Truma Ultrastore electric element location

[Kraken]

Hi everyone,

 

I have a Truma Ultrastore in my Autotrail Cheyenne 696G which trips the mains RCD as soon as I switch it on. I'm assuming it's the element at fault but despite dismantling as much as I can I still can't see where it is on the boiler. I've removed the outer cover and tried to follow the cabling but the only wires I can see look much too thin to carry much current and the exploded diagram that I have shows the element but not where it fits. I'm hoping it's not necessary to remove the boiler itself. Can anyone advise please?

[Derek Uzzell]

Welcome to the Ou&AboutLive forums.

 

An Ultrastore boiler's 230V heating element is inside the boiler itself. It’s rather like the 230V heating element of a domestic immersion heater, or the heating element of a 230V electric kettle (except you can’t take the lid off an Ultrastore boiler!) The attached cross-section photo should help, with the horizontally-positioned element poking into the boiler’s water reservoir from the right.

 

Whether you’d need to remove the boiler to replace the 230V element would really depend on the boiler’s accessibility in your Auto-Trail motorhome.

[Kraken]

Thanks for the reply Derek, I've now found the element but what a pain to get at.

 

Pipes are off, element securing nuts off but I'm stuck with the nuts on the small electrical component adjacent to and wired into the element which has to come out at the same time. Very little clearance between the nut and the body so it's hard to get on it straight with a socket (also working upside down and in a mirror doesn't help!). They seem to be somewhere between 5 & 6mm as the sockets I've got just won't fit cleanly. Does anyone know exactly what they are so I can make sure I get the right tool? The studs are so tiny that they could easily break or strip.

 

Edit: been trying to upload a pic of this but without success

[Kraken]

Here you go B-)

[Derek Uzzell]

I think the “small electrical component” you need to get the nuts off to remove is a temperature sensor, but I can’t advise on the size of the nuts. Cheap box spanners seem to go no smaller than 6mm size, so you might have to opt for ‘mini’ sockets (example of an inexpensive set here)

 

https://www.amazon.co.uk/Rolson-36109-Socket-Set-Pieces/dp/B000WDTI1C/ref=sr_1_11?ie=UTF8&qid=1531202506&sr=8-11&keywords=small+spanner+set

 

to obtain a good fit on the nuts.

 

There are quite a few on-line entries about replacing a Truma water-boiler’s 230V element

 

https://tinyurl.com/yb845gng

 

and the 2nd posting on the following Practical Caravan forum thread provides some detail of the procedure involved.

 

https://www.practicalcaravan.com/forum/technical/27840-truma-ultrastore-element-replacement-questions

 

I’ve looked at a few of the on-line entries (but not found any guidance on the temperature-sensor nut size) and the general advice seems to be

 

a) That water may still remain in the heater even after it has been drained down - so be prepared for water gushing out when the element is removed.

 

b) That a failed element may have deformed and prove tricky to extract.

 

c) That the wattage of the element differs according to the model of Truma boiler - so ensure you choose the correct replacment..

 

d) That the temperature-sensor’s small nuts (that you are asking about) may NOT be provided with replacement elements - so don’t lose them when youeventually get them off!

 

e) Don’t overtighten the nuts.