I might be wrong, but I don't think you can put in on house contents ins as the Ins Cos usually have a value limit for any one item and I think the pump might exceed the limit. For example, if you have a house full of valuable antiques or a Lowry painting on the wall, all exceeding the limit, you have to list them and their value. It might be worthwhile finding out if you stated it as a specific item valued at £xxxxx, how much extra they would charge. I'd be surprised if they bumped the premium up by £84 p.a.
Another option - does the pump supplier offer any Insurance?
Best of luck and I'm sure other pump users will come along with their recommendations. (I'm not a pump user)