Hi all. I am back for a brief visit and some advice so please don't try
to wind me up. Last looked in before Xmas so I have just marked 79,000
headers as read without reading a single one. :-(

I am under the impression that back in the dim and distant past you
could get immersion heaters where the load could be set at 1, 2 or 3 kw.
A quick google has led me only to 3 kw nominal (well one was 2.7)
heaters so do such animals still exist? If so where available or if not
is there some sensible way of reducing the power consumption of a 3 kw
immersion heater to the levels referred to above?

--
Roger Chapman

Roger Chapman wrote:

is there some sensible way of reducing the power consumption of a 3 kw
immersion heater to the levels referred to above?

Turn it on for 1/3 the time?

In article ,
Roger Chapman writes:
Hi all. I am back for a brief visit and some advice so please don't try
to wind me up. Last looked in before Xmas so I have just marked 79,000
headers as read without reading a single one. :-(

I am under the impression that back in the dim and distant past you
could get immersion heaters where the load could be set at 1, 2 or 3 kw.
A quick google has led me only to 3 kw nominal (well one was 2.7)
heaters so do such animals still exist? If so where available or if not
is there some sensible way of reducing the power consumption of a 3 kw
immersion heater to the levels referred to above?

I do recall seeing a 1kW one about 40 years ago. You may
find they're still used in situations with limited power,
like on a boat. I also recall seeing switched power ratings
but it was done by switching 2 immersion heaters.

Connecting two in series will get you 1/4 of the power.

I suppose you could connect a diode to half-wave rectify,
which is half power, but you would need to mount it safely
(could use the bottom of the cylinder as a heatsink with
suitable insulation), and if you are doing this to limit
current draw rather than power consumption, then you still
have the full current draw every half cycle and the power
factor will be less than 1.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 05/10/2012 17:12, Andy Burns wrote:
Roger Chapman wrote:

is there some sensible way of reducing the power consumption of a 3 kw
immersion heater to the levels referred to above?

Turn it on for 1/3 the time?

Sorry if I did not make myself clear. What I want to do is limit the
instantaneous power consumption.



--
Roger Chapman

On Oct 5, 5:03*pm, Roger Chapman wrote:
Hi all. I am back for a brief visit and some advice so please don't try
to wind me up. Last looked in before Xmas so I have just marked 79,000
headers as read without reading a single one. :-(

I am under the impression that back in the dim and distant past you
could get immersion heaters where the load could be set at 1, 2 or 3 kw.
A quick google has led me only to 3 kw nominal (well one was 2.7)
heaters so do such animals still exist? If so where available or if not
is there some sensible way of reducing the power consumption of a 3 kw
immersion heater to the levels referred to above?

--
Roger Chapman

In days of yore, immersion heaters could have new elements fitted (or
ones of any size). They are virtually all 3Kw now and disposable..

You can get electric elements for water heaters of various sizes.
This is probably your best chance or some sort of electronic voltage
control device.

Alternatively why not get two and connect them in series or use a
three heat switch?
They were used in days of yore on electric cookers. There were two
elements that could be connected in series, parallel or just one
element.

http://el35454.wikispaces.com/Three+Heat+Switch

On 05/10/2012 17:28, Roger Chapman wrote:
On 05/10/2012 17:12, Andy Burns wrote:
Roger Chapman wrote:

is there some sensible way of reducing the power consumption of a 3 kw
immersion heater to the levels referred to above?

Turn it on for 1/3 the time?

Sorry if I did not make myself clear. What I want to do is limit the
instantaneous power consumption.

Why? Usually if you need to use an immersion heater you want it on max.
It still takes a while to heat up from cold even so.

Unless your wiring is not up to 3kW current requirements. I can't see
why you want to do this. Two in series will get you one quarter power.

There are no obvious advantages of taking longer to heat up the cylinder
full of water unless it is *exceptionally* badly insulated or you do not
have sufficient mains power. There are vastly overpriced 1kW "solar"
immersion heaters offered to cater for that latter scammarket (prices
start at about 10x that of normal 3kW units).

