In article , critcher writes
It wouldn't do any harm to insulate it too, over the top.
On an install I looked at recently the external condensate run had been done in 38mm waste to make freezing less likely.
32mm min is a requirement for condensate pipework outside in many boiler installation instructions.
s/syphon/trap/ B-)
That's what my Vaillant boiler does, however in may case this goes into the tank of a condensate pump which in Winter tends to activate every 2-3 hours or so, pumping 1/4 litre of water at a time out over a flat roof into a drainpipe. I've had it freeze many times during prolonged spells of sub- zero weather as the external pipe run is quite long and horizontal due to the roof. I would estimate that in Winter I get around 2 litres of water a day produced, I suppose in theory I could have it drain into a bucket but it would require emptying at least every other day.
I've also known short, steep sections of external pipe to freeze even when well insulated, the mechanism appears to be that the last few drips of water emerging from the pipe end freeze, then more freeze on top, until an ice plug has formed. The solution was as suggested elsewhere: reroute the pipe to tee into an internal waste pipe.
How about a simple up'n'over into a trap then a tank:
==== | | ===== C | |======== | | | | | | ===== | | Tank
C continues on to the outside
The "Up" give you automatic diversion if C is blocked The water trap prevents fumes escaping (many boilers require condensate drains downstream of traps on sinks etc).
No moving parts - idiot proof, as long as the tank has sufficient capacity.
oops, yes.
Ideally the condensate should only be run externally in a larger bore pipe. The 21mm (ish) pipe from the boiler should never be run through a low temperature space for any distance. Running internally and joining to a 40mm (or larger) waste pipe should ensure that its difficult to get a complete freeze up of the larger pipe outside.
Hot water seems to use very little gas compared to heating if my summer v winter gas bills are anything to go by so you wouldn't expect much condensate from it anyhow. My condensate pump only seems to activate once every couple of weeks in summer v. every few hours in winter.
If people are not getting any condensate produced when the heating is on it suggests their system is not operating at maximum efficiency, probably the water is coming back too hot from the radiators to get the steam to condense. Condensing the steam should add about 5% to the boiler efficiency IIRC.
Do most boilers do this? My Vaillant has a siphonic system, so the water goes out in short, warm pulses. The pipe is on a NW wall, so gets no sun in Winter but even at -10C it's never frozen. It slopes at 45 deg., so that might be its salvation.
Because the siphon has a very low head, I clean it out every couple of years as very little would be needed to block it.
Although I have no experience of it I did see on the WB website the other day that they have a gadget for just this situation.
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