Need a replacement boiler

You can put thermostatic vents on the bedroom rads to slow them down.

Your present boiler is piped incorrectly.

463 sqft of EDR? Yeah, probably oversized.

If you have those radiators turned off all the time, you can choose not to count them in your EDR total. There is a lot of extra capacity in the Net Sq Ft of Steam value that boilers are rated with (which is matched to total EDR). It will depend on what your total is compared to those radiators.

But you can decide once you get a total and decide on a line of boilers…one size or another might make more sense at that point.

It will have the capacity. And I agree with you, but we see dozens of new home owners whose systems are barely operational.

@nate70500

There are three contractors listed in Connecticut that are choices in the "Find a contractor in your area" selection on this sight. Try that. As to the radiators that are overheating. The rads themselves might be too large. When the contractor comes by they should do all of the proper measurements to properly size your new system.

Removing the asbestos around the pipes and bringing your system up to code/proper working order is of course, what should be expected.

Please never give this advice to anyone. To not include the edr is going to cause many issues especially the day they finally turn them back on due to change of use patterns.

if someone says their rooms are so warm that they never turn on those radiators, I'm sorry, but I don't see the harm in not including them in the boiler size. As I said, every single boiler comes automatically oversized by 33% from the factory even if you perfectly match it. So even in the unlikely case that someone would turn those radiators back on, there would be likely be plenty of "slop" to provide steam to them. Note the poster currently has a 463 sq ft boiler.

Please read what I wrote, which I find to be reasonable. You can disagree, but here is what I wrote:

It will depend on what your total is compared to those radiators.

But you can decide once you get a total and decide on a line of boilers…one size or another might make more sense at that point.

Why is it OK for so many contractors to dramatically oversize boilers, not even size them, or just bump up to the next larger one because the correct sized one is not in stock, but it's forbidden to give this kind of advice for the homeowner to make a thoughtful decision based on radiators they actually use?

I have to agree w charlie when asked to not include radiators to a edr for a replacement boiler due to them shutting them off or not using those rooms i will usually give a quote for the correct size boiler and leave it at that . If they have some else do the job w a undersized boiler , that's fine but i will not be the one reasonable for installing a boiler which will not meet the connected edr and leave them cold on design day it a bad business and just plain silly . I some times read what advice some give and laugh being its easy to give advice without having to be held reasonable for said advice and also make a living in the process. From not flushing and washing out your boiler to the no need for a equalizer or insulation on the system piping i shake my head and grin and say ok they know better then some one who does it for a living ,solves issue, installs and repairs these systems for a couple of decades or from them just having a steam system in your home possibly installing and maintaining your own system and being a steam fan there's a huge difference from that to earning a living and providing a service to those in need without guessing cause no one pays for guessing they pay for results and when dealing w old stuff there's alot more then guess work it called experience and this is what people pay for not guessing or theories they pay and they want real results .

peace and good luck clammy

Why Wait?

Time is the issue not size of the boiler. 20 minutes at X btus or 50 minutes at 0.75 X btus. That is the increase in infiltration.

This, and this.

@Jamie Hall an atmospheric vented boiler can send 50 to 60 percent excess air up the chimney during a fire. True power burners are 25 to 30 percent plus whatever is dragging in by the barometric damper. A properly sized boiler is within 10 to 15 percent of the edr while undersized boilers may have a 100 percent duty cycle and still leave the building cold in places. Let me get an actual set of numbers together instead of theoretical numbers and maybe start another thread.

From original poster: " Unfortunately the previous owner didn't take good care of it and the bottom is starting to rot out. I'd love to keep it going but would rather not have it die in the middle of the winter"

By RTW:

After you find out the cost$$$ of boiler replacement and anticipated troubleshooting after a new install, you may find yourself reconsidering keeping what works and just using updated maintenance/ repair from a steam professional from this site. You will find many, many posts on this site about all the problems with newly replaced boilers done incorrectly

I wish you well in your endeavor and hope you post results. Like I said before, I have the identical boiler thats working just fine - with just annual cleaning and tweaking/maintaining the vents ( I did replace the fire box and burner decades ago).

Regards,

RTW