Well, after some months of prodding, measuring, drilling and generally mucking my front room about, I have had to concede that an electric fire is the only prcatical solution. We need something to complement the CH, but we have no chimney so fuel burners are out! What I need to do now is find the most effecient electric heater available - we're not likely to use it often, but just need something to give a quick blast of heat when the CH hasn't kicked in. Does anyone have any experince of brands / models / designs that are particularly good? What should I look out for?

All electric fires have exactly the same efficiency: 100%. However, their effectiveness in making the user feel warm may vary depending on the heat delivery method (i.e. radiant versus convective). Thus a fan heater may feel less effective if it induces drafts compared to a radiant electric fire that makes the user feel warm due to radiation. But the heat output of any electric fire is exactly equal to the electrical input. So don't be confused by such marketing bullhsit as "digital control" or "high tech ceramic element".

Since you want a quick blast of heat, I'd imagine something with a high radiant output might be best for your situation.

Hope this helps,

Paul in Montreal.