Hi,

I require a under sink water heater and my plumber is recommending a
10L 3Kw pressurised water heater but when I have been searching for
one it seems they are either vented or unvented and no mention of
pressurised. It will have a cold water feed from the mains. Can anyone
shed any light on this? Also, will I need special taps?

Thanks,
Darren

wrote in message
...
Hi,

I require a under sink water heater and my plumber is recommending a
10L 3Kw pressurised water heater but when I have been searching for
one it seems they are either vented or unvented and no mention of
pressurised. It will have a cold water feed from the mains. Can anyone
shed any light on this? Also, will I need special taps?

Thanks,
Darren


For the purposes of this discussion, pressurised = unvented.

On most models, you do not require special taps. It's just a mini-megaflo.
Mains CW in, HW stored at pressure, mains pressure HW out.

There are some stranger models around.
These are un-pressurised, yet provide mains-pressure HW, and work like this:

Mains cold comes in, to the tap in the first instance.
The tap does not open directly to the spout, it opens to a return pipe to
the cylinder.
The tap then opens the CW supply to the cylinder.
This then forces the stored HW out a seperate pipe to the spout, at mains
pressure.
In this config, the cylinder is not pressurised, it is open to the spout at
all times.
The pressure is only applied when the cold supply is turned on.

These require a special tap ( with a return pipe to the cylinder. )

Sounds like the plumber probably knows what he's doing, and you ought to let
him get on with it.


--
Ron

Ron Lowe wrote:
wrote in message
...
Hi,

I require a under sink water heater and my plumber is recommending a
10L 3Kw pressurised water heater but when I have been searching for
one it seems they are either vented or unvented and no mention of
pressurised. It will have a cold water feed from the mains. Can
anyone shed any light on this? Also, will I need special taps?

Thanks,
Darren


For the purposes of this discussion, pressurised = unvented.

On most models, you do not require special taps. It's just a
mini-megaflo. Mains CW in, HW stored at pressure, mains pressure HW
out.
There are some stranger models around.
These are un-pressurised, yet provide mains-pressure HW, and work
like this:
Mains cold comes in, to the tap in the first instance.
The tap does not open directly to the spout, it opens to a return
pipe to the cylinder.
The tap then opens the CW supply to the cylinder.
This then forces the stored HW out a seperate pipe to the spout, at
mains pressure.
In this config, the cylinder is not pressurised, it is open to the
spout at all times.
The pressure is only applied when the cold supply is turned on.

These require a special tap ( with a return pipe to the cylinder. )

Sounds like the plumber probably knows what he's doing, and you ought
to let him get on with it.

What Ron said :-)

I've fitted several of these - the pressurised ones, no problem, they work a
treat.



--
Dave - The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257

"The Medway Handyman" wrote in message
.uk...
Ron Lowe wrote:
wrote in message
...
Hi,

I require a under sink water heater and my plumber is recommending a
10L 3Kw pressurised water heater but when I have been searching for
one it seems they are either vented or unvented and no mention of
pressurised. It will have a cold water feed from the mains. Can
anyone shed any light on this? Also, will I need special taps?

Thanks,
Darren


For the purposes of this discussion, pressurised = unvented.

On most models, you do not require special taps. It's just a
mini-megaflo. Mains CW in, HW stored at pressure, mains pressure HW
out.
There are some stranger models around.
These are un-pressurised, yet provide mains-pressure HW, and work
like this:
Mains cold comes in, to the tap in the first instance.
The tap does not open directly to the spout, it opens to a return
pipe to the cylinder.
The tap then opens the CW supply to the cylinder.
This then forces the stored HW out a seperate pipe to the spout, at
mains pressure.
In this config, the cylinder is not pressurised, it is open to the
spout at all times.
The pressure is only applied when the cold supply is turned on.

These require a special tap ( with a return pipe to the cylinder. )

Sounds like the plumber probably knows what he's doing, and you ought
to let him get on with it.

What Ron said :-)

I've fitted several of these - the pressurised ones, no problem, they work
a treat.

