Immersion Problem

Hi guys, I’m trying to fit an immersion in my 500L upright tank and unfortunately I drilled the hole a little lower than I should have.

I can just about reach in and hold the inner flange by hand and have someone tighten the immersion nut but it just results in the inner flange spinning and is barely catching any of the thread.

To “solve” this I just smothered the outside of the hole in silicone and it has been watertight but it leaks with hot water.

Basically is there any way of “shaving” the tank wall a couple of mm just where the immersion is so that it’s thinner and will therefore grab more of the immersion thread so that it’s a watertight seal.

Anyone else encountered this problem? 
Cheers 

dyson123 said:

Hi guys, I’m trying to fit an immersion in my 500L upright tank and unfortunately I drilled the hole a little lower than I should have.

I can just about reach in and hold the inner flange by hand and have someone tighten the immersion nut but it just results in the inner flange spinning and is barely catching any of the thread.

To “solve” this I just smothered the outside of the hole in silicone and it has been watertight but it leaks with hot water.

Basically is there any way of “shaving” the tank wall a couple of mm just where the immersion is so that it’s thinner and will therefore grab more of the immersion thread so that it’s a watertight seal.

Anyone else encountered this problem? 
Cheers 

Click to expand...

You could hire a floor Edge Sander which will take it down with 24 grit sandpaper.

Take a look at Den's posts in January of this year 14th~19th. Search bar at the top of this page. Subject/search title : Question for Immersion Heater Users.
Read the information and look at the photos. @Den used a two piece immersion gland which I think allows for a greater wall thickness and would I think also make it quicker and easier to replace the immersion, if and when required. I got something like three years out of my previous one. I don't have a gland as I was just about able to get the thread started.

Have a look at https://www.toolstation.com/mechanical-flange/p38614 that might help? Cheap too at less than £5. It's called a Mechanical Flange.

The old adage measure twice cut once comes to mind ????

Pjj said:

The old adage measure twice cut once comes to mind ????

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Trouble is it's hard to measure the wall thickness. I only just had enough thread on my immersion and only then by making sure I removed all the burrs left around the edge from cutting the hole. You're right though measure twice at least where you can.

Ive ordered a 2 part mechanical flange from eBay that Den suggested in his thread. Hopefully that solves the issue ??

dyson123 said:

Ive ordered a 2 part mechanical flange from eBay that Den suggested in his thread. Hopefully that solves the issue ??

Click to expand...

If you have a Toolstation near you they sell them. It should sort it as the mechanical flange clamps the tank wall then the immersion screws into the mechanical flange.

Davy G said:

Trouble is it's hard to measure the wall thickness. I only just had enough thread on my immersion and only then by making sure I removed all the burrs left around the edge from cutting the hole. You're right though measure twice at least where you can.

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With a welded tank it’s easy to see how thick the sections are as they overlap and can be measured easily from outside the tank . The ibc tanks are not a uniform thickness as they are blown mouldings but usually a immersion element will fit with the boss on it reasonably easily , I have not got one myself but have helped friends fit them . 

Mine is on a Wyedale flat tank. The wall is thicker than on an IBC I think.
Possibly about 8~10mm at a guess.

What you need to do is this -

Buy this - https://www.amazon.co.uk/Sealpro-ProSeal-80726-Temperature-Silicone/dp/B000FW7VNW/ref=sr_1_4?crid=1AJYNJ84PTDM8&dchild=1&keywords=gasket+paste&qid=1630450861&sprefix=gasket+pas%2Caps%2C157&sr=8-4

Put a bead of it around the rear flange before you lower it into the tank, it will be tricky getting it into place. Use a wire coat hanger to lower it into place.

Put a bead onto the outer flange and lightly tighten up, leave it 24 hours to set and then tighten up.

Lower a steel rod (wider then the rear part of the flange) into the tank close to the hole you made, grab hold of the rod with a set of pliers through the hole you have made so that the back of the flange can be pulled really tight against the inside of the tank.

Get a set of water pump pliers to tighten up the front of the flange. Try using the seal that came with the flange it can be filed down if you are struggling to grab thread.

Silicone is not going to create a seal it wont bond with a polyethylene tank. Not very much does bond to it.

PTFT tape around the immersion and dont over tighten it...
 

dyson123 said:

Hi guys, I’m trying to fit an immersion in my 500L upright tank and unfortunately I drilled the hole a little lower than I should have.

