This is probably a daft idea, but I'd be interesting to see if there is any mileage in it! Combi boilers tend to work best in smaller properties, so for a larger property would it be possible (or make any sense) to have 2 combi boilers serving different parts of the house?
By "larger" I don't mean a mansion I mean a 4 bedroomed house with 3 showers!
Thanks for any thoughts on this.

On Wed, 25 Apr 2012 19:57:44 +0100, kent wrote:

This is probably a daft idea, but I'd be interesting to see if there is
any mileage in it! Combi boilers tend to work best in smaller
properties, so for a larger property would it be possible (or make any
sense) to have 2 combi boilers serving different parts of the house?
By "larger" I don't mean a mansion I mean a 4 bedroomed house with 3
showers!
Thanks for any thoughts on this.


ah the old ones are always the best....

you been reading back perchance?

Jim K

On Wednesday, 25 April 2012 20:05:20 UTC+1, Jim K wrote:
On Wed, 25 Apr 2012 19:57:44 +0100, kent wrote:

This is probably a daft idea, but I'd be interesting to see if there is
any mileage in it! Combi boilers tend to work best in smaller
properties, so for a larger property would it be possible (or make any
sense) to have 2 combi boilers serving different parts of the house?
By "larger" I don't mean a mansion I mean a 4 bedroomed house with 3
showers!
Thanks for any thoughts on this.


ah the old ones are always the best....







nope! Thought of it all by myself! Is it that stupid then?









you been reading back perchance?

Jim K



On Wednesday, 25 April 2012 20:05:20 UTC+1, Jim K wrote:
On Wed, 25 Apr 2012 19:57:44 +0100, kent wrote:

This is probably a daft idea, but I'd be interesting to see if there is
any mileage in it! Combi boilers tend to work best in smaller
properties, so for a larger property would it be possible (or make any
sense) to have 2 combi boilers serving different parts of the house?
By "larger" I don't mean a mansion I mean a 4 bedroomed house with 3
showers!
Thanks for any thoughts on this.


ah the old ones are always the best....

you been reading back perchance?

Jim K

kent wrote:
On Wednesday, 25 April 2012 20:05:20 UTC+1, Jim K wrote:
On Wed, 25 Apr 2012 19:57:44 +0100, kent wrote:

This is probably a daft idea, but I'd be interesting to see if
there is any mileage in it! Combi boilers tend to work best in
smaller properties, so for a larger property would it be possible
(or make any sense) to have 2 combi boilers serving different
parts of the house? By "larger" I don't mean a mansion I mean a 4
bedroomed house with 3 showers!
Thanks for any thoughts on this.


ah the old ones are always the best....


nope! Thought of it all by myself! Is it that stupid then?

You have just made a new friend. He wll be along shortly to back you to the
hilt and claim you are a genius, second only to himself and Einsein.

--
Adam

On Wednesday, 25 April 2012 20:42:01 UTC+1, wrote:
kent wrote:
On Wednesday, 25 April 2012 20:05:20 UTC+1, Jim K wrote:
On Wed, 25 Apr 2012 19:57:44 +0100, kent wrote:

This is probably a daft idea, but I'd be interesting to see if
there is any mileage in it! Combi boilers tend to work best in
smaller properties, so for a larger property would it be possible
(or make any sense) to have 2 combi boilers serving different
parts of the house? By "larger" I don't mean a mansion I mean a 4
bedroomed house with 3 showers!
Thanks for any thoughts on this.


ah the old ones are always the best....


nope! Thought of it all by myself! Is it that stupid then?

You have just made a new friend. He wll be along shortly to back you to the
hilt and claim you are a genius, second only to himself and Einsein.

--
Adam

Oh dear, I didn't mean to stir the s*** ! Does this mean I am unlikely to get any rational answers?!

On 25/04/2012 20:51, kent wrote:
On Wednesday, 25 April 2012 20:42:01 UTC+1, wrote:
kent wrote:
On Wednesday, 25 April 2012 20:05:20 UTC+1, Jim K wrote:
On Wed, 25 Apr 2012 19:57:44 +0100, wrote:

This is probably a daft idea, but I'd be interesting to see if
there is any mileage in it! Combi boilers tend to work best in
smaller properties, so for a larger property would it be possible
(or make any sense) to have 2 combi boilers serving different
parts of the house? By "larger" I don't mean a mansion I mean a 4
bedroomed house with 3 showers!
Thanks for any thoughts on this.


ah the old ones are always the best....


nope! Thought of it all by myself! Is it that stupid then?

You have just made a new friend. He wll be along shortly to back you to the
hilt and claim you are a genius, second only to himself and Einsein.

--
Adam

Oh dear, I didn't mean to stir the s*** ! Does this mean I am unlikely to get any rational answers?!

No, you will probably get plenty ;-)

(There is/was a famous poster/troll/poet(bad)/legend in his own
lunchtime to this group who used to champion this particular solution
as a cure to every ill known to man).

So the basics; yes you can have two combis so long as the total demand
on your gas supply does not reach above about 60kW (assuming a normal
domestic meter). So a pair of 24kW ones is ok, a pair of 35kW ones would
be too much. (depends also on what other gas appliances you have)

You can have them completely independent of each other, but the only
real benefit would be the ability to position them so as to reduce the
time spent waiting for hot water at a tap, plus the ability to get some
heat and hot water when one goes wrong.

