As a result of poor system flushing 7 years ago when new boilers were installed we have had to carry out major surgery on two Viessmann system boilers at a client’s in Morpeth.

Mr and Mrs N. had a new heating system in 2012. The house had a large heating demand partly due to its size and also its thermal efficiency. They decided to opt for the Viessmann weather compensation route using a 300L multi coil cylinder, solar thermal and two 200W system boilers.

Derek and I we’re called in to look at why one of the boilers was running hot and occasionally tripping out.

Dirty stuff!!

The first port of call was to look at the inside of the two magnetic filters. As you can see from the above picture there is an awful lot of debris in these filters; either the system was very dirty and / or the filters had not been cleaned out for 7 years.

The investigation didn’t stop there; the internal diverter valve was extracted and found to be in a similar condition. This was given the once over by Derek and replaced but didn’t produce the result expected. This indicated further blockages inside the main hydraulic pipe work within the boiler.

The next step was to replace this pipe work which required a full strip down of the boilers internal components including the fan, gas valve, condensate system and flow and return pipes.

Inspection and reassembly

With all the main components removed the pipes were inspected and found, once again, to be chocked with black debris. The heat exchanger was taken outside and flushed through with the garden hose.

The boiler was reassembled and gas tightness tested as well as checking the flue integrity.

The system was thoroughly tested to ensure both boilers were working in sequence to supply heat to the system demands.

The system is working well now but we have advised the owners that a full system flush with intensive cleaning chemical is needed.