Hi all

I am trying to improve the operation of my central heating system and would
appreciate the opinions of the more experienced group members.

The story is:

Originally 3 bed detached 1970s house.

Additions since built:

1 Kitchen extension with 1 rad single panel rad 1200 x 600
1 Back room extension with 1 double panel rad 1000 x 600
1 Bedroom/En suite with rad and towel rail (see link)

http://www.thesculls.freeuk.com/Radpipes.jpg

Referring to image (which shows upstairs piping and radiators only), the
problem is little heat to new bedroom rad 7 and almost nothing to towel rail
6.
Downstairs main runs are 22mm, but upstairs is all 15mm.
Not sure if it is significant, but the new part that hardly works is piped
in plastic - see link for plastic/copper joint location.

Another factor that may affect the towel rail operation is the height.
Somewhere I seem to remember reading that a certain distance was required
between the top of a towel rail and the underside of the loft CH header
tank. In my case this distance is approx 650mm.

I have tried major throttling of the downstairs rads to improve flow
upstairs, but do not seem to be able to get acceptable performance of
upstairs and downstairs rads to include items 6 and 7.

So the question:

Looking at the pipe runs and radiator sizes involved upstairs, are 15mm
mains simply not up to the job?

Thanks to anyone who has even managed to read this far!

Phil

"TheScullster" wrote in message
...


Looking at the pipe runs and radiator sizes involved upstairs, are 15mm
mains simply not up to the job?

Do the pipes branch off from a 22mm feed or do they run in 15mm from the
ground floor?


Thanks to anyone who has even managed to read this far!

Have you tried bleeding the system?
Have you tried opening (just a bit) the lock shield valves on 6&7?

"TheScullster" wrote in message
...
Hi all

I am trying to improve the operation of my central heating system and
would
appreciate the opinions of the more experienced group members.

The story is:

Originally 3 bed detached 1970s house.

Additions since built:

1 Kitchen extension with 1 rad single panel rad 1200 x 600
1 Back room extension with 1 double panel rad 1000 x 600
1 Bedroom/En suite with rad and towel rail (see link)

http://www.thesculls.freeuk.com/Radpipes.jpg

Referring to image (which shows upstairs piping and radiators only), the
problem is little heat to new bedroom rad 7 and almost nothing to towel
rail
6.
Downstairs main runs are 22mm, but upstairs is all 15mm.
Not sure if it is significant, but the new part that hardly works is piped
in plastic - see link for plastic/copper joint location.

Another factor that may affect the towel rail operation is the height.
Somewhere I seem to remember reading that a certain distance was required
between the top of a towel rail and the underside of the loft CH header
tank. In my case this distance is approx 650mm.

I have tried major throttling of the downstairs rads to improve flow
upstairs, but do not seem to be able to get acceptable performance of
upstairs and downstairs rads to include items 6 and 7.

So the question:

Looking at the pipe runs and radiator sizes involved upstairs, are 15mm
mains simply not up to the job?

Thanks to anyone who has even managed to read this far!

Phil

The inserts on plastic pipe reduce the 15mm to 12mm. This may contribute.
Even if the pipes are too small for the heat load you should still be
getting flow to all the rads. If all downstairs rads are off does all
upstairs work OK? Have you increased the pump speed? Check the pump
impeller, it may be shattered from debris in the system.

"dennis@home" wrote:

Do the pipes branch off from a 22mm feed or do they run in 15mm from the
ground floor?

Haven't opened the boxing yet, but I'm pretty sure that the
upstairs/downstairs split is half way up ground floor wall (heating solenoid
valve is approx level with wall mounted boiler, believe the 22/15 split to
be there also).


Have you tried bleeding the system?

I have drained, refilled and flushed numerous times when replacing old rads.

Have you tried opening (just a bit) the lock shield valves on 6&7?

Yes


Thanks

Phil

"Doctor Drivel" wrote:

The inserts on plastic pipe reduce the 15mm to 12mm. This may contribute.

Not sure if inserts have been used!
Tees are push fit Hep2o in main 15mm runs rather than compression fittings.
How are these removed? I have heard mention of sliding collars but can't
see them on this type of fitting!