You could also merge their outputs together, but that then starts
getting slightly more complicated. It should alleviate some of the
problems with low flow rates of hot water that many of the less powerful
combis are famous for - but will ultimately be limited by the gas
supply, and so still won't be able to match other systems[1] if high
delivery rates of hot water are your goal.

On the downside, its a more complex system that may confuse some tasked
with maintenance, and you will incur two lots of service charges etc.

Also don't ignore the possibility of using one combi to heat a cylinder
of water as well as being able to provide hot water on demand itself.
(this can make sense where, one hot water outlet would be a long pipe
run from a main cylinder, and hence the combi can feed it directly, or
alternatively, when you have a gravity fed system that works well for
bath filling, but lacks pressure for showers.

[1] Some "other" systems would include the various hybrid
instant/storage combis, with built in unvented tanks of water cylinders.


Also see:

http://wiki.diyfaq.org.uk/index.php?..._Water_Systems



--
Cheers,

John.

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

Also don't ignore the possibility of using one combi to heat a cylinder
of water as well as being able to provide hot water on demand itself.
(this can make sense where, one hot water outlet would be a long pipe
run from a main cylinder, and hence the combi can feed it directly, or
alternatively, when you have a gravity fed system that works well for
bath filling, but lacks pressure for showers.


That's a very neat idea which had never occurred to me: but that said,
after various problems with two different combis I'll never have another
if I have a choice.

On Wednesday, 25 April 2012 22:26:02 UTC+1, John Rumm wrote:
On 25/04/2012 20:51, kent wrote:
On Wednesday, 25 April 2012 20:42:01 UTC+1, wrote:
kent wrote:
On Wednesday, 25 April 2012 20:05:20 UTC+1, Jim K wrote:
On Wed, 25 Apr 2012 19:57:44 +0100, wrote:

This is probably a daft idea, but I'd be interesting to see if
there is any mileage in it! Combi boilers tend to work best in
smaller properties, so for a larger property would it be possible
(or make any sense) to have 2 combi boilers serving different
parts of the house? By "larger" I don't mean a mansion I mean a 4
bedroomed house with 3 showers!
Thanks for any thoughts on this.


ah the old ones are always the best....


nope! Thought of it all by myself! Is it that stupid then?

You have just made a new friend. He wll be along shortly to back you to the
hilt and claim you are a genius, second only to himself and Einsein.

--
Adam

Oh dear, I didn't mean to stir the s*** ! Does this mean I am unlikely to get any rational answers?!

No, you will probably get plenty ;-)

(There is/was a famous poster/troll/poet(bad)/legend in his own
lunchtime to this group who used to champion this particular solution
as a cure to every ill known to man).

So the basics; yes you can have two combis so long as the total demand
on your gas supply does not reach above about 60kW (assuming a normal
domestic meter). So a pair of 24kW ones is ok, a pair of 35kW ones would
be too much. (depends also on what other gas appliances you have)

You can have them completely independent of each other, but the only
real benefit would be the ability to position them so as to reduce the
time spent waiting for hot water at a tap, plus the ability to get some
heat and hot water when one goes wrong.

You could also merge their outputs together, but that then starts
getting slightly more complicated. It should alleviate some of the
problems with low flow rates of hot water that many of the less powerful
combis are famous for - but will ultimately be limited by the gas
supply, and so still won't be able to match other systems[1] if high
delivery rates of hot water are your goal.

On the downside, its a more complex system that may confuse some tasked
with maintenance, and you will incur two lots of service charges etc.

Also don't ignore the possibility of using one combi to heat a cylinder
of water as well as being able to provide hot water on demand itself.
(this can make sense where, one hot water outlet would be a long pipe
run from a main cylinder, and hence the combi can feed it directly, or
alternatively, when you have a gravity fed system that works well for
bath filling, but lacks pressure for showers.

[1] Some "other" systems would include the various hybrid
instant/storage combis, with built in unvented tanks of water cylinders.


Also see:

http://wiki.diyfaq.org.uk/index.php?..._Water_Systems



--
Cheers,

John.

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

Thanks John for such a detailed and considered response. Our old boiler will have to replaced soon and I have been thinking about options. Combi appealed because without stored water losing heat I figured it would be more efficient. However if 2 (or even 3) people wanted to shower at the same time I didn't think that one combi boiler would be able to deliver sufficient hot water. This is a fairly standard 4 bedroomed house with gas central heating and a gas fired stove, but all cooking appliances are electric.

BTW how do I stop my typing going all the way across the page, whilst yours are in neat blocks?!

On Wednesday, April 25, 2012 7:57:44 PM UTC+1, kent wrote:
This is probably a daft idea, but I'd be interesting to see if there is any mileage in it! Combi boilers tend to work best in smaller properties, so for a larger property would it be possible (or make any sense) to have 2 combi boilers serving different parts of the house?
By "larger" I don't mean a mansion I mean a 4 bedroomed house with 3 showers!
Thanks for any thoughts on this.

The guy who services my gas boiler has two in his house.

On 25/04/2012 22:26, John Rumm wrote:

Also don't ignore the possibility of using one combi to heat a cylinder
of water as well as being able to provide hot water on demand itself.

This is exactly what I specified for our extension, and was surprised
when the plumber said that it was a little unusual. Seemed blumin'
obvious to me. The combi-boiler provides direct hot water for the
kitchen and utility room (the boiler being about six feet from those two
taps). We have a mains pressure hot water cylinder which is placed on
the other side of the wall behind the master bedroom en-suite and
provides hot water for all the bathrooms/toilets. The end result is
that the majority of hot water usage - the kitchen and our shower - is
through the absolute minimum of pipework possible.

