaffolding was put on the roof 4 storeys up from the basement. Vehicular access from a mobile work platform wasn’t possible due to the pavements being 1 metre above the road – this job was not straightforward in any respect.
We routed a new Viessmann plastic flue liner through the chimney, following the line of the old Osprey flue. As there were 4 chimney pots on the stack, and some of the others were still being used, we configured the Viessmann in ‘open flue’ mode. We also specified their special order metal flue terminal, as a plastic one could be melted with live adjacent chimneys.
The flue terminal comes in one colour, the same one as a Model T Ford. It also comes welded to a rectangular flange base for fitting flat atop a chimney. For this job, we wished to retain the old round ceramic chimney pot, so that it matched the adjacent ones.
So we cut the metal baseplate into a precise circle so we could sit it just within a groove inside the old chimney pot, and resprayed the black metal with a cream outdoor enamel, to closely match the chimney pot.
And all this while it was snowing.
In order to improve the efficiency, and for technical reasons to do with cold feed and vent pipe layouts, we converted the heating system to a ‘sealed type’ with a nitrogen filled German Reflex expansion vessel in the basement. NB: If your central heating expansion vessel was made in Italy it was probably the cheapest one in the shop.
We converted the radiators over to the Honeywell (now wishing to be called Resideo) Evohome system, which gives 12 separate zones of heating control – using all the existing pipework and radiators! It now controls the hot water separately too, again with no additional pipework. The days of manually turning all the radiators on and off are over.
The new boiler is quieter than the old one, and occupies a tiny proportion of the space. The air supply for combustion is introduced into the cellar by a discreet slot in the outside wall, labelled on the inside for future servicing technicians – although hopefully we will be performing this task for the forseeable future.
The radiators were subject to a complete Powerflush and Magnetic (Magnacleanse) preparation, as usual. We fitted an Adey Magnaclean dirt filter to protect the Viessmann boiler.
We have found the 100W Compact unit to be very robust and reliable, and with the multitude of flue options, it is fit for the brave to configure for any eventuality.
If you have a domestic or light commercial boiler replacement looming, if we cover your area, we may have the answers to your questions.