What size immersion for 117L 900 x 450 cylinder?

[cam112233]

So i'm a 4th year apprentice doing gas repairs and servicing, don't really get involved in cylinders too much unless changing a 3port or something because at my company the plumbing department change all cylinders

I've got a private job of changing the above cylinder due to it leaking in several places, I'm not really sure what size immersion heater I need to buy for the job though due to having no experience changing them. It's a top entry immersion slot only on the new cylinder but the old one has an immersion at the top and on on the side at the bottom

900mm is about 35'' so I could really fit a 27'' immersion or should I fit a smaller one for any reason??

 

[ShaunCorbs]

direct or indirect cylinder ?

 

[gpbeck]

You need a qualification to do this work.

 

[Last Plumber]

So i'm a 4th year apprentice doing gas repairs and servicing, don't really get involved in cylinders too much unless changing a 3port or something because at my company the plumbing department change all cylinders

I've got a private job of changing the above cylinder due to it leaking in several places, I'm not really sure what size immersion heater I need to buy for the job though due to having no experience changing them. It's a top entry immersion slot only on the new cylinder but the old one has an immersion at the top and on on the side at the bottom

900mm is about 35'' so I could really fit a 27'' immersion or should I fit a smaller one for any reason??

If you aren't qualified or insured you would be better to pass it onto the company you work for and ask to be involved in the job. Only my opinion but it is safer, you should be legally covered and you'll gain experience from doing the work under supervision if it's the first time.

 

[Ric2013]

Advantage of a a smaller immersion is the customer may only want to heat the top half of a cylinder to wash up in summer months instead of a large quantity of water.

@gpbeck What qualification would you be looking for, assuming it's a vented cylinder?

 

[gpbeck]

Advantage of a a smaller immersion is the customer may only want to heat the top half of a cylinder to wash up in summer months instead of a large quantity of water.

@gpbeck What qualification would you be looking for, assuming it's a vented cylinder?

OP should really have mentioned it was vented before seeking help, I think? We still don’t know. Would you want someone asking that question doing the job?

If you heat up just the top half of a cylinder you’ve got a Legionella hazard there.

 

[SimonG]

27", one of the titanium ones.

 

[Ric2013]

OP should really have mentioned it was vented before seeking help, I think? We still don’t know. Would you want someone asking that question doing the job?

If you heat up just the top half of a cylinder you’ve got a Legionella hazard there.

By that yardstick, you've got a legionella hazard anyway as 27" doesn't quite reach the bottom of the cylinder either.

Agreed it is a strange question for someone who considers himself competent to do the job, but in fairness I'm qualified to NVQ2 too and my understanding was that it was considered acceptable practice to have a shorter top-entry immersion as a "top-up". I'm not sure where I got this idea from though, as it's not something I've ever done or seen done, so I can only assume I saw a diagram in a text book?

This is not intended as a dig at you, by the way. I'm just making the point that we are both qualified to a certain level and yet we don't have an identical understanding of the regulations so I don't know that having to ask the question is proof of incompetence. Were I closer to home, I would check the WRAS guide at this point.

In practice, if you had two side-entry immersions, the top one could be used in much the same way and there would also be some stored water that is probably going to be above 25°C and below 60°C.

Back to the OP. If the cylinder is an unvented model, then he certainly shouldn't be installing it.

 

[gpbeck]

Entirely agree. I run my lower element for 3 hours once a week to do the deed.

 

[Ric2013]

Entirely agree. I run my lower element for 3 hours once a week to do the deed.

Which is very different from putting a short immersion in as the only immersion heater, when we don't know for a fact that there is another source of heat that will be used to pasteurise the cylinder.

Good spot, and thanks for picking me up on that!
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Which is very different from putting a short immersion in as the only immersion heater, when we don't know for a fact that there is another source of heat that will be used to pasteurise the cylinder.

Good spot, and thanks for picking me up on that!

I've just agreed with you and thanked you for picking me up on a dangerous assumption. Did you actually mean to 'dislike' my post?