--
Regards,
Martin Brown

On Oct 5, 5:46*pm, Martin Brown
wrote:
On 05/10/2012 17:28, Roger Chapman wrote:

On 05/10/2012 17:12, Andy Burns wrote:
Roger Chapman wrote:

is there some sensible way of reducing the power consumption of a 3 kw
immersion heater to the levels referred to above?

Turn it on for 1/3 the time?

Sorry if I did not make myself clear. What I want to do is limit the
instantaneous power consumption.

Why? Usually if you need to use an immersion heater you want it on max.
It still takes a while to heat up from cold even so.

Unless your wiring is not up to 3kW current requirements. I can't see
why you want to do this. Two in series will get you one quarter power.

There are no obvious advantages of taking longer to heat up the cylinder
full of water unless it is *exceptionally* badly insulated or you do not
have sufficient mains power. There are vastly overpriced 1kW "solar"
immersion heaters offered to cater for that latter scammarket (prices
start at about 10x that of normal 3kW units).

--
Regards,
Martin Brown

One advantage ie to tailor the immersion heater to the output of a Pv
panel (ie not to imort electricity.
There is apparently a device that does just this. I am checking it out
now.

On Oct 5, 5:46*pm, Martin Brown
wrote:
On 05/10/2012 17:28, Roger Chapman wrote:

On 05/10/2012 17:12, Andy Burns wrote:
Roger Chapman wrote:

is there some sensible way of reducing the power consumption of a 3 kw
immersion heater to the levels referred to above?

Turn it on for 1/3 the time?

Sorry if I did not make myself clear. What I want to do is limit the
instantaneous power consumption.

Why? Usually if you need to use an immersion heater you want it on max.
It still takes a while to heat up from cold even so.

Unless your wiring is not up to 3kW current requirements. I can't see
why you want to do this. Two in series will get you one quarter power.

There are no obvious advantages of taking longer to heat up the cylinder
full of water unless it is *exceptionally* badly insulated or you do not
have sufficient mains power. There are vastly overpriced 1kW "solar"
immersion heaters offered to cater for that latter scammarket (prices
start at about 10x that of normal 3kW units).

--
Regards,
Martin Brown

Here it is.
http://solarimmersionheaterswitch.co.uk/

On 05/10/2012 17:46, Martin Brown wrote:
On 05/10/2012 17:28, Roger Chapman wrote:
On 05/10/2012 17:12, Andy Burns wrote:
Roger Chapman wrote:

is there some sensible way of reducing the power consumption of a 3 kw
immersion heater to the levels referred to above?

Turn it on for 1/3 the time?

Sorry if I did not make myself clear. What I want to do is limit the
instantaneous power consumption.

Why? Usually if you need to use an immersion heater you want it on max.
It still takes a while to heat up from cold even so.

To take advantage of 'free' electricity from PV panels without
constantly monitoring cloud cover. Heating the DHW with bought in
electricity is some 3 times as expensive heating with gas so it makes no
sense to use an immersion heater unless there is a minimal chance of the
imported electricity demand exceeding 1 kw for any length of time.

Unless your wiring is not up to 3kW current requirements. I can't see
why you want to do this. Two in series will get you one quarter power.

But as I only have one immersion heater boss that is a non starter.

There are no obvious advantages of taking longer to heat up the cylinder
full of water unless it is *exceptionally* badly insulated or you do not
have sufficient mains power. There are vastly overpriced 1kW "solar"
immersion heaters offered to cater for that latter scammarket (prices
start at about 10x that of normal 3kW units).

I didn't come across any such 1 kw units during my search and I don't
think £200 would be a cost effective solution. But that sum is much less
than a wireless gizmo that purports to avoid importing electricity but
retails ITRO £1500.

--
Roger Chapman

On Oct 5, 5:03*pm, Roger Chapman wrote:
Hi all. I am back for a brief visit and some advice so please don't try
to wind me up. Last looked in before Xmas so I have just marked 79,000
headers as read without reading a single one. :-(

I am under the impression that back in the dim and distant past you
could get immersion heaters where the load could be set at 1, 2 or 3 kw.
A quick google has led me only to 3 kw nominal (well one was 2.7)
heaters so do such animals still exist? If so where available or if not
is there some sensible way of reducing the power consumption of a 3 kw
immersion heater to the levels referred to above?

