Setback Temperature.

andyblac ✭✭
edited March 12 in The Boiler Room

Hi Guys,

ATM at night I am not using a setback temp and I just put my heating into "Frost Protection" mode. I am curious to know how many of you use a setback temp, and if so what temp do you use ?

Is it more efficient to use a setback temp or not, I have house built in the 1970's and even though I have had cavity wall insulation installed, Triple Glazing, and Roof Insulation, it still looses heat at night i.e. when outside is 0˚c the internal temp can be as low as 12˚c in the mornings, so my heating goes full belt first thing to get rooms to target temp. I am just curious if it would be more efficient to set a setback temp of 15˚c at night, so my target temp of 17˚c for during the day would more easily reached. Would it save on GAS usage or not?


  • The answer is "it depends". The are too many variables to say which method would save energy and maintain your desired temperatures. The only way to know is to test each method for (say) a week, and record the daily gas use. For our insulated '60s house, with 10 years of energy data, it used more gas when the heating was occassionally on overnight. Provided the house warms up quick enough in the morning, there's litttle point in heating overnight and wasting energy.

  • andyblac
    andyblac ✭✭
    edited March 15

    thx, I was asking because when I set my max flow rate to 50/55˚c I have one room that struggles to reach target temp in the morning in mid winter (rad could be doing with being larger, but not enough room to make bigger), as the room can drop to as low as 12˚c and the target temp is 18.5˚c the boiler can go on full for 4 hours before it reaches target temp, my idea was to set a setback of 16˚c so it does not have as long to go to reach target, and as my boiler is connected via OpenTherm it should only trickle heat over night to keep at 16˚c.

  • wateroakley
    edited March 15

    As you say, you could set the one room as a separate zone (with SRV or Stat?) to 16 deg C overnight and set the other zones/rooms to 'off' . That would let the boiler service the one rad and keep the room warm.

    A temperature rise of 1.5 degree per hour suggests that something is undersized. A boiler temp of 50/55 deg C is bit low and that will contribute to the problem. If you have children, some of the boiler manufacturers suggest 65 deg C as a temperature setting. You'll need to be above 60 deg C to kill Legionella bacteria in the HW. That's why HW tanks on an air source heat pump system will have a weekly immersion heater hot cycle.


  • @wateroakley I have a Combi Boiler so no Hot Water tank, and 50/55˚c is the optimum temperature for the condensing action in the boiler. Guess I'll just have to try it again, currently my max flow is set to 65˚c so that rad can heat the room within the hour.