Even if the pipes are too small for the heat load you should still be
getting flow to all the rads. If all downstairs rads are off does all
upstairs work OK?

I will try this. Not sure if I've tried this before or not!
If flow is still not adequate, is it a mains size increase? If so, how much
do I need to upgrade and is plastic the way to go?


Have you increased the pump speed?

Reluctant to do this as I have had pump over problems in the past!
Is it likely that the two issues are related?


Thanks for help

Phil

TheScullster wrote:

Downstairs main runs are 22mm, but upstairs is all 15mm.
Not sure if it is significant, but the new part that hardly works is piped
in plastic - see link for plastic/copper joint location.

Plastic ought to make no difference...

Another factor that may affect the towel rail operation is the height.
Somewhere I seem to remember reading that a certain distance was required
between the top of a towel rail and the underside of the loft CH header
tank. In my case this distance is approx 650mm.

So long as when you bleed it you get water out of the top eventually
then you ought to be ok.

I have tried major throttling of the downstairs rads to improve flow
upstairs, but do not seem to be able to get acceptable performance of
upstairs and downstairs rads to include items 6 and 7.

It does sound like a balancing problem (or perhaps lack of flow from the
pump in general - have you tried a faster pump speed (watch you don't
cause it to start pumping over)))

It may be you need to go back and rebalance the whole system from scratch.

So the question:

Looking at the pipe runs and radiator sizes involved upstairs, are 15mm
mains simply not up to the job?

15mm is good for upto 6kW of total rad output and you are going to be
nowhere near that...

--
Cheers,

John.

/================================================== ===============\
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| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

TheScullster wrote:

The inserts on plastic pipe reduce the 15mm to 12mm. This may contribute.


Not sure if inserts have been used!

I think that is a bit of a red herring anyway... yes the inserts will
reduce the diameter a little, but flow resistance is a function of not
only the diameter of the pipe, but also the length - and inserts are
short. So a reduction to 12mm for a couple of cm every now and then will
make a negligable difference.

Also note that your total heating load should still be satisfied even if
you had a complete run of 12mm pipe - you only have a couple of not huge
rads on this pipe run IIUC.

Have you increased the pump speed?


Reluctant to do this as I have had pump over problems in the past!
Is it likely that the two issues are related?

Could be...

It might be you need to tackle the problem with more pump speed and then
sorting any pump over issues.

What make/model of boiler is it?


--
Cheers,

John.

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\================================================= ================/

"John Rumm" wrote:

It might be you need to tackle the problem with more pump speed and then
sorting any pump over issues.

I believe that the pump over problems occur when hot water only is being
heated in cylinder.
The system is S plan with the hot water valve in the airing cupboard close
to the tank.
The CH valve is close to the boiler, I believe at the 15/22
upstairs/downstairs split.
I think that pump over occurs when the CH stops calling for heat and only
hot water demand remains.
Have increased the height of the vent loop to the apex of the roof, but
still seem to remember problems when running at pump speed 3.


What make/model of boiler is it?

Glow worm Space Saver 50 - yes I know this is old and a bit undersize after
all the mods.
I wanted to iron out the problems, then introduce new boiler and pump.



Thanks for input

Phil

TheScullster wrote:

What make/model of boiler is it?


Glow worm Space Saver 50 - yes I know this is old and a bit undersize after
all the mods.

I doubt that can be converted to sealed system operation (since that is
an guarenteed way to fix overrun problems!), but it might be worth
checking with Gloworm.

I wanted to iron out the problems, then introduce new boiler and pump.

A new boiler will be able to run sealed anyway - so you could lose the
vent and header tank etc anyway.


--
Cheers,

John.

/================================================== ===============\
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\================================================= ================/

"John Rumm" wrote:

A new boiler will be able to run sealed anyway - so you could lose the
vent and header tank etc anyway.

