they offer different sized tanks either conventional or power vented tanks. depending on the agents most of them are quite honest. if you choose to go with national home services, you will pay rental fees for the water heater tank for the good life of the tank. you have the option of buying out the tank which depends on the type of model you opt for. keep in mind that it is an open market as of 2009 where the government disallowed enbridge/direct energy and union gas/reliance from automatically locking their customers into mandatory contracts. anyone with a tank over the age of i would say minimum of 4 years (because energy star ratings have been changed by the government) should seriously consider calling their water heater provider to request free servicing and maintenance or the full costs of buying their tank and any costs associated with early termination fees.