Cylinder Immersion Heater Install

[Monkey Wrench]

I have today tried to replace the bottom immersion heater on an Economy 7 direct hot water cylinder but ended up with a major problem.
The heater element came out relatively easily part from being quite stiff to undo which I put down to the age of the cylinder.
I removed the old heater element, cleaned the thread and removed all the gunk/dirt from the mating surface for the new immersion.
I then tried the new immersion in the thread, gave it about half a turn without any problem then removed it to apply the gasket and some
FERNOX LX to the mating surfaces for good measure.

However, I then tried to put the new immersion back into the cylinder but could not locate it on the thread to get it going.
After several attempts, it went into the thread but would only go about 1 1/2 turns and then binded
with still along way to go before it would have been water tight. I struggled with it for about 10 minutes, removed it and tried the old element which
went in about 2 1/2 turns before again binding well before the fibre washer was touching the cylinder.
After about an hour and a half (should be a 15 minute job max) of trying the get the new immersion into the thread I gave up.

The new immersion will just not turn fully into the thread not matter how many times I try and neither will the old one. The thread looks fine with
no obvious signs of cross threading but even an immersion blank plate wouldn't go fully into the thread either.

Does anyone please have any suggestions how I can resolve this ?

Thank you

 

[scotty plumber]

Hi, If the old immersion came out fine then the old immersion will not go back in fine after attempting to put the new one in it sounds like you have damaged the threads on the cylinder, you should have managed to get the new one in most of the way with just your hands or did you use your key straight away??

 

[mcniven]

New cylinder reqd done this before :-(

 

[mikegas]

try some lubricant on the threads, does sound like the threads are crossed though

 

[scotty plumber]

A little perseverance can sometimes fix this

 

[Monkey Wrench]

Thank you for the prompt responses.

Once I'd got the new immersion on the thread I turned it by hand about 2 turns before it started to bind, assuming that it was just a bit of dirt on the thread,
I then used the key for about another half a turn before it wouldn't turn anymore without a lot of pressure and thats when i backed off.

I guess the thread might be crossed but there's no visible sign of it. If it is, is there anyway of getting it back again either by re-cutting/threading it or another
simpler solution. The theads look sound without any visible damage but after 2 1/2 turns the immersion doesn't sit square in the thread but at a slight angle.

This is the first time I've evr had this problem changing an immersion element !

 

[PlumbBobBob]

when you offer the immersion up turn it the wrong way slowly until you feel the thread click you may even hear it. then turn it the right way and it should go in properly. when the thread clicks it is just finding the start of the thread.

 

[Billy Bob Bob]

Thank you for the prompt responses.

Once I'd got the new immersion on the thread I turned it by hand about 2 turns before it started to bind, assuming that it was just a bit of dirt on the thread,
I then used the key for about another half a turn before it wouldn't turn anymore without a lot of pressure and thats when i backed off.

I guess the thread might be crossed but there's no visible sign of it. If it is, is there anyway of getting it back again either by re-cutting/threading it or another
simpler solution. The theads look sound without any visible damage but after 2 1/2 turns the immersion doesn't sit square in the thread but at a slight angle.

This is the first time I've evr had this problem changing an immersion element !

it can sometimes be difficult to start off being a economy 7 cylinder i presume the immersion is on the side sometimes as hard as you try the weight of the element stops you putting it in strait just make sure you correct this as you start the thread off steves tip also works

 

[tamz]

You are not the first person to do this and won't be the last. Your best bet of fixing this is to remove the cylinder and lay it on its side where you can see the threads properly. Try using the edge of a small screwdriver and run it around the threads from inside out. This may uncross it enough to get it started again with a bit perseverance. When screwing the new one in keep the cover on it. It makes it easier to hold and judge if it is straight.
If that doesn't work it is new cylinder time unless you know how to solder one in or can be bothered to cut in an essex flange.

 

[kay-jay]

You are not the first person to do this and won't be the last. Your best bet of fixing this is to remove the cylinder and lay it on its side where you can see the threads properly. Try using the edge of a small screwdriver and run it around the threads from inside out. This may uncross it enough to get it started again with a bit perseverance. When screwing the new one in keep the cover on it. It makes it easier to hold and judge if it is straight.
If that doesn't work it is new cylinder time unless you know how to solder one in or can be bothered to cut in an essex flange.

im damn sure i'd give a flange a go before shelling out for a new cylinder if it was me!

 

[quality]

A local engineering machine shop would have a tap that you could try to clean the thread out

 

[Monkey Wrench]

Thank you all the help and advice.

when you offer the immersion up turn it the wrong way slowly until you feel the thread click you may even hear it. then turn it the right way and it should go in properly. when the thread clicks it is just finding the start of the thread.

