maintenance of a Hot Water recirc system

Koan

Hi all my system is steam but a friend has converted to hot water.

Their system:
circa 1910 with American Radiator radiators. Main feed is 3" supply! furnace is a gas fired Balderus with 1&1/2 inch copper for the first 5 feet going into a 25' long steel 3" main. 3" section is insulated (asbestos), but initial copper is not - is in a basement, was clearly originally a steam system. 2 floors of radiators, a couple rads on second floor do not get hot.

They have lived there for 4 yrs, never bled radiators. I assume that is the first task.
Does the 1& 1/2" diam copper going to a 3" main pose an issue?? - hopefully not.
I would think not insulating the first several feet would be more of a concern.

I am more familiar with steam than circulating hot water. As they have done absolutely NO maintenance what should be the first order of business in maintaining the system?

I know one does not blow down and refill a hot water circulating system, are there any kind of anode rods?
at this point all I can suggest is to bleed the top rads first when the pump is running and insulate the furnace output pipes.

What should the temp and pressure gauge read?? (up to what amount)
I can get some pics later.
thanks!

Koan

Does one ever drain and refill this type of system or is it best not to ??

SWEI

Koan said:

circa 1910 with American Radiator radiators. Main feed is 3" supply! furnace is a gas fired Balderus with 1&1/2 inch copper for the first 5 feet going into a 25' long steel 3" main. 3" section is insulated (asbestos), but initial copper is not - is in a basement, was clearly originally a steam system.

Are you certain it was originally steam and not gravity hot water?

Photos would help -- both of the boiler with associated pumps/piping and also both ends of a representative radiator or two.

Koan

Was thinking the time the hous was built and the 3" main with a smaller return were clues it was steam, as well as the boiler pit in the basement. But you cannot see any of that as you point out. I'll try to get some pics in a couple weeks. Thank you!