Must confess I am reluctant to take the sealed system route.
Partly due to lack of confidence in existing within-concrete-floor plumbing.
Partly from the safety angle - blocked relief valves etc.
As stated, the house is 1970s build. Do you happen to know whether there
were quality issues around this time for flux/solder.
The original piping is bedded in sand filled channels wrapped in hession or
similar.
I seem to remember some problems with joints failing with age and
spontaneously separating.
After a failed 15mm elbow discovered soon after moving in, I am perhaps
overly concerned about the possibility of a repeat performance.
To be fair this was a fitting failure due to expansion rather than a failure
of a soldered joint.

Phil

In an earlier contribution to this discussion,
TheScullster wrote:

"John Rumm" wrote:

A new boiler will be able to run sealed anyway - so you could lose
the vent and header tank etc anyway.

Must confess I am reluctant to take the sealed system route.
Partly due to lack of confidence in existing within-concrete-floor
plumbing. Partly from the safety angle - blocked relief valves etc.
As stated, the house is 1970s build. Do you happen to know whether
there were quality issues around this time for flux/solder.

Even a sealed system will run at a *lower* pressure than your mains cold
water supply. Presumably that is ok?
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

On Tue, 27 Sep 2005 08:50:23 +0100, in uk.d-i-y "TheScullster"
wrote:

http://www.thesculls.freeuk.com/Radpipes.jpg

Referring to image (which shows upstairs piping and radiators only), the
problem is little heat to new bedroom rad 7 and almost nothing to towel rail
6.

[snip]

Looking at the pipe runs and radiator sizes involved upstairs, are 15mm
mains simply not up to the job?

Assuming no physical blockage the first step would be to check the
balancing http://www.diyfaq.org.uk/plumbing/rad-balance.html

You have to consider the whole system not just the upstairs.

Balancing WILL allow you to get heat to all radiators, but that may
involve turning the hot ones down to almost zero flow (and hence low
output). Then you will know which runs are causing the low flow and be
able to think about how to fix it. Once balanced, you can decide to
sacrifice the rads on the bad run and open up the others again to
restore heat to the rest of the house.

Phil
The uk.d-i-y FAQ is at http://www.diyfaq.org.uk/
The Google uk.d-i-y archive is at http://tinyurl.com/65kwq
e-mai1: editor (a t) diyfaq (stop) o r g (stop) uk = make obvious corrections

On Tue, 27 Sep 2005 10:18:22 +0100, in uk.d-i-y John Rumm
wrote:

TheScullster wrote:

I have tried major throttling of the downstairs rads to improve flow
upstairs, but do not seem to be able to get acceptable performance of
upstairs and downstairs rads to include items 6 and 7.

It does sound like a balancing problem (or perhaps lack of flow from the
pump in general - have you tried a faster pump speed (watch you don't
cause it to start pumping over)))

It may be you need to go back and rebalance the whole system from scratch.

Ahh... didn't notice you already suggested that.

So the question:

Looking at the pipe runs and radiator sizes involved upstairs, are 15mm
mains simply not up to the job?

15mm is good for upto 6kW of total rad output and you are going to be
nowhere near that...

That is the maximum heat load 15mm can carry, over some maximum given
length of flow + return. Lower loads can be carried further. Sorry I
don't have the actual lengths to hand.

Phil
The uk.d-i-y FAQ is at http://www.diyfaq.org.uk/
The Google uk.d-i-y archive is at http://tinyurl.com/65kwq
e-mai1: editor (a t) diyfaq (stop) o r g (stop) uk = make obvious corrections

"Phil Addison" wrote in message
...
On Tue, 27 Sep 2005 10:18:22 +0100, in uk.d-i-y John Rumm
wrote:

TheScullster wrote:

I have tried major throttling of the downstairs rads to improve flow
upstairs, but do not seem to be able to get acceptable performance of
upstairs and downstairs rads to include items 6 and 7.

It does sound like a balancing problem (or perhaps lack of flow from the
pump in general - have you tried a faster pump speed (watch you don't
cause it to start pumping over)))

It may be you need to go back and rebalance the whole system from
scratch.

Ahh... didn't notice you already suggested that.

So the question:

Looking at the pipe runs and radiator sizes involved upstairs, are
15mm
mains simply not up to the job?

15mm is good for upto 6kW of total rad output and you are going to be
nowhere near that...

