The condensing boiler frozen condensate pipe problem is popular at this time of year so here is my question:
The boiler is a Vaillant eco TEC plus and yes the insufficiently large diameter un-lagged external condensate pipe does freeze in very cold weather and I will sort it out in due course but that is not the question. I have noticed that the condensate never comes out in a gush as the syphonic description implies that it should. What I observe is a slow trickle of condensate when there is a plume from the exhaust which stops when the boiler shuts down.
Browsing other peoples reported condensate problems suggest that this is a common occurrence and there is even one report that someone tested a brand new syphonic trap only to find that it also fails to syphon and merely trickles.
So the question is has anyone observed a Vaillant eco TEC plus condensate trap working 'syphonically' or do they all just trickle?
Brian