Types of Multi-Family Furnaces and What to Look For

[Vishal P.]

I am currently looking to buy a 6 unit building and have been visiting properties for inspection. Every time I visit a property and inspect the furnace, I find the furnace and its piping overwhelming and confusing. Is there any education material out there where I can learn more about the multi family furnaces and it's working? Here are some questions: 1- Types of large Multifamily furnace options 2- Which systems require more maintenance than others 3- How are the systems split for each unit 4- Things to look for during inspection 5- Which systems should be installed for 6 unit building 6- Any other useful tips and advices Thanks in advance!

[Mark Elliott]

hi, vishal. i am an hvac technician. i can answer some of the questions for you. first, it seems that you are saying that each unit has its own furnace. is that correct? basically, what you need in btu for each unit can be calculated by multiplying the square footage of each unit by 3.5. i. e., a 1000 sq ft unit would need a 35,000 btu furnace at minumum. then you have to consider the distance from the furnace to the unit is services. if the building is a 3 story with a couple of apartments on the top floor, then those units should have at least 10,000 more btu than the calculation calls for. if each unit has the furnace within the apartment, then the calculation is what you go by. most systems are pretty much the same, but, just like a car, there are some brands that simply cost more to repair based on parts and such. trane seems to be among the most expensive. i recommend goodman. easy to install, easy to work on and parts are reasonable. no one can calculate the timing of repairs on any unit. i have seen 3 year old furnaces need work and i have seen some go for several years without an issue. too many variables to figure that out. if you are talking about having one unit for the entire building, same formula applies to the sq footage, however, i would not recommend this because inevibly, some apartments will not get as much heat as others, and with one furnace, you cannot control the heat going to each apartment. a boiler system could do that but if you don't already have one, it is going to be massively expensive to have one put in. in an inspection, look for the age of the furnace, this can be found in the model number in most furnaces. usually the 1st and second digits are the month it was build, and the 3rd and 4th is the year. however, this is not on all furnaces. basically, get the model number and look it up on line. anything over 15 years old is probably on its last leg and about as fuel efficient as a campfire. also, look for how clean the furnace is. if it is dirty, chances are it hasn't been service often enough. i would have it cleaned out at least once every 3 years at a minimum. change the filter at least once a month, especially in the winter months. a clogged filter not only can lead to premature damage to the heat exchanger, but will also effect the output and efficiency of the unit and could possibly poison your tenants with co2 gas. i hope this helps you, please let me know if you need any further assistance