Replacing steam boiler

Sanddy0908

I need help choosing a new boiler, i have an old burham boiler it has a domestic hot water coil in it which is no longer need it because i have separate hot water heaters. Question is should the next boiler be the same size or should it be smaller BTU wise since im not getting a boiker with domestic water coil? Please help from tge experts

KC_Jones

The domestic coil won't have anything to do with the sizing of the steam boiler. If you would like help with sizing we can walk you through that process fairly easily.

Steam boilers are sized to the radiation. So you would add up the size of all the radiators and come up with an EDR rating for the system, then that is compared directly to the nameplate rating on the boiler.

https://www.weil-mclain.com/sites/default/files/wm-boiler-replacement-guide.pdf

Start on page 9 in the above link. If you get stuck post back and we should be able to help you through.

Sanddy0908

This is the Tag of my boiler would you recommend  grabbing a boiler withb a D.O.E of 201 MBH or 151 MBH

KC_Jones

The calculations need to be done for the system size, can't properly size off of a boiler tag.

jhewings

Many boilers are not correctly sized. It is not a good idea to get the same size that you have now. It is better to do the calculation.

Hap_Hazzard

Replacing a boiler with a boiler of the same size assumes that the boiler was sized correctly to begin with and that no radiators have been added, removed or resized. Most boilers end up oversized because, every time a replacement is installed, the installer goes by the size of the existing boiler but adds a little "to be on the safe side." My own boiler is undersized because an addition was built, so they had to add a few radiators, but they didn't install a bigger boiler. Later, when they replaced the boiler, they probably got a bigger one, "to be on the safe side." but it still isn't enough for the total radiation. The only way to get a boiler of the correct size for the installed radiation is to determine the EDR of every darned radiator and add it all up. You can go a little over, but you should never go under.

Sanddy0908

Thanks everyone for the information  Really appreciate it. You guys are amazing! Heading back out to confirm the exact size they were. Things are starting to make sense.