Readers of this blog will know that we regularly get commissions from owners of listed properties for their heating upgrades.

Today, we are in a Grade 1 listed country house in Ditchling, Sussex, UK, dating back to the 16th century, or possibly earlier.

Henry VIII was believed to have bought this house for Anne of Cleves;  later residents included William Pitt*.

*William Pitt will also appear as a case study for our professional services shortly!

In more recent times the house was owned by a radio and TV personality;  our customer has recently moved in and we were engaged to provide an updated, more efficient, heating and hot water system.

These type of properties tend to be difficult to keep warm economically, because there are lots of chimneys, single glazed windows and a general lack of building fabric insulation.   Any heat put into a room doesn’t tend to stay around for long, so most owners of listed buildings have more than a few sets of woolly socks on hand.

The listing requirements make the addition of insulation, and, for instance, changes to the heating, onerous if it involves any changes to the appearance.

Anne of Cleves’ house, Ditchling (photo from, by Jonnee)

The house is full of period features, but we’ll  show a photo of the upper stairs to give an idea.

Ricky on the stairs

Ricky on the stairs

We found two late 1990s Vaillant boilers in the cellar, linked together in tandem, together with a Vaillant Vantage unvented  HW cylinder.

As we found it

As we found it.  Wiring typical of what many domestic installers think is acceptable…. HW cylinder expansion vessel supported on a timber prop.  Left hand boiler leaking.

When we inspected closer, we found that one of the Vaillant units, although externally identical, was a combination boiler, the other a system boiler.

Only one boiler was wired to come on with the heating – although both were linked hydraulically to the heating circuit…this meant the combi heat exchanger was being heated by the other boiler.  Furthermore, the outlet for Hot Water from the combi boiler had been linked into the unvented cylinder.

One of the boilers had been leaking and clearly had not been serviced for a long time.

Corrosion had taken a hold

Corrosion had taken a hold inside the system boiler

Our suspicions that the original installers were completely out of their depth was confirmed by the gas supply pipework being hopelessly undersized – gas pipe sizing is very often dangerously wrong (ie: too small) when a jobbing plumber/combi boiler small domestic installer tries their hand at bigger stuff.

Rather than the 48kw of boilers previously fitted, we calculated that a single 40Kw boiler would be more than adequate, so we specified a Worcester-Bosch Classic Regular 40Kw boiler.

The unvented hot water cylinder had been installed incorrectly, with the discharge pipe simply routed internally to the floor

This pipe (immediately to the left of cylinder) would have flooded the house if there had been a fault

– so we moved the cylinder and raised it up to allow a safe, building regs compliant installation.  We also adapted the safety valves to make the Vantage cylinder compatible with the new boiler.

Installation nearly complete

New installation nearly complete.  We had to raise the existing cylinder to get the expansion safety pipe out of the building at ground level.

We installed a 12 zone Evohome to control the heating and hot water.  This incorporated existing underfloor heating and radiators, and as is usual with Evohome, caused very little disruption to the house, in this case just requiring some new radiator valves.

The heating system is now amongst the most modern and efficient available, given the constraints of a listed building of this age.

Room by room heating control

Room by room heating control by Evohome

The new Worcester boiler is backed by an 8yr manufacturer parts and labour warranty, when fitted by Hot Water & Central Heating Ltd.

As a footnote, this is the fourth Evohome zoned system we have installed for relations of this family – they are committed to the benefits this innovative system provides.