I've just moved my cold water storage tank to the next
floor up, to give enough head for a shower to work. In
scrabbling around in the airing cupboard I found half
a label on the hot water cylinder saying "Grade 4 -
???? maximum 6 metres". Doing some background
checks confirms this means "maximum head of 6 metres".

Grr. With the cold water tank now moved, the hot
water cylinder has a head of 8 meters. Is there a
safety margin on cylinders that this is within, or
do I have to rip out the airing cupboard and replace
the cylinder? There's no room to move the cylinder
upstairs with the cold water tank.

Thanks.

(I should never have started this job....)

--
JGH

On Thu, 18 Oct 2007 20:20:24 -0700 someone who may be
wrote this:-

I've just moved my cold water storage tank to the next
floor up, to give enough head for a shower to work. In
scrabbling around in the airing cupboard I found half
a label on the hot water cylinder saying "Grade 4 -
???? maximum 6 metres". Doing some background
checks confirms this means "maximum head of 6 metres".

Grr. With the cold water tank now moved, the hot
water cylinder has a head of 8 meters.

Presumably the cylinder is connected up and has not failed yet.

You might get away with it, at least for a time. You will note from
http://www.plumbingpages.com/feature...Wnewarkstd.cfm that such
a cylinder is pressure tested to 1 bar, which is more than an 8m
head.

It may survive in this situation for months or years or decades, who
knows? However, if it does fail a lot of hot water may well pour
over someone.

I wouldn't leave it as it is.



--
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

"David Hansen" wrote in message
...
On Thu, 18 Oct 2007 20:20:24 -0700 someone who may be
wrote this:-

I've just moved my cold water storage tank to the next
floor up, to give enough head for a shower to work. In
scrabbling around in the airing cupboard I found half
a label on the hot water cylinder saying "Grade 4 -
???? maximum 6 metres". Doing some background
checks confirms this means "maximum head of 6 metres".

Grr. With the cold water tank now moved, the hot
water cylinder has a head of 8 meters.

Presumably the cylinder is connected up and has not failed yet.

You might get away with it, at least for a time. You will note from
http://www.plumbingpages.com/feature...Wnewarkstd.cfm that such
a cylinder is pressure tested to 1 bar, which is more than an 8m
head.

It may survive in this situation for months or years or decades, who
knows? However, if it does fail a lot of hot water may well pour
over someone.

I wouldn't leave it as it is.

As he now has the expense of installing new cylinder he may want to consider
a heat bank (thermal store) cylinder and have mains pressure water
throughout the house. No pumps and great showers.

David Hansen wrote:
wrote this:-
a label on the hot water cylinder saying "Grade 4 -
maximum head of 6 metres".

Grr. With the cold water tank now moved, the hot
water cylinder has a head of 8 meters.

Presumably the cylinder is connected up and has not failed yet.

I haven't refilled it yet.

It may survive in this situation for months or years or decades, who
knows? However, if it does fail a lot of hot water may well pour
over someone.

I can picture the rooms filling up to the windows...

I wouldn't leave it as it is.

I've put a temporary bypass in so I can test the rest of
the pipework, and shall just have to live without hot water
until next week until I order a number 3 cylinder.

--
JGH

David Hansen wrote:
wrote this:-
water cylinder has a head of 8 meters.

a cylinder is pressure tested to 1 bar, which is more than an 8m
head.

According to http://www.paroscientific.com/convtable.htm
1000mbar = 10.19716m of water

Eeee. So tempting. 20% margin. I shall have to do some
careful measuring and a bit of testing. I've spent a week
without hot water

--
JGH

On Oct 19, 4:20 am, wrote:

Grr. With the cold water tank now moved, the hot
water cylinder has a head of 8 meters. Is there a
safety margin on cylinders that this is within, or
do I have to rip out the airing cupboard and replace
the cylinder? There's no room to move the cylinder
upstairs with the cold water tank.

Thanks.

