What water and overnight set-back temperatures do you use?

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  • dty
    Automated Home Ninja
    • Aug 2016
    • 489

    What water and overnight set-back temperatures do you use?

    The title says it all, really.

    What temperature do you have your DHW cylinder set to? Are you using open vent, sealed or pressurised?

    What temperature do you have your CH overnight set-back set to?
    Last edited by dty; 9 February 2017, 10:58 PM.
  • HenGus
    Automated Home Legend
    • May 2014
    • 1001

    #2
    Originally posted by dty View Post
    The title says it all, really.

    What temperature do you have your DHW cylinder set to? Are you using open vent, sealed or pressurised?

    What temperature do you have your overnight set-back set to?
    I have an unvented OSO 250l cylinder. My HW is set to 62C with a differential of 7C. Through experiment, I have found that this temperature range suits an old thermostatic shower. HW is timed to come on at 0700-0900 and 1630 - 2000. During the summer, with a gas hob, I use about 1 cubic metre of gas a day.

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    • dty
      Automated Home Ninja
      • Aug 2016
      • 489

      #3
      Thanks HenGus. I've just clarified the second question, which was about CH, not DHW.

      Comment

      • dty
        Automated Home Ninja
        • Aug 2016
        • 489

        #4
        I'm using over 25 cubic metres a day at the moment! You can see why I'm interested in this stuff!

        Comment

        • killa47
          Automated Home Guru
          • Jan 2016
          • 123

          #5
          I have a Megaflow 250L unvented cylinder and set DHW at 60C with a differential of 5C. All my CH temps are set at 10C for overnight operation (mean spirited) unless we have very young or very old family visitors, then I run overnight at 15C to 18C. I do not use Optimisation. Hope that is of use.
          Last edited by killa47; 10 February 2017, 01:44 PM.

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          • DBMandrake
            Automated Home Legend
            • Sep 2014
            • 2361

            #6
            Originally posted by dty View Post
            The title says it all, really.

            What temperature do you have your DHW cylinder set to? Are you using open vent, sealed or pressurised?
            Open vent 100 litre cylinder - I did have it set to 50 for a long time but increased it to 55 about a month ago as I couldn't quite run a full bath without temporarily turning the temperature up, and I find 60 far too hot from a tap, to the point of scalding. 55 seems a good compromise that isn't quite scalding but can fill the bath well. I have the differential set to 5 degrees.
            What temperature do you have your CH overnight set-back set to?
            All rooms except the bedroom are set back to 5 degrees at night. The bedroom is scheduled to 17 through the night mainly for our 10 month old son.

            I learnt the hard way in the first winter I had evohome that only setting the downstairs rooms back to say 12 or 14 degrees resulted in a lot of gas being burnt needlessly through the night and my costs actually went up not down!

            Likewise when the house is vacant during the work day every room is scheduled to 5 degrees, and I let optimal start figure out when to turn things back on again so things are warmed up for the time that people start arriving home.
            Originally posted by dty View Post
            I'm using over 25 cubic metres a day at the moment! You can see why I'm interested in this stuff!
            How many kWh in 25 cubic metres ?
            Last edited by DBMandrake; 10 February 2017, 01:26 PM.

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            • killa47
              Automated Home Guru
              • Jan 2016
              • 123

              #7
              Further observations on our system.

              I found 10C works out ok for overnights temps except when outside temps are at or close to frost levels. I used to monitor whether any zones were triggering the boiler overnight when set at 10C (our house rooms are 10ft tall. outside double skin brick walls uninsulated) but have only seen this happen once or twice - so I temporarily dropped the setpoint.

              A word of warning leaving some rooms at 5C or even 10C - We came home one day and spotted condensation water on the dining room internal windows behind the curtains, causing some mould on the lining. I have since increased the temp in that room (rarely used) up to 16C to maintain a lukewarm temp to minimise condensation.
              Last edited by killa47; 10 February 2017, 02:05 PM.

