best heating boiler for MFR

[Joe Kato]

I have a 3 story 3 fam with separate utilities and the 2nd floor boiler need replacement in the near future.. Its stamped 1981, and there are burn marks on the outside of it.. The tenants are seeing high gas bills just to keep 1000 SQ FT of livings space at 62 deg. Looking at high efficiency gas boiler since there is $1500 rebate on 95% products, but I see these old boilers last for 30 years.. Are the new high efficiency boilers just as reliable? And should I get a combination boiler and domestic hot water combined, or keep separate for easier maintenance. I am taking a long view of this purchase, so don't want to think about it for 10+ years...

thanks in advance for any insight.

[Bill S.]

@Joe Kato I seriously doubt that your boiler is just providing less heat as a sign of failing, that not a symptom that I've experienced. It could be out of adjustment or the burners can be sooted up (burns inefficiently). The piping could be air locked (no hot water circulating). Circulating pump could be bad (again no hot water circulating). Fins on the heaters clogged with lint and grease (no transfer of heat from water to the air). You should have a qualified boiler person service the unit. Be sure to tell them exactly what's going on. A boiler is actually a fairly simple device (fire on tubes of water) and I have not experienced them just sort of trailing off with heat output. I have a boiler that is gas fired that was converted from coal to gas by sticking a gas burner in it. I would guess it is pushing 100 years. I have others in the 40-50 year range. In lots of cases they last a very long time. I'm sure they will fail some day but when they do, I expect they will just stop working altogether. They might leak but that would certainly be visible and unless it's a boat load of water it wouldn't reduce the heat output.

The smoke on the exterior of the unit is from poor ignition which might be due to starving for combustion air (no fresh air supply in a small utility room) or the improper adjustment I mentioned before.