using System;

using System.Linq;

​

​

class House

{

    public Dishwasher[] Dishwashers{get;set;}

}

​

class Dishwasher 

{

    public string Name {get;set;}

}

​

public class Program

{

    public static void Main()

    {

        var houses = new [] {

            new House(){ Dishwashers = new [] { new Dishwasher(){ Name="DW1"}, new Dishwasher(){ Name="DW12"} }},

            new House(){ Dishwashers = new [] { new Dishwasher(){ Name="DW2"}, new Dishwasher(){ Name="DW22"} }}

        };

        var allDishwashers = houses.SelectMany(h=> h.Dishwashers);

        Console.WriteLine(string.Join(",", allDishwashers.Select(dw=> dw.Name).ToArray())); 

    }

}