Immersion heater.

[Ian Field]

Thinking ahead just in case it blows...............

The issue is length - I could measure the outside dimensions of the tank,
but without taking the element out there's no guarantee there's no
obstructions inside - and I could just measure the element if I took it out.

The easy way out is to buy one of the shorter folded elements, but I'm
wondering if the effect on convection would be good or bad.

The tank is square, not cylindrical.

Thanks for any help.

[N_Cook]

The other issue is undoing without deforming the ever thinner copper of
the tank. Heat up the thread section with a blow lamp before attempting
to undo . Moderate torque plus tapping spanner with hammer , before
upping the torque.

[Ian Field]

"N_Cook" <div...@tcp.co.uk> wrote in message
news:n7gqsv$71l$1...@dont-email.me...

The local DIY store offers a very flimsy looking pressed steel spanner that
won't put enough torque on the element to do any damage.

There's a more robust looking box spanner on Ebay that would apply the
torque with less risk of buckling.

The last element came out surprisingly easily - so I'm remaining optimistic.

[Geo]

On Sun, 17 Jan 2016 22:23:04 -0000, "Ian Field"
<gangprob...@ntlworld.com> wrote:


>The last element came out surprisingly easily - so I'm remaining optimistic.

What size was it back then?.. :-)

I have a 27 inch element fitted at the top of a 42 inch cylinder.
Water heating is normally by the CH coil but I occasionally test the
immersion heater to make sure it works.

The manufacture's leaflet states:-
"... this heater will only effectively heat water ABOVE, it is
important that the correct length be fitted, i.e. if an 18" heater is
used in a 36" cylinder only 45-50% of the water will be heated"

I have sensors at the top, 2/3 and 1/3 levels and a typical immersion
heater test over a few hours shows that the tank is not fully heated.
https://dl.dropboxusercontent.com/u/28554318/DECimmhtr.pdf

[Ian Field]

"Geo" <nhhu...@dea.spamcon.org> wrote in message
news:8tsp9bh9c3o1fbep1...@4ax.com...

> On Sun, 17 Jan 2016 22:23:04 -0000, "Ian Field"
> <gangprob...@ntlworld.com> wrote:
>
>
>>The last element came out surprisingly easily - so I'm remaining
>>optimistic.
>
> What size was it back then?.. :-)
>
> I have a 27 inch element fitted at the top of a 42 inch cylinder.
> Water heating is normally by the CH coil but I occasionally test the
> immersion heater to make sure it works.
>
> The manufacture's leaflet states:-
> "... this heater will only effectively heat water ABOVE, it is
> important that the correct length be fitted, i.e. if an 18" heater is
> used in a 36" cylinder only 45-50% of the water will be heated"

Its square and not cylindrical, and the element is horizontal at the
bottom - that may not accommodate as long an element as diagonal in a
cylinder.

There is another threaded bush half way up the tank that I could add a
second element if I wanted to.

[Geo]

On Mon, 18 Jan 2016 18:41:40 -0000, "Ian Field"
<gangprob...@ntlworld.com> wrote:


>Its square and not cylindrical, and the element is horizontal at the
>bottom - that may not accommodate as long an element as diagonal in a
>cylinder.

OK - with you now.
Some simulations here:-
https://blogs.mentor.com/robinbornoff/blog/2014/12/19/domestic-hot-water-heating-wat-er-waste-of-energy-part-2-warm-up/

>There is another threaded bush half way up the tank that I could add a
>second element if I wanted to.

useful only if yiou want to keep water hot for handwashing etc without
heating the whole tank.

[Mike Tomlinson]

En el artículo <teRmy.108034$a_7....@fx43.am4>, Ian Field <gangprobing
.al...@ntlworld.com> escribió:

>Thinking ahead just in case it blows...............

You'll get a much better response in uk.d-i-y. sci.eletronics.repair is
a rather weird place to ask a question about an immersion heater.

--
(\_/)
(='.'=) Bunny says: Windows 10? Nein danke!
(")_(")

[Geo]

On Tue, 19 Jan 2016 08:57:36 +0000, Mike Tomlinson
<mi...@jasper.org.uk> wrote:

>You'll get a much better response in uk.d-i-y. sci.eletronics.repair is
>a rather weird place to ask a question about an immersion heater.

Yebbut you need so many filters - Harry, Roddy, Denis, Toughguy etc

[Mike Tomlinson]

En el artículo <l4as9bteecu0lep0a...@4ax.com>, Geo <nhhu-
o3...@dea.spamcon.org> escribió:

>Yebbut you need so many filters - Harry, Roddy, Denis, Toughguy etc

Aye, that's true. Can't say I blame you :)

[Ian Field]

"Geo" <nhhu...@dea.spamcon.org> wrote in message

news:haur9b10acanfd5c4...@4ax.com...

A well insulated tank costs more to heat up from cold than keep topped up by
the thermostat.

Not as bad heating half a tank from cold, but I'm guessing it would still
cost slightly more.

[MJC]

In article <8Ivny.98086$Mi6....@fx35.am4>,
gangprob...@ntlworld.com says...

>
> A well insulated tank costs more to heat up from cold than keep topped up by
> the thermostat.

That is a meaningless comparison.

For any given tank, the energy you waste depends on how hot it is for
how long. You will always waste less by letting it cool down. But that
may be less convenient!

Mike.

[Tim R]

On Tuesday, January 19, 2016 at 1:59:21 PM UTC-5, Ian Field wrote:

> A well insulated tank costs more to heat up from cold than keep topped up by
> the thermostat.
>
> Not as bad heating half a tank from cold, but I'm guessing it would still
> cost slightly more.

Except the rate of heat loss is dependent on the delta T between inside and outside. Colder tanks lose less heat, if they haven't already reached minimum, than warm tanks being kept warm, so it takes less energy.