What would you do, what brands do you suggest? --65.94.xxx.xxx

Replacing the boiler is not going to give a energy saving without improving the efficiency of the hot water system which means installing a indirect hot water tank around 80 Us gallons or around 300 liters. Indirect hot water tanks lose less one degree per hour instead of 7 to 12 degrees per hour direct fired hot water tanks produce. Next there needs some redundancy where it is better to install two smaller boilers where with a Tekmar electronic boiler control system the hot water, heat would be electronically controlled. Have had very good results with Tekmar boiler controls where on and off a sensor goes bad where it is easy to replace. On boilers there are two options one two high efficiency gas boilers either NTI Ny thermal TX 200 series which means two boilers where there is redundancy or Slant fin power vented gas boiler mid efficiency Victory series with closed combustion option where combustion air is taken from outside. Higher efficiency then conventional boilers while using many of standard parts that most boilers use except the power vented motor. These are cast iron boilers but do not condense like the high efficiency boilers. It is important to install a Spiro vent air and dirt separators then clean up the black sludge from the heating system. Slant fin has office in Mississauga where you get more information about boilers. More often then not one will boiler will used for heating where the other boiler will come on and off for heating and the indirect hot water tank. Visit some the Slant fin website and you tube about boilers, indirect hot water tanks. In the apartment building found having two boilers saved the day when one boiler failed on Sunday or weekend. If the windows, insulation has been upgraded the system maybe over sized where having two smaller boilers the system will be automatically right sized as the electronic boiler control will use what is needed. --147.194.xxx.xxx

You said it yourself. Fewer parts. No circuit boards etc. I just found a pump in this basement for a big old heater we used to have in one of the buildings. Dad put it on the shelf years ago as a spare. I think if you get some spare parts for the things that break on this old heater then you will be OK. Meanwhile maybe you can do some searching and find a solution that doesn't include a lot of circuit boards. Any chance of installing separate heaters for each unit? Gas on the wall maybe? How many units? --73.33.xxx.xxx

High efficiency gas boilers operate differently then a conventional boiler. First there is sensor on the outside of the building which regulates the firing rate of the boiler so on warmer days the boiler fires at a lower rate along with warm weather shut down which shuts off the boiler on the warmer day, nights. There is no on off firing where the boiler is running but firing at a lower rate. There is no mass where a high efficiency gas boiler only holds around 4 liters of water so having air and dirt separator is more critical. Rarely does a electronic PCB go but sensors, flame rod sensors fail sometimes. Doubt we will ever go back to simple designs now as everything has more electronics. --147.194.xxx.xxx

what brand is your boiler? some of those old ones will outlast the new ones you put in and less sensors and stuff to go wrong!! i know a few people with 50 year old boilers while my father in law averaged 13 years from a couple new ones. dont worry about replacing gas valve or aquastat till it goes. just my 2 cents..... --99.92.xx.xx

tell your heating guy to make sure he carries all the spare parts needed - If it aint broke dont fix it. --24.34.xx.xxx

I love the durability and simplicity of my current boiler. I have had it 14 years, its 50 years old. Ironically had I replaced it when I bought the building, I would probably be looking at having to replace the "new" boiler soon. --65.94.xxx.xxx

At the last service they should have left a tag with with that data on test out. --24.34.xx.xxx

In the apartment building went with high efficiency low mass gas boilers which were used for heating and heating the indirect hot water tank. The pros much lower gas consumption, faster recovery times for the indirect hot water tank, payback over the 10 to 15 life expectancy. The cons more maintenance, dirt, air separators required, technicians not so familiar with service. Found it very rare for a control board to fail where sensors along flame rod sensor can fail which is easy to replace. A Tekmar electronic boiler control will be paid for in less then one heating season. A close in between is the Slant fin victory series with a closed loop where the combustion is taken from outside. Opening a account with Desco where can buy a lot of heating, plumbing supplies is worthwhile. If a new boilers are installed then install unions on everything so if have to changed out it can be done in the minimum amount of time. So even if the boilers are changed in 10 to 15 years the savings are paid for. --147.194.xxx.xxx