--
Roger Chapman
How about this?
http://solarimmersionheaterswitch.co...-heater-power-
halve/immersion-heater-power-reducer/

On 05/10/2012 18:04, harry wrote:

snip

Here it is.
http://solarimmersionheaterswitch.co.uk/


dons German helmet

Interesting!

retires back into the undergrowth

Several different items on offer including low input immersion heaters.
Not sure yet which is the right course of action.


--
Roger Chapman

"Roger Chapman" wrote in message
...
Hi all. I am back for a brief visit and some advice so please don't try to
wind me up. Last looked in before Xmas so I have just marked 79,000
headers as read without reading a single one. :-(

I am under the impression that back in the dim and distant past you could
get immersion heaters where the load could be set at 1, 2 or 3 kw. A quick
google has led me only to 3 kw nominal (well one was 2.7) heaters so do
such animals still exist? If so where available or if not is there some
sensible way of reducing the power consumption of a 3 kw immersion heater
to the levels referred to above?

Bung it onto a 3Kw dimmer.

On Fri, 05 Oct 2012 17:28:18 +0100, Roger Chapman
wrote:

On 05/10/2012 17:12, Andy Burns wrote:
Roger Chapman wrote:

is there some sensible way of reducing the power consumption of a 3 kw
immersion heater to the levels referred to above?

Turn it on for 1/3 the time?

Sorry if I did not make myself clear. What I want to do is limit the
instantaneous power consumption.

Thyristor power controller. You could get them for drills & similar,
as most power tools have built in controllers look for a motor speed
control. I bought a biggish one [20A] for about a tenner from Ebay.

Why waste energy? Providing your wiring is adequately rated you will
loose more energy through the tank insulation during the extended warm
up time than you will from the resistance change due to the higher
current flow.

Have you looked into fishtank heaters BTW?

Or even fish on their own, they will heat up water over time, but a
shower would probably involve a spreadsheet application relating to
ant's eggs, local temperature and breeding. I believe kippers are
noted for their tolerance to heat BTW.


HN

On 05/10/2012 18:42, brass monkey wrote:
"Roger wrote in message
...
Hi all. I am back for a brief visit and some advice so please don't try to
wind me up. Last looked in before Xmas so I have just marked 79,000
headers as read without reading a single one. :-(

I am under the impression that back in the dim and distant past you could
get immersion heaters where the load could be set at 1, 2 or 3 kw. A quick
google has led me only to 3 kw nominal (well one was 2.7) heaters so do
such animals still exist? If so where available or if not is there some
sensible way of reducing the power consumption of a 3 kw immersion heater
to the levels referred to above?

Bung it onto a 3Kw dimmer.

How much power would the dimmer dissipate if it was halving the output
of the immersion? The link Harry gave includes a a power reducer that
runs hot which I presume works on the same principle. Might work out as
an expensive and possibly unwanted space heater if the values are
significant.

--
Roger Chapman

"Roger Chapman" wrote in message
...
On 05/10/2012 18:42, brass monkey wrote:
"Roger wrote in message
...
Hi all. I am back for a brief visit and some advice so please don't try
to
wind me up. Last looked in before Xmas so I have just marked 79,000
headers as read without reading a single one. :-(

I am under the impression that back in the dim and distant past you
could
get immersion heaters where the load could be set at 1, 2 or 3 kw. A
quick
google has led me only to 3 kw nominal (well one was 2.7) heaters so do
such animals still exist? If so where available or if not is there some
sensible way of reducing the power consumption of a 3 kw immersion
heater
to the levels referred to above?

Bung it onto a 3Kw dimmer.

How much power would the dimmer dissipate if it was halving the output of
the immersion? The link Harry gave includes a a power reducer that runs
hot which I presume works on the same principle. Might work out as an
expensive and possibly unwanted space heater if the values are
significant.

