Protruding wall heater


Does anybody have a wall heater in their listening room? Mine protrudes out 10" and is 40" tall. The upper area where the vent is located is where the mirror lands for first and second reflections using the sound reflection mirror test.

When sound hits that heater area, there’s a slightly annoying treble haze if you will. How to treat this spot? Obviously, I can’t cover the vent openings. I keep picturing some kind of portable panel I can put in front of heater for listening sesh’s and take it away when not listening. I can’t find any such products, with the exception of a bulky tripod contraption on Amazon.

Any suggestions?

Thanks,
Paulo
128x128paul70
OP that's not that tall. Something as simple a cardboard. Stack sheets of cardboard the height and width you want and put foldable wings on either side to space it from the wall and to stand it up.. 1/2 - 1" thick should do.

Leave the top open. Prime and paint it with crinkle paint or a hammered finish.... I say 10.00 usd for the whole thing.. Move it when your not using it. 

Regards
You might try some fo.Q tape,
strategically placed.  Or some weights
on the heater's top shelf.

Or wedge some kind of block
between the bottom of the heater and 
the floor, if you listen to music with
the heater off.

Also pay attention to the way the heater
is attached to the wall, if you believe
this could be important.
You want a panel that stands by itself in front of it.

https://www.gikacoustics.com/product/freestand-acoustic-panel-gobo/

If you want to avoid blocking the heat you can locate the panel so it's in the way of the arriving signal, instead of the actual reflection point.
These are great, well thought out responses. I will consider all of them. Thank you.