I'm relocating my hot water cylinder in my bungalow to the loft near
the cold water tank. I know that the CW tank needs to be at least 1
metre higher than the showerhead, but does it also need to be higher
that the HW cylinder (or can they be positioned side by side)?

On 2006-10-31 18:30:34 +0000, "yogi" said:

I'm relocating my hot water cylinder in my bungalow to the loft near
the cold water tank. I know that the CW tank needs to be at least 1
metre higher than the showerhead, but does it also need to be higher
that the HW cylinder (or can they be positioned side by side)?

From the perspective of flow to the shower head it is the cold tank
that is the defining thing.


However, there is a problem in that there needs to be some amount of
vertical distance between the tank and the cylinder to accommodate the
vent pipe, and in any case as a minimum the water level of the cold
tank needs to be above that of the cylinder.

If there is not adequate vertical distance for the vent pipe, there
will be a tendency for it to suck in air.

Therefore as a minimum you need to be able to come up with a way to
support the cold tank solidly at a height above the cylinder once the
latter is moved to the loft.

If you can't do that, you will need to use something based around mains
water supply such as a thermal store.

"yogi" wrote in message
ups.com...
I'm relocating my hot water cylinder in my bungalow to the loft near
the cold water tank. I know that the CW tank needs to be at least 1
metre higher than the showerhead, but does it also need to be higher
that the HW cylinder (or can they be positioned side by side)?


Assuming that the cold water tank is a 'normal' vented tank fed off a 'ball
valve' ....
all of the cold-water mains pressure is 'lost' once the ball-valve closes.
[that's why such systems are styled ;- 'vented']
The pressure of the water at the cold water tank's outlet will be one~two
feet high. In other words the pressure (aka 'head') is merely that of the
top water surface, The shower head needs to be at least one metre _below_
the upper surface of the cold water tank. {It's not easily achieved:if you
place the tank of the bungalow's loft floor with the shower head perhaps
one~two metres above the bungalow's floor, How high are your ceilings?
If you place the hot water cylinder side-by-side - (do you mean standing on
the same platform with their bases at the same level?) - then the hot-water
cylinder will only fill to the level of the upper-surface of the cold water
tank. Water doesn't 'fall' up-hill A moments reflection, perhaps drawing it
out on paper, should indicate to you that the bottom of the cold water tank
needs to be higher than the top-most part of the hot-water cylinder. [There
should be a expansion pipe from the upper-most part of the Hot-water
cylinder bent over to discharge into the cold water storage tank too ...
have you thought of that?]

HTH,

--

Brian

Thanks Brian. I had envisaged having the HW cylinder on the loft floor
with the CW tank raised on a platform about 18" high so the top of the
CWT was slightly higher than the top of the HWC. As you suggest, I
should really raise the CWT higher so the bottom is above the top of
the HWC. Ceilings are about 8' high. I have thought about the expansion
pipe thanks.

Brian Sharrock wrote:
"yogi" wrote in message
ups.com...
I'm relocating my hot water cylinder in my bungalow to the loft near
the cold water tank. I know that the CW tank needs to be at least 1
metre higher than the showerhead, but does it also need to be higher
that the HW cylinder (or can they be positioned side by side)?


Assuming that the cold water tank is a 'normal' vented tank fed off a 'ball
valve' ....
all of the cold-water mains pressure is 'lost' once the ball-valve closes.
[that's why such systems are styled ;- 'vented']
The pressure of the water at the cold water tank's outlet will be one~two
feet high. In other words the pressure (aka 'head') is merely that of the
top water surface, The shower head needs to be at least one metre _below_
the upper surface of the cold water tank. {It's not easily achieved:if you
place the tank of the bungalow's loft floor with the shower head perhaps
one~two metres above the bungalow's floor, How high are your ceilings?
If you place the hot water cylinder side-by-side - (do you mean standing on
the same platform with their bases at the same level?) - then the hot-water
cylinder will only fill to the level of the upper-surface of the cold water
tank. Water doesn't 'fall' up-hill A moments reflection, perhaps drawing it
out on paper, should indicate to you that the bottom of the cold water tank
needs to be higher than the top-most part of the hot-water cylinder. [There
should be a expansion pipe from the upper-most part of the Hot-water
cylinder bent over to discharge into the cold water storage tank too ...
have you thought of that?]

HTH,

--

Brian

Thanks Andy. I had planned to have the bottom of the CWT tank about
18" higher than the bottom of the HW cylinder (so the top is only
slightly higher that the HWC), but I wasn't sure if that would be
enough to push water out the top of the HWC. Looks like I need to raise
it higher so the bottom of the CWT is higher than the top of the HWC.

Andy Hall wrote:
On 2006-10-31 18:30:34 +0000, "yogi" said:

I'm relocating my hot water cylinder in my bungalow to the loft near
the cold water tank. I know that the CW tank needs to be at least 1
metre higher than the showerhead, but does it also need to be higher
that the HW cylinder (or can they be positioned side by side)?

From the perspective of flow to the shower head it is the cold tank
that is the defining thing.


However, there is a problem in that there needs to be some amount of
vertical distance between the tank and the cylinder to accommodate the
vent pipe, and in any case as a minimum the water level of the cold
tank needs to be above that of the cylinder.

