The existing boiler was past its best as it was over 15 years old and many of the parts had become discontinued. The Potterton Derwent was state of the art in its day with its high output and simple design but new condensing technology has overtaken it making it very uneconomical.
First off was to specify a replacement which was a close tie between Viessmann and Worcester both of which offer boiler with advanced controls and weather compensation. In the end Worcester was chosen for their technical help and on-site support.
The Worcester WGB 162 65KW boiler and plate heat exchanger was chosen to link into the house’s existing 240v controls via Worcester’s advanced electronic 4121 boiler control computer. A plate heat exchanger was included in the system to protect the boiler from the older existing systems (and its debris ) and also because the existing system was an unpressurised system whereas the boiler runs at 1Bar pressure.
Removing the existing boiler was not an easy task as it was so heavy (330kgs) but once drained and dismantled it could be lifted out in sections. The next part of the job was to prepare the walls for fitting the new boiler and carefully plan out the positions of the other equipment to minimise unnecessary bends so as to maximise the flow characteristics of the system.
Once the system pipework had been thoroughly planned the support system could be installed and the pipework attached to the existing system and new appliances.
This was closely followed with the new condensate system which had to utilise a condensate pump which was required as there wasn’t an adequate waste gully on the outside of the building and we were uncomfortable about discharging up to 7 litres per hour of condensate water into a soak away.
Once the pipework and equipment has been pressure tested it was time to fit the Buderus Logamatic 4121 controller which could be located in the existing airing cupboard and connected to the boiler via a data cable. Unfortunately Worcester Bosch has not designed a wireless system, this would have been very much easier in this case.
The controller is specifically designed to allow for system weather compensations (see – http://bit.ly/MacWComp) which achieves an additional 2% on to an already very efficient boiler.
Once the wiring diagram has been fully understood it was just a matter of attaching the necessary heat and flow sensors and commissioning the MEC2 handset.
Worcester Bosch have a very capable technical help department that allows connection through FaceTime if you get stuck on the system set up.
With the boiler commissioned and working its just a matter of setting the heating and hot water times and letting the system take over. The final element is fitting the insulation to the pipework and handing it over to the clients after talking them through the controls.
This was a great job, the customer was delighted with the work especially as we were £3,000 cheaper than the competition!