How much time left on this ticking time bomb

please edit to remove prices, we can't talk about prices of services.

that boiler is about twice the size that you need.

there are add on power venters that can be added to atmospheric boilers. that might not be a bad option if the chimney needs more than just a liner.

if the leak is between sections rather than within a section you could potentially disassemble it and reseal it. people have had some success screwing and epoxying a plate over some leaks depending on where they are.

the added makeup water will corrode other parts of the system so if you keep running it with a lot of water loss you may be spending more money on repairing rotted out returns and mains too.

it is possible you could hire movers or millwrights or something like that to move the old boiler out and the new boiler in and pipe it yourself but your vent situation sounds like you need to find someone that really knows what they are doing to deal with the vent and setting up combustion.

there are boiler fill filter cartridges that you can put in the feed to the boiler that do some demineralization. use the unsoftened water and the cartridge.

@parity_check21

If your EDR is really 650 your about 150,000 btu/hr oversized.

If you have any leaks in the system now is the time to tighten things up before a new boiler gets installed. Also go through the venting and replace any vents and check the vent sizing.

Then you have to find the right contractor who will correctly install a new boiler.

Posting your location may help

Can you be a bit more specific, say, Berks County or Lancaster County?

ISTR @EzzyT sometimes goes that far- give him a try. If he doesn't, he might have a suggestion:

https://heatinghelp.com/find-a-contractor/detail/e-travis-mechanical-llc/

I think Pompetti in the "find a contractor" is someone that spends a lot of time here.

Leaking the rotted boiler could be a symptom rather than the actual leak. When a boiler takes on too much MU water it rots. Could be leaks elsewhere. If they are steam leaks you may not see them.

Did you identify where the leak is? If it s on flat parts of the boiler you could possibly dril&tap some holes and install metal plates (with some high temp silicon gasket).

that vent may be shot, or wrong, somewhere on that body is the model #, what is it?

then the boiler, what pressure are you running at? how clean is the pigtail? and what's the sight glass look like? post a picture showing each, then 1 or 2 more distant shots of the boiler, floor to ceiling, so we see all the pipes also, get 2 different angles,

with the creative piping of the boiler it could be burping a slug of water out of the boiler and out that vent or it could be bad or it could be bad from the slug of water. if the main vents look like that I would replace them with properly sized vents with the new boiler to protect the new boiler.

Hoffman #75 most likely, and yes, it's shot. @parity_check21 , that's at least part of your problem. Measure your steam mains' length and diameter, and we can tell you what to replace it with.

peerless 63-x-06 and a field controls or Tjernlund power venter of the appropriate size.

@parity_check21

How tall is the existing chimney and what is the max size liner that can be installed in it? Those two factors determine the btus you can fire.

power venters are designed to side wall vent natural draft appliances. they have to be installed by someone that knows what they are doing. there is more to it than just looking it up in a table.

No, You can never pressurize a chimney. what if your chimney is cracked? The flue gases would get pushed thru the crack. You can do as steamhead has stated. Put a chimney mounted draft inducer called a rooftop draft inducer. You need to add a control thou. It gets a little pricey. The ones i have worked on have variable frequency drive motors to main a specific draft.

@mattmia2 , we used to see those more than we do now. I wonder if Code changes limited their use?