At a guess maybe 10 watts.

On 05/10/2012 20:05, brass monkey wrote:
Bung it onto a 3Kw dimmer.

How much power would the dimmer dissipate if it was halving the output of
the immersion? The link Harry gave includes a a power reducer that runs
hot which I presume works on the same principle. Might work out as an
expensive and possibly unwanted space heater if the values are
significant.
At a guess maybe 10 watts.


That looks like the cheap option then. I assume it would cost
substantially less than the £49 power reducer.

--
Roger Chapman

Roger Chapman wrote:
Hi all. I am back for a brief visit and some advice so please don't try
to wind me up. Last looked in before Xmas so I have just marked 79,000
headers as read without reading a single one. :-(

I am under the impression that back in the dim and distant past you
could get immersion heaters where the load could be set at 1, 2 or 3 kw.
A quick google has led me only to 3 kw nominal (well one was 2.7)
heaters so do such animals still exist? If so where available or if not
is there some sensible way of reducing the power consumption of a 3 kw
immersion heater to the levels referred to above?

If you read though all the messages under all 79,000 headers you'll find
the answer to your question.

Bill

Roger Chapman wrote:


How much power would the dimmer dissipate if it was halving the output
of the immersion? The link Harry gave includes a a power reducer that
runs hot which I presume works on the same principle. Might work out as
an expensive and possibly unwanted space heater if the values are
significant.


Relatively little if it is a chopper dimmer (eg triac based).


--
Tim Watts Personal Blog: http://www.dionic.net/tim/

"A fanatic is one who can't change his mind and won't change the subject."

Tim Watts wrote:
Roger Chapman wrote:


How much power would the dimmer dissipate if it was halving the output
of the immersion? The link Harry gave includes a a power reducer that
runs hot which I presume works on the same principle. Might work out as
an expensive and possibly unwanted space heater if the values are
significant.


Relatively little if it is a chopper dimmer (eg triac based).


My 400W dimmers get perceptibly warm. I'd say a watt or so at full chat

--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.

On 05/10/2012 17:27, Andrew Gabriel wrote:
In article ,
Roger Chapman writes:
Hi all. I am back for a brief visit and some advice so please don't try
to wind me up. Last looked in before Xmas so I have just marked 79,000
headers as read without reading a single one. :-(

I am under the impression that back in the dim and distant past you
could get immersion heaters where the load could be set at 1, 2 or 3 kw.
A quick google has led me only to 3 kw nominal (well one was 2.7)
heaters so do such animals still exist? If so where available or if not
is there some sensible way of reducing the power consumption of a 3 kw
immersion heater to the levels referred to above?

I do recall seeing a 1kW one about 40 years ago. You may
find they're still used in situations with limited power,
like on a boat. I also recall seeing switched power ratings
but it was done by switching 2 immersion heaters.

Connecting two in series will get you 1/4 of the power.

I suppose you could connect a diode to half-wave rectify,
which is half power, but you would need to mount it safely
(could use the bottom of the cylinder as a heatsink with
suitable insulation), and if you are doing this to limit
current draw rather than power consumption, then you still
have the full current draw every half cycle and the power
factor will be less than 1.

Well that covers both the suggestions I was about to make, so, what he
said ;-)



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In article ,
The Natural Philosopher writes:
Tim Watts wrote:
Roger Chapman wrote:


How much power would the dimmer dissipate if it was halving the output
of the immersion? The link Harry gave includes a a power reducer that
runs hot which I presume works on the same principle. Might work out as
an expensive and possibly unwanted space heater if the values are
significant.


Relatively little if it is a chopper dimmer (eg triac based).


My 400W dimmers get perceptibly warm. I'd say a watt or so at full chat

A triac drops about 1.1V, so at 3kW (12.5A), that's going
to be about 14W from the triac.

Phase control of a 3kW load will generate quite a bit of
noise on the mains too, even allowing for RF suppression.
Power control of heating loads is normally done by using
zero crossing switching (e.g. on for 3 cycles, off for
3 cycles), as it avoids switching the mains other than at
the zero crossing points, and so generates no noise.

