CESTB340 1¾" 3kw 16" Immersion Heater (CESTB340)

Product Code: SH314C-AA1CA1(CESTB340)

This is a 3kw, 15inch 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.The element is bonded to the brass flange with an environmentally friendly, WRAS approved, epoxy bond, making for more robust hydraulic and corrosion proof performance.

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 Diamond-H WTS, 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.



£38.40 £32.00 (ex VAT)


Category: .

Additional information

Loading (kW)


Voltage (V)


Secondary Protection


Length (mm/Inch)


Element Diameter (mm)


Stat Inches


Sheath Material

Incoloy 800

Head Size (BSP)

C: 1.75″ BSP (1 ¾”)

Thermostat Type

Coltherm TSE or Thermawatt RTS-3, Cotherm TSE or Thermawatt RTS-3, Diamond-H WTS Dual Function Thermostat

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
— Asked by David Openshaw on September 8, 2014
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
— Asked by James Cheung on October 20, 2014
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.    
— Asked by Matthew Sillett on March 3, 2015
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?
— Asked by Alan Stewart on May 21, 2015
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
— Asked by bob cooper on May 26, 2015
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: 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
— Asked by Colin Raftery on October 12, 2015
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
— Asked by Jonah on November 30, 2015
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
— Asked by Al Kennedy on December 3, 2015
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
— Asked by james on January 25, 2016
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
— Asked by Brian Hunter` on January 26, 2016
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
— Asked by R.O.Smith on February 8, 2016
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?
— Asked by Matt Saunders on March 17, 2016
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 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
— Asked by Neil Swanson on June 7, 2016
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.
— Asked by James Cameron on August 22, 2016
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?
— Asked by Greg on August 5, 2016
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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