The house (a bungalow, 4 beds, two reception rooms and two studies) has
two main central heating zones. Furthermore, I also specified that the
two studies, which before my time were converted from the integral
garage and were plumbed with radiators on a branch of their own, are now
fed as a sub-zone of zone 1 (zone 2 being the bedroom end of the house).

This means that I could (if I got round to it) simply wire in a seperate
thermostatic control or timer/controller to enable the studies to be
heated if I am working at home in the winter without *any* of the rest
of the house being heated.

The system works by having a normally-open valve interrupting all of
zone 1 except the branch for the two studies. Therefore, the study
controller/thermostat can be be wired to activate the boiler and the
main zone 1 valve but also close the normally-open valve, thus
activating zone 1, but actually only heating the two studies.

So, if "Kent" has a large house and has a problem with the location of
the hot water, and is thinking about how to arrange the boiler/hot
water/heating zones, the answer is: you can do all sorts of things - but
to my mind the idea of having two seperate boilers is barmy!

Michael

In article
8032896.4120.1335391786004.JavaMail.geo-discussion-forums@vbq19,
kent wrote:
BTW how do I stop my typing going all the way across the page, whilst
yours are in neat blocks?!


Set the wordwrap to 75.

--
*Sleep with a photographer and watch things develop

Dave Plowman London SW
To e-mail, change noise into sound.

David Paste wrote:
On Wednesday, April 25, 2012 7:57:44 PM UTC+1, kent wrote:
This is probably a daft idea, but I'd be interesting to see if
there is any mileage in it! Combi boilers tend to work best in
smaller properties, so for a larger property would it be possible
(or make any sense) to have 2 combi boilers serving different parts
of the house? By "larger" I don't mean a mansion I mean a 4
bedroomed house with 3 showers!
Thanks for any thoughts on this.

The guy who services my gas boiler has two in his house.

He would not be the first person to have to sevice two boilers at the same
time.

--
Adam

On 25/04/2012 23:09, kent wrote:

BTW how do I stop my typing going all the way across the page, whilst yours are in neat blocks?!

With a newsreader:

http://wiki.diyfaq.org.uk/index.php?...up_access_tips


--
Cheers,

John.

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

On 25/04/2012 23:28, Dave Plowman (News) wrote:
In article
8032896.4120.1335391786004.JavaMail.geo-discussion-forums@vbq19,
wrote:
BTW how do I stop my typing going all the way across the page, whilst
yours are in neat blocks?!


Set the wordwrap to 75.

I think he is posting via google...

--
Cheers,

John.

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

kent wrote

BTW how do I stop my typing going all the way
across the page, whilst yours are in neat blocks?!

He's not using groups.google to post.

He's using a proper news client.

On 25/04/2012 23:05, kent wrote:

Thanks John for such a detailed and considered response. Our old boiler will
have to replaced soon and I have been thinking about options. Combi appealed
because without stored water losing heat I figured it would be more efficient.

I would not worry about that aspect much... firstly since the hot water
provision (however its done) is in reality only a fairly small part of
your total cost of heating. (one of the reasons why most of the solar
hot water systems never make financial sense)

If you hot water system loses heat, its into your house anyway in most
cases, so just less for the heating to do. An extra cylinder jacket will
also reduce it low levels.

However if 2 (or even 3) people wanted to shower at the same time I didn't think
that one combi boiler would be able to deliver sufficient hot water. This is a
fairly standard 4 bedroomed house with gas central heating and a gas fired
stove, but all cooking appliances are electric.

Before deciding on a solution, you need to make an assessment of the
capability of your cold main. If it can only supply 10 lpm (litres per
minute) or has very poor pressure, then any system that relies on
heating the incoming cold main on the fly, could be disappointing.

You can do some tests timing filling of a bucket of known volume from
your "best" tap. You can also get pressure gauges from toolstation etc
that will measure your actual supply pressure.

Assuming the mains can deliver a good flow rate, then you can look at
the options. Combis are not the only way to get mains pressure hot water
(unvented cylinders, heat banks, and thermal stores being others).

As to multiple showers, much depends on the shower in question and its
consumption. At a previous place I installed a 35kW combi when
converting the loft and losing the space for the cylinder etc. That
could (just) manage two showers at a time if there were no other demands
for water in the house while they were going on (there was a detectable
loss of "power" to each though).

Combis can be handy if you particularly need the space the cylinder
takes up, or not so good if you want a warm airing cupboard (although
there are ways round that)


--
Cheers,

John.

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

kent wrote:
On Wednesday, 25 April 2012 20:42:01 UTC+1, wrote:
kent wrote:
On Wednesday, 25 April 2012 20:05:20 UTC+1, Jim K wrote:
On Wed, 25 Apr 2012 19:57:44 +0100, kent wrote:

This is probably a daft idea, but I'd be interesting to see if
there is any mileage in it! Combi boilers tend to work best in
smaller properties, so for a larger property would it be possible
(or make any sense) to have 2 combi boilers serving different
parts of the house? By "larger" I don't mean a mansion I mean a 4
bedroomed house with 3 showers!
Thanks for any thoughts on this.

ah the old ones are always the best....

nope! Thought of it all by myself! Is it that stupid then?
You have just made a new friend. He wll be along shortly to back you to the
hilt and claim you are a genius, second only to himself and Einsein.

