Seized blanking plug on convector.

swvawethead

Hello - Thought I should break this out of the other thread.

We are on the home stretch of a boiler swap from oil to gas (Arcoliner to Buderus).
Since I have the opportunity to do this I am attempting to add a bleeder at the end of a convector loop before it drops down below the floor to return to the boiler. This is the only spot for a bleeder for this upstairs (main floor) loop when the system was originally installed in the mid 1950s. Not sure why they omitted this.
I have been soaking the square head blanking plug with Kroil and will give it more time after wire brushing around the threads to help with the soaking.

I am thinking I should use a pipe wrench to help offset the rotational force exerted on unscrewing the blanking plug.
The blanking plug is on the top of the 90 degree elbow with the convector pipe and down pipes sweated. Would be disaster to crack the solder while monkey around with the blanking plug.

Are there any other tricks you can suggest for this without risking damaging the sweated joints?
(This is before resorting to cleaning off the Kroil and carefully applying heat using a torch.)

Thanks for helping.

Jamie Hall

If it is at all possible use a backup pipe wrench on the fitting so that all your force is absorbed by that. If you have more than one person, you can also have a helper tap the plug while you are trying to turn it (I said "tap". Don't bash...). That often helps.

swvawethead

Jamie - thank you for the tips. Maybe flush my teenage son out of his room for extra hands. Back over there to wire brush the threads and add a bit more Kroil before another attempt. Have the pipe wrench and thanks again!

hot_rod

Not sure you need a bleeder? if you have a properly piped air purger at the boiler, it should keep your system 100% air free.

Paul48

You have the setup to purge the zones from the boiler room. You create flow from one direction. You don't have to worry about bleeding individual convectors, out in the system.

swvawethead

Thank you all - I am overdoing this no doubt and just returned from my second attempt. That puppy is seized in there and I am not going to take anymore chances. Looks like the elbow is also copper and possibly the plug is copper.

Was thinking a bleeder might help with initially filling the loop while pushing water through and not at all for bleeding during heating operation. This in addition to the boiler room setup. Maybe help let out the air at the top while pushing water through for filling.

Anyway, been using your suggestion pushing water through the loops with the boiler/pressure relief shut out of the flow.
Still getting some bubbles and wondering if the bypasses at the convectors are hindering this effort.

Will both the bypass and convector runs fill up if the bypass is set in the middle? If the bypasses are not filled and have air trapped I am not sure what will happen when the bypasses are opened.

Or should I fill the loops first with bypasses closed and then open them full for another blast of water?
And finally, it seems to help to let the pressure build up a bit before opening the drain but I have no idea of the PSI building up and not letting it go too long before opening the drain.

Going back in a bit to purge air out of the third loop from which I was attempting to remove the blanking plug.

Paul48

Isolate the boiler with the valves. Run a hose from the boiler drain out to the lawn. Open the zone you want to purge and close the others. Activate the fast fill with the boiler drain open to the lawn. Switch any bypasses back and forth. Then open another zone and close that one, do the same. After you've done the last zone de-activate the fast fill feature before closing the boiler drain.

Tinman

I like to use 5 gallon buckets for purging. At first, the air will buck the hose and then eventually work its way down to small bubbles until the point you don't see any bubbles at all. Then, you know you've got it.

hot_rod

Stephen Minnich said:

I like to use 5 gallon buckets for purging. At first, the air will buck the hose and then eventually work its way down to small bubbles until the point you don't see any bubbles at all. Then, you know you've got it.

A good way to see what comes out of the pipes when you purge into a bucket.

Solder balls, copper and steel pipe chips, teflon tape, etc.

Tinman

That too.

swvawethead

Re - Isolate the boiler with the valves. Run a hose from the boiler drain out to the lawn.

