Combi boiler - couple of questions

Adusiak95
Adusiak95 Posts: 3 Newbie
in LPG, heating oil, solid & other fuels
Hi everyone,

I am just a student renting a room in a house with a combi boiler. I tried googling my questions, but I did not find an answer. I hope someone here will be able to provide me with some explanation.
Recently we started receiving very high gas bills (British Gas). Last month it was 215 pounds. I think there might be something wrong with the boiler as the pressure is dropping to around zero each 24 hours. My landlord doesn't give a damn and says we should leave it as it is.
Can it be the reason why our bills are so high?
Also, how does it actually work? When the system in on 24/7 but, for example, only one radiator out of 7 is actually ON, will it use as much energy as when all of them are ON ?

I really hope you can clear this up for me.
Best regards,

Comments

  • Ectophile
    Ectophile Posts: 7,324 Forumite
    First Anniversary Name Dropper First Post
    If the pressure keeps dropping to zero, then either there's a water leak somewhere or the expansion vessel has failed.

    If it's the former, then the pressure when hot will be normal. If it's the latter, then the pressure gauge will go up to the maximum when the heating is started up, and will drop back too low when it goes off.

    Neither would be any reason why your bills would be too high.
    If it sticks, force it.
    If it breaks, well it wasn't working right anyway.
  • Cardew
    Cardew Posts: 29,036 Forumite
    Name Dropper First Anniversary First Post Rampant Recycler
    Adusiak95 wrote: »
    Hi everyone,


    Also, how does it actually work? When the system in on 24/7 but, for example, only one radiator out of 7 is actually ON, will it use as much energy as when all of them are ON ?

    ,

    A radiator is designed to dissipate heat from the hot water circulating in the Central Heating system. The gas boiler has to replace that lost heat. The more radiators turned on, the greater the heat loss that the boiler has to replace; and thus it uses more gas.

    Put it this way, it costs more to heat Buckingham Palace than a 1 bed flat.
  • dogshome
    dogshome Posts: 3,877 Forumite
    Name Dropper First Post First Anniversary
    The state of the boiler is unlikely to affect the billing.

    At a rough estimate your £215 bill is based on a consumption of around 5000 KWh
    What are the Start / End meter reads and dates on this bill?
    Which BG tariff are you on?
  • Adusiak95
    Adusiak95 Posts: 3 Newbie
    Ectophile wrote: »
    If the pressure keeps dropping to zero, then either there's a water leak somewhere or the expansion vessel has failed.

    If it's the former, then the pressure when hot will be normal. If it's the latter, then the pressure gauge will go up to the maximum when the heating is started up, and will drop back too low when it goes off.

    Neither would be any reason why your bills would be too high.
    It looks like the pressure is just dropping gradually. Let's say the heating is on all the time and pressure just drops gradually until it reaches zero ( it takes around 24 hours) and it never goes up during these 24 hours. If we don't repressurize the boiler, the gauge will be indicating 0 all the time, no matter if the heating is on of off.
  • Adusiak95
    Adusiak95 Posts: 3 Newbie
    Cardew wrote: »
    A radiator is designed to dissipate heat from the hot water circulating in the Central Heating system. The gas boiler has to replace that lost heat. The more radiators turned on, the greater the heat loss that the boiler has to replace; and thus it uses more gas.

    Put it this way, it costs more to heat Buckingham Palace than a 1 bed flat.
    That's logical and that's what I'm trying to explain to my flatmates. My question is, how does it work when it comes to numbers? Is the amount of energy used by each radiator proportional?
    And if all the radiators are turned off, but the heating is on (the option on is simply selected on the control panel) how much energy does it use? Of course, I don't expect you to give me an exact number, but is it a lot or almost nothing?

    We are all foreigners and the heating systems we have in our respective countries work differently.
  • Cardew
    Cardew Posts: 29,036 Forumite
    Name Dropper First Anniversary First Post Rampant Recycler
    Adusiak95 wrote: »
    That's logical and that's what I'm trying to explain to my flatmates. My question is, how does it work when it comes to numbers? Is the amount of energy used by each radiator proportional?
    And if all the radiators are turned off, but the heating is on (the option on is simply selected on the control panel) how much energy does it use? Of course, I don't expect you to give me an exact number, but is it a lot or almost nothing?

    We are all foreigners and the heating systems we have in our respective countries work differently.

    The heat output of radiators is proportional to their size(panel area); provided the water temperature is the same and they are both fully on. e.g. a 4 square metre radiator will produce twice the heat of a 2 square metre radiator, and cost approx twice as much to run.

    With all radiators switched off, your boiler is switched on, and the timed to give heating, we have another factor! You should have a room thermostat in the house. If the temperature on that thermostat is set higher than the room temperature in which the thermostat is situated(e.g thermostat = 20C, room = 18C) there will be heat demanded and the pump will run for circulate water but the boiler should not be firing up.

    If you don't want heating, and don't want to use the timer, simply turn down the wall thermostat.
  • tacpot12
    tacpot12 Posts: 7,943 Forumite
    First Anniversary Name Dropper First Post
    The boiler should be switching itself off when the water pressure drops below about 0.5 Bar. If it is not doing this, it is dangerous and should not be used until it is repaired (the low pressure cutoff is a safety feature). It is your landlord's responsibility to arrange to repair the boiler. Are you dealing directly with the landlord, or is there a letting agent you could talk to/email?. You need to send an email (or write using a signed for delivery service) to the landlord/agent saying that the boiler is unsafe because it still operates with no water in the Central Heating System - that way the landlord can't later claim that the you didn't inform them. In the email I would include the date at which you first reported the problem to the landlord.

    You should have received a copy of a gas safety inspection certificate that covers all the gas appliances in the property. IF you didn't receive a copy, the landlord is in breach of their legal obligations and the boiler may be unsafe in other ways. As students, if you have a Student Accommodation office at your college/university, they should be able to help you get your landlord to meet their obligations.
    The comments I post are my personal opinion. While I try to check everything is correct before posting, I can and do make mistakes, so always try to check official information sources before relying on my posts.
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