CEST340 Immersion Heater

CESTB340 3kw 16" Immersion Heater

Product Code: CESTB 340

This is a 3kw, 16inch immersed length CESTB340 Incoloy Immersion Heater complete with combined (operating & safety cut-out) plug-in thermostat and is typically used within standard unvented domestic water cylinders.. Installed products will often carry the ThermTec brand which is owned and manufactured exclusively by Heatrod Elements in Manchester. The CESTB 340 can be used in all standard domestic water areas including normal use in hard water areas susceptible to limescale. If particularly aggressive water conditions are present or the duty/usage is higher than normal then we would recommend an equivalent product with titanium element which is the CESZB340.

This immersion heater is most commonly fitted with Cotherm TSE00187, TSR00014 and Thermowatt RTS-3 dual function thermostats  – see our “Thermostats & Controls” section for more details and to purchase these products.

The CESTB-340 is designed to meet European Standards EN 60335-2-73:2003 +A1:06 + A2:09 used with EN 60335-1:2012 for the safety of electrical appliances that heat liquids for household and similar purposes. Testing has been carried out and the product approved by NEMKO – certificate available on request

Installation Instructions for CESTB340 can be found here.


£34.79 £28.99 (ex VAT)

In stock


Category: .

Replacement for: .

Additional Information

Loading (kW)


Voltage (V)


Secondary Protection


Length (mm/Inch)


Element Diameter (mm)


Stat Inches


Sheath Material

Incoloy 800

Head Size (BSP)

1.75, 1.75″ BSP

Thermostat Type

Coltherm TSE or Thermawatt RTS-3, Cotherm TSE or Thermawatt RTS-3

FAQs for CESTB340

Q: Hello, i have a HE Tribune water cylinder and i have a small leak from the emersion heater. The heater is a ThermTec 2.75/3KW CESTB-340. can you get new seals for this or do they only come with a new heater? Thanks Dave

A: Hi Dave, These can be purchased separately, please find link below to the 1 3/4" o ring you would require. http://www.heatrodshop.com/product/immersion-heater-o-ring-1-75-inch-bsp

Q: Can the immersion stat be replaced for the CESTB-340 2.75/3KW? Because it looks like it is soldered onto the immersion heater. (I can't pull it out) Thanks James

A: Hi James, Yes the stat can be replaced, it is on spade connectors and just pushes onto the end of the elements. If it has been fitted for a while it need some persuading :)

Q: I have a brand new CESTB 340 immersion heater on a Prostel cylinder and the plastic cover has been cracked. Is it possible to purchase just a replacement cover? Many thanks.    

A: Hi Matthew Thanks for your inquiry, yes it is possible to buy just the terminal cap, the part number is TC-002 price £1.50+VAT, carriage 2-3 days £3.99+VAT next day £12+VAT. If you would like to purchase the item please feel free to contact us on 0161 727 3713. Thanks

Q: Is there a gasket available separately for immersion heater CESTB-340?

A: Yes these can be purchased separately, please see link http://www.heatrodshop.com/product/immersion-heater-o-ring-1-75-inch-bsp

Q: how can I lower the temperature of the heater it is a cestb 340, it has been set very high, regards bob

A: Hi Bob Thanks for your inquiry, if you disconnect the power to the immersion heater and remove the terminal cover, there is a thermostat with a temperature dial, if you turn this to a lower setting it will reduce the temperature at which the heater will reach. The settings on the dial range from 1-5 1=10°C and 5=70°C each increment goes up by 15°C. If you need any more info please feel free to contact us. Thanks

Q: This morning I had a CESTB340 fitted by a qualified plumber. I wish to know if there is a manufactures guarantee on the product and for how long does it last. I had a new domestic water heater (Tempest Stainless) fitted approximately 4 years ago which came as a unit with all things fitted. This plumber has charged me a little over £200 for supplying and fitting the CESTB340 unit ... I hope that the latest element lasts longer than the original. Thanks, Peter Kennedy.

A: Hi Peter, Thanks for your question, we offer a 12 month warranty on all our heaters, we wouldn't really be able to advise a "life span" Per se, as it really would depend on the application and how often you use it, Thanks Phil.

