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Thread: Evohome may not save you money..

  1. #1
    Automated Home Sr Member
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    Default Evohome may not save you money..

    Ok most of you it probably will, but in my case it looks like it wont.
    Our previous system had no thermostat and relied on trv's and a bypass to regulate room temperature. It had a standard twice a day on off timer, so bascially heating went on a bit in the morning and on a bit in the evening and I wrapped up warm the rest of the time, and spent most nights piling blankets on my bed.
    Now with evohome its convenience means that my bedroom never drops below 17 at night, other rooms go on and off when heat is anticipated or overridden as required and as I work from home at least 1 heater is on pretty much all the time..
    so in my case evohome has provided comfort if not savings...

  2. #2
    Automated Home Legend
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    I am retired, I was when I installed Evohome, the house is occupied most of the time by myself and or my wife. Our consumption went down, not a lot, and the comfort went up.

  3. #3
    Automated Home Jr Member
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    I don't keep the fine grain data that many on this forum do but rely on end of month meter reads which I've kept for a little under 6 years now. I installed Evo about 5 months ago and I know that comparisons are statistically unreliable given the climatic variations, changes in heating patterns etc. For example, part of last winter I had 5 rads out of use as I was doing some major re-decoration and ended up replacing 4 of them. In process I also decided to upgrade the rather ancient existing TRVs across all 16 radiators making meaningful comparison even more questionable. I do know that my averaged daily usage over the last 4 complete months has been about 20 KwH less compared with the daily average in the November - February periods averaged over the previous 5 years. In that time my condensing combi hasn't changed. Of course there are too many variables to make accurate claims and maybe it says something about my occasional laziness in not climbing the stairs to tweak manual valves but maybe, just maybe, the payback on Evohome will be in my lifetime. What I do know is that the place is considerably more comfortable as many so often say.

    Now if only that app proves more robust in future ......

  4. #4
    Automated Home Legend
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    Quote:

    Compared to the house with standard TRVs, the one with the PTRVs used 11.8% less gas over the 49-day wintertime experimental period, the boiler output reduced by 14.1% but the boiler efficiency dropped by 2.4% points due to the smaller and more intermittent heat load. Empirical modelling suggested similar percentage energy saving across geographical regions in the UK (11.812.5%). However, primarily because of differences in the cost of zonal control systems, but also because of differences in absolute energy demand between regions, the cost effectiveness was variable. At 2015 fuel prices, a luxury system (cost 1200) might yield a net saving of 3% on fuel bills over a 15 year period. A basic system (cost 120) may offer net savings of 11% over 15 years.

    There is moderate quality evidence that zonal control can save energy and be cost effective in homes where rooms are intermittently occupied. A small-scale UK field trial, a full-scale UK experiment, and computer modelling each conducted by different research teams, all showed savings in the region of 1018% compared to whole-house scheduled periodic heating. There was low quality evidence that low-cost zonal control systems can be cost effective.

    Unquote


    Worth a read:
    https://www.sciencedirect.com/scienc...64032118303381

  5. #5
    Automated Home Sr Member
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    I don't disagree, just that in my personal case, the added convenience has led to a more comfortable house but resulted in more usage. There were plenty of nights in my previous setup when I would be shivering in bed wishing I had some way to warm my room without having to venture downstairs and hit the override switch which would then result in heating the whole house, besides the fact that just getting out of bed would have been a pain.

  6. #6
    Automated Home Jr Member
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    Thank you for the pointer to that study HenGus. It throws up yet more variables that apply in my case and makes meaningful comparison probably even more unreliable. For example these days, my system can call for heat any time between 06.15 and 21.30 whereas previously there were three rigid on-off cycles through most days. My boiler is not OT but I do occasionally remember to tweak its flow temperature if there is a marked change of weather forecast for a few days. Changes in its efficiency probably contribute as much as anything in reality.

  7. #7
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    Quote Originally Posted by BuxtonJim View Post
    Thank you for the pointer to that study HenGus. It throws up yet more variables that apply in my case and makes meaningful comparison probably even more unreliable. For example these days, my system can call for heat any time between 06.15 and 21.30 whereas previously there were three rigid on-off cycles through most days. My boiler is not OT but I do occasionally remember to tweak its flow temperature if there is a marked change of weather forecast for a few days. Changes in its efficiency probably contribute as much as anything in reality.
    Putting to one side the complexity of Evohome (my wife and I are both retired), I have concluded that I would probably have to live another lifetime to recover the capital cost of a 14 radiator Evohome system in our new well-insulated home. There are certain Evohome functions that I miss, but the benefits of zoning would be marginal given that the upstairs heating zone is invariably above the set temperature within an hour or so of the CH coming on at 7am with a boiler flow temperature of 65C.

  8. #8
    Automated Home Jr Member
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    To really recover your cost with these systems two conditions must be satisfied:

    - You have (or potentially can have) heating on for comparable amount of time with the old and new set up. If you hardly heated your home as OP its a no brainer that the cost will be more...
    - You must have some serious heating losses from your home due to its size/age. Modern flats - forget it, for example.

    Most of the time its really a convenience rather cost makes people stay on these systems when they realise they been conned by marketing claims (those who haven't researched it before)...

  9. #9
    Automated Home Legend paulockenden's Avatar
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    For me it's all about firstly comfort and secondly convenience. Any cost savings are a distant third, and I think it's crazy that anyone sells Evohome (or indeed any smart heating system) primarily on cost.

  10. #10
    Automated Home Guru
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    Obviously it's the user that determines how the system is used. If the objective is more comfort you'll likely see a higher usage with this system. In my case most of my home was effectively unheated because mostly due to the UFH in the living room the central thermostat did not call for any heating. Working from home I found myself running up and down the stairs to turn up the thermostat to something like 27 degrees Celsius to create some comfort in my working area and back to normal if things got too hot. Evohome gives me the control I need and as it happens I'm also seeing some 10-15 percent decrease in average usage since I installed the system but as far as I'm concerned the system already payed itself back a hundred times.

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