It was a Peerless M1-04-SV-WPC. It has electric ignition rather than a pilot burning continuously. The did lots of new piping, put in a new expansion tank, did some new wiring, installed a new thermostat since my old one was ancient, etc. Got a 1 year warrenty on parts and labor. They spend the whole day working non-stop and made sure everything was installed in the best possible way for allowing future access to anything that might need to be worked on and to the water heater (which is also housed in the same tight space). The total cost was $4600.