--
Adam

Oh dear, I didn't mean to stir the s*** ! Does this mean I am unlikely to get any rational answers?!
more or less yes.

Ill give you one:

a sealed mains pressure tank and a system boiler is cheaper than two
combis and wont suffer from lack of hot water when two people take a
bath/shower


--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

kent wrote:

Thanks John for such a detailed and considered response. Our old boiler will have to replaced soon and I have been thinking about options.

Combi appealed because without stored water losing heat I figured it
would be more efficient.

However if 2 (or even 3) people wanted to shower at the same time I
didn't think that one combi boiler would be able to deliver sufficient
hot water.

This is a fairly standard 4 bedroomed house with gas central heating and
a gas fired stove, but all cooking appliances are electric.

heatloss from a sealed tank is neglible

I leave mine on 24x7

--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

kent wrote:
BTW how do I stop my typing going all the way across the page, whilst yours are in neat blocks?!
abandon google groups as a means of posting.


--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

Michael Kilpatrick wrote:
On 25/04/2012 22:26, John Rumm wrote:

Also don't ignore the possibility of using one combi to heat a cylinder
of water as well as being able to provide hot water on demand itself.

This is exactly what I specified for our extension, and was surprised
when the plumber said that it was a little unusual.

the cost of a combi and tank exceeds the cost of a system boiler and
tank really so its a waste of money with no advantages

The general rule is the money you have a tank dont have a combi: they
are a cheap low footprint abortion suitable for CH and one-at-a-time hot
water and if they are to given a decent hot water flow-rate more
expensive than a sealed tank and system boiler

On 25/04/2012 23:58, John Rumm wrote:

As to multiple showers, much depends on the shower in question and its
consumption. At a previous place I installed a 35kW combi when
converting the loft and losing the space for the cylinder etc. That
could (just) manage two showers at a time if there were no other demands
for water in the house while they were going on (there was a detectable
loss of "power" to each though).

I ran mains water feed in 22mm right through to a 35Kw combi. and 22mm
out where it splits to 15mm to go upstairs and downstairs bathrooms.

After fitting a Mira Eco shower head to one shower (introduces air into
water flow) the boiler quite happily runs both showers at once with no
noticeable fluctuation in flow temp when turning one shower on or off.
Would improve things even more if I fitted a 2nd "eco" shower head the
same, but at the moment the main bathroom has no walls, ceiling or floor
let alone a shower.

And for the record the Mira eco shower head gets absolutely no
complaints from the rest of the fam. but I had to fit the supplied
pressure reducer thingie into the shower hose to stop the vibrations/noise.

On 26/04/2012 01:32, The Natural Philosopher wrote:
Michael Kilpatrick wrote:
On 25/04/2012 22:26, John Rumm wrote:

Also don't ignore the possibility of using one combi to heat a cylinder
of water as well as being able to provide hot water on demand itself.

This is exactly what I specified for our extension, and was surprised
when the plumber said that it was a little unusual.

the cost of a combi and tank exceeds the cost of a system boiler and
tank really so its a waste of money with no advantages

The tank is twin-coil - we have solar thermal fitted.

Michael

On Apr 25, 11:05*pm, kent wrote:
On Wednesday, 25 April 2012 22:26:02 UTC+1, John Rumm *wrote:
On 25/04/2012 20:51, kent wrote:
On Wednesday, 25 April 2012 20:42:01 UTC+1, *wrote:
kent wrote:
On Wednesday, 25 April 2012 20:05:20 UTC+1, Jim K *wrote:
On Wed, 25 Apr 2012 19:57:44 +0100, *wrote:

This is probably a daft idea, but I'd be interesting to see if
there is any mileage in it! *Combi boilers tend to work best in
smaller properties, so for a larger property would it be possible
(or make any sense) to have 2 combi boilers serving different
parts of the house? By "larger" I don't mean a mansion I mean a 4
bedroomed house with 3 showers!
Thanks for any thoughts on this.

ah the old ones are always the best....

nope! *Thought of it all by myself! *Is it that stupid then?

You have just made a new friend. He wll be along shortly to back you to the
hilt and claim you are a genius, second only to himself and Einsein.

--
Adam

Oh dear, I didn't mean to stir the s*** ! Does this mean I am unlikely to get any rational answers?!

No, you will probably get plenty ;-)

(There is/was a famous poster/troll/poet(bad)/legend in his own
lunchtime *to this group who used to champion this particular solution
as a cure to every ill known to man).

So the basics; yes you can have two combis so long as the total demand
on your gas supply does not reach above about 60kW (assuming a normal
domestic meter). So a pair of 24kW ones is ok, a pair of 35kW ones would
be too much. (depends also on what other gas appliances you have)

You can have them completely independent of each other, but the only
real benefit would be the ability to position them so as to reduce the
time spent waiting for hot water at a tap, plus the ability to get some
heat and hot water when one goes wrong.

You could also merge their outputs together, but that then starts
getting slightly more complicated. It should alleviate some of the
problems with low flow rates of hot water that many of the less powerful
combis are famous for - but will ultimately be limited by the gas
supply, and so still won't be able to match other systems[1] if high
delivery rates of hot water are your goal.

On the downside, its a more complex system that may confuse some tasked
with maintenance, and you will incur two lots of service charges etc.

Also don't ignore the possibility of using one combi to heat a cylinder
of water as well as being able to provide hot water on demand itself.
(this can make sense where, one hot water outlet would be a long pipe
run from a main cylinder, and hence the combi can feed it directly, or
alternatively, when you have a gravity fed system that works well for
bath filling, but lacks pressure for showers.