I can just about reach in and hold the inner flange by hand and have someone tighten the immersion nut but it just results in the inner flange spinning and is barely catching any of the thread.

To “solve” this I just smothered the outside of the hole in silicone and it has been watertight but it leaks with hot water.

Basically is there any way of “shaving” the tank wall a couple of mm just where the immersion is so that it’s thinner and will therefore grab more of the immersion thread so that it’s a watertight seal.

Anyone else encountered this problem? 
Cheers 

Click to expand...

I'd throw away your tank and buy a new one. Measure 3 times cut once 

ched999uk said:

Have a look at https://www.toolstation.com/mechanical-flange/p38614 that might help? Cheap too at less than £5. It's called a Mechanical Flange.

Click to expand...

Don’t know why that is still on their site they sold out a year ago and said to me they won’t restock had to get mine online can’t remember the online shop though. 

dyson123 said:

Ive ordered a 2 part mechanical flange from eBay that Den suggested in his thread. Hopefully that solves the issue ??

Click to expand...

There is definitely a few more mm for the immersion to get a bite, hopefully it workouts for you?

Apw1210 said:

I'd throw away your tank and buy a new one. Measure 3 times cut once 

Click to expand...

I’ve looked at it, 4-8 weeks for delivery at the moment 

Apw1210 said:

I'd throw away your tank and buy a new one. Measure 3 times cut once 

Click to expand...

Based on my own experience with a tape measure, it's easier said than done! ?

spruce said:

Based on my own experience with a tape measure, it's easier said than done! ?

Click to expand...

I'm not the only one then.

Update. After taking delivery of a new tank I originally tried to use one of the two part mechanical flanges that clamp the tank and then immersion screws into the flange. 
I couldn’t get this to work though as the part that sits inside the tank had nothing to grip on to with a wrench to stop it spinning whilst outer part was tightened up.

I ended up just using a mechanical flange backnut on the inside that was very thick, this allowed me to hold it with an ultra wide (70mm) jawed wrench whilst my helper screwed the immersion in.

The tank walls are so thick that you’re literally only catching one thread of the immersion.

Anyway it’s holding water and I’m delighted to finally solve my issue.

It’s definitely so much easier to do with the tank out of the van, at least it was in my case. Can see it being easier in the van with a flat tank or in a bigger van.

I’ve no idea how this can be done without the use of a wrench to hold the backnut inside the tank. I’m no weakling but holding it by hand whilst the immersion was tightened up was just impossible.

Hopefully this will help someone

dyson123 said:

Update. After taking delivery of a new tank I originally tried to use one of the two part mechanical flanges that clamp the tank and then immersion screws into the flange. 
I couldn’t get this to work though as the part that sits inside the tank had nothing to grip on to with a wrench to stop it spinning whilst outer part was tightened up.

I ended up just using a mechanical flange backnut on the inside that was very thick, this allowed me to hold it with an ultra wide (70mm) jawed wrench whilst my helper screwed the immersion in.

The tank walls are so thick that you’re literally only catching one thread of the immersion.

Anyway it’s holding water and I’m delighted to finally solve my issue.

It’s definitely so much easier to do with the tank out of the van, at least it was in my case. Can see it being easier in the van with a flat tank or in a bigger van.

I’ve no idea how this can be done without the use of a wrench to hold the backnut inside the tank. I’m no weakling but holding it by hand whilst the immersion was tightened up was just impossible.

Hopefully this will help someone

Click to expand...

I used a large Stillsons Wrench to hold the inside backnut. It will hold a circular nut providing it is set spot-on and used the correct way round (rotated towards the Jaws) . It wasn't easy as I could only get one hand and arm in the tank. It is crucial to set the wrench adjustment correctly. The tolerance for this is very small. I set the adjustment to the back nut before I tried fitting the immersion and i practiced till I had it sorted in my head. I had also thought about using an adjustable strap wrench (the type used for oil filters). But that was even more fiddly to use one handed in the tank.

This is why I've always said "Make sure you can reach the immersion from the filler cap, and do a dry rehearsal with everything ready to hand, before cutting the hole). It's also another reason I chose a flat tank, as I was able to fit the immersion just off the bottom. I agree it seems ridiculous that they make a backing nut that goes inside a tank without spanner-flats. However now it's fitted you might find you can get a turn with a Stillsons but it probably won't be easy.

Glad you got it done and thanks very much for the update. ??

My installation went flawlessly mate of mine had installed in no time.