Old steam to FHW conversion - HELP!

Dan_17

I am a Mechanical Engineer with a very strong mechanical background, a great set of tools, and zero practical experience with heating systems. (potentially very dangerous, I know)

We just bought a house with a forced hot water oil fired heating system that at one time was a 2-pipe steam (or possibly hw pre circulator..??) system.

Our kitchen renovation plan includes removing the radiator in there and replacing it with 2 kickspace heaters. This loop is the only copper part of the system, the rest of it is black iron.

A family friend with 15 yrs experience (he used to work for my bro-in-law's home heating business) was just here and said that he could not drain the system for me because he had no idea how to refill it properly. Here is some more info:

-3 story house, oil fired burner from 1970 (w/orig receipt!)
-fairly new circulator and some plumbing
-unclear history of work to plumbing
-shutoffs on all 3 returns and expansion tank
-no other shutoffs
-several T's with blockoffs on feeds (old rad's removed?)
-loop in question is new-ish and copper and also is tapped off another loop between rad and shutoff
-all rads have shutoff valves and bleeders

All I really need to know is how to properly drain this system and then refill it. We will be adding ball valves to the copper loop while the renovations are taking place which will allow it to remain shut off while the rest of the system is still functional.

It would seem to me that if I closed all of the return shutoffs and opened all of the rad valves (and bleeders?), then the water would drain out of everyting except the return lines. Then I could open all of the bleeders and slowly fill until the air was out of each rad - from the first floor on up.

Can someone shed some more light here? This poor guy drove an hour in the pouring rain and then spent another half hour explaining what an albatross this system is. He seemed to think that we need LOADS of work just to make it serviceable, or at the very least days to get it back up and running after it is drained. I trust his opininon about the albatross thing, but someone has worked on this system during this decade so there must be some trick that he is unaware of. Any insight will be greatly appreciated.

Many thanks in advance,
-Dan (Boston)

gerry gill

I dont get the problem..

drain the boiler by opening its boiler drain and a top floor radiator bleeder...refill by adding water and bleeding air from each and every radiator..

Steamhead

Was it gravity hot-water or steam?

Take some pics of the radiators and main lines for us. If the main supply and return lines are the same size, it was gravity hot-water. If the returns are smaller than the supplies, it was steam.

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ed wallace

old system

turn water off to boiler attach hose to boiler drain then open go open bleed valve on rad wait a few hours for system to empty

Dan_17

It was a steam system

Looks like the returns are smaller, but only in the basement. All of the other pipes - the vertical ones - are the same size.

Steamhead

Whoever converted it

may not have put vents everywhere they should have. Each radiator should have one, and any high points on the main should be vented too.

Open the ones at the top and start draining. When the water drops below the next level of radiation, open those vents and so on. When filling, first close all the vents, turn on the water, then vent the first level one radiator at a time. Then do the second level one rad at a time, and so on.

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