Two quotes for the same house can differ by a factor of two. Usually that is not one contractor overcharging — it is the two of them quoting different work.
The heater itself is often less than half the total. Labour, the fittings, the permit where one is required, disposal of the old unit and any code work needed to bring the installation current make up the rest. A quote that is dramatically cheaper than the others has usually left something out of that list rather than found a cheaper heater.
An expansion tank, if the house is on a closed system and does not have one. A new drip pan and drain line. Earthquake or seismic strapping where required. Replacing supply flex lines and the shutoff valve, which should be done at the same time because access is never cheaper than when the old unit is out. Bringing venting up to current code on a gas unit — this one can be a significant cost and it is also the one you least want skipped. A difficult location, such as an attic installation, adds labour.
Any line item you cannot get explained in plain language. A new unit substantially larger than the old one without a reason tied to how the household actually uses hot water. Extended warranties sold at the door. And a replacement recommended without the unit having been diagnosed first — if nobody has told you what failed, you do not yet know you need a replacement.
Tankless costs considerably more to install, particularly if the gas line needs upsizing or the venting has to change, which is common in a retrofit. It uses less energy standing idle and will not run out mid-shower. In Fort Bend County's hard water it needs descaling to keep its warranty and its efficiency, so build that into the comparison. Tankless makes most sense when you are replacing anyway and intend to stay in the house long enough to get the difference back.
Often yes, depending on the jurisdiction and the scope. A licensed contractor will know what the local authority requires. Permitted work matters at resale and for insurance.
A tank past about twelve years is on borrowed time, and replacing it on a Tuesday by choice costs less than replacing it on a Sunday after it has emptied itself into the garage.
Only if the household needs it. A larger tank costs more to buy and more to keep hot every day for the life of the unit.
Send the details and we'll route it to a licensed local contractor.