Fixing electric immersion heater of hot water cylinder..

sujsuj

I have this electric immersion heater with my hot water cylinder ( part of Oil Boiler heating system) which is not working. I couldn't find any detailed specification from the existing (faulty?) electric heater except TIH 550 (Tesla!). Photos attached. Not sure TIH550 available in different lengths..? I want to be clear what to buy  before removing existing one. Please help 

I watched this video to do the repair. Noticed he drained water. But now the immersion heater is at the top, should I still  need to drain the water completely from  the tank.?  Or just make sure water is not till the top.?
https://www.youtube.com/watch?v=mZ2MT0SKVZY

Looks like I need to buy tool to rotate head, Any other useful tips please.
Thanks in advance.

grumbler

As there isn't an expansion vehicle, this looks like a vented cylinder. Do you have a water tank in your loft?

If you can find the valve isolating the tank from the cylinder (and cold water in your bathroom), then you can avoid draining the the tank and will need only to drain the very top of the cylinder and the pipe above it.

https://www.wolseley.co.uk/product/tesla-tih550-incoloy-immersion-heater-and-radiator-stat-27-(20)/  - the specifications.

You can buy exactly the same or a similar one with the same power and height.

Are you sure it's faulty? Before replacing, it's worth checking it's conductivity/resistance with a multimeter. Make sure your know what are you doing - isolate it reliably from the mains electricity or, better, just switch everything off in your CU.

ThisIsWeird

That cove in the video has covered it really well.

Yes, crack open the immersion with the cylinder still full - it makes it stronger and more rigid. But do have the hose fitted first, with the end draining somewhere suitable, and the draincock checked for undoing looseness - if this goes pear-shaped for any reason, you'll want to be able to drain that cylinder without hesitation.

And, of course, power 100% disconnected, and cold feed to the tank off!

He's covered it all. The one thing I'd add is, if the immersion element is hard to undo - and it will be - one way to encourage it is to apply undoing force with the spanner, and then add a few gentle-firm taps with a mallet on the spanner too, to shock it into breaking the tight seal.

Once 'cracked', drain off enough water - as you undo the element, you'll soon know if you've drained enough...

And after cleaning up the thread and mating surfaces, I personally like to give the threads a smear of something like copper-ease, or just silicone grease, for when you next need to replace it - 15 years hence...

Newbie_John

I have had a similar one - Thermowatt, and all I needed to do is to press the reset button - inside under that black cover, similar for yours:
https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.teslauk.com/pdf/downloads/Resetting%20the%20TS%20Series%20Thermostat.pdf&ved=2ahUKEwjNxeaxjJCDAxUE0wIHHVypDYgQFnoECBgQAQ&usg=AOvVaw1sGFOm_eyi6rK34yXpgMZC

It needs little bit force to press it and it will click if that was the problem.

But if you take the cover off and see any burn marks, smell burn then may be worth replacing just the thermostat - simple ones are under £30.

I recently replaced my Thermowatt with Tesla Smart Thermostat:
https://www.unventedcomponentseurope.com/2-1-4-3-kw-350mm-incoloy-plastic-cover-plug-in-no-stat.html/?utm_source=Google Shopping&utm_campaign=Copy Unvented Components Europe&utm_medium=cpc&utm_term=484607&gclid=Cj0KCQiA7OqrBhD9ARIsAK3UXh1LCrJbmZhzboYbYcgzbtSiYFxxStKMz4ODhhfkHclSDYwwqzxDvqgaAkmSEALw_wcB

Anyway, all the above you can try without emptying the tank - hope it helps.

sujsuj

grumbler said:

As there isn't an expansion vehicle, this looks like a vented cylinder. Do you have a water tank in your loft?

If you can find the valve isolating the tank from the cylinder (and cold water in your bathroom), then you can avoid draining the the tank and will need only to drain the very top of the cylinder and the pipe above it.

https://www.wolseley.co.uk/product/tesla-tih550-incoloy-immersion-heater-and-radiator-stat-27-(20)/  - the specifications.

You can buy exactly the same or a similar one with the same power and height.

Are you sure it's faulty? Before replacing, it's worth checking it's conductivity/resistance with a multimeter. Make sure your know what are you doing - isolate it reliably from the mains electricity or, better, just switch everything off in your CU.

Yes , I have a big water tank in the loft.

Ok so steps are..
1. Power OFF, I might switch off everything in CU
2. Close Loft water Tank to Cylinder Valve (inlet to Cylinder) to stop Cylinder filling up again
3. Disconnect power connection to heater
4. Use Immersion spanner to loosen head 
5. Check and replace with new if needed
6. Open valves

But I didn't get
- Isolate Cold water in your bathroom >> I didn't get this..? Do I need to close Tank to Cold water pipes valve..? why this is needed..?
- I have seen TIH 550 both straight one and one with bent...which one I should go..? Or one with bend is for side entry and longer one is for top entry??
- I have seen Tesla smart heaters with App control etc, is that of any benefit as my electric heater is backup plan only

sujsuj

ThisIsWeird said:

That cove in the video has covered it really well.

