Hey mattressworldus,
Welcome to the Mattress Underground 
! Thanks for your question.
[quote]I just moved to a new home this year. I have been looking for 2-3 mattresses since the beginning of this year.
- I bought King size Serta Caldiero perfect sleeper, it sank in after 2 months. I was told it’s hybrid but when I did more research I found out it’s innerspring.
- Bought Serta blue fusion 100 firm - not delivered yet[/quote]
Congrats on your new home and on your mattress shopping journey ! Question for you, mattressworldus: what brand/ type mattress were you sleeping on prior to your recent mattress purchases and what qualities did you like/ dislike about it? What other mattresses have you tried that you liked, perhaps while travelling or visiting others? When you say “you were told that the Serta Caldiero Perfect Sleeper was a hybrid” but research later proved “it is an innerspring”, are you saying you have a preference for a hybrid mattress? For your mattress shopping research, here are some Phoenix primer articles you may find useful: “Mattress Specifications You Need to Know”, “Five Steps to Your Perfect Mattress”, and “Mattress Durability Guidelines: How Long Will a Mattress Last?”, these will lay a foundation for understanding how the relationship between materials, construction, components and quality all affect the performance/ longevity of a mattress. With the Serta Caldiero Perfect Sleeper, there was very little online regarding its specs other than a listing of foam comfort layers over an 825 pocket coil base, possibly lacking in component durability for your higher BMI/ 32.1. For other consumers who may be following your research, Phoenix’s article, "Different Types and Categories of Mattresses"discusses the different types of mattress constructions, innerspring being the most common construction in the market. A choice of an innerspring mattress vs. a hybrid mattress is one of personal preference, as either would be a quality mattress depending on the quality/ durability of materials used.
[quote]I am doing more research now and checking out mattresses at stores.2. I am leaning towards sleep number but is it reliable? How long would it last? It’s lot of money and I am planning on keeping it for 10-15 years. I am afraid if this mattress sag but would I do? Does warranty cover sagging or it comes under normal wear and tear.
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Sleep Number uses air bladders as its support core, a technology that offers mixed results in terms of comfort and support. They are either very soft for the fractions of a second while they are compressing or very firm when you bottom out either onto a firm material underneath it or onto the firm, fully stretched bladder surrounding the now compressed air. Because of the complete absence of any progressive resistance, your heavier parts will always sink down rapidly until they bottom out (or the boundary of the firm bladder itself stops further compression) and the spinal alignment you end up with at this point is rarely aligned. This is a serious weakness of all air bladders unlike foam, innersprings, or waterbeds which all have progressive resistance in every area of the mattress and compress more gradually. You can learn more about airbeds and their functionality in Phoenix article, “Mattress Support Cores: Airbeds”. Regarding sag and other potential wear issues, you will need to read carefully through Sleep Numbers’ product warranties, (each model has a warranty specific to it); however, they state theirs are a “limited warranty covering defects in materials or workmanship” and seem to applicable more to the mechanical parts of the mattress. The warranty does not cover claims involving cover compressions, foam impressions, or comfort preferences. If you choose to go this route, talk with someone from Sleep Number as you would deal with them for any warranty issues and would want a thorough understanding of what your options are, as well as any costs you would incur (return shipping, a % of part replacement, etc.).
You don’t say, but what is your preferred sleep position(s)? Do you sleep on both sides of your king, or do you work from bed/ game on one side and sleep on the other? Do you have preferences for any certain materials, or any other concerns besides finding a “firm and cool mattress”? You may want to check out Phoenix’s “Determining Your Personal Statistics” to better understand the role your body shape/ weight distribution, sleep positions and preferences play in the mattress selection process. Also, have you set a budget for your king size purchase?
Looking forward to your updates…
Thanks,
Sensei