That is the maximum heat load 15mm can carry, over some maximum given
length of flow + return. Lower loads can be carried further. Sorry I
don't have the actual lengths to hand.


11C Temperature Difference Between Flow and Return
(81C flow - 70C return)

Pipe Size (mm) - approx kW/hour

15 - 6.0
22 - 13.4
28 - 22.5

Pipe Size : Approximate Maximum Non-condensing Load
20C Temperature Difference Between Flow and Return (70C flow - 50C return)

Pipe Size (mm) - approx kW/hour

15 - 9
22 - 24
28 - 70

The condensing boiler can use 22mm pipe where 28mm would be required for a
non-condensing boiler.

On Tue, 27 Sep 2005 21:57:48 +0100, in uk.d-i-y "Doctor Drivel"
wrote:


"Phil Addison" wrote in message
...
On Tue, 27 Sep 2005 10:18:22 +0100, in uk.d-i-y John Rumm
wrote:

TheScullster wrote:

I have tried major throttling of the downstairs rads to improve flow
upstairs, but do not seem to be able to get acceptable performance of
upstairs and downstairs rads to include items 6 and 7.

It does sound like a balancing problem (or perhaps lack of flow from the
pump in general - have you tried a faster pump speed (watch you don't
cause it to start pumping over)))

It may be you need to go back and rebalance the whole system from
scratch.

Ahh... didn't notice you already suggested that.

So the question:

Looking at the pipe runs and radiator sizes involved upstairs, are
15mm
mains simply not up to the job?

15mm is good for upto 6kW of total rad output and you are going to be
nowhere near that...

That is the maximum heat load 15mm can carry, over some maximum given
length of flow + return. Lower loads can be carried further. Sorry I
don't have the actual lengths to hand.


11C Temperature Difference Between Flow and Return
(81C flow - 70C return)

Pipe Size (mm) - approx kW/hour

15 - 6.0
22 - 13.4
28 - 22.5

Pipe Size : Approximate Maximum Non-condensing Load
20C Temperature Difference Between Flow and Return (70C flow - 50C return)

Pipe Size (mm) - approx kW/hour

15 - 9
22 - 24
28 - 70

The condensing boiler can use 22mm pipe where 28mm would be required for a
non-condensing boiler.

OK, but what I am missing is the maximum length for each load, in
particular the 15 and 22mm. It's normally readily available but my book
has gone missing.

Phil
The uk.d-i-y FAQ is at http://www.diyfaq.org.uk/
The Google uk.d-i-y archive is at http://tinyurl.com/65kwq
e-mai1: editor (a t) diyfaq (stop) o r g (stop) uk = make obvious corrections

In an earlier contribution to this discussion,
Doctor Drivel wrote:


11C Temperature Difference Between Flow and Return
(81C flow - 70C return)

Pipe Size (mm) - approx kW/hour

15 - 6.0
22 - 13.4
28 - 22.5


What the hell's a kilowatt per hour? [Bearing in mind that a kilowatt in its
own right is a measure of energy consumed/delivered per unit time]
--
Cheers,
Set Square
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"Set Square" wrote in message
...
In an earlier contribution to this discussion,
Doctor Drivel wrote:


11C Temperature Difference Between Flow and Return
(81C flow - 70C return)

Pipe Size (mm) - approx kW/hour

15 - 6.0
22 - 13.4
28 - 22.5

What the hell's a kilowatt per hour? [Bearing in mind that a kilowatt in
its
own right is a measure of energy consumed/delivered per unit time]

BTU/hr & kW = power
kW/hr & BTU = energy

Firstly, separate power and energy; this confuses many people.
Energy is Power x Time. A BTU is energy. Put it over one hour (energy x 1)
and we have "power"..... BTU/hr.

- The watt (W) - Is a unit of "power".
- kilowatt-hour (kWh) - This is a 'unit' of chargeable electricity and is a
unit of "energy". Yiou buy energy. Power results from the energy.

The kilowatt (kW) is simply 1,000 watts. A traditional electric heater rated
at 1,000 watts, or ten 100 watt light bulbs will consume one kilowatt
(power).