If there is not adequate vertical distance for the vent pipe, there
will be a tendency for it to suck in air.

Therefore as a minimum you need to be able to come up with a way to
support the cold tank solidly at a height above the cylinder once the
latter is moved to the loft.

If you can't do that, you will need to use something based around mains
water supply such as a thermal store.

On 2006-10-31 19:45:58 +0000, "yogi" said:

Thanks Andy. I had planned to have the bottom of the CWT tank about
18" higher than the bottom of the HW cylinder (so the top is only
slightly higher that the HWC), but I wasn't sure if that would be
enough to push water out the top of the HWC. Looks like I need to raise
it higher so the bottom of the CWT is higher than the top of the HWC.



That's really the minimum viable situation and gets you to the point
that the cylinder will be full.

The other thing will be to put in a 28mm pipe to feed water from the CW
tank to the cylinder.
The effect of this will be that when you draw HW from the 22 or 15mm
pipes from the cylinder, the flow
rate can't exceed that between the CW tank and HW cylinder. If you
don't have that then there is
a fair chance that the level in the vent pipe will drop and air will be
sucked in.

While you are doing this re-work you could look at running 22mm pipes
(hot from cylinder and cold from tank) as close as you can to the
shower. This may well improve flow.

The exercise as a whole won't improve pressure. That would need a
mains HW system or a shower pump.

Don't forget that water is very heavy. If you are going to raise
the CW tank and support the HW cylinder, there need to be substantial
timbers and positioning over a load bearing wall. It is not something
to put in the middle of an area on a few 75x50 joists.

"Brian Sharrock" wrote in message
...

If you place the hot water cylinder side-by-side - (do you mean standing
on the same platform with their bases at the same level?) - then the
hot-water cylinder will only fill to the level of the upper-surface of the
cold water tank. Water doesn't 'fall' up-hill.

Siphon?

Peter


--
Posted via a free Usenet account from http://www.teranews.com

"Peter Taylor" wrote in message
.. .

"Brian Sharrock" wrote in message
...

If you place the hot water cylinder side-by-side - (do you mean standing
on the same platform with their bases at the same level?) - then the
hot-water cylinder will only fill to the level of the upper-surface of
the cold water tank. Water doesn't 'fall' up-hill.

Siphon?

Peter
Peter; your point is?

Water in a "siphon" does _not_ fall up-hill. Siphonic action only results in
fluid from a pipe being discharged at a lower level (height aka head) than
the source , The pipe may or may not take a path which 'goes' up hill (being
pushed by the differential (air) pressure between the source and discharge
points,,,, but the fluid will go only go 'down-hill'.

Perhaps you need to retake Siphons 101 along with Sarcasm 101.

--

Brian

"Brian Sharrock" wrote in message
...

"Peter Taylor" wrote in message
.. .

"Brian Sharrock" wrote in message
...

If you place the hot water cylinder side-by-side - (do you mean standing
on the same platform with their bases at the same level?) - then the
hot-water cylinder will only fill to the level of the upper-surface of
the cold water tank. Water doesn't 'fall' up-hill.

Siphon?

Peter
Peter; your point is?

Water in a "siphon" does _not_ fall up-hill. Siphonic action only results
in fluid from a pipe being discharged at a lower level (height aka head)
than the source , The pipe may or may not take a path which 'goes' up hill
(being pushed by the differential (air) pressure between the source and
discharge points,,,, but the fluid will go only go 'down-hill'.

Perhaps you need to retake Siphons 101 along with Sarcasm 101.

It wasn't sarcastic, daft or maybe stupid I accept. I'm at home with flu
and feeling woozy, and probably my brain wasn't in gear. Your message
started me pondering about the possibility of water being siphoned out of
one tank into the other if the connections were at different levels and I
began to write you a message. But I couldn't work out what I was trying to
ask so I cut most of the message and just left the one word as a question.
No malice was intended but I'm sorry you were offended.

If you had a situation where the HWC inlet was higher than CWS tank outlet,
water flowing into the HWC would look as though it was flowing uphill. I
was trying to work out whether this could create a siphon, and whether the
water would keep flowing after a tap is turned off .......

Madness. It's the relative water levels that count, not the connections.
That's what I couldn't fathom last night. Doh! )

Peter


--
Posted via a free Usenet account from http://www.teranews.com

On Oct 31, 9:11 pm, Andy Hall wrote:
The exercise as a whole won't improve pressure.

So what does raising the cold water tank do if not increasing head and
pressure?

MBQ

On 31 Oct 2006 10:30:34 -0800 someone who may be "yogi"
wrote this:-

I'm relocating my hot water cylinder in my bungalow to the loft near
the cold water tank.

How about replacing both of these with a packaged unit consisting of
cylinder with tank above?


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

"Peter Taylor" wrote in message
.. .
"Brian Sharrock" wrote in message

Huge snip

Peter
Peter; your point is?

snip

....... I accept. I'm at home with flu

Thanks. I freely admit I posted too quickly.
My concern was that the OP might be confused - as the question as phrased
inferred a lack of 'appreciation' of the fundamentals.

--

Brian