Answers

We use Culligan for our house and they install.  Hiring a plumber is not necessary.

Willa, we recommend speaking with a professional plumber in your area. They will be able to assist with the purchase and install of a water softener to help with the hard water you are experiencing.

A tankless water heater can certainly be installed in a condominium - similar to any other structure. The easiest model is one that mounts externally - typically near the highest use of hot water or midway between multiple usage points. If there is some distance between the use locations, you can also install a D'mand pump to "call" the hot water so you are not wasting water waiting for the hot water to arrive. If you install a unit on the interior of your unit, e.g., in the previous water heater closet, the unit will require venting.  And - FYI - one reason people love to install an on-demand is that you can actually repurpose a former water heater closet creating more useable space in your condo.   One last piece of important information, you will need to check the size of your incoming water line.  Typically water lines are 3/4 inches in diameter.  On-demand units require incoming water lines of one inch.  So you may need to upgrade your plumbing to accomodate the increased size of your incoming water lines.  I hope that helps.

Yes you can. However every condominium association has its owns rules and regulations.

There is minimal maintenance to keep the water heater running good as new. Here is a quick link to some helpful steps http://www.wikihow.com/Maintain-a-Tankless-Water-Heater

Daniel, Gavigan Uses Tankless water heat ( Gas or LP) when ever possible. The industry and level of Quaity have surpassed common standards. Knowing how to check and possibly service the system is a a Must. The systems are low maintance although knowing Why and how to check if it's working is key incase of a power outage, freeze, or just need to know. 

PRO TIP: KNOW WHERE THE FLUSH Lever is and how to remedy in a freeze situation. See if you need a 7 or 9 Gallon system ( flow) 

Great comment! GAVIGAN HOMES GAVIGAN CONSTRUCTION 

Billy Gavigan