Q: Hi My daughter has a Manco Stainless Sterling steel water Cylinder. The label on the heater has Therm Tec Limitied, Immersion heater 2.75/3 kw 230/240 V 50hz Approved to EN80335.2.72. It states the heater is fitted with a Safety Thermal Cut out, with instructions on how to reset. There does not appear to be any part or serial number on the heater. Do you know how I can find out which replacement unit I require? Thanks

A: Hi Colin, thanks for your inquiry, we ideally need the BSP (Thread) the Immersed length and the KW rating, if you do have this I would advise giving us a ring so we can work you out an alternative. Regards Phil.

Q: Hi... is it possible to get spare caps for the ThermTec immersion heaters - I have two which have cracked and are therefore a bit dangerous? Thanks

A: Morning Jonah, thank you for your question, The item you're looking for is P/N TC-002, it's £2.50 + VAT, to order please ring 0161 727 3706, Thanks, Phil.

Q: Hello - I have a Gold UnVented Direct 120Litre Stainless Steel Cylinder installed - and I am looking to replace the lower immersion element .. can you please advice on correct part - is it 14" or 16"? The code on the part is CESTB-340? thanks Al

A: Afternoon Al, If you search on the website for a CESTB 340, it will come up with the correct heater, they are 16" hope this helps, kind Regards, Phil.

Q: hello after this product in 14inch? do you have cheers

A: Afternoon James, Thank you for your enquiry, I think we've already spoke about this, but It's a CESTB 335 which is the 14" version, £36.00 + VAT, If you want to order please ring, Kind Regards, Phil.

Q: Hello I need a direct replacement for a Thermtec ADHTB-327 It had been badly wired and burned the wiring. I believe the safety cut out and heater element can be replaced without having to drain the cylinder..... I could not see one on your website. I need it on Site by Thursday

A: Afternoon Brian, I think I spoke to you earlier but we do sell the ADHTB 327's please contact us for a price and availability, Regards, Phil

Q: Just checking a quotation - What would be the rough order of costs of supplying & fixing a slim-line CESTB340 litre domestic immersion heater rather than an "ordinary" 120 litre one. Many thanks

A: Afternoon, You would need to seek out a professional to fit the CESTB 340, we don't fit the heaters we only supply them, Kind Regards, Phil.

Q: Hi, Ive been asked to change a Thermtec Type HS immersion heater. Ref: T11/HS. 2.75 - 3KW Can you tell me what one from your range ill need to be compatible please?

A: Morning Matt, thank you for your question, we can produce one for you, which would be a AESTB327, please ring for price and availability, Regards Phil.

Q: Hi, I have a broken Thermatec Immersion Heater series AF,BF,CF,DF according to the instructions sheet. It is installed in the side of my tank about a 3rd of the way up the tank. Do you sell a replacement for this part as although its never been used it fails to work? Regards Chris

A: Morning Chris, What is the model of your element? - E-mail: sales@heatrod.com, Kind Regards, Phil.

Q: Hi guys, I have an Akvaterm heat store with a biomass heat source but also a Solar Array with an Immersun unit feeding the immersion. The immersion is a BESTB 340, but after 18 months the safety appears to have become trigger happy. On biomass cycles the tank can hit 80 degrees, but generally that's when there is no sun. I'm having to reset the unit daily. Replacing is straightforward, but is there anything I can do to improve performance? Neil

A: Afternoon Neil, you can use a different thermostat with a higher temperature cut-out. Though this would mean changing the immersion heater as the current unit has a push in thermostat and there isn’t one of them available with a higher temperature cut-out that we are aware of at the moment, Please feel free to ring up and speak to our technical dept though for alternative solutions, Regards, Phil.

Q: My domestic heating boiler is fitted with 2 X CESTB340 immersion heaters fitted with Thermowatt RTS-3 3412173 (RTS Plus) thermostats. The bottom thermostat has cut out three times in the past two weeks. Can you suggest a cause and can you tell me please where on the thermostat the red pointer should be set to. There is a plus and minus with arrow in between and after the plus there is a single dot and then two dots with no numerical indicator of temperatures.

A: Afternoon James, thank you for your question, the cut out normally "pops out" when the temperature reaches a certain level, you can see the temp range on our FAQ guide - http://www.heatrodshop.com/technical-faqs , Please ring our technical department if you have any further problems, Regards, Phil.

Q: Hello, I have a customer with a vented stainless steel cylinder with a top mounted immersion in an 1"3/4" boss. do you have a 27" immersion for this size tapping?

A: Morning Greg, Thank you for your question, we do have a alternative in 27" yes, it would be our part number CESTB 368, please ring 0161 727 3713 for a P&A, Regards, Phil.




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