Vaillant ecoTec 831 R1 Gas Use

Discussion in 'Plumbers' Talk' started by Jay 2 0, Sep 10, 2019.

  1. Jay 2 0

    Jay 2 0 Member

    Hi All! It's been A while but I have a question regarding the above Boiler which I have had in for a number of years now. During the summer months I have not used the heating but my Gas Bills have Increased oddly. The only other Gas appliance in the house is our Hob.

    I was wondering if any of you know of any test that can be performed on this boiler so I can see if the Boiler is in fact using too much Gas? Any help would be great. Short of asking the Gas supplier coming out and charging me if the Gas Meter is working fine.

    Thanks again. Jay
  2. Mike83

    Mike83 Well-Known Member

    What’s increased.
    Your gas bills or gas consumption?
  3. harrisjohnpaul

    harrisjohnpaul New Member

    When you run the hot water for two mins see how much gas m3 per hour at the gas meter you use.
    A simple calculation can be done to check kw of boiler.

    A tightness test will also tell you if you have a gas leak
  4. Jay 2 0

    Jay 2 0 Member

    Ok So m3 at the meter, converted to Kw/h and then multiply by 30 for a 1hour boiler Kw/h test?

    Also, would you happen to know how to change the Kw/h on this boiler using the small display?
  5. The Teach

    The Teach Well-Known Member

    The boiler gas settings are factory set although they can be changed by a proper gas boiler technician.The gas settings need annual checks,part of actual boiler servicing.
    gas meter accuracy can be checked but they charge for the gas meter to be exchanged and sent to an independent testing company,as you know after testing a certificate is issued if the meter is over reading then you can claim money back from your gas supplier and get the meter exchange cost reimbursed.

    Make a note of the gas meter readings for 7 days (Wednesday to Wednesday) at the same time of day will give an idea of your consumption ;)
    consider a smart meter for convenience of reading and checking daily usages.

    The boiler could be faulty,during the next annual service ask the gas boiler technician to test & ensure the boiler is running as efficiently as possible.
    Inside the boiler there is a diverter valve,this could be passing heated water intended to heat up your tap water but passing it into the central heating pipework.if the hot water preheat (warmstart) is selected with the above fault will consume unnecessary gas.

    the warmstart is optional,it can be turned off by the user.

    The 831 is a powerful boiler,the hot water system could be designed to need a higher use of gas to achieve the desired hot water flow rates. Every property is different.

  6. kiaora

    kiaora Well-Known Member

    The two ways to calculate the gas consumption on the hot water,

    1, If you have on old meter as in cubic feet,

    Run hot tap in bath if possible, time in seconds how long it takes to use 2 cubic feet of gas, try to be a accurate as possible.

    2, if metric meter,

    Run hot tap, take meter reading / start stopwatch,
    Arter 2 minutes exactly, take meter reading, the difference is the information required.

    Post results on here,
    There will be lots of people on the forum, to tell the gas consumption, net and gross !

    Good luck

  7. Jay 2 0

    Jay 2 0 Member

    Cheers Peter

    So I ran a test with following parameters: Constant Hot Water set to 40 degrees C, ran hot tap for 2 mins and it used 0.05m3

    Seems low but does this seem right?

  8. kiaora

    kiaora Well-Known Member

    16.14 Kw. ! A bit low ?
    The boiler must have cut off mid test ?
  9. kiaora

    kiaora Well-Known Member

    Need it on max, with good flow rate
  10. Baxi Boy

    Baxi Boy Active Member

    Set the boiler to maximum water temperature,read the meter including the red fractions part and run the boiler for 2 minutes with tap fully open,or if you happen to want to run a bath,maybe longer 6 minutes perhaps,then from the meter readings calculate how much gas you have used and convert it to the 1 hour.
    A 31kw boiler should use 3.43 cubic metres an hour at maximum output.(0.343 in 6 minutes)
  11. dobbie

    dobbie Well-Known Member

    The only convenience a smart meter has is convenience for the supplier.
    Adamantly refuse to have one, putting people out of work and getting a spy installed in your house.
    Baxi Boy likes this.
  12. Jay 2 0

    Jay 2 0 Member

    Cheers for that I will try this test..
    Baxi Boy likes this.
  13. Baxi Boy

    Baxi Boy Active Member

    I am assuming that you have a metric gas meter,I don’t think any old types measuring cubic feet are still around!

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