immersion heater element length

[mrpeevly]

Be great to have everybodys opinion on this, the issue although not catastrophic is just nagging me I really can not see what the issue is, unless I was really unlucky.

3 years ago I changed a blown element in my immersion heater, the element was of the 27" variety, I thought, hey why not put a 30" one in and have more hot water. Upon fitting the 30" it would not heat the water sufficiently no matter how high the thermostat was set, I fitted a 27" instead and all was well, oh well probably a faulty element. However a couple of weeks ago, the element stopped working again, I replaced it will a 30" version and exactly the same thing happened, the water would not get hot enough, I am now back with a 27" one, again.

Was I really unlucky and got two dodgy elements, or is there something else I am not seeming that, stops the longer element from heating to the required temperature?

Thanking you in advance

 

[doitall]

Is it on a timer, because you are heating more water with the longer one

 

[mrpeevly]

I am using the immersion manually, just turning it on when I want a bath or whatever.

I have left it on all night, but even this did not get the water "that" hot, I could put my hand under the running tap.

 

[holty]

glad in this instance, 3 inch bigger means less seriously though sounds like youve got a problem. if you keep changing elements so much in the space of 3 years.only seen elements go this quick with well water and very aggresive at that.

 

[doitall]

Did you put a longer stat in, or use the old one

 

[holty]

have to give it to DIA. very obvious, but good diagnosis

 

[mrpeevly]

I used the stat that came with the element, in all cases, I guess maybe I am cursed regard 30" elements. However I am determined to have one now, as it wont work first time, grrrrrrrr.

I just thought, I am buying the elements from TLC, and as such they are cheap, should I spend a bit more for a "better" one, if so what manufacturer would people recommend?

 

[doitall]

What size cylinder is it.

Is the cold feed getting hot.

 

[JohnD]

Essex water is fairly hard. Incalloy elements are supposed to be long-lasting. They cost a few pounds more.

Presumably your cylinder is well-insulated with a manufacturer's foam layer or at least one fibreglass jacket? And all the hot pipes (including the one rising up from the top of the cylinder) have Climaflex or similar round them? And when the element doesn't get the cylinder hot enough you have verified that it is drawing current and checked that the thermostat is not set too low? There isn't a hot water loop to a remote bathroom is there?

If the element is pouring 3kW of heat into the water, it must be getting out somewhere, if the water isn't getting hot enough.

 

[heatingman]

the immersion length is governed by the height of cylinder.

 

[Agile]

This is an interesting problem and one which I cannot guess at the cause of from the limited information given.

Can you take and post a picture on here showing the cylinder and the end of the immersion.

Together with a close up of the 30" showing the wired connections?

Then perhaps we may see something obvious or just compound the oddity.

Tony

 

[ChrisR]

The thermostat will be at the top of the cylinder.
If you have a bathroom radiator on the primaries, the extra length could encourage thermal circulation round the primary pipes.
That would cool the cylinder, especially at the bottom, and give you an average lower temperature assuming there was sufficient heat loss.

 

[seco services]

i was always told a top entry must be 200mm less than the height of the cylinder itself.

 

[doitall]

What size cylinder is it.

Is the cold feed getting hot.

The reason I ask the question was, that maybe it was going up the cold feed, if the bottom of the tank heated up below the cold feed, you could get parastatic circulation.

 

[matt1e]

is there something else I am not seeming that, stops the longer element from heating to the required temperature?

Thanking you in advance

yes you are trying to heat more water (due to the longer lenth) with the same power (prob 3kw) element, it will take longer to heat

matt