Removing baseboard heater/heating loop and purging air

Question

I need to rip a baseboard heater out: the cabinet, the copper piping, everything. There is no longer a need to heat that room (reasons: outside the scope of this question).

This is fuel oil with an oil burner that moves hot water through copper pipes that are placed on a big loop. Here is a basic drawing of the piping:

I believe the overarching steps here are:

1. Turn the circuit breakers off for my oil burner and the zone valves (I have 2 of them but only 1 is pictured above); that way the valves can't possibly call for heat, and the oil burner can't service the heat if it wanted to
2. After my zone valve in the drawing, there is a T-branch in the copper piping and one of the branches is what services the baseboard I need to rip out. But that baseboard is daisy chained on a circuit with other, downstream ones that I want to keep. There is a gate valve on this branch. After the water moves through all of the baseboards (including the one I am tearing out) it comes back and returns to the oil burner, and there is another gate valve there near the return. So I think I can isolate the entire baseboard "loop"'s water supply by shutting both gate valves off.
3. Now I can cut the copper piping out after the inbound gate valve (that is now shut off) and before the outbound gate valve (which is also shut off). This is illustrated by the 2 Xs and dotted line in my drawing. The baseboard loop is now completely detached from the rest of the plumbing of the house.
4. Let the pipes I have just cut drain into large 55-gallon containers and pump them out of the house. It is important to note that there are no bleed valves on the baseboard cabinets anywhere in this loop, so I'm all ears on ideas to drain this loop properly! My only thought would be to (since I'm getting rid of the baseboard and piping anyways) just drill some holes in the piping at its highest point.
5. Do the demolition; cut the pipes, remove the baseboard cabinets, return all the copper for some well-earned moola, etc.
6. I now have two exposed, opened ends of copper piping: the place after the first zone valve where I cut out the piping leading up to the baseboard. And the place before the 2nd T branch where I cut out the piping leading back from the baseboard. Connect these two pipes together (my dotted line).
7. Turn both gate valves back on, allowing water to flow back through the new pipe I just installed
8. Turn the power back on to the oil burner and then the zone valves

I think these are the main steps, but please keep me honest. I think one major piece I'm missing is how to purge air out of the line, as I will be introducing quite a bit of air with the new pipe I'm adding, and I don't want the system to become air-bound. But I'm unsure of how to do this purging, and I'm also not sure what else I might be missing.

Here is what the piping looks like after Gate Valve B, just before the water returns to the oil burner:

To my untrained eyes, it seems like this is a series of valves and fittings meant for the purpose of draining or filling water back into the system, purging air, etc.

I can confirm that in between the oil burner and the Zone Valve, there is an expansion tank and an air line separator that is functioning, so that may help as well.

I have a transfer pump and hoses. And lots of buckets. I'm just not seeing the forest through the trees as to how to use all of these together to make sure my system does not become airbound.

Can anyone help point me in the right direction here? Thanks in advance!

Answer 1

Break down of work process.

1- Turn off power

2- close both valves

3- there will be pressure in the pipe (before you cut it)

4- OPTIONALLY: On thee most convenient (accessible) end install self-piercing saddle vale to release pressure and drain the pipe using a 1/4 inch tube. (you will not need it afterward), it is just for your convenience not to have water all over the place.

5- now you have empty pipe between the valves and can cut the pipe off as planned and install new bypass.

6- air removal: Install an air vent valve before the Gate valve called B. If you are not in to soldering use sharkbite hardware. Like "SharkBite 3/4 Inch Stop Valve with Drain and Vent,".

7- when filling water leave the SharkBite vent/drain open till water comes out which would have removed most of the air out of the system.

Answer 2

The procedure looks good except for 6. You should instead cap of the stubs where the lines used to branch off. A water-based radiant system is a parallel system, so if you cut out a local loop then you need to cap off the point where you cut them out. You don't want to create a short there. (it's not going to hurt anything other than affect what the maximum heat output of that zone can be, down to nothing if an airlock develops there). If instead there are other radiators the you will need to bridge the part you connected.

For draining, if you are demolishing that loop anyway you can go around and cut the lines at the radiators to create bleed ports. That's going to be easier than drilling.

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As for bleeding the air out of the lines for refilling, double check that there aren't bleed nipples, they may be disguised as part of the inlet/outlet valves for the radiators. What you think may be regulation valves might instead be bleed nipples. Also check the capped ends of the radiators. those may also function as bleed ports.

There might be an air separators at the boiler as well, loosen the caps and they will bleed out air that ends up settling in them. Running the circulation pump for a bit to move the water and then turning it off to let things settle a bit will help bleed the system, if your boiler is newer then it may come with a mode to do just that. Going around and turning on and off certain radiators to force flow through specific paths will help get the bubbles moving.

If neither are present then you can use a bucket a transfer pump and 2 hoses, one on the hot side gate vale (A) and one on the cold side gate valve (B). Shut the valve nearer the boiler and use the pump to force water from a bucket into the hot side and let it come out the cold side back into the bucket until the bubbles stop. Again you can go around and open and shut the various radiators to force water through every loop.

Answer 3

This concept is for not having to purge the system of air in the first place, because you never took out the water.

1. Use a "cold shot" system to locally freeze the pipes at the X's in your diagram (borrow, rent, or pay for, depending on acquaintances and war chest capacity). Cut out the pipe and old radiator between. Cut reasonably close to the freeze points, and trim until you have got about an inch or 3CM of pipe with no ice in it, so a "Sharkbite" fitting can attach to it.

2. Construct the replacement pipe to go between the two frozen ends. Attach Sharkbite valves on each end of the replacement pipe. Don't install the replacement pipe and valves into the gap yet.

3. Open both Sharkbite valves on the replacement pipe, then attach one free end to a water supply, and let the other end dangle. Turn on the water supply, let the replacement pipe fill up until there is no more air coming out the dangling end, only water. Close the dangling end's valve, then the other end's valve. Then disconnect the water supply. You now have a pipe with closed valves, full of only water.

4. Attach the Sharkbite ends of the replacement pipe to the frozen ends of the existing heating pipes. Open the valves. (You might remove the valve handles if you want, you'll never close these valves again.)

5. Turn off the cold shot system and let the freeze plugs thaw out.

Your heating system now has almost complete water fill, except for two tiny air bubbles at the spaces between the Sharkbite valves and where the freeze plugs were. These bubbles should be easily dealt with by the air scoop on the boiler setup.