Here we have an unusual case study. It is a listed building in a rural part of Kent, UK, on top of a hilly area.

This is the property. Picture by Malc McDonald

It has a large cellar covering most of the floor area of the house. In very heavy rainfall in 2019, the road (some considerable distance from the house) became flooded, and due to some collapsed drainage on the highway, a very large amount of water gathered in a pond.

At some point during the night, the water found its way into a cellar light, smashed the window, and quickly filled the entire cellar, all the way to the floor joists above.

The fire brigade and many pumps, dehumidifiers later, and we were being led through a damp blackened dark mess to look at the heating system, which along with all the electrical distribution, and been completely submerged.

The old boiler, and some water

Being a Grade II listed house, there was little we could do to change the configuration, and because of the timescales, there wasn’t time to make any significant changes.

What was left of the heating controls

Within a day, we had inspected and provided a quote to replace all the equipment.

All has been underwater, so it is scrap

The 70Kw Trainco oil boiler in the cellar weighed nearly 300Kg and getting it out was not going to be easy. The proposed Worcester Bosch Greenstar 32/50 unit to replace it was 280Kg, so we had to be careful. One local contractor who advertised themselves as being able to anything and everything had already run away.

But we had done this sort of thing before, only with less dirt, and more light.

Base going in

We constructed a plywood ramp down the cellar stairs. Then using 4×2″ timber framing we constructed a winching frame at the top of the stairs, which was inside the main hall.

Braced against wall floor and ceiling

By fabricating the timber winch frame on site we could wedge it accurately using load spreading plates against the internal walls, floor and ceiling joists, so that it could not move in any direction. This was done without making any fixings, there were no signs we had been there afterwards.

Ramp takes shape into cellar

Then we used our Tirfor winch, positioned high inside the wooden frame, to drag the old boiler out of the cellar and lower the new one down inside, using the ramp and a small amount of water to lower the friction. All went without a hitch.

Old boiler on the way out

The boiler flue used to pass underground and then up the rear wall of the house. being a condensing boiler, the old flue system was incompatible with the acidic saturated water vapours a modern high efficiency boiler produces. So it had to be removed and replaced.

The flue was replaced into the cellar, starting at the base, in insulated 8″ twinwall stainless steel rigid sections

This was the most difficult part of the job. The walls were tile hung, and the fixings were really difficult, we had to use chemical fixings in the end.

We put the rain cap on as we progressed, to prevent dirt entering

The length and height of flue meant it fell outside what Worcester-Bosch would permit. For instance, they require a 600mm straight section above the boiler before any bends.

We used our flue specialist design and manufacturing partner to use their computer modelling to design a bespoke flue system. This was then installed, to their design, by ourselves. They warrant the effectiveness of the design, which means that we don’t have to have it approved by Bosch. This approach is commonly used in commercial boiler plant design, but is not usually permitted in domestic gas situations.

Flue finished

Our customer was very fond of his Hive 3 zone control system, so we replaced all the controls with a new Hive set, this time not full of water. A Grundfos Magna light commercial circulator was fitted, and we were ready to go.

New Hive and wiring by us
New Grundfos Magna pump

You can read their comments on our Which? Trusted Traders review page!

New boiler in place