Our customer in South London owned a Grade II listed building.  It had been extended over the years but still retained many original features.

Front elevation

Interestingly from a heating perspective, it had warm air on the ground floor, and no heating on the 1st and 2nd floors, just a couple of towel rails.  The warm air was provided by a downflow Lennox open flue unit, and the hot water and towel rails by an Ideal Classic wall hung boiler.

The Ideal Classic cast iron boiler, about to be removed

Timer underneath boiler looked like it had been removed from another boiler. From one extreme to the other, see below.


This new Evohome controls the downstairs warm air, 11 zones of heating upstairs, hot water stored temperature. And it is remotely controllable via an iPad or iPhone (and Android if you don’t have an Apple).

A domestic gas meter fed the building, so to limit costs and upheaval it was important that we ended up with a new, larger heating system that fell within the 64Kw maximum available power.

The room is used for laundry – the old Lennox warm air, flue and ductwork in the centre of the picture

Our brief was to retain the warm air heating downstairs – but make it more efficient, and add around 14 radiators on the upper floors, including a significant number of refurbished iron period radiators.  Our customer wanted ideally to be able to control the heating and hot water from one place and use multiple zones, so we demonstrated the Honeywell Evohome, and it was just the ticket.

We specified an ATAG Q60S boiler, which is a quality Dutch wall hung boiler, of circa 60Kw output.  The ATAG boiler range is interesting because they have a very wide modulation range, so it can run below 10Kw all the way to 60kW.  The ATAG low loss pump header was fitted beneath the boiler, and a simple horizontal flue.

New 60Kw ATAG system boiler

The gas warm air heater was removed and replaced with a MultiCalor MC30 air handling unit;  this uses boiler circulation water as the heat source, and is both quiet and efficient.  Sophisticated internal electronics match the DC fan speed with heat throughput.  In this way, the ATAG boiler provides the energy source for the hot water, radiators and warm air.

New MultiCalor air handling unit and bespoke ductwork

We fitted 12 radiators to the previously unheated areas upstairs, and connected the two existing towel rails to the new system.  Nearly every room has independent time and temperature routines via the Evohome system.  We used refurbished iron radiators in many of the areas, these have a much better casting quality than new units, and of course, are recycling at its best.

The only trouble is lifting them (a 4 man struggle), and the fitting takes around four times as long as a simple wall hung convector.  But do they look good?

This one is nearly finished

We were really impressed with the ATAG boiler and already have plans to install some more.  They have some very useful flue systems, including long twin pipe solutions, similar to a Keston but with reliability too.  Before I go, I’ll show you inside the ATAG.

Transparent inner casing in the ATAG Q60S

We used a low loss header system with the boiler and individual circuit pumps, all controlled via Honeywell’s Evohome.  With the exception of the boiler room, there were virtually no visible pipes.  And the whole job was helped enormously by the fantastic food and coffee offered by our customer.