Thanks for the tip. I've not had a chance to look at the cylinder today but will give it a try tomorrow.

it can sometimes be difficult to start off being a economy 7 cylinder i presume the immersion is on the side sometimes as hard as you try the weight of the element stops you putting it in strait just make sure you correct this as you start the thread off steves tip also works

The cylinder has two immersions and both are on the side. The blown element was the Economy 7 immersion and is located about 5 inches from the bottom of the cylinder making the job even more of a hassle as the drain-off had been installed above the centre line of the immersion heater.

You are not the first person to do this and won't be the last. Your best bet of fixing this is to remove the cylinder and lay it on its side where you can see the threads properly. Try using the edge of a small screwdriver and run it around the threads from inside out. This may uncross it enough to get it started again with a bit perseverance. When screwing the new one in keep the cover on it. It makes it easier to hold and judge if it is straight.
If that doesn't work it is new cylinder time unless you know how to solder one in or can be bothered to cut in an essex flange.

Ive taken the cylinder out and its currently in the garage awaiting my attention. I will certainly try running a screwdriver around the threads but, having had a quick look earlier, I noticed that the second thread in from the outside of the cylinder seems to be slightly flattened so maybe thats causing the problem ! If I can get the new element in square would that cut another edge or am I being too optimistic ?

I've cut-in Essex flanges before but not 2 1/2 inch in diameter ! Do they even exist ? The other thing is how would I blank/seal the gaping hole left by the immersion (or am I missing something) ?

A local engineering machine shop would have a tap that you could try to clean the thread out

I will certainly give that a go if nothing else works.


Thanks again

 

[PlumbBobBob]

one thing i would say is be careful that you don't rip the copper when you tighten the immo up. i would wait until the cyl is back in place until you finally tighten it up when it is full of water to help support the sides.

 

[Monkey Wrench]

one thing i would say is be careful that you don't rip the copper when you tighten the immo up. i would wait until the cyl is back in place until you finally tighten it up when it is full of water to help support the sides.

Thanks for that SteveB.

The only problem is that the immersion is at the bottom of the cylinder and so surely I'd need to tighten it before filling with water to prevent leaks.
I didn't try loosening it (for removal) until after completely draining the cylinder for this very reason and, because the drain-off was the same height
as the immersion, I had to remove the hot water outlet in order to put in a hose to siphon the water out.

Thanks again.

 

[heatybob]

this happened to me,what worked for me was i ran in a 2 1/2" mild steel nipple which basicaly recut the brass thread,ithen took more care with the new immersion:sweatdrop: best of luck mate

 

[Monkey Wrench]

this happened to me,what worked for me was i ran in a 2 1/2" mild steel nipple which basicaly recut the brass thread,ithen took more care with the new immersion:sweatdrop: best of luck mate

Thanks for that Heatybob.

Where did you get a 2 1/2 inch mild steel nipple from ?

 

[REDSAW]

try a thread file on it?.

 

[quality]

Crosslings, pirtek or any hydraulics outlet would have nipple that size

 

[heatybob]

as above,bss pipeline center etc,maybe worth a try for a couple of quid,it worked for me

 

[PlumbBobBob]

just a thought if it's a normal cylinder and not a combination one you could put a new drain in while it is out. just put a tee into the cold feed at the bottom and bring a drain to the front where you can get to it at the base.

 

[heatybob]

just as an add on,and this may sound silly but just to let you know that for some reason different manufacturers have differant size threads in so much that GF fittings as stocked by bss are a lot smaller than say Crane(pipeline)this applies to all sizes,dont know why 2" is 2". 1" is 1" to me(nobody ever been able to answer that one)off topic i know but can be a pain if your using fittings from both mans. keep altering the threads etc

 

[kay-jay]

This is why i hate immersions . I always try a stat change first cos most of the time its not actually the element........hopefully the op hasn't ended up in a pickle unnecessarily

Sent from my GT-I9100 using Tapatalk

 

[Monkey Wrench]

Thanks for the posts.

try a thread file on it?.

Do you have idea what the pitch of the threads are so I could get the right size thread !

Crosslings, pirtek or any hydraulics outlet would have nipple that size

as above,bss pipeline center etc,maybe worth a try for a couple of quid,it worked for me

Do I actually ask for a "mild steel nipple" or is it called something else ?

just a thought if it's a normal cylinder and not a combination one you could put a new drain in while it is out. just put a tee into the cold feed at the bottom and bring a drain to the front where you can get to it at the base.

