There are any number of good brand name boilers out there. Find out what your local contractor carries and make sure he services afterwood. Your old system has only a few components, whereas the new one comes with all kinds of safety controls and electronic parts. You will find installation is one thing and service is another. Generally people think of plumbers instead of heating conractors when it comes to boilers. Any plumber will install but they're not much on service. It may be down the road condidering the boiler is new but you never know. As far as boilers go anything you get will probably cut you bill in half. Being an 80 yr. old unit it must have been a conversion job which is very inefficient to begin with and second the water content in your new boiler will probably be about 14 gal. compared to maybe 50 or so in your one. Just the heating time of the wter and delivery to the heating units will be a big savings. Rember your old boiler was made for wood or coal, the new packaged boiler was made for gas. Depenking where you live you might have to get the chimney lined also to match the size of the vent pipe on the boiler. Just something to think about when pricing.

If you have an old gravity system you probably have some large pipe sizes in that system as well as some big old radiators that hold large amounts of water. Nobody in his right mind would sell you a modern boiler to tie into your old dinosaur. Everything these days is forced hot water. If you were to introduce the amount of cold water sitting in your pipes and radiators into a hot cast iron boiler as quick as a pump will do that new boiler probably won't last you an entire season. Its called cold shocking and is about the only thing that will kill a cast iron boiler. If your system has the big old pipes and radiators I just described I would highly suggest going with finned baseboard. A by pass from the supply right into the return might work but you're still heating huge amounts of water to heat your house. Great big waste of energy.

mr.havac is correct but if this helps I had the same concern years ago on a job as the one described. They needed a boiler but there was just no money to change the pipes or readiators since this was a two story house. I installed the now boiler but made sure to put in a 1" by-pass line from the supply to the return with a ball valve to temper the water coming back to the boiler to avoid thermal shock which could possibly crack the boiler. This was put in about 15 years ago and is still running today trouble free. My suggestion though would be to make sure your contractor takes the time to do this right. I don't know about today, but back then if the boiler would have cracked and it didn't have the by-pass the manufacturer wouldn't have covered it. It is not the best thing to do but sometimes circumstances determine what we do.

We only have 1" pipes and no tank in the attic. I've been told I need an electric re-circulating pump but no mention of new radiators. Regarding cost savings, I'm only paying about $2000 a year for heat, hot water & cooking gas. Will the difference between an 85% efficiency boiler and 90% efficiency be noticeable in my bills?

A "mod con" or modulating & condensing boiler would be perfect for an old gravity system. Super comfort and you don't have to worry about thermal shock like you do with a low priced cast iron 80% boiler. Since you don't need really hot water in mild weather, the boiler will run cooler and very efficiently in those time. Only in bitter weather will the water temp crank to the max at which point boiler efficiency drops. That's why this type of boiler isn't always the best way to go with baseboard fin-tube.

Your boiler will come with the circulator(electric pump) as part of your boiler package. As far as the pipes and no tank in the attic go you lost me. What has that got to do with the new boiler. Whatever boiler you choose, the decision on 80 or 90% will be yours. Only you know if the savings will be worth the cost. With the radiators and larger lines as I stated makes sure he puts in some type of by-pass to combat thermal shock.