Where can I buy a box spanner for a 1.5inch BSP immersion heater? (2" across flats)

[MikeH]

I need such a spanner to remove a failed IH, and to install a replacement; in a domestic hot water cylinder made by Opus (Cyprus).
I am aware that in general the distance across the flats may vary somewhat from brand to brand, despite all having 1.5" BSP threads.
In my case, both old and new IH are 2 inches (50.8mm) across flats.

The manufacturer of the old IH (Thermis) cannot help, ditto the maker of the new one; ditto Opus;
I can't find one at ScrewFix, ToolStation, Dickie Dyer, PlumBase, Rothenberger, Faithfull, Draper, Trade Counter Direct, eBay, or Amazon;
Monument do a 50mm one (too small),
FFX do a box spanner for Land Rover nuts (but it is 52mm - too big),
automotive tools shops tend to do 46 or 50mm, not 2inch,
OSO do a 56mm? one for 1.25inch nut (OSO - 1 1/4" Immersion Box Key 73450 - Specialists in plumbing & heating spares - https://www.unventedcomponentseurope.com/oso-1-1-4-immersion-box-key-73450.html)

Driving me nuts!
Please help!

Oh, OK, I did find this one on Amazon:

Urrea 2732SW 2-Inch 121-Point Straight Striking Wrench: Amazon.co.uk: DIY & Tools

Free delivery and returns on all eligible orders. Shop Urrea 2732SW 2-Inch 121-Point Straight Striking Wrench.

www.amazon.co.uk

but delivery may be 1-3months, cost £61 + import fees...; no reviews; seems suspicious

//Mike

 

[snowhead]

Does it have to be a box spanner, is it in a recess?
Large adjustable or Pipewrench (Stilson) would fit otherwise.

The Landrover one at 52mm should fit without slipping but if it does you should be able to hammer the flats in slightly to reduce the size.
Or use a thin piece of steel as a shim inside to reduce the size.

 

[rpm]

The Monument one and a second cut flat file.

 

[MikeH]

Thanks snowhead.
Plan A: borrow my mate's Landrover spanner, see how well it works (obviously I have no idea how tight the IH stuck)
Plan B: shim - strip of 0.5mm steel carefully bent into a hexagon to fit snugly inside 52mm to reduce it to 51mm. Ideally, would use a 2" nut as a former.
We'll see!

 

[MikeH]

Update:

• job done
• turns out the old and new IHs were 2 1/8" across the flats (54mm)

(bad measurement by me (unable to get calipers into the recess) and by the vendor of the replacement)

• I borrowed a deepish 55mm socket, which fitted well enough
• the old IH was in a bad way, after just a year (yes, I have recommended water treatment to customer)

Thanks, all, for looking in.

//Mike

 

[snowhead]

Definitely needed replacing then 🤣