Anyone used/owned a "whole house" 22mm blending valve on the outlet of a
stored water system?

Worth having?

Effects on flow rate?

Any brands to recommend / avoid?


May be ripping and replacing the current conventional cylinder with a
Unistore unvented unit shortly. The current one is undersized and is
hence run a little hotter to maintain adequate energy storage - but this
makes the hot water rather too hot at basins etc. The new one will be
larger, and given our hard water, probably run at no more than 60 degrees.

--
Cheers,

John.

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On Fri, 27 Jul 2012 17:11:52 +0100, John Rumm wrote:

Anyone used/owned a "whole house" 22mm blending valve on the outlet of
a stored water system?

Our thermal store has a blending valve on it's output (mains pressure,
heated on demand, DHW). To get what I consider "hot" water at the taps
(50C) it has to be wound almost to the top of it's range. Between 50C and
60C you start to enter the temperature ranges that can cause tissue
damage (scalding). In the case of our thermal store that can be over 80C
at the top, that is decidely too hot to have coming out of the taps...

Worth having?

Depends how hot you intend to have the stored hot water. Bear in mind
legionella (or other bacterial nasties) with water stored below 60C or
there abouts. Modern systems have controls that take the stored water up
above 60C or more every so often to kill the bugs.

Effects on flow rate?

Can't comment as we switched from gravity to mains at the same time. Our
system will deliver 20 odd litres/min (IIRC) at 50C.


--
Cheers
Dave.

On 27/07/2012 20:03, Dave Liquorice wrote:
On Fri, 27 Jul 2012 17:11:52 +0100, John Rumm wrote:

Anyone used/owned a "whole house" 22mm blending valve on the outlet of
a stored water system?

Our thermal store has a blending valve on it's output (mains pressure,
heated on demand, DHW). To get what I consider "hot" water at the taps
(50C) it has to be wound almost to the top of it's range. Between 50C and

What is its range BTW?

60C you start to enter the temperature ranges that can cause tissue
damage (scalding). In the case of our thermal store that can be over 80C
at the top, that is decidely too hot to have coming out of the taps...

Worth having?

Depends how hot you intend to have the stored hot water. Bear in mind
legionella (or other bacterial nasties) with water stored below 60C or
there abouts. Modern systems have controls that take the stored water up
above 60C or more every so often to kill the bugs.

Yup, the setup I am planning allows for a weekly kill the bugs session.
I will over spec the size of the cylinder rather than run it extra hot
though since hopefully that will reduce the rate of scale accumulation.


--
Cheers,

John.

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

On 27/07/2012 17:11, John Rumm wrote:

Anyone used/owned a "whole house" 22mm blending valve on the outlet of
a stored water system?

Worth having?

Effects on flow rate?

Any brands to recommend / avoid?


May be ripping and replacing the current conventional cylinder with a
Unistore unvented unit shortly. The current one is undersized and is
hence run a little hotter to maintain adequate energy storage - but
this makes the hot water rather too hot at basins etc. The new one
will be larger, and given our hard water, probably run at no more than
60 degrees.


If you're going to use Vaillant controls then it is probably worth it,
the weekly legionella killing cycle causes scalding hot water, though it
can be disabled. You can choose what time you want it to carry out the
cycle though, I find it best when no one is going to use the hot water
as its supposed to hold the tank at 70ºc for an hour.

--
David

On 27/07/2012 22:17, gremlin_95 wrote:
On 27/07/2012 17:11, John Rumm wrote:

Anyone used/owned a "whole house" 22mm blending valve on the outlet of
a stored water system?

Worth having?

Effects on flow rate?

Any brands to recommend / avoid?


May be ripping and replacing the current conventional cylinder with a
Unistore unvented unit shortly. The current one is undersized and is
hence run a little hotter to maintain adequate energy storage - but
this makes the hot water rather too hot at basins etc. The new one
will be larger, and given our hard water, probably run at no more than
60 degrees.


If you're going to use Vaillant controls then it is probably worth it,
the weekly legionella killing cycle causes scalding hot water, though it
can be disabled. You can choose what time you want it to carry out the
cycle though, I find it best when no one is going to use the hot water
as its supposed to hold the tank at 70ºc for an hour.

Yes, good point. According to the specs for the 210L cylinder, it only
loses heat at about 80W... at that rate it would take days to get back
to 60 if you don't draw off much water!


--
Cheers,

John.

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

"John Rumm" wrote in message
o.uk...

Yes, good point. According to the specs for the 210L cylinder, it only
loses heat at about 80W...


Only 80W, that's more than 2kWhr a day, it needs another foot of insulation
around it.

On 28/07/2012 09:39, dennis@home wrote:


"John Rumm" wrote in message
o.uk...

Yes, good point. According to the specs for the 210L cylinder, it only
loses heat at about 80W...


Only 80W, that's more than 2kWhr a day, it needs another foot of
insulation around it.

1.9 according to its spec. Should be enough to keep the airing cupboard
warm, and not having the extra foot of insulation will mean there is
space for clothes as well.

--
Cheers,

John.

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

On Fri, 27 Jul 2012 17:11:52 +0100, John Rumm
wrote:

given our hard water, probably run at no more than 60 degrees.

I hadn't thought of this before. Does increasing the temperature make
a big difference to scale formation? I know chemical reactions are
faster when it is hot, but would 10C make that much difference in this
case?