When I've designed phase control circuits for high power,
I have used MOSFETs instead, which will have half the
power dissipation of a triac (and that's only because it's
AC, otherwise it would be much less). You can also do some
more interesting things, such as switching on and off more
than once per half-cycle, e.g. just switching off at the
cycle peaks. However, you need different driving circuitry,
and you need two MOSFETs (for AC).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 05/10/2012 18:07, Roger Chapman wrote:

Unless your wiring is not up to 3kW current requirements. I can't see
why you want to do this. Two in series will get you one quarter power.

But as I only have one immersion heater boss that is a non starter.


You can get dual element immersion heaters
http://www.advancedwater.co.uk/prod-032-255-0002.html


--
mailto:news{at}admac(dot}myzen{dot}co{dot}uk

On Friday, October 5, 2012 5:03:07 PM UTC+1, Roger Chapman wrote:

I am under the impression that back in the dim and distant past you

could get immersion heaters where the load could be set at 1, 2 or 3 kw.

A quick google has led me only to 3 kw nominal (well one was 2.7)

heaters so do such animals still exist? If so where available or if not

is there some sensible way of reducing the power consumption of a 3 kw

immersion heater to the levels referred to above?


There are many ways to reduce immersion heater power. What's sensible depends entirely on the reason you want to do this.
- simmerstat
- capacitor
- choke
- triac dimmer
- diode
- 2 elements in series
- smpsu
- transformer
- connecting the neutral end of the element to the water instead of the mains neutral (usually not a good plan, but can be)
- series lightbulbs (not often a good option)
- wind your own external element
- and others


NT

"Roger Chapman" wrote in message
news
On 05/10/2012 20:05, brass monkey wrote:
Bung it onto a 3Kw dimmer.

How much power would the dimmer dissipate if it was halving the
output of
the immersion? The link Harry gave includes a a power reducer that
runs
hot which I presume works on the same principle. Might work out as an
expensive and possibly unwanted space heater if the values are
significant.
At a guess maybe 10 watts.


That looks like the cheap option then. I assume it would cost
substantially less than the £49 power reducer.

Actually, they don't seem to be cheap. I spose you could always hang a BT139
in place of the triac in a normal 500w dimmer with appropriate heatsink ( if
you find one which uses a triac instead of a quadrac). Just a thought.

On Fri, 05 Oct 2012 17:03:07 +0100, Roger Chapman
wrote:

Hi all. I am back for a brief visit and some advice so please don't try
to wind me up. Last looked in before Xmas so I have just marked 79,000
headers as read without reading a single one. :-(

I am under the impression that back in the dim and distant past you
could get immersion heaters where the load could be set at 1, 2 or 3 kw.
A quick google has led me only to 3 kw nominal (well one was 2.7)
heaters so do such animals still exist? If so where available or if not
is there some sensible way of reducing the power consumption of a 3 kw
immersion heater to the levels referred to above?


http://www.chandleryworld.co.uk/cata...5547-1543.html

harry expressed precisely :
On Oct 5, 5:46*pm, Martin Brown
wrote:
On 05/10/2012 17:28, Roger Chapman wrote:

On 05/10/2012 17:12, Andy Burns wrote:
Roger Chapman wrote:

is there some sensible way of reducing the power consumption of a 3 kw
immersion heater to the levels referred to above?
Turn it on for 1/3 the time?

Sorry if I did not make myself clear. What I want to do is limit the
instantaneous power consumption.

Why? Usually if you need to use an immersion heater you want it on max.
It still takes a while to heat up from cold even so.

Unless your wiring is not up to 3kW current requirements. I can't see
why you want to do this. Two in series will get you one quarter power.

There are no obvious advantages of taking longer to heat up the cylinder
full of water unless it is *exceptionally* badly insulated or you do not
have sufficient mains power. There are vastly overpriced 1kW "solar"
immersion heaters offered to cater for that latter scammarket (prices
start at about 10x that of normal 3kW units).