In your electricity bill, what you pay for is the product of power and time.
This is obvious - the one kilowatt electric heater on for three hours is
going to cost three times as much as for one hour. Therefore the chargeable
electricity 'unit', on your bill, is the kilowatt-hour (kWh). This is by
tradition in the world of electricity metering called a 'unit'. What you
are paying for is energy, rather than power

One unit of electricity (one kWh) buys you a:

- 1 kilowatt electric heater burning for one hour.
- 100 watt light bulbs burning for ten hours.
- 8 kW shower for seven-and-a-half minutes.

The one 1 kilowatt electric heater running for six hours would use six
units, but if you left the 8 kW shower running for half an hour it would use
four units.

Electricity meters give readings in 'units' (kWhs) directly. This simplifies
bill calculations.

Gas is now charged for by the kWh too. 3412 BTU/hr = 1 kW

In relation to what a pipe can deliver in heat. The boiler took energy (gas
or electricity) and turned it to power - or did it? This heat is fed to
radiators. The heat travelling to the rads in the pipes is now energy as
far as the rads or fan convector heaters are concerned.

A powers station takes energy, water, oil, or coal, burns the energy to make
power, which turns the generator which produces energy, which goes down a
cable to your house and turns an electric motor and produces power.


I think that is. It's late.

In message ws.net,
Doctor Drivel writes
BTU/hr & kW = power
kW/hr & BTU = energy

Firstly, separate power and energy; this confuses many people.
Energy is Power x Time. A BTU is energy. Put it over one hour (energy x 1)
and we have "power"..... BTU/hr.


.... ...

- The watt (W) - Is a unit of "power".
A powers station takes energy, water, oil, or coal, burns the energy to make
power, which turns the generator which produces energy, which goes down a
cable to your house and turns an electric motor and produces power.



Oh dear, he's found a new website

--
geoff

raden wrote:

- The watt (W) - Is a unit of "power".
A powers station takes energy, water, oil, or coal, burns the energy
to make
power, which turns the generator which produces energy, which goes down a
cable to your house and turns an electric motor and produces power.



Oh dear, he's found a new website

not a good one either... started off ok, but kind of loses the plot
toward the end ;-)

--
Cheers,

John.

/================================================== ===============\
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\================================================= ================/

On Tue, 27 Sep 2005 21:57:48 +0100, in uk.d-i-y "Doctor Drivel"
wrote:

The condensing boiler can use 22mm pipe where 28mm would be required for
a
non-condensing boiler.

Could you explain why there is a difference between the condensing boiler
and a non-condensing boiler?
I can't see why there would be a difference.

"raden" wrote in message
...
In message ws.net,
Doctor Drivel writes
BTU/hr & kW = power
kW/hr & BTU = energy

Firstly, separate power and energy; this confuses many people.
Energy is Power x Time. A BTU is energy. Put it over one hour (energy x
1)
and we have "power"..... BTU/hr.
... ...

- The watt (W) - Is a unit of "power".
A powers station takes energy, water, oil, or coal, burns the energy to
make
power, which turns the generator which produces energy, which goes down a
cable to your house and turns an electric motor and produces power.

Oh dear, he's found a new website

Maxie, the web site is Inside my head.

"dennis@home" wrote in message
.uk...
On Tue, 27 Sep 2005 21:57:48 +0100, in uk.d-i-y "Doctor Drivel"
wrote:

The condensing boiler can use 22mm pipe where 28mm would be required
for
a
non-condensing boiler.

Could you explain why there is a difference between the condensing boiler
and a non-condensing boiler?
I can't see why there would be a difference.

It operates at a wider temperature differential.

You can increase the efficiency of a non-condensing boiler. Insert a
blending valve on the boiler return set to 60C (it doesn't go below
dew-point inside the boiler). This is common practice with commercial
boilers using a motorised mixing valve. This mixes system return water with
flow water from the boiler. Design the system to run at 80C flow and 60C
return, and balance the system to achieve 20C across the heat loads. I
would only do this with a one-piece heat exchanger. You can then downsize
the pipes. Note: the makers would always say runs at 80C flow and 10C temp
differential. If you know what you are doing you can greatly improve
efficiencies

"John Rumm" wrote in message
...
raden wrote:

- The watt (W) - Is a unit of "power".
A powers station takes energy, water, oil, or coal, burns the energy
to make
power, which turns the generator which produces energy, which goes down
a
cable to your house and turns an electric motor and produces power.

