050 HPM 0415

HPM April 2015

Got a story? Ring us on 01732 748041 or e-mail twood@unity-media.com TRAINING/TECHNICAL Fault finding tips for oil-fired boilers Martyn Bridges, director of marketing and technical support at Worcester, Bosch Group, provides some trouble-shooting tips in response to some of the questions that are most frequently asked in Worcester’s training rooms... Before carrying out fault-finding you should be competent to do so. OFTEC qualified technicians fall into this category. Always carry out a polarity check, including live to neutral, live to earth, neutral to earth, which would require 230 volts live to neutral, 230 volts live to earth and 0 volts neutral to earth. You should also carry out an earth continuity check before carrying out further fault finding checks. Before working on any electrical components carry out the nine steps to safe electrical isolation procedure. I’ve installed an oil-fired combi boiler but when I run the water for a bath, it begins very hot, but by the time the bath is full, the running water out of the tap is not as hot. Is this how it is supposed to be? Wall mounted gas-fired combi boilers are very lightweight and high in output when compared to an oil-fired boiler. They provide instantaneous hot water continuously for as long as the hot water tap is open. Therefore, many installers and end-users are familiar with combi boilers that work in this way. Oil-fired boilers are heavier and with significantly thicker heat exchangers and increased thermal mass, they, therefore, cannot heat water from cold either instantly or continuously. The boiler incorporates a thermal store which takes around ten minutes to heat up. Once heated, the energy within the store and the boiler output combine, to heat the incoming cold mains at high flow rates; but for a given quantity, generally around 25 gallons of water WWW.HPMMAG.COM Before carrying out fault finding on an oil-fired boiler you must be an OFTEC qualified technician can be heated in one draw, more than enough to fill a bath. Is it possible to install a solar hot water system alongside an oil-fired combi boiler? Unlike other options available on the market, the entire oil-fired boiler range from Worcester is compatible with solar technology. Take the Greenstar Heatslave II oil-fired combi boiler, for example, which works extremely well with solar technology due to its in-built hot and cold water sensors. The boiler automatically allows pre-heated water from the solar technology to pass through it and onwards to the taps, without the need for any further heating from the boiler. The boiler will only heat the water from the solar panels if it was to cool down to below a usable temperature. In the summer, the solar hot water is quite often enough for a house and the boiler won’t need to react at all. In the depths of winter however, when there is not enough sunlight to warm the water, the boiler will kick in and heat it up - this process is all automatic so there is no need for additional controls. Alternatively, if the customer possesses an 50 APRIL 2015 HEATING & PLUMBING MONTHLY older oil-fired combi-boiler, which is not compatible with solar, there is a way around this. The solar panels could be connected directly to a hot water storage cylinder, which is then connected directly to a portion of the house such as the bathroom or shower. This means that the existing oil-fired combi boiler will work separately, to supply the rest of the house, such as the kitchen sink and the downstairs toilet. This is quite a common way of installing this system when the homeowner does not want to replace their oil-fired boiler. There is a law that installers need to be aware of when installing this type of system, as the storage tank needs to reach a specific temperature to eliminate any potential legionella issues. When installing solar with cylinder storage, installers need to ensure there is the provision to pasteurise the cylinder which can be achieved by using zone valves, a cylinder thermostat and a time clock. Installers should be encouraged to keep an eye out for oil opportunities enquiry number 139


HPM April 2015
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