I am shopping for a washer and dryer set. I see combos and separated sets in market. What is advantage and disadvantages of each kind? I am not short in space but one unit is a nice to have. Also I am interested in electricity consumption comparison.
One issue I can see, is that in 35 years I've bought three washers and one electric dryer. If you are referencing to is attached stacked units you may be replacing a working dryer because it is attached to the broken washer. The dryers have so few moving parts they are easily and inexpensively repaired. The same can't be said for washers.
The combo is only useful if you have a very small space and cannot afford to have separate units taking up extra space. They will have lower capacities and not perform as well as standalone units. Another issue is that with separate units, if your washer breaks, you can simply buy a new washer and keep the existing dryer. With a combo unit you would need to replace both in that case.
It's unclear of what you are asking. There are three scenarios I can think of:
These are common in apartments where you have a top-load washer on the bottom and a front-load dryer on the top. The advantage is that these are usually cheap and, obviously take up little floor space. Disadvantages is that you have to lift heavy wet laundry up into the dryer, and these units are typically not the latest in energy saving models.
standard units with stacking kit
Most of the front-load washers and dryers today can be stacked together with a kit. They have the same advantages of the all-in-one unit plus: it's typically easier to lift the laundry into the dryer as front-load washers dry the clothes much better than top load washers; you can buy the latest in water and energy savings.
These are one unit that both washes and dries the clothes. The advantages: 1 unit instead of two means a lot less space is taken up; you don't have to transfer laundry; they use a 'dehydration' system for drying rather than forced hot air so they can a) be installed without a vent and b) use less energy to dry. The big disadvantages are: they can take a lot longer to do a load of laundry; you can't typically put as much laundry into the cycle.
Of course, with the single unit, you can always start with one and if it's not meeting your capacity needs, get a second one as well.
If you can fit them in, get separate units.
Washer-dryers tend to be much less reliable than separate units.
With a washer dryer you can only dry a half load - this means either doing twice as many washing loads, or taking half the washing out before drying it, then swapping over and putting the other half in, which kind of defeats the purpose.
If you put too much in (and it's always tempting to put too much in), drying will take hours and hours.