I've been struggling to get heat into the boiler. So I instrumented it to understand the heat losses and to optimise the burner location.

Then I made two types of steam raising blowers.
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Left: compressed air jet Right: electric suction fan

What is interesting is that both give a similar performance. Below is my calculated heat input to the boiler versus time for the two blowers and you can see them switched on, off, on and then finally off.

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The heat input to the boiler using the simple methylated spirit burner increases from ~50W to ~350W with either blower on.