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Thread: Evo Home new install

  1. #1
    Automated Home Lurker
    Join Date
    Oct 2020

    Default Evo Home new install


    This is my first post following purchasing the Evohome heating/hotwater set up.

    I am just about to start installing my Evohome system. I have bought the Connected thermostat pack and Hot water Kit to start with.

    My intention is to get these up and running first, using the controller as the thermostat, ie run the house as a single zone as it is at presently, then install the radiator controllers at a later stage. I need 12, so it also helps spread the cost. There are another 2 radiators without TRV's, a towel rad in the bathroom, and the radiator in the hall by the thermostat, so I have to make a decision about these, which could take it upto 14 controllers required. One of the drivers for this was the step daughter gets home just after 3pm, so we can heat just her bedroom which she rarely leaves, rather then the entire house, and also heat just the lounge later at night when I am still up, but others have gone to bed.

    At present I have the Evohome controller running, but it is not controlling the heating as yet. I wanted to see how closely it was calibrated to the existing digital thermostat first which is a known quantity. I have had to adjust the differential by 1 degree to get it like for like, but I do feel its a backward step going from seeing temps displayed in tenths to nearest 1/2 degree, which also makes the calibration more difficult. I contacted Honeywell, who frustrating said the equipment couldn't display in tenths, ie telling me something I already knew, but offered no explanation why. I am sure its just a configuration/firmware tweak, but given the target market are customers who want more control, this seems at odds with that having being 'dumbed down' to only show to the nearest 0.5 degree.

    I have the hot water sensor also installed in 'dummy mode' at present, so it also displaying the hot water temp. At present this is 10 degrees below were I would expect it to be. I have an OSO sealed tank, so no spare insertion wells for the sensor. I have it slotted under the insulation at present, but have bought some thermal paste so I can get a better contact. I am also going to reposition slightly so it is in a vertical plane, which ensures more of the probe is in contact with the cylinder surface.

    For the wiring, I am replacing the existing controller with the 2 BRD91's which in turn will control the HW and CH feeds to the wiring centre, ie the boiler will continue to be controlled by the live feeds from the 3 port valve. This seems the simplest way for now. I've installed wiring centres before when converting heating systems with no house thermostat, and only a single valve so understand the principles, but I don't do it every day, so I may look in the future at the fig 4 set up, and the variations for that, ie locking the CH valve open, but I would need valves on all rads in that configuration, and doing this incrementally reduces the risk in my mind for ****ing the wiring up whilst also changing everything else at the same time.

    On the 2 rads with only lockshields, and no TRV's, I am thinking to leave the towel rad like this, so any call for heating this gets warm, but once I am multizone, swapping the other rad in the hall so it can be individually controlled. The boiler is a worcester Greenstar, I can't see anything obvious in the pipework externally to see how the ABV works. This is the area I am having some doubts around. It is in the loft, so not straightforward to sit next to it and see what happens on the pump over run. I think the 3 port valve acts as the ABV as it is always open to at least one of the circuits, and in that case I would need to keep one radiator on lock shields to act as a bypass on the heating side.

    Thanks for reading, and do shout out if you spot any obvious errors in my general thinking and logic.


    Last edited by Justino; 29th October 2020 at 07:19 PM.

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