[1] Some "other" systems would include the various hybrid
instant/storage combis, with built in unvented tanks of water cylinders..

Also see:

http://wiki.diyfaq.org.uk/index.php?..._Water_Systems


Thanks John for such a detailed and considered response. *Our old boiler will have to replaced soon and I have been thinking about options. *Combi appealed because without stored water losing heat I figured it would be more efficient. *However if 2 (or even 3) people wanted to shower at the same time I didn't think that one combi boiler would be able to deliver sufficient hot water. *This is a fairly standard 4 bedroomed house with gas central heating and a gas fired stove, but all cooking appliances are electric.


If you're after efficiency without any big spend, look at the
possibility of a drain heat exchanger on the showers. That can recover
a good percentage of the heat a shower uses.
http://wiki.diyfaq.org.uk/index.php?...Heat_Exchanger


NT

Michael Kilpatrick wrote:
On 26/04/2012 01:32, The Natural Philosopher wrote:
Michael Kilpatrick wrote:
On 25/04/2012 22:26, John Rumm wrote:

Also don't ignore the possibility of using one combi to heat a cylinder
of water as well as being able to provide hot water on demand itself.

This is exactly what I specified for our extension, and was surprised
when the plumber said that it was a little unusual.

the cost of a combi and tank exceeds the cost of a system boiler and
tank really so its a waste of money with no advantages

The tank is twin-coil - we have solar thermal fitted.

And that is relevant how?

(Other than demonstrating value for money is not a concept you are
familiar with).


Michael


--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

On Apr 25, 11:45*pm, "Rod Speed" wrote:
kent wrote

BTW how do I stop my typing going all the way
across the page, whilst yours are in neat blocks?!

He's not using groups.google to post.

He's using a proper news client.

Really? What makes you say that?

MBQ

On Apr 26, 1:32*am, The Natural Philosopher
wrote:
Michael Kilpatrick wrote:
On 25/04/2012 22:26, John Rumm wrote:

Also don't ignore the possibility of using one combi to heat a cylinder
of water as well as being able to provide hot water on demand itself.

This is exactly what I specified for our extension, and was surprised
when the plumber said that it was a little unusual.

the cost of a combi and tank exceeds the cost of a system boiler and
tank really so its a waste of money with no advantages

For our boiler in the kitchen the advantages would be:

Instant hot water at the kitchen tap for those small washing up jobs
and no long pipe run from the tank.

Potable hot water.

I would never consider connecting a combi to a shower, however. No
combi could come near our present pump fed mixers for performance
(hence the need for the instant hot water when the kids have drained
the tank).

MBQ

On 26/04/2012 08:01, www.GymRatZ.co.uk wrote:
On 25/04/2012 23:58, John Rumm wrote:

As to multiple showers, much depends on the shower in question and its
consumption. At a previous place I installed a 35kW combi when
converting the loft and losing the space for the cylinder etc. That
could (just) manage two showers at a time if there were no other demands
for water in the house while they were going on (there was a detectable
loss of "power" to each though).

I ran mains water feed in 22mm right through to a 35Kw combi. and 22mm
out where it splits to 15mm to go upstairs and downstairs bathrooms.

After fitting a Mira Eco shower head to one shower (introduces air into
water flow) the boiler quite happily runs both showers at once with no
noticeable fluctuation in flow temp when turning one shower on or off.
Would improve things even more if I fitted a 2nd "eco" shower head the
same, but at the moment the main bathroom has no walls, ceiling or floor
let alone a shower.

And for the record the Mira eco shower head gets absolutely no
complaints from the rest of the fam. but I had to fit the supplied
pressure reducer thingie into the shower hose to stop the vibrations/noise.

Likewise I had fitted a water reducing head to one of those showers
(when it was the only one) because the tank based system would otherwise
run out of cold water. That one did not mix air, but made a more
directional jet, and used an ring of jets rather than a whole circle if
that makes sense. I left it on when fitting the combi and adding the
second shower, but added one of the pressure reducing disks to make the
(non thermostatic) valve more sensitive to adjustment, and stop it
squeaking (it was a Mira 88 - not designed for mains pressure).


--
Cheers,

John.

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

On 26/04/2012 01:32, The Natural Philosopher wrote:
Michael Kilpatrick wrote:
On 25/04/2012 22:26, John Rumm wrote:

Also don't ignore the possibility of using one combi to heat a cylinder
of water as well as being able to provide hot water on demand itself.

This is exactly what I specified for our extension, and was surprised
when the plumber said that it was a little unusual.

the cost of a combi and tank exceeds the cost of a system boiler and
tank really so its a waste of money with no advantages

It depends on the circumstance.

For example, I may opt for an unvented cylinder here when I replace the
boiler, but go for a combi rather than a system boiler if I can find one
that will cope with weather comp and dual temp operation. The logic
being the cylinder is clustered with all the bathrooms in the centre of
the house, but the kitchen and utility (where the boiler will be) is a
long pipe run away. So having the combi feed potable water to the
kitchen only would make sense.

The general rule is the money you have a tank dont have a combi: they
are a cheap low footprint abortion suitable for CH and one-at-a-time hot
water and if they are to given a decent hot water flow-rate more
expensive than a sealed tank and system boiler


--
Cheers,

John.

