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Discuss Boiler heating efficiency question in the Central Heating Forum area at

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  1. adgo1

    adgo1 New Member


    I have recently moved into a flat and was wondering how to use the boiler most efficiently to heat the radiators.

    I have an ecotech boiler and there is a setting to increase/decrease the temperature of the water (see pic).

    There is a thermostat in the living room, I put it on about 21 degrees. What difference does the temperature setting on the boiler make if the thermostat is at 21? Will I spend more on heating bills if its set higher, even though the thermostat stays on 21?

    Also if I have it turned to zero like in the photo, is that more/less efficient for the hot water in the shower and taps?

    Sorry if these are simple questions but I'm new to this.


  2. king of pipes

    king of pipes Trusted Plumber GSR

    Set it to 65 degrees and experiment the lower you can go the lower your bill will be achieving a satisfactory comfort level will also require sufficient insulation ie loft and walls , dont keep turning it to its lowest setting find your comfort level and leave it set there.cheers kop
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  3. Chalked

    Chalked Plumber GSR

    Leave the boiler thermostat between 60-70 degrees.
    Use he room thermostat to control temperature and reduce bills. 1 degree, can lower you yearly cost by 10%.
    Put on a jumper.
  4. adgo1

    adgo1 New Member


    Thanks for your replies.

    Over the summer I had it set as zero as I wasn't using the radiators. Is that OK to do when you don't need to use radiators?

    Is hot water linked to the boiler thermostat in any way or is it controlled separately?
  5. Chalked

    Chalked Plumber GSR

    Do you have a cylinder or is it a combi.
  6. king of pipes

    king of pipes Trusted Plumber GSR

    You should have a timer on the boiler which controls its on and off times, if you turn your room thermostat down this will keep the heating off , if its a combi hot water is available when you turn the hotwater tap on and the temperature is adjustable on the boiler , if its heat only then the boiler temperature needs to be set at 65-70 degrees at all times . cheers kop
  7. robj20

    robj20 Member

    It was my understanding that the lower the boiler flow temperature the better for efficiency.
  8. Last Plumber

    Last Plumber Plumber GSR Top Contributor!!

    Is it a Combi or a System Boiler ?
  9. townfanjon

    townfanjon Trusted Plumber GSR Top Contributor!!

    Its more the return mate , it needs to be under 55/54 so the boiler fully condenses.
    Eg , a boiler flow temp of say 65 degrees will return around 15 / 20 degrees lower which is obviously than 55 .

    The only problem with a low flow temp is that it may struggle to heat the house in cold conditions, this is when radiator sizing is very important.
  10. robj20

    robj20 Member

    That's what I meant, but on the boiler we only control the flow temp.
    Mine tends to start of at about 75c the quickly drops to around 30c.
  11. adgo1

    adgo1 New Member


    It's a combi ecotech plus vaillant.

    Just wanting to know the most efficient way of using this in different situations (radiators needed or not needed). Never used one before and first time living on my own and using one of these before.

    On a related note, I was told that once your heating is turned on, you pay the same in energy whether one or all your radiators are turned on. Is that true or do you pay more per each radiator turned on?


    Last edited: Oct 20, 2017
  12. robj20

    robj20 Member

    On the whole the more radiators you have turned on the more it's going to cost you. If you are on your own only heat the rooms you're using and keep doors closed.

    You want to set the boiler to as low a temperature as possible while still being able to heat the rooms. You will get to a point where you set the boiler too low and the rooms will never be able to reach the temperature you set on the thermostat so then turn the boiler back up a bit.
  13. Damselfly

    Damselfly GSR

    I would suggest that if you are looking to increase the efficiency of your heating system you get Vaillant controls fitted to your system. Their most basic controls, that utilise ebus technology, have anticipation technology to modulate gas consumption, right up to weather compensation controls that control energy usage based on outside temperatures. Got to the Vaillant website on to ‘find an installer’ and request a visit to get advice on the best way to utilise the learning technology inside your boiler to optimise your fuel consumption. It’s worth paying a call out out to get detailed advice face to face. These boilers are great if used correctly. If you already have Vaillant controls then whoever comes can explain them to you properly so you can get the best out of them.
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  14. Last Plumber

    Last Plumber Plumber GSR Top Contributor!!

    I would need to see the system and weigh it up to be able to give you good advice. So would anyone else really.

    However, seeing as we are on a Forum I would only suggest you set the heating knob to 60 and the Hot water to whatever you prefer to be honest but I always leave them on 60 too, ( customer can adjust as they please).

    If you have thermostatic radiator valves, set living rooms to 21 degrees C (depends on the head but more often than not around half way or number 3).

    Set bedrooms, hallways, landings, kitchens, dining rooms etc to 18 degrees C ( number 2 or 2/5).

    Bathrooms ( 4 or 4/5). 22 deg C.

    Room stat, Set to 20/21.

    Start there and see how comfortable you are. All Properties are different. Owing to type of build, insulation, climate, heat emitters, Heating system, whether they are exposed, in a city, etc, the list goes on.
    There are differences in when each individual feels comfortable too.

    Damselfly is right with the comments, if you did go down that route, you should check whether your Boiler is 100% compatible with the newer technology.
  15. Matchless.plumb

    Matchless.plumb Trusted Plumber GSR

    Low boiler pressure ?
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