--
Regards,
Martin Brown

Here it is.
http://solarimmersionheaterswitch.co.uk/

What terrible grammar and spelling for a commercial web-site.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

In message , Harry
Bloomfield writes
harry expressed precisely :
On Oct 5, 5:46*pm, Martin Brown
wrote:
On 05/10/2012 17:28, Roger Chapman wrote:

On 05/10/2012 17:12, Andy Burns wrote:
Roger Chapman wrote:

is there some sensible way of reducing the power consumption of a
3 kw
immersion heater to the levels referred to above?
Turn it on for 1/3 the time?

Sorry if I did not make myself clear. What I want to do is limit

instantaneous power consumption.
Why? Usually if you need to use an immersion heater you want it on
max.
It still takes a while to heat up from cold even so.
Unless your wiring is not up to 3kW current requirements. I can't
see
why you want to do this. Two in series will get you one quarter power.
There are no obvious advantages of taking longer to heat up the
cylinder
full of water unless it is *exceptionally* badly insulated or you do not
have sufficient mains power. There are vastly overpriced 1kW "solar"
immersion heaters offered to cater for that latter scammarket (prices
start at about 10x that of normal 3kW units).
--
Regards,
Martin Brown

Here it is.
http://solarimmersionheaterswitch.co.uk/

What terrible grammar and spelling for a commercial web-site.

Don't know about the grammar. Everything keeps jumping around on its own
before you have time to read it! I hate sites like that.
--
Ian

On 05/10/2012 18:01, harry wrote:
On Oct 5, 5:46 pm, Martin Brown
wrote:
On 05/10/2012 17:28, Roger Chapman wrote:

On 05/10/2012 17:12, Andy Burns wrote:
Roger Chapman wrote:

is there some sensible way of reducing the power consumption of a 3 kw
immersion heater to the levels referred to above?

Turn it on for 1/3 the time?

Sorry if I did not make myself clear. What I want to do is limit the
instantaneous power consumption.

Why? Usually if you need to use an immersion heater you want it on max.
It still takes a while to heat up from cold even so.

Unless your wiring is not up to 3kW current requirements. I can't see
why you want to do this. Two in series will get you one quarter power.

There are no obvious advantages of taking longer to heat up the cylinder
full of water unless it is *exceptionally* badly insulated or you do not
have sufficient mains power. There are vastly overpriced 1kW "solar"
immersion heaters offered to cater for that latter scammarket (prices
start at about 10x that of normal 3kW units).

One advantage ie to tailor the immersion heater to the output of a Pv
panel (ie not to imort electricity.
There is apparently a device that does just this. I am checking it out
now.

Which explains precisely why the scammers for "Green" solar PV energy
can get 10x more money for something that is only 30% as good. It is
completely insane to generate high grade electrical energy and then use
it to heat water when you can heat water directly in a solar panel with
far greater efficiency.

The only problem is that the latter does not attract enough misguided
bribery to make it cost effective. Our energy policy is a farce!

--
Regards,
Martin Brown

On Oct 6, 9:36*am, Martin Brown
wrote:
On 05/10/2012 18:01, harry wrote:









On Oct 5, 5:46 pm, Martin Brown
wrote:
On 05/10/2012 17:28, Roger Chapman wrote:

On 05/10/2012 17:12, Andy Burns wrote:
Roger Chapman wrote:

is there some sensible way of reducing the power consumption of a 3 kw
immersion heater to the levels referred to above?

Turn it on for 1/3 the time?

Sorry if I did not make myself clear. What I want to do is limit the
instantaneous power consumption.

Why? Usually if you need to use an immersion heater you want it on max..
It still takes a while to heat up from cold even so.

Unless your wiring is not up to 3kW current requirements. I can't see
why you want to do this. Two in series will get you one quarter power.

There are no obvious advantages of taking longer to heat up the cylinder
full of water unless it is *exceptionally* badly insulated or you do not
have sufficient mains power. There are vastly overpriced 1kW "solar"
immersion heaters offered to cater for that latter scammarket (prices
start at about 10x that of normal 3kW units).