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

On 26/04/2012 11:42, The Natural Philosopher wrote:
Michael Kilpatrick wrote:
On 26/04/2012 01:32, The Natural Philosopher wrote:
Michael Kilpatrick wrote:
On 25/04/2012 22:26, John Rumm wrote:

Also don't ignore the possibility of using one combi to heat a
cylinder
of water as well as being able to provide hot water on demand itself.

This is exactly what I specified for our extension, and was surprised
when the plumber said that it was a little unusual.

the cost of a combi and tank exceeds the cost of a system boiler and
tank really so its a waste of money with no advantages

The tank is twin-coil - we have solar thermal fitted.

And that is relevant how?


Because we get lots of nearly-free hot water when the sun shines, the
kitchen/ulitity room/washing machine get on-demand hot water from the
boiler with the absolute minimum water waste owing to proximity to the
boiler, and we get a shower in the master en-suite likewise with the
absolute minimum water waste, owing to proximity of the shower to the
cylinder. Our gas bill has shrunk enormously. It shrunk a fair bit when
the new boiler was put in, and shrunk *massively* a year later when the
solar thermal was eventually installed. Why would I care if a combi
boiler costs more than a system boiler? It is of absolutel no
consequence to me given the gains I have achieved.

(Other than demonstrating value for money is not a concept you are
familiar with).

Tosh. The marginal cost of the twin-coil cylinder was irrelevant as the
whole central heating was replumbed, the old boiler had to be removed
and the hot cylinder needed to be moved and improved, as part of the
extension plans. Not only that, but as we installed solar PV at the same
time as the solar thermal (a year after the extension, with the
twin-coil tank ready and waiting), the scaffolding and installation
costs were all more efficiently utilised. Not only that, we took the
oportunity to undertake a rebuild of the chimney (living room fireplace)
which were getting very near to essential, thus eliminating the need for
scaffolding again at a future date.

Besides that, you appear to be working on the assumption that value for
money is the sole concern. Perhaps it hadn't occurred to you that
someone who can afford to save water might feel that it's worth paying
more for if it did turn out to be more expensive. Rather like the six
cubic metres of water in the rain harvester tank under the patio, which
waters the garden, fills the ponds and flushes all the toilets in the
house. Unlike the boiler, solar etc, I don't really know whether the
rain harvester will ever pay for itself - it was quite expensive to
install - but then, I can throw water around the garden to my heart's
content when everybody else is scowling under a hosepip ban. Hah!

Michael

On Wed, 25 Apr 2012 23:30:14 +0100, ARWadsworth
wrote:

David Paste wrote:
On Wednesday, April 25, 2012 7:57:44 PM UTC+1, kent wrote:
This is probably a daft idea, but I'd be interesting to see if
there is any mileage in it! Combi boilers tend to work best in
smaller properties, so for a larger property would it be possible
(or make any sense) to have 2 combi boilers serving different parts
of the house? By "larger" I don't mean a mansion I mean a 4
bedroomed house with 3 showers!
Thanks for any thoughts on this.

The guy who services my gas boiler has two in his house.

He would not be the first person to have to sevice two boilers at the
same
time.

you quiet at work again? ;)

Jim K

Man at B&Q wrote
Rod Speed wrote
kent wrote

BTW how do I stop my typing going all the way
across the page, whilst yours are in neat blocks?!

He's not using groups.google to post.

He's using a proper news client.

Really? What makes you say that?

Its listed in the header.

I was talking about who he asked the question
of, not the individual asking the question.

And the individual he asked the question of said that in his reply too.

On Wed, 25 Apr 2012 12:51:19 -0700, kent wrote:

Oh dear, I didn't mean to stir the s*** ! Does this mean I am unlikely
to get any rational answers?!

No, it just means you are likely to get some irrational ones ;-)

Multiple boilers in larger properties is quite a sane idea. Generally,
however, they are ganged together so that either boiler can run quite
efficiently at the lower output required for heating in spring and autumn-
ish weather, with both coming on together for winter loads. This also
gives a degree of fault tolerance as a fault in one boiler doesn't leave
you entirely without heating, and may not even be noticed in milder
weather. However the controls required (including a mechanism for
detecting that just one boiler has failed, before the other one goes as
well and you really don't have any heating!) is more complicated and/or
expensive.

Combi boilers aren't generally ganged though: in the larger properties in
which ganged boilers would be called for the hot water demand (e.g.
multiple bathrooms etc) is likely to be greater than even 2 combis
working together can supply.

However a 4 bedroom house isn't large enough to likely require more power
for heating than a single domestic boiler can supply (and if it does
you'd be better advised reducing the heat losses than adding boilers!)
Given that the hot water requirement is the critical factor then some
form of stored water system ('Megaflo'-type unvented, or thermal store/
heat bank) or just a storage combi (e.g. Worcester's Highflows) would be
more appropriate. If you are seriously concerned about backup for when
the boiler goes down a stored water system with immersion heater and a
few cheap convector heaters stored in the attic should do the trick.

--
John Stumbles -- http://yaph.co.uk

The astronomer married a star

On 26/04/2012 01:29 The Natural Philosopher wrote:

kent wrote:
BTW how do I stop my typing going all the way across the page, whilst
yours are in neat blocks?!
abandon google groups as a means of posting.

It's not just Google Groups, iPads don't wrap text either. I've tried to
find a fix so I can read my daughter's emails a little more easily but
have failed miserably.

Anyone aware of a fix? Angle grinders don't count...

