Please heeeeeelp... how to understand is your old wires good for installing 200 amp panel and which panel is the best ???? This is what I have right now , but I want to install ac and heating , so that's why I need more space for breakers .... don't know what to do .... I think it's all about the size of main wires , don't want to burn my house )

 

You need new entrance cable, meter socket, breaker panel, ground rods, plumbing ground and more.
You will also need an inspection, maybe a permit.
Your best bet is to hire an electrician.

 

You need to do a load calculation and if the panel is adequate you can add a subpanel. http://www.nojolt.com/load_calculations.shtml

 

https://m.youtube.com/watch?v=KbO-4k6IaUs

Mod Note: That video is questionable at best. No mention of turning off power before beginning or of wiring the service entrance at the beginning. Stopped watching half way through.

 

Why I cannot leave everything like that and just replace the panel ??? It's looks like the main wires are 2/0 copper so it's gonna be work for 200 amp panel .... and I did breakers wiring before ...

 

Omg .... I'm so stupid ... I need only one or two more spaces , because I got old heating system (30 amp breaker , 2spaces ) and cloth dryer ( 30 amp, 2 spaces ) which I don't want to install .... so the total gonna be 5 available for heat pump , ac, and water heater I need 6 , and I want to add one for microwave, so I guess subpabel will we ok ... but I don't know which one is better ...

 

If this panel has the first whole house disconnect means (switch or breaker) then you will need to have the power company pull your meter while you change the panel. Usually main panel changes are best left for an expert.

Main panel changes usually need a separate permit in addition to the permit for general electrical work. Also, wiggling the fat main wires into place is tricky.

Adding a subpanel and moving some existing circuits to it to free up space in the main panel for the subpanel feed requires only the usual in-house electrical work permit. The meter does not need to be pulled. You may still need a load analysis.

 

The entrance wire in the photo of post #1 is not 2/0 copper and is not 200 amp wire. Also you have a code violation in the upper right of the panel where aluminum and copper are under the same lug.
Have an electrician give you an estimate.

 

I've been doing electrical work for ~20 years and feel comfortable doing just about everything around the house, but I still would hire a licensed and insured electrician to do anything with the service entry wires or meter. 240v @ 1000A (or more) is NOT something I want to play around with.

As others have said, a subpanel might work, but you'd need to determine if your existing service is sufficient.

I also believe panel upgrade and/or service upgrade is not a novice/intermediate DIY project.

 

So , here is a deal.... in my panel I'm gonna take out breakers for old furnace which one is 50 amp , and breaker for cloth dryer 30 amp... I have one free breaker spot ( total gonna be 5 breaker spots ) ... for new heat pump 3 ton I need 30 amp breaker ( I can put it instead cloth dryer ), for ac same thing 30 amp breaker , and I need two spots for water heat ... so, what I gonna do , just simply installation of tandem breaker 15 amp and I'll be ready to go with all my stuff ... one thing - I have to calculate load for panel , but I thing it's gonna be all right because whole first floor of my house had electric heats in every (seven) room ...

 

This is not a think it will be alright. Do the demand load calculation before time and materials are wasted.

Based on this thread and the other forum I am getting the impression that you are over your head.

 

And how do you know the panel will accept tandem breakers? You really need to get a professional involved.

I also agree that you do not have 2/0 conductors feeding that existing 100 amp panel.

 

casualjoe states: which others have mentioned "strongly"; safety notation: unless the panel is rated for tandems do not attempt to use any tandem breaker that is not specific for that panel. Do not attempt to alter a circuit breaker that is a tandem that is not listed on the manufacturer panel to use in the panel. Not all panels accept tandem breakers.

Always remember something very important. Your "Home Owner's Insurance" company!!!! They will look for any reason not to cover a claim.