As the title! I was thinking of getting one of these. Looked on Electrons site and plumped for one but they didn't have one on display in store, so we decided to leave it for the time being.
I would be interested to know if anyone is using one of these though and how effective they are?
How big is the unit?
How big is the space?
How well insulated is the space?
What sort of orientation? South facing with a lot of glass? Or north with very little glass?
I know I'm not answering your question but it's like asking if one of those small little electrical heaters will work. In a small bathroom almost always yes. In a large drafty room no.
The other issue is even if it works is it worth the running costs. Those portable units are likely to have higher running costs when compared to a wall mounted unit. If you only want to use it rarely then what you save on purchase and installation cost more than offsets the running cost. If OTOH you hope to run it all the time do your sums carefully to make sure the running costs aren't going to be an issue.
Plus the modern wall mounted heat pumps can also provide you with heat.