One advantage ie to tailor the immersion heater to the output of a Pv
panel (ie not to imort electricity.
There is apparently a device that does just this. I am checking it out
now.

Which explains precisely why the scammers for "Green" solar PV energy
can get 10x more money for something that is only 30% as good. It is
completely insane to generate high grade electrical energy and then use
it to heat water when you can heat water directly in a solar panel with
far greater efficiency.

The only problem is that the latter does not attract enough misguided
bribery to make it cost effective. Our energy policy is a farce!

You are behind the times. Yes it does attract grants. (RHI)

On 05/10/2012 22:23, alan wrote:
On 05/10/2012 18:07, Roger Chapman wrote:

Unless your wiring is not up to 3kW current requirements. I can't see
why you want to do this. Two in series will get you one quarter power.

But as I only have one immersion heater boss that is a non starter.


You can get dual element immersion heaters
http://www.advancedwater.co.uk/prod-032-255-0002.html



Thanks for the link but it doesn't actually specify what the rating of
each element is. Just says 3 kw for the unit.
--
Roger Chapman

On 05/10/2012 22:06, Andrew Gabriel wrote:
In ,
The Natural writes:
Tim Watts wrote:
Roger Chapman wrote:


How much power would the dimmer dissipate if it was halving the output
of the immersion? The link Harry gave includes a a power reducer that
runs hot which I presume works on the same principle. Might work out as
an expensive and possibly unwanted space heater if the values are
significant.


Relatively little if it is a chopper dimmer (eg triac based).


My 400W dimmers get perceptibly warm. I'd say a watt or so at full chat

A triac drops about 1.1V, so at 3kW (12.5A), that's going
to be about 14W from the triac.

Phase control of a 3kW load will generate quite a bit of
noise on the mains too, even allowing for RF suppression.
Power control of heating loads is normally done by using
zero crossing switching (e.g. on for 3 cycles, off for
3 cycles), as it avoids switching the mains other than at
the zero crossing points, and so generates no noise.

When I've designed phase control circuits for high power,
I have used MOSFETs instead, which will have half the
power dissipation of a triac (and that's only because it's
AC, otherwise it would be much less). You can also do some
more interesting things, such as switching on and off more
than once per half-cycle, e.g. just switching off at the
cycle peaks. However, you need different driving circuitry,
and you need two MOSFETs (for AC).

Thanks for making my rusty electrical knowledge appear anything but
adequate.

These days I wouldn't attempt to build anything requiring electrical
skills beyond those needed to wire a house.

--
Roger Chapman

On Sat, 6 Oct 2012 08:39:54 +0100, Ian Jackson
wrote:

Here it is.
http://solarimmersionheaterswitch.co.uk/

What terrible grammar and spelling for a commercial web-site.

By ****, they know how to charge. Those 11" elements are 20quid from
my local stockist.

Don't know about the grammar. Everything keeps jumping around on its own
before you have time to read it! I hate sites like that.

You missed the goto /stop buttons.

On 05/10/2012 17:03, Roger Chapman wrote:
Hi all. I am back for a brief visit and some advice so please don't try
to wind me up. Last looked in before Xmas so I have just marked 79,000
headers as read without reading a single one. :-(

I am under the impression that back in the dim and distant past you
could get immersion heaters where the load could be set at 1, 2 or 3 kw.
A quick google has led me only to 3 kw nominal (well one was 2.7)
heaters so do such animals still exist? If so where available or if not
is there some sensible way of reducing the power consumption of a 3 kw
immersion heater to the levels referred to above?

Thanks to all those who have replied to this thread. I will be
investigating and perhaps investing in items highlighted here as already
on the market.

I had forgotten how time consuming reading this ng was so I will
withdraw back into the woodwork to perhaps surface briefly in another 9
months or so after another 79000 unread posts. ;-)

Goodbye for now.

--
Roger Chapman

"Roger Chapman" wrote in message
...

Thanks to all those who have replied to this thread. I will be
investigating and perhaps investing in items highlighted here as already
on the market.

I had forgotten how time consuming reading this ng was so I will withdraw
back into the woodwork to perhaps surface briefly in another 9 months or
so after another 79000 unread posts. ;-)

Goodbye for now.

