replacing an immersion heater

[TerryWaite]

Hi

I am due to change an indirect cylinder soon as it is leaking from one of the seams. Have ordered a new cylinder, I have done several boiler swaps but never a cylinder swap.

Just have a few questions.

1) are all immersion heater bosses the same size thread? and if so could I re-use the old immersion heater, or would it be better to order a new one? also what is the seal on immersion heaters is it jointing compound or a gasket?

2) cylinder stat- do these usually have thier own boss or can you strap them around the cylinder, if so do you have to cut away the insulation all the way round for the strap? and how high up does the stat go.

3) is there any way of repairing a copper cylinder that is leaking from one of the seams i.e. soldering over it? Or is it a new cylinder jobby.

Many thanks

 

[Bernie2]

Yes immersion heaters usually have the same size thread. You could use the old immersion heater if you can get it out. But how old is it? Its worth doing an electrical test on it before removing it to save all the time sometimes required to get it out only to find its faulty.

Yes they do have a gasket and you usually get one with a new immersion. Then its usual to use jointing paste on the gasket.

Position usually 1/3 up from base. Two types, strap on and one that fits into a thermostat cylinder bos. Usually if its a fixed foam insulated jacket and your using a strap on you just cut a pocket in the foam for the thermostat itself the strap goes around the outside of the jacket. The cylinder bos one screws into the bos.

You can repair cylinders using solder. But you need patience and a good self cleaning flux.

 

[JAP&H]

Hi TerryWaite

As far as I am aware the immersion boss thread is common to all makes of cylinder/heater.

I would replace the immersion, compared to the cost of a new cylinder less than £20 is no biggy. New immersions come with gasket, I usually add a sealant to thread when fitting.

Most cylinder stats need to be placed against the cylinder side, so yes the insulation needs to be removed, but for stat only. Strap should pass around insulation.

Never repaired one myself, doesn't sound impossible.

 

[Best]

Buy a new immersion. Saves you usually a very hard task of removing old heater, & besides, it could be rotten or ready to die.
Boss White is a good paste on washer, but does set hard.
If it is a strap stat, then use a knife with a long breakaway blade to cut fully into the deep foam.
Try to buy a cylinder that matches your pipe connections if possible.

 

[Mike Jackson]

All immersion heaters fitted now have to have a stat with a non self resetting thermal cut out so you would probably have to fit a new stat. By the time you've bought this and struggled to get the old one out it's easier and cheaper to fit a new one.

 

[jtsplumbing]

Every one else has told you all you need to know ! all I can add is try the Stainless Steel cylinders, come with all fittings, immersion heater you swap gasket for rubber `O` ring no sealent required, is cheeper than copper ans has a 25 year warranty

 

[TerryWaite]

Thanks for all the advice guys, dont think ill bother trying to repair the old cylinder, I reckon I could do it, but I think ill just weigh it in. Its only a 14" x 36" so not big bucks like. I will buy a new immersion, thanks Mike for the advice. And I will bear that in mind about the stainless steel cylinders, definitely worth thinking about going by what youre saying!

The only difficulty I forsee are if the connections are all in different places. I have seen some cylinders in really inaccessible locations and thought to myself, how the hell have these been piped up.

I see lots of cylinders with the cold feed going in the back, with no way of getting to the joint. Am I right to presume that any joints at the back like this cold feed are done out of position and then the cylinder lifted into position?

And WHY would you have a connection round the back, why not just have it at the front or sides where it is accessible?

regards

John

 

[Noxer]

i think you can order your new cylinder with 3 connections to the front.... and hot water draw off at the top.

and yeah you would do the back connection out of place first. and solder it and then i usually connect a reducer to connect a bit of pipe and 15mm drain off so you can drain it down just incase.

i drawed a little arrow to where i brought the drain off too, have fun mate.

 

[jtsplumbing]

Is that 15 mm F&R to cylinder ? Leaver's left on valves ! No drain off on F&R pipework to cylinder, Immersion heater not wired in ? Were is sensor of tap stat ?

 

[SafeGasInstall]

John you know my number fill free to call me again mate !

 

[Noxer]

There is a drain off on the F&R pipework my camera isnt that great. Sensor of the tap stat is cut in at the bottom the wire is pretty thin. Why cant you leave the levers on the valves? and yeah its run in 15mm, as thats how the old primaries are run and its next to the boiler house hot water is scalding hot as it is, not a little domestic boiler its run off communial heating.

im only a apprentice, so i wait for the electrician to wire up the immersion before i shock myself hehe LOL.

cylinder has been wired up and lagged when all done.