On Wed, 9 Jun 2021 15:44:08 +0100, GB
wrote:

I have a problem with an EI44 heat alarm in the kitchen, which goes off
when the gas hob is on. It's a small kitchen, and it's mounted at about
the maximum distance from the hob.

The best solution would be to replace it with an alarm that requires
*both* heat and smoke before it sounds.

Anybody have a suggestion, please?

I very much doubt if this would comply with fire regulations. I am
sure an alarm has to be triggered by presence of smoke (with heat
alarms possibly optional) and introducing a two-stage trigger would
not be permitted.