The cast iron baseboards are hammering

Double D

So the son of the plumber who installed the Steam boiler came out to put in some valves for purging and to get rid of the air.

KC_Jones

You don’t purge steam, I have no idea what they did there, but I suspect some serious confusion on their part. Also spending some of your money needlessly.

Hap_Hazzard

Well, you do purge air from steam radiators to allow them to fill with steam. That said, I'm not really sure what kind of a steam system this is. Those vents are for one-pipe steam, but those baseboards won't work well on a one-pipe system, and where they put that adjustable vent makes no sense to me. The piping doesn't look right for one- or two- pipe.

Jamie Hall

It is really important to know if this is one pipe steam or two pipe. Those vents which were put on are required for one pipe steam -- but must not be there for two pipe steam -- and the first picture of the end of one shows what might be a feed pipe (with the vent on it) and a return pipe, right below it, both going down through the floor.

If it's two pipe, then there should also be traps on the return pipes before they hook into the actual return.

If it's one pipe, then it's essential that there be very good pitch down towards the inlet end of the baseboard, and the inlet must be in the lower opening. Even then, it is very difficult to get baseboards to operate properly and stop banging.

Double D

It's one pipe steam. The supply line is the one with the hot water purge set up on it. That is where the old radiator was fed. The return side of the baseboard is a 3/4" copper pipe that runs over 40' and connects to the end of the main before it drops to the wet return. If you were to go through all the work needed to have any hope of getting that baseboard to work, 5 feet wouldn't have enough heat for that kitchen. A radiator needs to go back in and just abandon the idea of using cast base.

Jamie Hall

So one side of the radiator connects to the main... and the other side of the radiator connects to the main... 'fraid not. Two pipe air vent systems did work -- after a fashion -- but they weren't set up quite that way (to put it mildly).

Double D

That's correct, both sides connect to the main.

Jamie Hall

OK, let's think about it for a moment. You have two pipes which connect to the opposite (for all practical purposes) ends of the radiator. Both are connected to the same pipe at the other end. There will be essentially no flow in either of those pipes, since in order to have flow you have to have a pressure drop.

Now we put a vent on one of those two pipes. That vent is open, and steam will try to make it to the radiator from both ends. Well... it will get to that vent and close it, at which point the pressure rises to be the same as that in the main, and flow stops.

Result? No heat.

Double D

@Jamie Hall You just described to the tee how that baseboard is heating.

Hap_Hazzard

The only way to make these units work with one-pipe steam is to run a drip from the end opposite the supply. This drip should connect directly to the wet return. It should not connect to any other drips above the water line. The drips can be copper.