The centre line of the cold feed is exactly the same height as the centre line of the immersion heater and so any drain-off would still leave about an inch of water in the cylinder. Unbelievable IMO !

This is why I hate immersions . I always try a stat change first cos most of the time its not actually the element........hopefully the op hasn't ended up in a pickle unnecessarily

Sent from my GT-I9100 using Tapatalk

The first thing I checked was the stat which worked perfectly (live both sides) and I can confirm that the element has a split in the side.


Thanks again for all the excellent help and advice.

 

[WHPES]

If the old one goes in and out OK still, the threads are probably tight on the new one. Try a different make of element

 

[REDSAW]

dont you have a thread gauge?. get them from machine mart, toolstation etc. then file out thread.

 

[tamz]

Ive taken the cylinder out and its currently in the garage awaiting my attention. I will certainly try running a screwdriver around the threads but, having had a quick look earlier, I noticed that the second thread in from the outside of the cylinder seems to be slightly flattened so maybe thats causing the problem ! If I can get the new element in square would that cut another edge or am I being too optimistic ?

That is indeed what is causing the problem. It can be fixed. The good thing on your side is that copper threads are quite soft (that is why you stripped it in the first place) so can be fixed. It just needs a wee bit time and care taken.
Forget the 2 1/2" nipple idea. The thread is 2 1/4" BSP. You will struggle severely to get an iron taper nipple that size (2 1/4"). This is an unusual thread size not used on many other things. A thread file is no use as they are for external threads.
There are a couple of ways you can fix this. Basically you have to fix the bad (flattened) bit on the thread so the element will pass it and continue in the other threads. Once it passes the bad bit it will be fine.
Start by scraping the cylinder threads completely clean then follow the threads with a small flat bladed screwdriver or the edge of a small triangular file. If you have a dremmel you could use that. You need to take out the flattened bit.
Keep trying the immersion by hand. If you cant get it in by hand past the couple of turns where it jambed remove it and scrape the threads again. If you take your time and spend 20 minutes or so at it. You should be able to fix it.
If you really can't then it is plan B and how much you value your time against talking the customer into a new £300 odd cylinder!
Buy one of these.
Essex 2.25" E2/SX Immersion Heater Boss Flange CURVED surface cylinder tank e2/r | eBay (Btw the photo shows the washers on the wrong way round)
To fit this you need to cut off the old immersion boss and fit the flange in its place.
They are easy to fit. The hole doesn't need to be perfectly round. You can drill it out and file it if need be.

Plan C is fly me down to do it for you but you would be cheaper with a new cylinder :lol:

Just go for it.

 

[Monkey Wrench]

If the old one goes in and out OK still, the threads are probably tight on the new one. Try a different make of element

Unfortunately the old one will not now go in any further than the old one. Considering the problem I had getting the new one started in the first place,
I'm wondering if it that was the cause of the problem in the first place !

dont you have a thread gauge?. get them from machine mart, toolstation etc. then file out thread.

I don't have thread gauge but I do have a gap gauge (spark plugs etc) so I guess that'll do the same job just fine.

Thanks for the posts.

 

[Monkey Wrench]

Thank you Tamz, you've certainly given me hope.

I'll try Plan A first and if that doesn't work then plan B seems a good option. At the moment I'm hopeful that the "sorry you'll need a new cylinder" conversation will not have to happen.

Did I understand correctly that I could drill the old immersionn boss out ? If so, how about drilling a slightly larger hole and then cutting the boss out "very carefully" with a hacksaw
while obviously taking extra care not not distort the cylinder ?

Plan C, a nice thought but yes, it would be a new cylinder first.

Thanks again.

 

[Dannypipe]

If all else fails, and it is a new cylinder. Scrap the one you have £60 quid in scrap to you. Then buy a replacement in stainless steel not copper, as it will be cheaper and last just as long.

Screw fix sell one for about £160. Then it's cost you about £100. Which considering the time you are liable to spend putting this right, might be money well spent.

Sorry to hear of your problems.

 

[tamz]

T
Did I understand correctly that I could drill the old immersionn boss out ? If so, how about drilling a slightly larger hole and then cutting the boss out "very carefully" with a hacksaw
while obviously taking extra care not not distort the cylinder ?

If it comes to fitting a flange you will have to drill the old one out and file it into shape (it is easier done than it sounds). You won't be able to hacksaw it. We used to use a tool called a monodex cutter to fit these but in this instance even that wouldn't work so you are left with the drill and file method.
Because this is the type of guy i am, i went out to the yard (in my house coat in the baltic cold) and sourced (rumadged for) an old essex flange. These instructions are probably older than you because i have had them for years but here they are.

