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Oil Boiler Isolation Switch.

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Evenin' All,


Regarding an external ground sited domestic oil fired boiler for heating and hot water that has an internal switched fused connection unit nearby inside the house, what regulations will require an external electrical isolator adjacent to the oil boiler? You know the sort of thing, a double pole rotary isolator. 


Z.


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    Which is why installing a timer allows the boiler to preheat at a predetermined time is good practice  ?
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    Chris Pearson:




    Sparkingchip:

    The cost of having a boiler cycling 24/7 to keep stored hot water or the boiler itself up to temperature is very significant and wasteful.




    I cannot believe that this thread is still going. ?


    So why do that? Our boiler comes on bright and early so that we have hot water for showering first thing. It gives a boost at lunchtime so that we can wash dishes, etc. Then it comes on again in the evening, once again for food prep and washing up, followed by bathing. Is this unusual?


     




    Do you have other thermostatically controlled appliances like fridges and freezers on time switches as well Chris?


    Z.

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    Zoomup:




    Chris Pearson:




    Sparkingchip:

    The cost of having a boiler cycling 24/7 to keep stored hot water or the boiler itself up to temperature is very significant and wasteful.




    I cannot believe that this thread is still going. ?


    So why do that? Our boiler comes on bright and early so that we have hot water for showering first thing. It gives a boost at lunchtime so that we can wash dishes, etc. Then it comes on again in the evening, once again for food prep and washing up, followed by bathing. Is this unusual?



    Do you have other thermostatically controlled appliances like fridges and freezers on time switches as well Chris?



    Eh? ?


    Ideally, we would have a much better lagged HW cylinder, but it does slowly lose heat. To keep it hot all the time would be wasteful as Sparkingchip says. To keep the boiler on constantly would risk short-cycling. i.e. thermostat closes, boiler has to get up to heat, HW tank is heated, thermostat closes and now the heat in the boiler goes to waste. (The HW tank is adjacent to the boiler, so negligible losses in the pipes.)

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    The other problem with the traditional UK indirect water cylinder is that it can only accept a relatively small heat input - maybe 3 or 4kW for a traditional one, perhaps twice that for a newer 'high recovery' types - all due to the limited surface area of the coil. A gas boiler will kick out tens of kW - so if it's only supplying the hot water cylinder it'll soon bring the heating water up to maximum temperature and have to shut down (or modulate down/short-cycle) - and that's just the kind of thing that wrecks boiler efficiency. Heating the hot water at the same time as the radiators means the boiler is running flat out and so far more efficiently - but of course that only helps when there's space heating demand.

       - Andy.
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    If you know you are going to get up and shower at a specific time and you have a combi boiler that preheats in anticipation of you turning the tap on it will avoid you sending a lot of good clean drinking water to waste.


    I have worked for people who have water meters and they run the cold water off into buckets whilst they are waiting for their combi boilers to heat in the mornings and have numerous buckets of water stored around their homes for cleaning and watering plants etc.


    If you want to save money and polar bears fit a timer to your combi boiler.


    The boiler in the original discussion actually has heated water stored within it and isn’t actually a combi boiler as most people know them, it will keep firing 24/7 to stay hot rather than just heating when a tap is turned on.


     Andy Betteridge

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