You could always wire two 3kW heaters in series.
That would give ~750W.
Opps he's missed it!

Roger Chapman wrote:
On 05/10/2012 17:03, Roger Chapman wrote:
Hi all. I am back for a brief visit and some advice so please don't try
to wind me up. Last looked in before Xmas so I have just marked 79,000
headers as read without reading a single one. :-(

I am under the impression that back in the dim and distant past you
could get immersion heaters where the load could be set at 1, 2 or 3 kw.
A quick google has led me only to 3 kw nominal (well one was 2.7)
heaters so do such animals still exist? If so where available or if not
is there some sensible way of reducing the power consumption of a 3 kw
immersion heater to the levels referred to above?

Thanks to all those who have replied to this thread. I will be
investigating and perhaps investing in items highlighted here as already on the market.

I had forgotten how time consuming reading this ng was so I will withdraw
back into the woodwork to perhaps surface briefly in another 9 months or
so after another 79000 unread posts. ;-)

Goodbye for now.

Arrrgh! Aren't you going to tell us *why* you need a low wattage immersion
heater before you go??

Tim

"Tim+" wrote in message
...

Arrrgh! Aren't you going to tell us *why* you need a low wattage
immersion
heater before you go??

He wants to use the "free" electricity from his solar panels to heat water
as a low grade storage system.
After all a true "green" doesn't want anyone else to benefit.

On Saturday, October 6, 2012 8:06:32 PM UTC+1, dennis@home wrote:
"Tim+" timdownie2003 wrote in message

...



Arrrgh! Aren't you going to tell us *why* you need a low wattage

immersion

heater before you go??



He wants to use the "free" electricity from his solar panels to heat water

as a low grade storage system.

After all a true "green" doesn't want anyone else to benefit.

Or perhaps he wants to run his immersion heater off bell wire. 750w on 1A wire is 3x rated current, so he'd need about a 10% duty cycle to make it work


NT

On Sat, 6 Oct 2012 10:14:13 -0700 (PDT), harry wrote:

The only problem is that the latter does not attract enough misguided
bribery to make it cost effective. Our energy policy is a farce!

You are behind the times. Yes it does attract grants. (RHI)

"attract enough" the proposed levels for domestic installations are not
great. Oh and there is the small matter that the RHI scheme is not in
place.

The only thing currently available is the RHPP. £300, one off, for
qualifying solar thermal systems.

--
Cheers
Dave.

On Oct 6, 8:06*pm, "dennis@home"
wrote:
"Tim+" wrote in message

...

Arrrgh! *Aren't you going to tell us *why* you need a low wattage
immersion
heater before you go??

He wants to use the "free" electricity from his solar panels to heat water
as a low grade storage system.
After all a true "green" doesn't want anyone else to benefit.

Waste of time. It would never be economic to build a store big enough
to hold all that heat. A normal hot water cylinder only holds around
five or six Kwh. A couple of hours output from the PV.
Even more difficult is to prevent heat from having leaked out of the
store by the time you need it.

You can buy a gadget that turns down the heater to match available
power from the PV but I have looked into this, the savings don't
warrant the expense.

On Oct 6, 10:43*pm, "Dave Liquorice"
wrote:
On Sat, 6 Oct 2012 10:14:13 -0700 (PDT), harry wrote:
The only problem is that the latter does not attract enough misguided
bribery to make it cost effective. Our energy policy is a farce!

You are behind the times. Yes it does attract grants. *(RHI)

"attract enough" the proposed levels for domestic installations are not
great. Oh and there is the small matter that the RHI scheme is not in
place.

The only thing currently available is the RHPP. £300, one off, for
qualifying solar thermal systems.

Starting next year. I have a plan to take advantage of it.
The rep is coming tomorrow.
Apparently payments are to be made over the next seven years as well
as the £300. £0.17/Kwh (as assessed). Dunno whether it's inflation
linked & tax free as per the FIT payment.
My initial calculations come to around 8% return on outlay. But we'll
see when the rep comes.