How much gap if putting a sofa bed in front of radiator?

[Jenhouse]

Hi everyone.
In our spare bedroom/office we've put a futon sofa bed but the only placement that would work for the room would be in front of the radiator. (100cm wide single panel convection radiator).

Would leaving about 15-17cm gap be ok to avoid damage to the futon (the back of it is a slated oak base. And would that allow the radiator to heat sufficiently?

https://postimg.cc/QH50B1Y6
https://postimg.cc/H8M4y1zB

If keeping the radiator in this spot, we were thinking of maybe replacing it with a k1 Stelrad radiator of the same width, but maybe 60cm tall, so the BTU would be higher.

Otherwise, we were thinking of replacing it with a vertical radiator between the windows, but it would cost quite a bit of money and might look a bit odd as it's the first thing you would see when coming in the room.

How a vertical radiator would look
https://postimg.cc/0znGmfYW

Best not put furniture in front of a radiator. The wood will warp and most the radiator's heat will be lost, and it will look odd. Any option that means the radiator is fully exposed will be better.
ETA I think the radiator between the windows looks good and the room is nicely balanced.

We did this for several years with no problems. The room was warm and no harm came to the Futon sofa.
The radiator was a more modern version of your photo.

The upright radiator looks fine there.

I would definitely go with the upright radiator, it looks good there.

The upright radiator looks fine- I always think radiators are better on walls you can't otherwise use. So between the windows works or near a door (where you can't place furniture).

If you can't afford to move it, as it's a spare room, can you turn the radiator down? It doesn't necessarily need to be hot all the time?

You could get a higher radiator and also make it a double. Type 21 convectors have double panel, one set of internal fins. Type 22 have double panel and 2 sets of fins.

The extra thickness on the Type 22 is quite significant though, whereas on the Type 21 it is not much thicker than the single panel + convector you have.

To replace the wall radiator is quite cheap if you can diy. But to install the new vertical is very expensive as you will have to reroute the pipes.

What I would do is swap for a type 21 convector and see how that works out first.

If you go for a double panel plus extra height you could turn down the radiator temperature somewhat with a TRV (while reducing the thermal output), which could mitigate the effect on the wood while keeping the power higher than you have currently.