--
F

Jim K wrote:
On Wed, 25 Apr 2012 23:30:14 +0100, ARWadsworth
wrote:

David Paste wrote:
On Wednesday, April 25, 2012 7:57:44 PM UTC+1, kent wrote:
This is probably a daft idea, but I'd be interesting to see if
there is any mileage in it! Combi boilers tend to work best in
smaller properties, so for a larger property would it be
possible (or make any sense) to have 2 combi boilers serving
different parts of the house? By "larger" I don't mean a
mansion I mean a 4 bedroomed house with 3 showers!
Thanks for any thoughts on this.

The guy who services my gas boiler has two in his house.

He would not be the first person to have to sevice two boilers at
the same
time.

you quiet at work again? ;)

I have had a busy day thank you.

--
Adam

On Thursday, 26 April 2012 20:25:40 UTC+1, YAPH wrote:
On Wed, 25 Apr 2012 12:51:19 -0700, kent wrote:

Oh dear, I didn't mean to stir the s*** ! Does this mean I am unlikely
to get any rational answers?!

No, it just means you are likely to get some irrational ones ;-)

Multiple boilers in larger properties is quite a sane idea. Generally,
however, they are ganged together so that either boiler can run quite
efficiently at the lower output required for heating in spring and autumn-
ish weather, with both coming on together for winter loads. This also
gives a degree of fault tolerance as a fault in one boiler doesn't leave
you entirely without heating, and may not even be noticed in milder
weather. However the controls required (including a mechanism for
detecting that just one boiler has failed, before the other one goes as
well and you really don't have any heating!) is more complicated and/or
expensive.

Combi boilers aren't generally ganged though: in the larger properties in
which ganged boilers would be called for the hot water demand (e.g.
multiple bathrooms etc) is likely to be greater than even 2 combis
working together can supply.

However a 4 bedroom house isn't large enough to likely require more power
for heating than a single domestic boiler can supply (and if it does
you'd be better advised reducing the heat losses than adding boilers!)
Given that the hot water requirement is the critical factor then some
form of stored water system ('Megaflo'-type unvented, or thermal store/
heat bank) or just a storage combi (e.g. Worcester's Highflows) would be
more appropriate. If you are seriously concerned about backup for when
the boiler goes down a stored water system with immersion heater and a
few cheap convector heaters stored in the attic should do the trick.

--
John Stumbles -- http://yaph.co.uk

The astronomer married a star

Well John it certainly has made for some interesting reading and encouraged me to look a few technical points up on the internet. The conclusion I have come to is that for our four bedroom house I just need a condenser boiler to replace our old regular one (making sure that the condensing pipe is not in a location where it might freeze up) and install an electric shower if we really do want three people showering at the same time! Any idea how much just replacing the boiler might cost (with labour, not diy)?
The idea of having combi's really came from my wife who wants the airing cupboard space!
Anyway, thanks to all for your comments and suggestions.

On 26/04/2012 21:12, kent wrote:
On Thursday, 26 April 2012 20:25:40 UTC+1, YAPH wrote:
On Wed, 25 Apr 2012 12:51:19 -0700, kent wrote:

Oh dear, I didn't mean to stir the s*** ! Does this mean I am unlikely
to get any rational answers?!

No, it just means you are likely to get some irrational ones ;-)

Multiple boilers in larger properties is quite a sane idea. Generally,
however, they are ganged together so that either boiler can run quite
efficiently at the lower output required for heating in spring and autumn-
ish weather, with both coming on together for winter loads. This also
gives a degree of fault tolerance as a fault in one boiler doesn't leave
you entirely without heating, and may not even be noticed in milder
weather. However the controls required (including a mechanism for
detecting that just one boiler has failed, before the other one goes as
well and you really don't have any heating!) is more complicated and/or
expensive.

Combi boilers aren't generally ganged though: in the larger properties in
which ganged boilers would be called for the hot water demand (e.g.
multiple bathrooms etc) is likely to be greater than even 2 combis
working together can supply.

However a 4 bedroom house isn't large enough to likely require more power
for heating than a single domestic boiler can supply (and if it does
you'd be better advised reducing the heat losses than adding boilers!)
Given that the hot water requirement is the critical factor then some
form of stored water system ('Megaflo'-type unvented, or thermal store/
heat bank) or just a storage combi (e.g. Worcester's Highflows) would be
more appropriate. If you are seriously concerned about backup for when
the boiler goes down a stored water system with immersion heater and a
few cheap convector heaters stored in the attic should do the trick.

--
John Stumbles -- http://yaph.co.uk

The astronomer married a star

Well John it certainly has made for some interesting reading and encouraged me to look a few technical points up on the internet. The conclusion I have come to is that for our four bedroom house I just need a condenser boiler to replace our old regular one (making sure that the condensing pipe is not in a location where it might freeze up) and install an electric shower if we really do want three people showering at the same time! Any idea how much just replacing the boiler might cost (with labour, not diy)?
The idea of having combi's really came from my wife who wants the airing cupboard space!
Anyway, thanks to all for your comments and suggestions.


Having two combi boilers also allows you to have two zone heating as well.

This could help you to use gas more efficiently if you use a pair of
programmable room thermostats. These PRTs allow you to have different
temps during the course of the day, so during the night , you'd heat
upstairs only, keep downstairs at 5°C. During the day, you'd heta
downstairs only, and keep upstairs at a lower temp.

You'd have a downstairs boiler doing the downstairs rads and the
downstairs hot water taps.

