I have a Bryant cast-iron boiler that is original to the house (1972). The extrol tank and pump have been replaced before I moved in. I've been told it's starting to perc and I have noticed increased noises in the 3 winters I've been in the house. I'm on a slab with the boiler in a utility room about 10'X 8', which gets very, very warm when the boiler is running. I think I'm heating the room more than the water. This makes me think it's not very efficient although the metal label is stamped at 160000 input BTU's and 128000 output, so it was originally built for 80% efficiency. The previous owner left the water conditioner inoperable (I've added a new one) for about 10 years and any water drawn into the system would have a very high iron and mineral content. I think I'm heating more sediment than water!

The outer sheet metal is well rusted, and the whole unit is crooked. I've had a service contract through my gas company for the 3 years I've been here and whenever a service tech (from various contractors the utility company sends) has come for minor issues (2 out of 5 zone valves) they haven't said that it needs replacing but I can't help but think a new one will be more efficient. If gas prices are going up by 20% and if I'm running at only 60%, the increase in efficiency will offset the increase in energy. Is there a way to determine the current efficiency of the unit so I can decide if it's worth it to replace or not?

If I decide to replace, then the issue becomes which manufacturer? I've gotten one quote for a Crown, but never heard of them before nor in any of the internet research I've done.

Any advice is greatly appreciated.