I am curious what everyone's experience is with the High Efficiency Combi (heat and hot water) wall-mounted heating units. I am currently going through the process of converting from oil to gas on a 3 family rental building and trying to figure out what is the best approach.
I have one 2021 boiler, one 2006 boiler, and one very old boiler that needs to be replaced. All 3 water heaters are electric and toward the end of their usable life.
scenario 1: Total $19,400
1 new gas boiler, $6K
2 gas burners to use on existing boilers, $6K
3 new water heaters, $3,600
chimney liner, repair, waterproofing etc, $3,800
scenario 2: Total $17,625
3 new high efficiency wall mounted combi units $16,500
chimney work $1,125
I'd appreciate any insight regarding this process, the high efficiency units, maintenance, reliability, availability of parts, ease of use and repair or if there are any other alternatives I should be considering.