Will the flow rate from an unvented cylinder be the same as the cold
water mains flow rate for eg,
if my cold water flow rate from mains is 31 liters per minute will the
hot water also be the same flow rate?

Do new cylinders need to have an insulation jacket?

On 2008-01-02 14:34:52 +0000, said:

Will the flow rate from an unvented cylinder be the same as the cold
water mains flow rate for eg,
if my cold water flow rate from mains is 31 liters per minute will the
hot water also be the same flow rate?

Theoretically yes, but practically no because of additional resistance
of pipework. However, the starting flow rate is quite good so
shouldn't be a big issue.



Do new cylinders need to have an insulation jacket?

They normally come with one in the form of foam encasing the cylinder
or a cylinder inside a cylinder with foam in between.

On 2 Jan, 15:05, Andy Hall wrote:
On 2008-01-02 14:34:52 +0000, said:

Will the flow rate from an unvented cylinder be the same as the cold
water mains flow rate for eg,
if my cold water flow rate from mains is 31 liters per minute will the
hot water also be the same flow rate?

Theoretically yes, but practically no because of additional resistance
of pipework. However, the starting flow rate is quite good so
shouldn't be a big issue.



Do new cylinders need to have an insulation jacket?

They normally come with one in the form of foam encasing the cylinder
or a cylinder inside a cylinder with foam in between.

How long will water stay at a decent temperature for, if it was heated
in the morning?

wrote:

How long will water stay at a decent temperature for, if it was heated
in the morning?

Our Megaflo CL170 is on from 6.30am till 8.30am. It's still piping hot at
5pm.

wrote:
Will the flow rate from an unvented cylinder be the same as the cold
water mains flow rate for eg,
if my cold water flow rate from mains is 31 liters per minute will the
hot water also be the same flow rate?


No, the extra pipework runs will restrict it somewhat, as will any water
softeners in place on the HW side.

Conversely if the kitchen tap is fed off a 15mm spur, and the tank and
bath off 22mm runs, you may get MORE..



Do new cylinders need to have an insulation jacket?


They all come with em anyway.

wrote:
On 2 Jan, 15:05, Andy Hall wrote:
On 2008-01-02 14:34:52 +0000, said:

Will the flow rate from an unvented cylinder be the same as the cold
water mains flow rate for eg,
if my cold water flow rate from mains is 31 liters per minute will the
hot water also be the same flow rate?
Theoretically yes, but practically no because of additional resistance
of pipework. However, the starting flow rate is quite good so
shouldn't be a big issue.



Do new cylinders need to have an insulation jacket?
They normally come with one in the form of foam encasing the cylinder
or a cylinder inside a cylinder with foam in between.

How long will water stay at a decent temperature for, if it was heated
in the morning?

about 48 hours.

On 2 Jan, 16:12, The Natural Philosopher wrote:
wrote:
On 2 Jan, 15:05, Andy Hall wrote:
On 2008-01-02 14:34:52 +0000, said:

Will the flow rate from an unvented cylinder be the same as the cold
water mains flow rate for eg,
if my cold water flow rate from mains is 31 liters per minute will the
hot water also be the same flow rate?
Theoretically yes, but practically no because of additional resistance
of pipework. However, the starting flow rate is quite good so
shouldn't be a big issue.

Do new cylinders need to have an insulation jacket?
They normally come with one in the form of foam encasing the cylinder
or a cylinder inside a cylinder with foam in between.

How long will water stay at a decent temperature for, if it was heated
in the morning?

about 48 hours.

Brilliant!

wrote in message
...

Will the flow rate from an unvented
cylinder be the same as the cold
water mains flow rate for eg,
if my cold water flow rate from mains is
31 liters per minute will the
hot water also be the same flow rate?

31 litres/min at what pressure? Most unvented cylinders require a pressure
reducer which reduces flow. 22mm must be run from the stop to the cylinder
with no tee offs (he same with any main pressure DHW appliance, heat bank &
combi.

Don't buy an unvented cylinder. They require an annual service, which is
about £60. and they can do this:
http://www.waterheaterblast.com
They cannot be DIY installed.

Buy a heat bank/thermal store. mains pressure at higher pressures, so higher
flows, no annual service charge, can be DIY fitted. Also the CH can be run
off it too. The boiler operates in a superior hydraulic environment too.
Greater benefits all around.

AVOID unvented cylinders.

On Wed, 02 Jan 2008 07:34:04 -0800, dawoodseed wrote:

On 2 Jan, 15:05, Andy Hall wrote:
On 2008-01-02 14:34:52 +0000, said:

Will the flow rate from an unvented cylinder be the same as the cold
water mains flow rate for eg,
if my cold water flow rate from mains is 31 liters per minute will
the hot water also be the same flow rate?

Theoretically yes, but practically no because of additional resistance
of pipework. However, the starting flow rate is quite good so
shouldn't be a big issue.



Do new cylinders need to have an insulation jacket?

They normally come with one in the form of foam encasing the cylinder
or a cylinder inside a cylinder with foam in between.

How long will water stay at a decent temperature for, if it was heated
in the morning?

There are quite tight limits for the heat losses on modern cylinders.
If it takes the immersion 1.5 hours to heat it from cold it'll take about
30 times that (45hours?) to go down. I think the rule is about 1W/litre.


--
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

On Wed, 02 Jan 2008 16:11:45 +0000, The Natural Philosopher wrote:

wrote:
Will the flow rate from an unvented cylinder be the same as the cold
water mains flow rate for eg,
if my cold water flow rate from mains is 31 liters per minute will the
hot water also be the same flow rate?


No, the extra pipework runs will restrict it somewhat, as will any water
softeners in place on the HW side.

Conversely if the kitchen tap is fed off a 15mm spur, and the tank and
bath off 22mm runs, you may get MORE..


Also, ideally you would want to run the cold supply to the bathroom(s)
off the pressure balanced outlet from the Pressure Reduction Valve. This
will allow reasonable control even with plain manual mixers.

--
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

On Wed, 2 Jan 2008 07:34:04 -0800 (PST), wrote:

How long will water stay at a decent temperature for, if it was heated
in the morning?
My new bog-standard B&Q tank shows the following drops from 23:00 to 06:00 after
being heated - then left without any use:-
5 degrees C measured at the top
10 degrees C measured at approx 1/3 from the bottom.
i.e there is less volume of hot water available although what you get out
initially will still be a reasonable temperature.

An interesting side note of my measurents showed that if the heating was not
already in use (last October), the system reduced the temperature (by 2-3
degrees) of the lower portion of the cylinder initially (heat removed by coil to
pipe/boiler) and it took about 12 minutes for the temperature to return to its
original value.
I admit that my old boiler is not low-capacity and is several metres from the
cylinder.

Geo