I highly recommend the services of City Home Comfort (CHC). I was in a situation where the old heater (2011) was malfunctioning, and the Lessor told me that the unit was end of life and replacement parts could not be sourced. A replacement lease was quoted at 3x the monthly charge I have been paying.
Chris D of CHC was familiar with the Combi Boiler unit requirements and his team identified that the last vendor installed a tankless water heater in 2011 instead of the Boiler system the Builder had originally installed in 2008.
After providing a reasonable quote, Chris D came to the house and verified the Combi unit would operate as expected with the high velocity blower and that it would serve the needs of the 2200 sqft townhouse. The unit they quoted and installed is 18K BTU whereas other companies quoting were proposing units as small as 12K BTU.
I would recommend this supplier based on responsiveness, cost competitiveness and technical knowledge without hesitation.