You'd have an upstairs boiler doing the upstairs rads and the upstairs
hot water taps.

One of teh boilers could go where your existing boiler is, the other 2nd
boiler could go where your hot water cylinder is.

YOu may need to revise your heating pipework to get the two heating
zones created though.

Its a trivial matter to put in some 2 port zone valves on both the hot
water and the heating loops and a special switching arrangement so that
if one boiler fails, the other working boiler can then take on the whole
house..

On Wednesday, April 25, 2012 11:30:14 PM UTC+1, wrote:

He would not be the first person to have to sevice two boilers at the same
time.

Badumtish! Ladies and gentlemen, Adam is here all week, try the steak!

On 26/04/2012 21:28, Stephen H wrote:
On 26/04/2012 21:12, kent wrote:
On Thursday, 26 April 2012 20:25:40 UTC+1, YAPH wrote:
On Wed, 25 Apr 2012 12:51:19 -0700, kent wrote:

Oh dear, I didn't mean to stir the s*** ! Does this mean I am unlikely
to get any rational answers?!

No, it just means you are likely to get some irrational ones ;-)

Multiple boilers in larger properties is quite a sane idea. Generally,
however, they are ganged together so that either boiler can run quite
efficiently at the lower output required for heating in spring and
autumn-
ish weather, with both coming on together for winter loads. This also
gives a degree of fault tolerance as a fault in one boiler doesn't leave
you entirely without heating, and may not even be noticed in milder
weather. However the controls required (including a mechanism for
detecting that just one boiler has failed, before the other one goes as
well and you really don't have any heating!) is more complicated and/or
expensive.

Combi boilers aren't generally ganged though: in the larger
properties in
which ganged boilers would be called for the hot water demand (e.g.
multiple bathrooms etc) is likely to be greater than even 2 combis
working together can supply.

However a 4 bedroom house isn't large enough to likely require more
power
for heating than a single domestic boiler can supply (and if it does
you'd be better advised reducing the heat losses than adding boilers!)
Given that the hot water requirement is the critical factor then some
form of stored water system ('Megaflo'-type unvented, or thermal store/
heat bank) or just a storage combi (e.g. Worcester's Highflows) would be
more appropriate. If you are seriously concerned about backup for when
the boiler goes down a stored water system with immersion heater and a
few cheap convector heaters stored in the attic should do the trick.

--
John Stumbles -- http://yaph.co.uk

The astronomer married a star

Well John it certainly has made for some interesting reading and
encouraged me to look a few technical points up on the internet. The
conclusion I have come to is that for our four bedroom house I just
need a condenser boiler to replace our old regular one (making sure
that the condensing pipe is not in a location where it might freeze
up) and install an electric shower if we really do want three people
showering at the same time! Any idea how much just replacing the
boiler might cost (with labour, not diy)?
The idea of having combi's really came from my wife who wants the
airing cupboard space!
Anyway, thanks to all for your comments and suggestions.


Having two combi boilers also allows you to have two zone heating as well.

This could help you to use gas more efficiently if you use a pair of
programmable room thermostats. These PRTs allow you to have different
temps during the course of the day, so during the night , you'd heat
upstairs only, keep downstairs at 5°C. During the day, you'd heta
downstairs only, and keep upstairs at a lower temp.

While all this is true, its also trivial to arrange with a single
boiler. It just needs an extra zone valve in a S+ configuration.

http://wiki.diyfaq.org.uk/index.php?...s:_S_Plus-plan

You'd have a downstairs boiler doing the downstairs rads and the
downstairs hot water taps.

You'd have an upstairs boiler doing the upstairs rads and the upstairs
hot water taps.

Ok if one shower is upstairs and the other down perhaps...

One of teh boilers could go where your existing boiler is, the other 2nd
boiler could go where your hot water cylinder is.

Meaning that SWMBO does not get the airing cupboard space back...

YOu may need to revise your heating pipework to get the two heating
zones created though.

Its a trivial matter to put in some 2 port zone valves on both the hot
water and the heating loops and a special switching arrangement so that
if one boiler fails, the other working boiler can then take on the whole
house..

Sure, but I can't see it buying you much.


--
Cheers,

John.

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

"kent" wrote in message
news:2859757.1168.1335380264153.JavaMail.geo-discussion-forums@vbez18...
This is probably a daft idea, but I'd be interesting to see if there is
any mileage in it! Combi boilers tend to work best in smaller properties,
so for a larger property would it be possible (or make any sense) to have
2 combi boilers serving different parts of the house?
By "larger" I don't mean a mansion I mean a 4 bedroomed house with 3
showers!
Thanks for any thoughts on this.

Do they still do hot-water-only gas boilers?

I had a house a few years ago with an ancient combi downstairs, and an
equally ancient separate hot water boiler in the upstairs bathroom (which
was supremely reliable; no electrics, just gas and water, and no secondary
heat exchangers and 3-way valves to clog up. Just the occasional
transatlantic call explaining how to ignite the pilot..).

So each floor had it's own hot water source. And it came in extremely useful
when the combi started playing up. (In fact I eventually plumbed it so the
upstairs boiler supplied all the hot water.) Unfortunately when the combi
was replaced, the upstairs heater was taken out too; big mistake as I
continued having boiler problems for years.

I would go with a 2-boiler solution, although it would be wasteful if one is
only used for hot water (and will it even work if the CH flow just comes
straight back without going through radiators?).

--
Bartc