Okay! Got a better idea of the problem.
For choosing the relay, there will be two different sets of ratings to look at before choosing which works best. The relay will have two items, the coil or part which makes the relay move and the contacts which act as the switch for the other equipment.
For the coil, we want to have it work at the same voltage as you are feeding the coil. If using 110 AC, get a coil that works at that range but they will often be rated much wider like from 50 to 200 volts. Just get somewhere between the high and low rating or one that says 110AC .
For the contacts that actually make/break the circuit it is controlling, get the same idea for voltage as before and then make sure the contacts are rated higher than the expected load total. So add up the current used by all the equipment controlled by the relay.
heater 200 watt, light 150 watt and pump at .5 amp?
Go to a converter online to convert the amps to watts or watts to amps, depending on how the relay is rated and then find a relay that can handle more than that amount of current. The point is that all the ratings make come up as different ways of saying much the same (watt, amp, horsepower, so we need to convert them all to the same unit of measurement) Not technically the same but close enough for what we do on this. Point is to be sure to have a relay that can handle more work (current? ) than we ask it to do. Overrating doesn't harm things, while underrated contacts will fail too soon.
Often the choice involves what is handy to find in the size and shape wanted and also keeping the price down. Bigger coils with bigger contacts often cost more but not if one has a salvage relay on hand?/