I apologize for double checking.
The following is what I've been doing.
I am filling and purging one zone at a time.
And the zone with a split loop, I am filling one loop at a time for that zone.
When you say isolate the boiler with the valves, you mean fill the system without the boiler being part of the circuit?
As you suggested this will not trigger the relief.
I can fast fill and purge air out the drain that is mounted just above the shutoff in the return to the boiler.
I can shutoff the supply out of the boiler when I am sending water through the zones.
Water past the pump to the zones and out the drain installed in the return before the shutoff to the boiler.

(From earlier fill routine the boiler should be filled with water already.)

Instead of out to the lawn, I am running the hose to a bucket that is placed in a shower pan.

During the fill process, I am periodically closing the drain to slightly build up pressure before reopening which seems to help help shove any trapped air.

It feels like the fast fill is not sending water through the pipes at fast enough force to help fill and push out the air.
Maybe not fully open the drain?
In order for me to go around opening and closing the bypasses I would need to leave the water running unattended while doing this alone. There are six bypasses on the main floor and five downstairs at boiler level.

swvawethead

When I am running around opening and closing the bypasses while the fast fill is sending water through the zone pipes, can I slightly close off the drain valve to maybe help build up a little pressure? Not sure if this will make any difference. And I would not be able to watch for bubbles in the bucket.

EBEBRATT-Ed

Your best bet is to get the air out with the instructions given above.

However, an altrnative instead of removing the plug you could drill and tap it with a 1/8 pipe tap and install a 1/8 coin vent

Paul48

Power purge with 2 hoses. It can still be done, even though your valve configuration is wrong (one of my first posts). You just have to be careful as you finish to just have the auto fill on in normal function, not fast fill. This eliminates the flow restriction of the auto fill. The second hose out on the lawn lets you run around and take care of things like bypasses, by yourself, without worrying about buckets overflowing. If you have ever had pipe work done in the house......when you open a faucet afterwards, it spits and it's done.

swvawethead

Can't thank you enough for all the helpful tips and technical information.
Just returned from filling the lines and hopefully purged the air. One zone and also loop at a time - with the boiler isolated - fast filled the lines and drained into the bucket in the shower stall. Lots of black flakes and particles coming out along with occasional spurts of bubbles. Did the fill/purge in two rounds for each zone. First with the bypasses fully on. After finishing, shut off the drain and the fast fill and went back to the bypasses and turned them off (for full flow through the convectors). Turned on the fast fill and waited about 10 seconds before opening the drain. Did this routine for all three zones and also for the two split loops.
Occasional bubbles visible in the bucket after adjusting the bypasses so definitely the routine worked - I hope.

The extremely stubborn bypass valve stems are now rotating freely after much soaking with Kroil and wire brushing around base of the stem.

I sure hope this eliminates the trickling flowing noise in the one of the two split loops on the main floor as if the pipes were not fully filled with water when the pump was running (without boiler heating). Crew will be back tomorrow and hopefully the gas inspection will be done and gas company notified.

Quite relieved actually that I no longer will bother with removing the blanking plug to add the bleeder.

swvawethead

Thought this might be helpful to anyone fussing with an original install from the 1950s.
The single spot at the end of a split loop before it dropped back down to the boiler return had a blanking plug I wanted to add a bleeder to before refilling the system. Ended up giving up on that out of fear of messing up the sweat joints.
The other half of the split loop had four (!) bleeders at various points and I was able to swap out all the leaky ones with new.

Well, despite the power fill/purge setup in the boiler room that successfully filled the other loops I ended up having to use the four bleeders on the split loop to completely fill it.

The split loop that did not have any bleeders and with the single stuck blanking plug was completely full without any need to fuss with a bleeder.

So the original installers from the 1950s had everything in place to help me fill the split loop that required using the bleeders.

Appreciating the old time workmanship of the original solder jobs, material, etc. in the convector runs and only thing we reconfigured was changing to pumping away and splitting out a zone during the oil to gas boiler swap.

Thank you for the helpful suggestions on coaxing off the blanking plug and I am glad it ended up best left alone.