The link above was the only one i could find on google but you would be able to order one from a merchant.
Take your time. It can be fixed with a bit patience and the flange is your fall back.
There are other ways to do this but they are too hard to explain. It is something you need to be shown to understand.
Good luck. Take your time and you will get there.

 

[Monkey Wrench]

If all else fails, and it is a new cylinder. Scrap the one you have £60 quid in scrap to you. Then buy a replacement in stainless steel not copper, as it will be cheaper and last just as long.

Screw fix sell one for about £160. Then it's cost you about £100. Which considering the time you are liable to spend putting this right, might be money well spent.

Sorry to hear of your problems.

Thanks for that Dannypipe.

Screwfix also do a direct 900 x 450 stainless steel cylinder for £140.- which would be the one I'd go for if required. However, there's nothing on the Screwfix website to say if the cylinder has one or two immersions (I assume it would have to be two for a direct cylinder) or where they are positioned !

If it comes to fitting a flange you will have to drill the old one out and file it into shape (it is easier done than it sounds). You won't be able to hacksaw it. We used to use a tool called a monodex cutter to fit these but in this instance even that wouldn't work so you are left with the drill and file method.
Because this is the type of guy i am, i went out to the yard (in my house coat in the baltic cold) and sourced (rumadged for) an old essex flange. These instructions are probably older than you because i have had them for years but here they are.
View attachment 5328
The link above was the only one i could find on google but you would be able to order one from a merchant.
Take your time. It can be fixed with a bit patience and the flange is your fall back.
There are other ways to do this but they are too hard to explain. It is something you need to be shown to understand.
Good luck. Take your time and you will get there.

Excellent stuff Tamz. Thank you

If it comes to it, I think £40 on a flange is still better than £140 on a cylinder as I certainly don't mind spending extra time trying to get it right.

 

[MattWeth]

As usual, great advice from Tamz.

Unless it's properly goosed, I'd think you've got a pretty good chance of reclaiming the thread. I've not done it on an immersion thread but I've rescued a lot of threads in steel, alloy, brass etc on vintage motorbikes and such. If you've got access to some scrap steel and a bench grinder (or even a dremmel at a pinch), make yourself a bent tool with a tip ground to as near the thread angle as you can (use the male immersion thread as a guide). Use this to slowly and carefully chase round the thread in the cylinder to clean it and reshape deformed sections. Work slowly and carefully with light pressure - the copper is soft but it'll have work hardened on the deformed bits. You'll probably find that part of the thread peak has collapsed into the root and is causing the binding problem you're having so your tool will need to be sharp.

Good luck.

 

[Monkey Wrench]

As usual, great advice from Tamz.

Unless it's properly goosed, I'd think you've got a pretty good chance of reclaiming the thread. I've not done it on an immersion thread but I've rescued a lot of threads in steel, alloy, brass etc on vintage motorbikes and such. If you've got access to some scrap steel and a bench grinder (or even a dremmel at a pinch), make yourself a bent tool with a tip ground to as near the thread angle as you can (use the male immersion thread as a guide). Use this to slowly and carefully chase round the thread in the cylinder to clean it and reshape deformed sections. Work slowly and carefully with light pressure - the copper is soft but it'll have work hardened on the deformed bits. You'll probably find that part of the thread peak has collapsed into the root and is causing the binding problem you're having so your tool will need to be sharp.

Good luck.

Thanks for that Matt Werth.

When you say a tip, I guess this will like an inverted V with the V being the same dimensions as the groove of the thread !

I've made a couple of attempts today to reclaim the thread without success. Whats happening is that I can get the immersion into the thread about a turn and a half before it binds but the immersion is high on one side meaning that there are more threads exposed on one part of the male thread than the other. This obviously means that the immersion is not going into the thread square which I presume means that either the first or second thread is crossed. I can identify in a couple of places where a small thin line goes across the high point of a couple of threads and it is these that I have been concentration on reforming. However, is it possible to reclaim a cross thread as surely you need to add metal/brass not take it away.

Regretably, I dont think an immersion flange is going to be a viable solution as there are a number of small uneven indentations in the copper around the immersion boss in a couple of places and so I'm not convinced that the flange seal would have enough flexibilty to seal all the highs and lows.

Thanks again.

 

[MattWeth]

The tool is basically a diamond shaped point on something you can handle with some control - think a single male thread.

If the immersion isn't going in square then it's definitely crossed.

