Thanks. It's so interesting to see everything that's going on in a cycle. I'm going to watch it again, and time the cycle. I understand now what you mentioned before about how the curve can be shifted up and down, without actually changing it. Also, I hadn't realised boilers would report the flue temperature.
I still have the FS Baxi 80,000 BTU, so my cycles are one and a half minutes on and four minutes off.
I hadn't realised you could run OT and WC together. I'd assumed they would conflict in some way?
The phrase "sensible heat" makes me think of a Monty Python sketch.
I think it ran out at just over 7 minutes.
Well not the curve exactly but the target nominal temperature
Over the evening as the temperature dropped so did the internal temperature so I adjusted the curve to 2 which was too high so this morning dropped it to 1.8.
WC and OT together are fine if they're designed to work together otherwise I don't know what would be the outcome.
Next I'm reconnecting the OT room control but disabling it's room input so it becomes a remote boiler/time control. The reason is I notice the OT curve is curved, as it should be, but the boiler curve is linear which probably will make not a jot of difference but I have to see.
At home again tomorrow so more experiments.
1 1/2 minute burn times isn't great and you'll be losing a few percentage points but not more than 3 or 5 I'd guess. Air temp is unaffected by downtime it's just the warmth in the flue products on post and pre-purge. 3 minutes and it's 1-1.5%.
You've looked at parallel coil heat exchangers, serial coil heat exchangers some with retarder some without, large lumps of aluminium cast exchangers, the same with tubes running through them, cross tubular exchangers, some with twice as many tubes as another and larger yet the same efficiencies. Little wonder flue temperatures are not always made available.
Making the boiler condense is making the best of what the design is capable of, making the design the best it can be is another matter altogethe4r