Yes, crack open the immersion with the cylinder still full - it makes it stronger and more rigid. But do have the hose fitted first, with the end draining somewhere suitable, and the draincock checked for undoing looseness - if this goes pear-shaped for any reason, you'll want to be able to drain that cylinder without hesitation.

And, of course, power 100% disconnected, and cold feed to the tank off!

He's covered it all. The one thing I'd add is, if the immersion element is hard to undo - and it will be - one way to encourage it is to apply undoing force with the spanner, and then add a few gentle-firm taps with a mallet on the spanner too, to shock it into breaking the tight seal.

Once 'cracked', drain off enough water - as you undo the element, you'll soon know if you've drained enough...

And after cleaning up the thread and mating surfaces, I personally like to give the threads a smear of something like copper-ease, or just silicone grease, for when you next need to replace it - 15 years hence...

I have seen two types of Immersion Spanner 

1. https://www.screwfix.com/p/rothenberger-cranked-immersion-spanner/20266
2. https://www.screwfix.com/p/monument-tools-box-immersion-spanner/29549

I think first one is for easier removals and second one is for more harder one..? Thanks

Section62

sujsuj said:

I have seen two types of Immersion Spanner 

1. https://www.screwfix.com/p/rothenberger-cranked-immersion-spanner/20266
2. https://www.screwfix.com/p/monument-tools-box-immersion-spanner/29549

I think first one is for easier removals and second one is for more harder one..? Thanks

The first one is cheaper.

The second one allows torque to be applied in a more balanced manner and helps reduce the risk of deforming the cylinder.  Check the cost of a new cylinder and then decide whether it is worth spending the extra fiver on the better tool.  Or not.

The second type also usually means less insulation needs to be removed from the cylinder to get the spanner fitting squarely onto the immersion heater.

grumbler

sujsuj said:

grumbler said:

As there isn't an expansion vehicle, this looks like a vented cylinder. Do you have a water tank in your loft?

If you can find the valve isolating the tank from the cylinder (and cold water in your bathroom), then you can avoid draining the the tank and will need only to drain the very top of the cylinder and the pipe above it.

https://www.wolseley.co.uk/product/tesla-tih550-incoloy-immersion-heater-and-radiator-stat-27-(20)/  - the specifications.

You can buy exactly the same or a similar one with the same power and height.

Are you sure it's faulty? Before replacing, it's worth checking it's conductivity/resistance with a multimeter. Make sure your know what are you doing - isolate it reliably from the mains electricity or, better, just switch everything off in your CU.

But I didn't get
- Isolate Cold water in your bathroom >> I didn't get this..? Do I need to close Tank to Cold water pipes valve..? why this is needed..?

Most likely the valve is on the pipe going down from the tank and isolates cold water supplying both the bathroom an the HW cylinder.

- I have seen TIH 550 both straight one and one with bent...which one I should go..? Or one with bend is for side entry and longer one is for top entry??

It doesn't heat the whole cylinder. The longer it is, the bigger amount of water at the top it heats. I think, generally, for such a big cylinder you need a longer heater.

- I have seen Tesla smart heaters with App control etc, is that of any benefit as my electric heater is backup plan only

You are right. If it's for backups only, there is no point in it being singing and dancing - and less reliable as a result.

ThisIsWeird

sujsuj said:

ThisIsWeird said:

That cove in the video has covered it really well.

Yes, crack open the immersion with the cylinder still full - it makes it stronger and more rigid. But do have the hose fitted first, with the end draining somewhere suitable, and the draincock checked for undoing looseness - if this goes pear-shaped for any reason, you'll want to be able to drain that cylinder without hesitation.

And, of course, power 100% disconnected, and cold feed to the tank off!

He's covered it all. The one thing I'd add is, if the immersion element is hard to undo - and it will be - one way to encourage it is to apply undoing force with the spanner, and then add a few gentle-firm taps with a mallet on the spanner too, to shock it into breaking the tight seal.

Once 'cracked', drain off enough water - as you undo the element, you'll soon know if you've drained enough...

And after cleaning up the thread and mating surfaces, I personally like to give the threads a smear of something like copper-ease, or just silicone grease, for when you next need to replace it - 15 years hence...

I have seen two types of Immersion Spanner 

1. https://www.screwfix.com/p/rothenberger-cranked-immersion-spanner/20266
2. https://www.screwfix.com/p/monument-tools-box-immersion-spanner/29549

I think first one is for easier removals and second one is for more harder one..? Thanks

Yes. Same size, one just stronger.

ThisIsWeird

Section62 said:

sujsuj said:

I have seen two types of Immersion Spanner 

1. https://www.screwfix.com/p/rothenberger-cranked-immersion-spanner/20266
2. https://www.screwfix.com/p/monument-tools-box-immersion-spanner/29549

I think first one is for easier removals and second one is for more harder one..? Thanks

The first one is cheaper.

The second one allows torque to be applied in a more balanced manner and helps reduce the risk of deforming the cylinder.  Check the cost of a new cylinder and then decide whether it is worth spending the extra fiver on the better tool.  Or not.

The second type also usually means less insulation needs to be removed from the cylinder to get the spanner fitting squarely onto the immersion heater.

Good point - by using the two-handed one with two hands - pull/push - the element should have nothing but an even turning force on it.

sujsuj

Ready with tool for weekend work ....