Plumbing/Heating: expected life of a domestic boiler?

Factual Questions
21

That sounds like a basic boiler where the very hot heating water output probably uses a copper coil heat exchanger inside the household hot water tank. I assume the boiler output mixes with cold water for the household supply. It’s all the same parts in different places. In my case I have a separate electric hot water heater. When the boiler is running in the cold months it’s heat exchange coil produces household hot water but the coil has limited volume and a long hot shower won’t be one or other. So the household water supply comes out of the boiler to feed the electric hot water heater. It doesn’t need to use much electricity in the winter, and the oil burner is off in the summer so I’m not paying for AC to cool off the heat it produces.

I think your system is actually quite similar. However, I have no idea how long your independent hot water tank and exchanger will last. Counter to expectations, the pumps and valves and relays may last longer than the plumbing. They are pretty reliable these days, I have zone valves that are probably close to 50 years old. The spring the oil company said they would no longer service them for me because parts were unavailable. They haven’t needed any service since I bought the house 25 years ago and I left them in place when I changed the boiler. There are excellent quality water lubricated pumps now that are relatively inexpensive if they do break, and pretty long lasting anyway. So boilers have decreased in quality over the years while related electrical plumbing appliances have improved.

22

Oil I can attest to. I can’t tell you how long gas boilers last. These aren’t huge boilers in most homes, the fireboxes now have a refractory liner that needs replacing after approx. 10 years to survive. Of course there are many different types of boilers, maybe you’ve seen some with the old style heavy cast iron construction.

23

I’m looking at my Weil-Mclain right now; it was built in late 1979. It’s not that big. Maybe installed in 1980, so it’s over 40 years old. I’ve changed a few relief valves and the gas valve once, but that’s it.

24

I was looking at an older than that Weil-McLain that had to be tossed after maybe as much as 50 years. That was about 10 years when I replaced it with the current version of that same model of Weil McLain oil boiler. As mentioned I already had to change the firebox lining since then. It is not expected to last like the old one did. It is expected to be somewhat more efficient, that’s what thinner walls get you, but not longer life.