No announcement yet.

OT combi boiler affected by snow

  • Filter
  • Time
  • Show
Clear All
new posts

  • OT combi boiler affected by snow

    Here in the UK, a form of gas central heating boiler called a "combi" is common. It runs the central heating radiators and when a hot water tap is turned on, it throttles up to max output and the production of hot water is given priority.
    My boiler is in my garage and the air inlet and concentric exhaust pass through the wall. The inlet is annular, about 4" diameter with the exhaust of about 2 1/2" diameter extending about 3" further out. So the inlet is 3/4" wide or less.

    The UK has been having easterly winds from the continent for a few days, just below freezing and my part of the West has had about 4" of snow, mostly fine wind blown flurries.
    Last night about 11pm, we noticed that there was no hot water, so I went out to look at the boiler. First thing that I noticed was the flue was packed with snow, so I brushed it off and had a look at the boiler. It was in failure mode and I reset it and it lit up, but there was a sound of gurgling water, not good.
    This boiler is a Worcester Bosch condensing type and there was water build up causing the problem. Two possible causes were fine windborne snow particles melting in the burner chamber and a failure to drain.
    I started by drilling a small hole in the plastic drain pipe close to the boiler outlet in a position easy to reseal with tape. Nothing came out. Fortunately, W B had a clip on cap on the condensate reservoir and I drained about 3/4 of a pint (400ml) and everything seems to be working ok now.
    I think the high winds created a vortex of fine snow dust in the small walled yard where the flue was situated.

  • #2
    We had that when the 1st started venting thru the wall. Call the company & see if you can use elbows or if the have a better olution.
    "Let me recommend the best medicine in the
    world: a long journey, at a mild season, through a pleasant
    country, in easy stages."
    ~ James Madison


    • #3
      My daughter's combi did the same. Loads and loads of similar cases reported. She poured warm water on the condensate drain pipe and it thawed out readily enough. Had a couple of repeats in the last two days but the temps are due to rise sharply tomorrow when we get some warm air off the Atlantic and it's unlikely to be a problem again.
      Peter - novice home machinist, modern motorcycle enthusiast.

      Denford Viceroy 280 Synchro (11 x 24)
      Herbert 0V adapted to R8 by 'Sir John'.
      Monarch 10EE 1942


      • #4
        I think that the syphon may be blocked as I had drilled a small hole in the drain near the boiler and nothing came out. For now, the cap at the bottom of the syphon is off and a bucket is catching the condensate. I will investigate further when the weather gets better.


        • #5
          This kind of problem is also reported with self-defrosting fridges when the drain tube freezes so it shuts down the fridge. You can also get algae growing in the tube over time as they like the warm damp conditions.