Help me understand our central heating!

135

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  • marks87
    marks87 Posts: 180 Forumite
    First Post First Anniversary Combo Breaker
    Cardew wrote: »
    All boilers these days are condensing boilers. It is important to understand that they operate most efficiently when they are in condensing mode. There are thousands of websites that explain the principle of a condensing boiler but this is sufficient:



    To get the water temperature returning to the boiler as low as possible, the output temperature should be as low as possible; and that essentially is the purpose of weather compensation. It senses the outside ambient temperature and adjusts the boiler water temperature.

    So basically, using weather compensation is good because it should allow the boiler to be more efficient? That's good to know.
    Pincher wrote: »
    That is so clever: so is it actually connected to the internet?
    Or does it have its own GSM connection?

    It's internet-connected via WiFi. Nearly all settings are via an app that works from anywhere (so for instance the timer setting can be adjusted if we're going to be home earlier or later than expected, to avoid the house being cold/the heating being on unnecessarily).
  • Pincher
    Pincher Posts: 6,552 Forumite
    Combo Breaker First Post
    marks87 wrote: »
    So basically, using weather compensation is good because it should allow the boiler to be more efficient? That's good to know.

    In its true form, weather compensation is about temperature stability, used on the industrial scale, to avoid spoiling the product in reaction chambers. By anticipating heat loss, you add heat to maintain a set point (temperature) within a precise range.

    I have a 30kW boiler, which is great for heating up hot water quickly, but I could probably run the central heating on a 10kW boiler, which will condense more.

    You can run a simple boiler manually at 50 degrees just by turning a knob, or dialing the output down, and still have lots of condensation.
  • matelodave
    matelodave Posts: 8,606 Forumite
    First Anniversary Name Dropper Photogenic First Post
    My heating system has weather compensation which adjusts the central heating flow temperature in accordance with the outside temperature - so when it's cold, say 0 degrees then the flow temperature is about 40 degrees. When it's a not so cold say 10 degrees then the flow temperature is reduced to around 30 degrees. This balances the difference in heat loss from the house.

    We've got a heat pump which feeds underfloor heating so the flow temperatures are a lot lower than a system with radiators. It does mean however that the house is a lot slower to react to rapid temperature changes and takes a long time to heat up.

    The system is running virtually continuously but at a low level and as we are at home all day this suits us. The room temperatures are only reduced by about 3 degrees overnight.

    Each room has it's own programmable thermostat so their temperatures are adjusted to suit their useage. ie bedrooms & bathroom is only turned up during the mornings and bed time, whereas the study and living room are on all day.

    Hot water is only heated to 45 degrees to maximise the efficiency of the heatpump
    Never under estimate the power of stupid people in large numbers
  • stevegrass777
    stevegrass777 Posts: 70 Forumite
    If you want the rest of the house a bit warmer leave the living room door open a bit,that door is your control over the temperature of the rest of the house,if you are happy to have the rest of the house a bit cooler to save money keep the door shut,if you are needing the rest of the house a bit warmer just open the door a bit,if you want it warm throughout the house open it wide.
    It's that simple.
  • Pincher
    Pincher Posts: 6,552 Forumite
    Combo Breaker First Post
    matelodave wrote: »
    Hot water is only heated to 45 degrees to maximise the efficiency of the heatpump

    Legionella?
  • matelodave
    matelodave Posts: 8,606 Forumite
    First Anniversary Name Dropper Photogenic First Post
    edited 10 October 2016 at 3:18PM
    No because it automatically heats it up to 60 degrees for half an hour every Saturday to avoid it and as the tank is well insulated it doesn't need to be reheated on Sunday so it really doesn't cost us any more.

    However I don't really understand how I can get legionella into the system as it's fed directly from the cold water mains which is well chlorinated and the system is sealed & pressurised. It doesn't have any open tanks for it to get in.