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              • Mavis
                Automated Home Ninja
                • Oct 2014
                • 322

                #8
                I have all our rads set to 10c overnight. I have opt on for start and off. I have never had heating on overnight, even when my son was born. (S'pose it was the way I was brought up).
                We also had a PIV installed when we moved to this house - best thing we ever did. Now we never get any condensation on the windows.

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                • mylesm
                  Automated Home Guru
                  • Nov 2015
                  • 153

                  #9
                  Hot Water Set to 55c
                  3 CH Zones controlled by Zwave Stats and Zone Valves Living area Zones set to 21c from 07:00 to 23:00 and then set back to 17c Bedroom Zones set to 19c 07:00 to 23:00 and set back to 17c Zones hardly ever come on During night I have Just got up here now its -1c outside but zones are still reading 18c and Boiler did not run during night

                  I got house Externally Insulated about 3 years ago and installed HRV this has made a huge difference to the comfort levels in the house no Condensation no ice box rooms etc

                  Comment

                  • G4RHL
                    Automated Home Legend
                    • Jan 2015
                    • 1580

                    #10
                    I am set to 10C overnight (22:30 and to 06:00) in all rooms apart from my conservatory. The room temperatures rarely ever drop below 14C during the night even on very cold nights. My conservatory is set to 5 C with set points taking it up to 6C and back to 5C every so often. Sometimes the heating does come on in the night and it is the TRV in the conservatory dong its stuff because the temperature has dropped below 5c. I have read somewhere that in the Winter the comfort level for humans averages between 20c and 24c but in the Summer it is 23c to 26c due to humidity changes. The drier the air the higher the temperature for comfort level. I can't convince my wife of that. She is always cold"

                    Comment

                    • killa47
                      Automated Home Guru
                      • Jan 2016
                      • 123

                      #11
                      Originally posted by Mavis View Post
                      I have all our rads set to 10c overnight. I have opt on for start and off. I have never had heating on overnight, even when my son was born. (S'pose it was the way I was brought up).
                      We also had a PIV installed when we moved to this house - best thing we ever did. Now we never get any condensation on the windows.
                      Mavis - What is a PIV

                      Comment

                      • G4RHL
                        Automated Home Legend
                        • Jan 2015
                        • 1580

                        #12
                        When I looked it I got

                        "Post Indicator Valve (PIV) is a valve that is installed in the main water service line serving a buildings automatic fire sprinkler system. Its purpose is to allow the fire department to control the water that is flowing into a building in the event of a fire"

                        I also got Particle Image Velocimetry plus a reference to ***ual performance!. I have remote controls for many things but there are some limits!!

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                        • killa47
                          Automated Home Guru
                          • Jan 2016
                          • 123

                          #13
                          G4RHL - Be careful ! You might be venturing down a path of no return with your Velocimetry device !!

                          I was being somewhat lazy not googling it and expected no end of false trails re the hunt for PIV.

                          However, I wonder if Mavis meant PVI - in which case it is a "Positive Ventilation Input" unit which can be fitted in a loft (or other areas) and reduces or eliminates condensation.

                          The condensation in our dining room was due to setting the Evo setpoint being a bit too low - hence revising the temp to 16C to avoid this. As our house is 85+ years old, there is no cavity so little used rooms can cool down appreciably in winter.

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                          • Mavis
                            Automated Home Ninja
                            • Oct 2014
                            • 322

                            #14
                            Originally posted by killa47 View Post
                            Mavis - What is a PIV
                            It's Positive Input Ventilation.



                            We have got the Nuaire Drimaster Heat. Some people can't get away with them as there is a draft - we are in a double fronted bungalow and it is installed in the hall. I have the heat bit of it wired into a socket (as opposed to the mains) and it is plugged into a LightwaveRF socket, timed to come on for a couple of hours in the morning and then on in the evening from around 4pm.

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                            • chrisgare
                              Automated Home Guru
                              • Dec 2013
                              • 182

                              #15
                              58 degrees for water and 5 degrees on all 12 zones overnight i.e. off. Too much gas used if left on overnight at higher temperatures. I tried 10 degrees a long time ago but there was no point as far as I can see.

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