Our customer lives in a remote rural location near Warlingham, in Surrey, UK.
They asked us to provide a proposal to update their old Grant boiler. Interestingly, it had rotted through a few years previously, and their heating technician had located a comparatively healthy heat secondhand heat exchanger in Cornwall, which he had successfully fitted.
The ladder type steel radiators suffered from perpetual air and some had stopped working, others had lost the upper sections and were partially cold, something which venting could not cure.
I was intrigued because although the system was fitted with a header tank, there was also a large expansion vessel which had been fitted a couple of years ago, that was full of water. Normally you would expect it to be half full of air or nitrogen. All in all the system seemed in poor shape.
Further investigation showed that the heating pipes were an early form of pushfit plastic, manufactured by a company called Bartol and sold as Acorn. Such pipe was treated in the 1970s as a new dawn, because the heating industry would no longer have a reliance on copper – which had been subject to shortages in the period – and of course, the plastic would not support corrosion.
Sadly it was not a great success, because later on it was discovered that single wall Polybutylene pipe can allow oxygen to permeate inwards through the outer wall of the pipe. This meant that, ironically, corrosion was far greater than with conventional metal pipes – many maintenance providers subsequently cancelled domestic repair contracts where they found this pipe had been used in heating installations.
In time, improved ‘barrier’ plastic pipes were launched where an oxygen proof material was inserted between two layers of polybutylelene. These are the pipes commonly used today, and oxygen ingress is eliminated. The successor to the Bartol system is Hepworth’s Hep20, they bought the old firm out.
In consequence our customer’s system was severely rusted up and clogged. Two Powerflushes with a Magnacleanse magnet were required, and even the radiator valves were clogged up. Some radiators had to be removed and hosed out in the garden, and their valves bypassed with tube just to get them unblocked. We were causing issues by moving the rust around the system.
A Worcester-Bosch Danesmoor oil boiler was used; Worcester are familiar with non-barrier plastic tube and use of this invalidates their boiler warranty. So we added a plate heat exchanger to hydraulically separate the radiators from the boiler system.
We pressurized the Acorn system to 1.0 bar in an effort to help prevent oxygen ingress, and added a magnetic filter to the circuit. Filters were also added to the plate exchanger to help prevent this from getting blocked up.
This allowed the boiler to be completely unaffected by future rusting of the radiators. Replacing the pipes will not be easy as they are buried within the screed and if the system continues to give problems, we will probably suggest using copper finned radiators, such as those made by Jaga.
The next thing we were asked to look at was the water supply. The local area has a very poor water supply, and we measured around 9 litres per minute, and a static pressure of under 1.0bar.
We recommended a Mainsboost pumped accumulator, to lift the water flow rate, and pressure to 3.0Bar (flow rate is dependent on pipework and taps inside the property).
This was partnered with our favourite Fabdec 3S Excelsior unvented cylinder, with uses a patented air injection system to make it virtually maintenance free.
The water system performance was completely transformed with the accumulator and unvented system; our customer can no longer fill the bath while making, and drinking, a cup of tea. If fact they”d be lucky to get the kettle filled up before the bath overflows.
Finally, the ‘piece de resistance’; the system was equipped with Honeywell’s Evohome heating zoning system. This product, first launched in 1996 on an unexpecting and unappreciative World, is simply superb. In 2019 it is still the best heating zoning system money can buy, and in this case, was supplied and installed at a 5% VAT rate. What is there not to like?