And I've just had to replace one of mine- only 2.5yrs old but very hard
water area... You can't replace just the element -immersion heater stylee-.

It was an Ultraheat which dont seen to be about any more- the new one is a
Redring. (15l 3kw)

Tim..

On Jan 19, 9:06*pm, "Ron Lowe" wrote:
There are some stranger models around.
These are un-pressurised, yet provide mains-pressure HW, and work like this:
Mains cold comes in, to the tap in the first instance.
The tap does not open directly to the spout, it opens to a return pipe to
the cylinder.
The tap then opens the CW supply to the cylinder.
This then forces the stored HW out a seperate pipe to the spout, at mains
pressure.
In this config, the cylinder is not pressurised, it is open to the spout at
all times.
These require a special tap ( with a return pipe to the cylinder. )

And have the annoying habit of continually dripping, with people
trying to turn the tap off harder, which makesno different to the
dripping.

Owain

In article ,
writes:
On Jan 19, 9:06*pm, "Ron Lowe" wrote:
There are some stranger models around.
These are un-pressurised, yet provide mains-pressure HW, and work like this:
Mains cold comes in, to the tap in the first instance.
The tap does not open directly to the spout, it opens to a return pipe to
the cylinder.
The tap then opens the CW supply to the cylinder.
This then forces the stored HW out a seperate pipe to the spout, at mains
pressure.
In this config, the cylinder is not pressurised, it is open to the spout at
all times.
These require a special tap ( with a return pipe to the cylinder. )
And have the annoying habit of continually dripping, with people
trying to turn the tap off harder, which makesno different to the
dripping.

but knackers the washer, causing a genuine drip.

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

On Sun, 20 Jan 2008 10:35:49 +0000, Tim.. wrote:

"The Medway Handyman" wrote in
message .uk...
Ron Lowe wrote:
wrote in message
news:5a0c9c84-e553-45a9-8cbf-
...
Hi,

I require a under sink water heater and my plumber is recommending a
10L 3Kw pressurised water heater but when I have been searching for
one it seems they are either vented or unvented and no mention of
pressurised. It will have a cold water feed from the mains. Can
anyone shed any light on this? Also, will I need special taps?

Thanks,
Darren


For the purposes of this discussion, pressurised = unvented.

On most models, you do not require special taps. It's just a
mini-megaflo. Mains CW in, HW stored at pressure, mains pressure HW
out.
There are some stranger models around. These are un-pressurised, yet
provide mains-pressure HW, and work like this:
Mains cold comes in, to the tap in the first instance. The tap does
not open directly to the spout, it opens to a return pipe to the
cylinder.
The tap then opens the CW supply to the cylinder. This then forces the
stored HW out a seperate pipe to the spout, at mains pressure.
In this config, the cylinder is not pressurised, it is open to the
spout at all times.
The pressure is only applied when the cold supply is turned on.

These require a special tap ( with a return pipe to the cylinder. )

Sounds like the plumber probably knows what he's doing, and you ought
to let him get on with it.

What Ron said :-)

I've fitted several of these - the pressurised ones, no problem, they
work a treat.

And I've just had to replace one of mine- only 2.5yrs old but very hard
water area... You can't replace just the element -immersion heater
stylee-.

It was an Ultraheat which dont seen to be about any more- the new one is
a Redring. (15l 3kw)

That sounds like it's a unit that just escapes all the really serious
regs.
So you may fit it with out a G3 ticket,
plug it into (a FCU on) a 32A ring circuit,
no discharge or vent pipes required (it forces expansion upstream into
the mains).



--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

In message , Tim..
writes

And I've just had to replace one of mine- only 2.5yrs old but very hard
water area... You can't replace just the element -immersion heater stylee-.

It was an Ultraheat which dont seen to be about any more- the new one is a
Redring. (15l 3kw)

Umm.. In an effort to avoid this, I installed ours in the *hot* water
(softened) circuit.

The instructions were pretty insistent about expansion issues but I
really could not see any extra safety concerns provided there was ample
feed pipe length and no local shut off valves.

regards

--
Tim Lamb