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[Reply #15 on:]

No need for PID and all that complexity.

You may have concluded this... but in my opinion,  the PID would serve you well and could eliminate the need for a fan altogether if you do it right.

[Reply #16 on:]

here's what I am achieving with simplistic control

algorithm is
if temp < target then
 turn on heater
else
 turn off heater

the ramp up slopes are less than I would like
the cool down is even slower
I open the door a smidge as soon as reflow is done
the sudden drop at the end is door fully open

[Reply #17 on:]

next step is to add a fan in the floor
a) to aid cooldown
b) might improve ramp-up as well!

I notice that th heaters are on full time during ramp up
is my oven under powered?
or is the profile "close enough for government work"?

[Reply #18 on:]

next step is to add a fan in the floor
a) to aid cooldown
b) might improve ramp-up as well!

My understanding of a convection fan (during heating) is it circulates the hot air more evenly (so there are no hot spots and shadows).
I've read to achieve a fast ramp up (200C in 2 minutes), insulating the glass door, or you need to have more powerful heating element.

(my oven has 4 heaters, and can achieve the 200C in 3 minutes from a totally cold oven, for the first batch)

the cool down is even slower

Yup... this is my problem. 
Even opening the door isn't doing it for me....
I have a big oven, 16cu.ft., big enough for a 12" pizza), so more heat trapped inside too.
 
For others using a small bread toaster oven, opening the door is sufficient for them. I think I really need an exhaust fan, or something.

[Reply #19 on:]

mine is 9 litre capacity with 1 kW of heating (4 elements 2 above, 2 below)
glass door is double skinned
but the oven body is just sheet metal
I've been running with its "triusers" off while I get things working
maybe putting the outer cover on will help

[Reply #20 on:]

I use a 4 element oven, 2 top & 2 bottom, 1500W, observations with k-type thermocouple to digitlal multimeter are that it heats up fast enough.
skyjumper found the same a while ago - 3 elements not quite enough.

[Reply #21 on:]

I use a 4 element oven, 2 top & 2 bottom, 1500W, observations with k-type thermocouple to digitlal multimeter are that it heats up fast enough.
skyjumper found the same a while ago - 3 elements not quite enough.

+1. I agree.

Using 1500 watts here too.