1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

Optimum gas boiler temperature?

Discussion in 'Plumbing and Central Heating' started by fitzykev, 26 Dec 2019.

  1. fitzykev

    fitzykev

    Joined:
    13 Apr 2011
    Messages:
    53
    Thanks Received:
    1
    Location:
    Antrim
    Country:
    United Kingdom
    It would never be touched. The shower is just to the other side of it. The wall is tiled that side. I must just check no water is seeping through
     
    • Thanks Thanks x 1
  2. Sponsored Links
  3. vulcancontinental

    vulcancontinental

    Joined:
    26 Jun 2010
    Messages:
    9,900
    Thanks Received:
    3,712
    Location:
    Bedfordshire
    Country:
    United Kingdom
    Not often I disagree with Ianmcd but there will be an efficiency increase if you change from standard to condensing appliances; how much depends on the boiler. It's fashionable to think of continued running at low temperatures as cheaper also than cycling but too much depends on how the house loses heat and if there is an anti-cycle delay on the boiler, what it is set for and the type of heat exchanger. It's pointless measuring the condensate from that boiler to determine how it is condensing as the flue and exchanger condensate exit together I believe. To give any reference to how efficient the exchanger is you need the condensate from the exchanger alone unless you subscribe to the belief that condensate in the flue warms the incoming combustion air to any significant extent.
     
    • Thanks Thanks x 2
  4. JimCrow

    JimCrow

    Joined:
    31 Jan 2011
    Messages:
    463
    Thanks Received:
    129
    Location:
    St. Kilda
    Country:
    United Kingdom
    Best get it checked anyway.

    asbestos cement board.JPG
     
    • Thanks Thanks x 1
  5. John D v2.0

    John D v2.0

    Joined:
    26 Aug 2016
    Messages:
    6,157
    Thanks Received:
    848
    Country:
    United Kingdom
    I wouldn't say it warms it significantly so i don't subscribe to that view either.
    However assuming a concentric flue, where does the latent heat of any condensation in the flue go?

    I do agree measuring condensate volume doesn't tell the whole story, if the boiler isn't condensing at all the efficiency can still vary, but once it's in condensing mode it would be ok.
    Even in non condensing mode it would be a bit better than an old school boiler just due to the lower flue gas temperature, but i think that's common knowledge around here anyway.
     
  6. vulcancontinental

    vulcancontinental

    Joined:
    26 Jun 2010
    Messages:
    9,900
    Thanks Received:
    3,712
    Location:
    Bedfordshire
    Country:
    United Kingdom
    Look at the plume at the terminal, the latent heat goes to the same place as sensible heat in the flue products, the atmosphere.
     
  7. Sponsored Links
  8. John D v2.0

    John D v2.0

    Joined:
    26 Aug 2016
    Messages:
    6,157
    Thanks Received:
    848
    Country:
    United Kingdom
    We were talking specifically what condenses in the flue itself, i agree that when the flue gas leaves the terminal the is still a lot of condensing to happen but the condensate from that won't end up in the condensate drain, more likely end up as rain.
     
  9. vulcancontinental

    vulcancontinental

    Joined:
    26 Jun 2010
    Messages:
    9,900
    Thanks Received:
    3,712
    Location:
    Bedfordshire
    Country:
    United Kingdom
    Based on what? Hot flue gases are surrounded by cold ambient air through a thin tube. In winter the ambient air can be between -5 and 14 degrees. And still there's a plume, that shows the efficiency of the boiler then the flue in removing latent heat with is less than 10% of the potential of the fuel burned.
     
  10. John D v2.0

    John D v2.0

    Joined:
    26 Aug 2016
    Messages:
    6,157
    Thanks Received:
    848
    Country:
    United Kingdom
    sorry, let's start again as I think we're on different pages of the book by now:):
    • my suggestions measure the condensate output to compare relative efficiency (all this assumes the flue gas leaves at 100% humidity, i.e. condensing mode)
    • you mentioned that also covers flue condensation, but only hex condensation should be taken into account (unless people believe it warms the intake air much)
    • my point if there is condensation forming in the flue, there must have been a surface cooler than the flue gas for it to form on
    • condensing water out transfers heat to the surface
    • the other side of the surface is the intake air along almost the whole length of flue
    • so almost all the condensation in the flue will return heat to the intake air
    Yes I agree it won't be much heat, but in that case there won't be much condensate from the flue.
     
  11. gas112

    gas112

    Joined:
    27 Oct 2009
    Messages:
    17,265
    Thanks Received:
    5,148
    Country:
    United Kingdom
    That wall is asbestos but prob asbestos cement as opposed to the more dangerous AIB but providing it doesn't get disturbed it's ok to leave. But it has already been drilled at some point
     
    • Like Like x 1
Sponsored Links
Loading...

Share This Page