IRL you'd notice the heat coming up without interacting with the source, like you would feel it, or see the smoke.
My suggestion is to add smoke starts to come up from the tables, starts with very low amount of smoke and it keeps going darker or bigger.
Or we have an indication above the table shows its heat, maybe the 'pourwater' order has some colors, cyan for cold, orange for starting to get warm, red for hot
The UI already appears when you're close the the table so we would RPly feeling the heat without clicking on check heat, this makes us able to get rid of check heat button.
Also we may need some furniture to slow down the heat, like Air Condition system with a bigger radius than the vents (as its already too small) this would help the tables to get hot in longer time.