Can I replace a single socket with a double and safely connect a dishwasher which is on once a day, max power consumption 2100w and a hot tub, probably on all the time but not sure how often heater cycles on, max power consumption 2200w

Hot tub would be plugged into an external socket, but this would be run like an extension lead and plugged into the internal double socket with an rcd.

Thanks

Can I replace a single socket with a double

Only if its on a ring circuit capable of handling 26A continuously.

Of course you could just swap a single socket on a spur to a dual socket and be fine for ages, but then someone else comes along not realising what you’ve done and fully loads the dual socket.

NB When re-wiring my house I came across just this in the living room, I just stuck a 13A fuse inline where it was T’ed off the ring; as I didn’t want to take up the floor to change it to a ring fed socket.

Ok, thanks. I’m guessing from its position it’ll be a spur. Think ill just get electrician in to sort it.

There’s a number of questions to ask before you get to an answer. Ring or spur? Cable size? Fuse or breaker type/rating? What else is on the circuit?

Can I replace a single socket with a double and safely connect a dishwasher which is on once a day, max power consumption 2100w and a hot tub, probably on all the time but not sure how often heater cycles on, max power consumption 2200w

Hot tub would be plugged into an external socket, but this would be run like an extension lead and plugged into the internal double socket with an rcd.

Thanks

Yes you can.
If the socket is on a fused spur (check it is fitted with a 13A fuse, not a nail 😉 ) then the maximum rating for the spur will be 13A, you could theoretically fit as many sockets as you like as the maximum draw cannot exceed 13A.
If it’s an unfused spur then one double or one single max.
If it’s on a ring main then you can change a single to a double, most likely fused at 32A at the consumer unit.
If there’s no return on the ring then it’ll be fused at 16A but changing a single to a double will be fine.

All of the above is assuming the original wiring is to a modern standard and was originally installed correctly rather than repeatedly bodged by successive owners who thought they knew what they were doing.

please don’t take this the wrong way but if you’re not confident then pay some one to do it for you.