You can reclaim the thread - as long as you can create a clean path for the new thread, it doesn't matter if there are a couple of gaps in the threads on the cylinder. But you'll only get one proper chance at it - if you mess up and create a 'new' but still crossed thread then it's effectively beyond recovery and you'll have to investigate flanges etc. Start on a known good part of the thread and work out towards the damaged threads. The good thing with an immersion is that it's big and you can see what you're doing - I've managed it on weird American 3/8" fine cycle threads at the bottom of blind holes in alloy castings 🙂

 

[Monkey Wrench]

The tool is basically a diamond shaped point on something you can handle with some control - think a single male thread.

If the immersion isn't going in square then it's definitely crossed.

You can reclaim the thread - as long as you can create a clean path for the new thread, it doesn't matter if there are a couple of gaps in the threads on the cylinder. But you'll only get one proper chance at it - if you mess up and create a 'new' but still crossed thread then it's effectively beyond recovery and you'll have to investigate flanges etc. Start on a known good part of the thread and work out towards the damaged threads. The good thing with an immersion is that it's big and you can see what you're doing - I've managed it on weird American 3/8" fine cycle threads at the bottom of blind holes in alloy castings 🙂

Thanks again MattWerth

Here are a couple of pictures of the thread. The first picture is at the start of the first thread and the second is about a 3/4 further round.



Do you thing these are retrievable or am I wasting my time ?

My father has a bench grinder so I can certainly fabricate the necessary tool if you thik it moght do the trick.

Thanks again.

 

[MattWeth]

I'd certainly give it a go - you can see in the second picture where the thread has crossed. There are no guarantees with this but it'll cost you next to nothing to try.

In the end it depends on whether you think it's worth your time - you might be better starting with a new cylinder - your call really.

 

[johnnyplumb]

tamz has already mentioned soldering in the new immerser, this is what i'd do, it will cost you nothing exept your time to do. remove the cylinder to make it easier. clean & flux both threads then tighten new immerser in as far as you can, remove stat & any other plastic bits from immerser before soldering.you have nothing to loose and everything to gain as the cylinder is no good to you as it is. good luck.

 

[Monkey Wrench]

I'd certainly give it a go - you can see in the second picture where the thread has crossed. There are no guarantees with this but it'll cost you next to nothing to try.

In the end it depends on whether you think it's worth your time - you might be better starting with a new cylinder - your call really.

Ive got nothing to lose so I'll definitely give it a try.

tamz has already mentioned soldering in the new immerser, this is what i'd do, it will cost you nothing exept your time to do. remove the cylinder to make it easier. clean & flux both threads then tighten new immerser in as far as you can, remove stat & any other plastic bits from immerser before soldering.you have nothing to loose and everything to gain as the cylinder is no good to you as it is. good luck.

Thanks for the post Johnnyplumb.

I must have missed that bit completely as I can't find any mention of soldering in the new immersion from tamz. However, if all else fails, I'll definitely give it a try. Its certainly going to take a lot of heat to get both threads hot enough for the solder to flow !

Thanks again.

 

[scotty plumber]

I replaced a very old 2-stud immersion heater today! Took me 3-hours however it did go reasonably ok considering how much i hate doing them!!!!!!

 

[Monkey Wrench]

I'd certainly give it a go - you can see in the second picture where the thread has crossed. There are no guarantees with this but it'll cost you next to nothing to try.

In the end it depends on whether you think it's worth your time - you might be better starting with a new cylinder - your call really.

The first crossed thread seems to be the very first one (second picture top thread). I'm just wondering how this can be recovered with the pointed tool you have descibed as, because there is no thread above it to cut in to, how will the tool removed the crossed thread on that particular thread ?

I replaced a very old 2-stud immersion heater today! Took me 3-hours however it did go reasonably ok considering how much i hate doing them!!!!!!

Well done, if only all jobs went that smoothly !

 

[MattWeth]

The first crossed thread seems to be the very first one (second picture top thread). I'm just wondering how this can be recovered with the pointed tool you have descibed as, because there is no thread above it to cut in to, how will the tool removed the crossed thread on that particular thread ?

Start the tool in a good thread below the first damaged one and cut 'outwards' towards the damaged section.

 

[Monkey Wrench]

Start the tool in a good thread below the first damaged one and cut 'outwards' towards the damaged section.

Ok, thank you.

 

[Monkey Wrench]

Just to update, I'm afraid that all attempts to reclaim the thread using the excellent advice given on this forum proved futile and I ended up
buying a stainless steel "direct" cylinder form Screwfix which, together with a 27" immersion, worked out at £138 in total which is a pretty good
deal IMO.

Considering the "sacrificial anode" in the original cylinder had completely rotted away and the inside of the cylinder had started to deteriorate
accordingly it was probably just was well.

Thanks again for all the excellent advice.