Hi,

A grade 4 cylinder will take a suprising amount of pressu

http://www.maib.gov.uk/cms_resources/fleur-de-lys.pdf

See para 2.2.2

I'd be inclined to rig up a hose to give a 10m head on the cylinder
and leave it a couple of days to check it doesn't leak (10m head =
1bar).

cheers,
Pete.

Pete C wrote:
JGH wrote:
Grr. With the cold water tank now moved, the hot
water cylinder has a head of 8 meters. Is there a

A grade 4 cylinder will take a suprising amount of pressu
I'd be inclined to rig up a hose to give a 10m head on the cylinder
and leave it a couple of days to check it doesn't leak (10m head =
1bar).

Carefully measuring shows the bottom of the cylinder to be
7.54m below the top of the header tank, so 25% within the
10m (1bar) test pressure. I shall fill it up, and then turn off
the stop-tap to the header tank (so I only have a 25gal flood!)
and leave it a few days to test.

--
JGH

On Fri, 19 Oct 2007 12:14:22 -0700 someone who may be
wrote this:-

It may survive in this situation for months or years or decades, who
knows? However, if it does fail a lot of hot water may well pour
over someone.

I can picture the rooms filling up to the windows...

It will not sound funny if the water pours over someone and kills or
injure them. That may sound far fetched, but it is not as far
fetched as many think. The last well known death involved a baby and
a pressurised cylinder in the loft, so it is not directly compatible
to your situation, but there is still a risk. There is a fair amount
of energy stored in a hot water cylinder.

As I said, the cylinder may well last for decades in this condition,
but I wouldn't take the risk. I would however use the opportunity to
consider installing a cylinder with a solar coil or a thermal store
with provision for solar.



--
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

David Hansen wrote:
It will not sound funny if the water pours over someone and kills or
injure them. That may sound far fetched, but it is not as far

In the current location, a bust HWC will gradually fill up my cellar,
ruining the computer equipment in the basement at the front, and
probably leaking into the neighbours' cellars,

but I wouldn't take the risk. I would however use the opportunity to
consider installing a cylinder with a solar coil or a thermal store
with provision for solar.

My boiler is on it's last elbows anyway, and I want any replacement
to not be in the bathroom as the current one is, so I'm tempted to
go for a combi and do away with the cylinder anyway. The only
concern I have is I have got used to having 25gal of hot water on
instant tap whenever I get into the shower, and I would like at some
future point to harvest sunlight to top up the water heat.

--
JGH

wrote in message
ups.com...
David Hansen wrote:
It will not sound funny if the water pours over someone and kills or
injure them. That may sound far fetched, but it is not as far

In the current location, a bust HWC will gradually fill up my cellar,
ruining the computer equipment in the basement at the front, and
probably leaking into the neighbours' cellars,

but I wouldn't take the risk. I would however use the opportunity to
consider installing a cylinder with a solar coil or a thermal store
with provision for solar.

My boiler is on it's last elbows anyway, and I want any replacement
to not be in the bathroom as the current one is, so I'm tempted to
go for a combi and do away with the cylinder anyway. The only
concern I have is I have got used to having 25gal of hot water on
instant tap whenever I get into the shower, and I would like at some
future point to harvest sunlight to top up the water heat.

Use a heat bank (thermal store)

On Tue, 23 Oct 2007 03:06:05 -0700 someone who may be
wrote this:-

My boiler is on it's last elbows anyway, and I want any replacement
to not be in the bathroom as the current one is, so I'm tempted to
go for a combi and do away with the cylinder anyway.

Whether such things are worthwhile partly depends on how much
simultaneous demand there is for hot water. They can work reasonably
well in single person flats, but generally run out of steam with
larger households, where a stored water system is a better option.

The only
concern I have is I have got used to having 25gal of hot water on
instant tap whenever I get into the shower, and I would like at some
future point to harvest sunlight to top up the water heat.

I suggest that you have a look around to see where a boiler and
cylinder/themal store could go. Remember while looking that a
combination boiler is going to be larger than an ordinary boiler,
though not as large as an "ordinary" boiler plus cylinder.


--
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