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Oil Boiler Isolation Switch.

Zoomup
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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    My job looks interesting and a bit beyond the average. The boiler installer has just completed the installation except the electrics. I have been told that the boiler is a Grant X Vortex Combi 26kW. There is underfloor heating downstairs and a different heating zone upstairs which may be under floor or rads, I haven't looked yet. Then there is the hot water as well. I have yet to work out how to get the boiler to fire up for either heating zone. I suppose that I will need a mains relay or two.


    Any suggestions please?

    https://grantengineering.ie/media/1733/grant-vortex-pro-external-combi-addendum-installer-add-0123-rev-0-3-november-2018.pdf


    Z.


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    S-plan with two port valves that have the required relays built into them and a three channel programmer.


    Andy Betteridge
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    Sparkingchip:

    S-plan with two port valves that have the required relays built into them and a three channel programmer.


    Andy Betteridge




    Thanks Andy. Will the valves have relays or micro switches built into them? As the boiler is a combi boiler can the hot water side just be left on a permanent mains supply with no timer/programmer, as the boiler will fire up when it detects a water pressure reduction as a tap opens? 


    Z.

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    So long as it is all on one phase and one fuse, (and I hope it is), then you can have n zones, so  n thermostats  (and maybe n timers )in series with the n valve operated switches.

    When the timer and 'stat says 'go' for that zone, the valve gets power and pulls over, and when it is open for water to flow  the swithc on the valve does its thing, and the boiler gets power on the 'firing' signal  - if more than one  valve(s) are open  as more than one zone is asking for heat, then there are many switches in parallel, all on, the boiler is OK with that, it only goes off when the last zone valve shuts.


    Yes HW is normally pressure drop based.

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    yes its a combi. so you link the hw-on and permanent live in the internal plug within the boiler.

    The plumber will have installed the zone valves already, are there roomstats and controllers or programmable roomstats? It goes time first (programmer), then temperature (roomstat) then zone valve brown, then orange from zone valve to boiler switched live in the internal boiler plug
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    Zoomup:




    Sparkingchip:

    S-plan with two port valves that have the required relays built into them and a three channel programmer.


    Andy Betteridge




    Thanks Andy. Will the valves have relays or micro switches built into them? As the boiler is a combi boiler can the hot water side just be left on a permanent mains supply with no timer/programmer, as the boiler will fire up when it detects a water pressure reduction as a tap opens? 


    Z.


     




    Although it is a combi there is probably provision to preheat the boiler and hot water at predetermined times to make it less wasteful of water and the users time by avoiding running water to waste whilst it warms up.


    Andy Betteridge 

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    OlympusMons:

    yes its a combi. so you link the hw-on and permanent live in the internal plug within the boiler.

    The plumber will have installed the zone valves already, are there roomstats and controllers or programmable roomstats? 


     




    Downstairs there is a programmable room stat but the tenant wants just a simple rotary room stat as he finds the digital programmable one too confusing.  Upstairs is a mystery as I have not had a chance to view it yet as the boiler installers were in the way and I wanted to look quietly on my own. I may just have a simple single channel programmer for the space heating. Hot water permanently on. Upstairs and downstairs each with separate room stats. I will look properly tomorrow.


    Yes Mike, just one single phase circuit is involved. 


    Tomorrow I may just get the system working after a fashion and return to fine tune things later. My main concerns are that the property has no electricity meter and is supplied by a very long underground sub-main from next door's garage.  It used to be just one house. Also I will be looking at the main bonding and other safety related issues.


    At present all of the lighting circuits and the boiler circuit are not R.C.D. protected.


    Z.




     

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    The living area should be one heating zone and the sleeping accommodation another one with the provision for setting different heating periods and room temperatures, the boiler should noty cycle in the middle of the night to deliver instant hot water when no one needs it.


    Do it right and you will save the bill payer a lot of money by significantly reducing the bills for oil.


    I plumbed a heating system for the boiler guy to come and install the boiler as he could not do it all for various reasons, it was a two bed cottage so there were two heating zones with a programmable thermostat in each zone and a timer for the hot water located in the kitchen, so three separate timers which sounds OTT for a two bed cottage, but very efficent.


    Andy B.
  • 0

    Sparkingchip:

    The living area should be one heating zone and the sleeping accommodation another one with the provision for setting different heating periods and room temperatures, the boiler should noty cycle in the middle of the night to deliver instant hot water when no one needs it.


    Do it right and you will save the bill payer a lot of money by significantly reducing the bills for oil.


    I plumbed a heating system for the boiler guy to come and install the boiler as he could not do it all for various reasons, it was a two bed cottage so there were two heating zones with a programmable thermostat in each zone and a timer for the hot water located in the kitchen, so three separate timers which sounds OTT for a two bed cottage, but very efficent.


    Andy B.




    Yes I can see the benefits of that design Andy. Thanks.


    Z.

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    Downstairs there is a programmable room stat but the tenant wants just a simple rotary room stat as he finds the digital programmable one too confusing.  Upstairs is a mystery as I have not had a chance to view it yet as the boiler installers were in the way and I wanted to look quietly on my own. I may just have a simple single channel programmer for the space heating. Hot water permanently on. Upstairs and downstairs each with separate room stats


    See table 12 here

     https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/697525/DBSCG_secure.pdf

    Time and temperature controls required for each heating circuit, circuit defined as being controlled by a zone valve. UFH needs longer heat up times so a separate timer from any radiator system upstairs would make sense anyway. 

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