How to remove stubborn immersion heater blanking plug?

[Rob]

I know there are a few home DIYers/pros on the forum so I thought I may as well ask here. I need to get a very stubborn blanking plug off my hot water cylinder which looks like it has been there for well over 40 years. Tried getting some decent torque on it and the copper just started to move about. It is one of these:

Did not have the propane torch or penetrating oil but before I do use them I thought I would ask if I should. Can I use penetrating oil on a water cylinder? Are there any potential potable water contamination issues with using penetrating oil? I assume there is no harm in using the torch?

 

[silvercruiser]

Are you trying to remove it with the tank Drained? if you are refill it and get a good fitting spanner to give it one good wallop. obviously have your drain hose attached ready to drian it again. if the tanks empty it just buckles and moves. they are normally Boss whited in which sets quite nicely over the years so the first wallop normally frees them. just be careful if has been in that long of dezincefication

 

[Rob]

Half drained the tank using the hot tap in the bath. The plug I am trying to remove is in the top. Will try it with it filled but all the valves are seized or the handles have been broken off so need to rely on the bath tap to drain it and the valve in the street to fill. I guess I could try and get to the tank in the loft to ensure that the level is very low before I try to remove it to minimise the volume of water above the plug. The entire system will be replaced before the winter, but just need a way of getting hot water until then.

 

[Tractionman]

Rob, as silvercruiser says def. do it with cylinder filled, it adds more weight/stiffness to cylinder - having said that the copper is thinner than a car panel and is prone to buckle /tear if too much force is used. I tore the top on one before using stilsons, and the proper type spanner for the job does not exert enough force for stuck plug, 40 years ago we were in the realms of using putty as a sealer then later on plumbers mait. the putty, especially, sets rock hard with age and gets baked on. be careful with heat on the copper as this is the part you need to expand, not the thick solid brass plug. I think the threaded flange is brazed or silver soldered in so may fail with loads of heat if you don`t burn through first. Yes a single sharp blow mentioned, to shock it has some merit, but can still twist the copper. I have got several off by using a small cold chisel and firmly tap with the "sharp" edge on the flats of the blank plug, moving to opposing sides as you go. This shocks it, breaking the seal and you can control the amount of "hit" with the hammer and see as you go - chews the blank up though!
Penetrating oil I would think would have no effect if it is rock hard putty and if it did get through there would not be too much contamination. Water from the hot tank is not potable, you do not DRINK water from hot taps, but I accept you may clean your teeth with it - oh, and wash in it. hope you succeed but if you do replace cylinder weigh it in to at least part offset cost of new one
John

 

[Tractionman]

Rob, just noticed your latest post. the hot tank/copper cylinder should be filling from cold storage tank in loft, which in turn is filled from mains in street, you can shut incoming water from stopcock normally under kitchen sink OR the street OR by tying up ball valve in storage tank in loft.
John

 

[yogi]

If its in that long be prepared for doom!!

Why are you trying to open it?

Not being nosy just there might be another solution.

 

[silvercruiser]

Rob, ive just read your second post. do not attempt this on a bank holiday you are setting yourself up for a major fail. if you have seized valves and your relying on the bath tap to drain you will be in shite street if you buckle of split the cylinder as the copper cylinder will still be full! do you not have a drain point near to the bottom of the copper cylinder?

 

[Tractionman]

Yogi, reading through Rob`s post,I guess to fit immersion heater to get hot water.
John

 

[Tractionman]

silvercruiser you are right if it splits low down, there be shit loads of water in there (or all over the floor) bank holiday or not!. in my experience if it goes its the top dome around the flange that tears so not too much spillage, but still in the sh/t. but could strain other joints. thats why I suggested controlled tapping with hammer/cold chisel, less risk of splits, I have had results that way, having torn one using other methods.
John

 

[Chris]

Been there Rob. Stubborn blanking plug. New immersion element waiting to go in. Well, one ripped tank later and a new waterway down the stairs later ............

 

[Rob]

Thanks for the advice guys. To answer a few questions. We need to make the house habitable after it has been vacant for over a year. The back boiler did not come with any safety certificates, nor did anything else for that matter. To get the boiler going we would need to get someone in to check the boiler over but we intend to bin it before the winter. The cheaper solution is to fit an immersion heater to the old cylinder. This is only a temporary solution until we replace it all.

I have been using the stopcock in the street as I cannot find one behind the sink or anywhere else in the house then using the bath hot water tap in the bath to half empty the cylinder. The plug is in the top so I do not need to empty all of it. Will try filling it up just until the tank in the loft starts to fill and then try taping the wrench. If that fails I will use the blow torch, but I assume you need to use the torch above the water line as all the heat will just get absorbed by the water?

 

[yogi]

The 'back boiler'? Assume you mean one behind an open fire/range NOT gas?

If so I wouldn't worry bout a safety cert, it can't really go wrong once there is water in it because its an open heating system (no pressure, header tank above it, circulating pump on a thermostatic switch somewhere near it (probably).

Do yourself a favor and plumb in a couple of stop cocks while your in plumbing mode!!

I stand to be corrected but messing with an ancient cylinder is going to be nothing but grief, it may well be full of lime anyway depending on where you live. Fit a new cylinder and then its done.

 

[frank rabbets]

Total nightmare those large diameter plugs. Get the torch on it with the cylinder half empty but don't heat the copper. Then quench it with water. The plugs expansion should stress the joint/thread against the copper and cooling it might leave a gap.

Make sure the expansion pipe over the cold tank is not blocked when you drain the cylinder. My mate drained his on an old house and there was an enourmous rumble of thunder as the cylinder collapsed with atmospheric pressure.

 

[Rob]

The back boiler is gas and it looks very ropey/ancient. Not touching that thing unless someone qualified says it's safe.

I could fit a stopcock behind the kitchen sink but the extension it is in needs knocking down and rebuilding. Also don't want to commit to a new cylinder yet as if there is enough mains pressure we will probably go with a combi boiler, which incidentally can't be installed until the extension is rebuilt.

 

[Rob]

Thanks for the tips Frank. Will give it a go today.

 

[Bat21]

Half drained the tank using the hot tap in the bath....

Eh? How have you managed to do that? The draw off to the hot taps is at the top of the tank surely?

 

[Chris]

Agree. Typically, hot water is 'pushed' out of the top of the tank by the cold water fill coming in at the bottom. If you turn the water supply off you normally have to drain the tank from the bottom.

 

[silvercruiser]

yes agreed



unless Rob has some sort of take off from the side of the cylinder like an Essex flange that would allow him to bring the water level down to this.

 

[Rob]

Will look into that as I am sure the tank got lighter when I "drained" it. If there is a drain valve on the tank it can only be round the back where I can't see.

 

[silvercruiser]

they are normally on the 28/22mm pipe that comes from the cold water storage tank down to the bottom of the cylinder and that will be where the drain cock will be. you might be lucky that it works but its probably in the same state as the blanking plug your trying to remove. i normally cut the pipe at the top of the cylinder and put a hose in to pull it out with my pump. but ive got the luxury of my van,tools etc and im normally replacing the cylinder. Good luck, its a shame im not nearer or i would give you a hand.