    Is there any evidence of legionella in the water systems of domestic premises? or is it another H&S bandwagon
    Never under estimate the power of stupid people in large numbers
  • Pincher
    Pincher Posts: 6,552 Forumite
    Combo Breaker First Post
    matelodave wrote: »
    Is there any evidence of legionella in the water systems of domestic premises? or is it another H&S bandwagon

    Forty years ago, I found a pigeon in the loft cold tank.
    It had a lid, total mystery to me how it got in there.

    Why do they bother with the oxygen mask above my seat?
    Will it really save my life if something happened?

    It's when you are sitting in a third world bread van, packed full of backpackers, driving on the edge of a precipice, that you really appreciate the insistence on MOTs and that brakes should work.
  • marks87
    marks87 Posts: 180 Forumite
    First Post First Anniversary Combo Breaker
    The morning and evening temperatures have been colder these past couple of days and with weather compensation enabled the system seems to be doing what we kind of expected central heating to be like.

    The timer kicks in at 7am then 5pm, heats all rooms (up to the TRV setting, except the Living room natch) then keeps a small heat flowing to maintain it for the rest of the morning/evening.

    On the first night the living room got a bit too hot while the other rooms were comfortable, but with none of the TRVs fully-open. So I set the room influence to "medium", and yesterday it was much more balanced.

    The only thing now is that the boiler seems to be always "on" (electrically) whereas previously it would only come "on" intermittently. But I guess the electrical consumption is minimal, and the efficiency savings for using weather compensation (and thus better condensing) offset it?

    The issue we now have is that our energy plan is ending and we need to find a new one. But we have no idea how much gas and electric we're going to use :rotfl: I guess, though, using the Ofgem "estimated" figures will work because even if we don't know the absolute energy use, having a rough idea of the balance between gas and electric will produce the best deal in terms of unit price, even if the headline figure isn't quite right.
  • Pincher
    Pincher Posts: 6,552 Forumite
    Combo Breaker First Post
    The traditional central heating was based on a clicking thermostat, which has a relay contact switch, which is either ON or OFF. This meant the boiler (non-condensing) was either on or off.

    This meant the room temperature was up and down, and the plot of the temperature was a saw tooth wave form. ON the thermostat clicks, the boiler heats up to 20 degrees, then OFF it clicks, and the house cools down to 18 degrees, then ON it clicks, and so on.

    In a weather compensation set up, you are accepting the fact that the house is losing heat at a rate of 5kW (or whatever, depending on your insulation), so the boiler simply supplies heat at 5kW, ALL the time. The extra refinement is, when the outside is 2 degrees, the controller decides to output at 6kW, in anticipation of greater heat loss.

    The Wave app should allow you to configure how sensitive the reaction to temperature change is.

    By being on a continuous simmer, the boiler is condensing all the time.

    I was horrified to find that the Gas Safe engineer tried to install the Glowworm based on a clicking on/off thermostat, because that was all he knows! :eek:

    Died in his sleep about three years ago. Rest in Peace, and be happy in an analogue heaven, none of this fandangled digital non-sense. :A
  • lstar337
    lstar337 Posts: 3,441 Forumite
    First Anniversary Name Dropper First Post Combo Breaker
    Pincher wrote: »
    I was horrified to find that the Gas Safe engineer tried to install the Glowworm based on a clicking on/off thermostat, because that was all he knows! :eek:
    We have a gas safety inspection every year because we rent. The guy that does it doesn't seem to understand our boiler either. I have set it up on a very low output which is perfect for us because the house is A rated so it doesn't need a lot of heat, and it keeps the boiler condensing because of the low return temperature.

    Every time he gets his hands on it he writes a note at the bottom of his report saying "returned boiler to optimal settings". These "opimal settings" are nothing more than cranking the output temperature to the absolute max and setting it to always on so it ignores my timers!

    Now not only do his "optimal settings" stop the boiler from ever having a chance at condensing, but is also results in radiators that burn to the touch, and a house that is like a sauna!

    Now I'm pretty sure he looks at my boiler settings and thinks "Idiots been messing with the boiler again", but to me it is he that is the idiot! He clearly has no idea how the boiler should be set.

    Next time I will leave a note telling him the boiler settings are to be returned to how I had them prior to his tests!
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