Oh dear, he's found a new website

not a good one either... started off ok, but kind of loses the plot
toward the end ;-)

Unable to focus. Lost the thread eh.

In article ws.net,
Doctor Drivel wrote:
A powers station takes energy, water, oil, or coal, burns the energy to
make power, which turns the generator which produces energy, which goes
down a cable to your house and turns an electric motor and produces
power.

So a hydro-electric station burns the water?

--
*Never put off until tomorrow what you can avoid altogether *

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

Doctor Drivel wrote:

Maxie, the web site is Inside my head.

http://www.drivelonline.com/starting_physics.htm

Looking up www.drivelonline.com
Connecting to www.drivelonline.com
Please Wait....

404 Page not found


--
Cheers,

John.

/================================================== ===============\
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|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In an earlier contribution to this discussion,
Doctor Drivel wrote:

"Set Square" wrote in message
...
In an earlier contribution to this discussion,
Doctor Drivel wrote:


11C Temperature Difference Between Flow and Return
(81C flow - 70C return)

Pipe Size (mm) - approx kW/hour

15 - 6.0
22 - 13.4
28 - 22.5

What the hell's a kilowatt per hour? [Bearing in mind that a
kilowatt in its own right is a measure of energy consumed/delivered
per unit time]

BTU/hr & kW = power

Correct

kW/hr & BTU = energy


WRONG! Well, actually, BTU is energy but kW/hr isn't. kW-hr would be - but
that's different because it's power *multipled* by time rather than
*divided* by time.

But even if you (incorrectly!) believe kW/hr to be a measure of energy, your
pipe capacity heading is *still* wrong! A given size of pipe will deliver a
certain amount of energy *per unit time* - in other words, a certain amount
of *power*. So your units need to be kW - *not* kW/hr or even kW-hr.

[And yes, I *do* have a degree in Physics]
--
Cheers,
Set Square
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"Doctor Drivel" wrote in message
eenews.net...

It operates at a wider temperature differential.

But the temperature differential is determined by the size of the radiators
and the flow rate and not by the boiler.
I still don't see why there is a difference between the two types.


You can increase the efficiency of a non-condensing boiler. Insert a
blending valve on the boiler return set to 60C (it doesn't go below
dew-point inside the boiler). This is common practice with commercial
boilers using a motorised mixing valve. This mixes system return water
with
flow water from the boiler. Design the system to run at 80C flow and 60C
return, and balance the system to achieve 20C across the heat loads. I
would only do this with a one-piece heat exchanger. You can then downsize
the pipes. Note: the makers would always say runs at 80C flow and 10C
temp
differential. If you know what you are doing you can greatly improve
efficiencies



Increaseing the temperature difference reduces the efficency of the
radiators.
(The top would be at 80C the bottom 60C assuming no losses in the pipework
(insulation).)

Incidently mine runs at 85C flow and 75C return but its sized to maintain
temps down to -15C not -1C like most are.

Don't do this with normal radiators they will burn at that temperature.
(Skirting heating works well at that temperature.)

I think you will find that is the reason they use mixing valves and low
tempreture flows in business.
It is better to have large radiators at 60C than be sued by running them at
80C+.

Doctor Drivel wrote:

In relation to what a pipe can deliver in heat. The boiler took energy (gas
or electricity) and turned it to power - or did it?

No it took fuel, and released the potential energy from it.

This heat is fed to
radiators. The heat travelling to the rads in the pipes is now energy as
far as the rads or fan convector heaters are concerned.

I think you will find that "heat" is energy as far as anything (or one)
is concerned.

A powers station takes energy, water, oil, or coal, burns the energy to make
power, which turns the generator which produces energy, which goes down a

No, power does not come into it. power is a measure of the rate of doing
work. It is not until you use the energy that you can ascertain the two
bits of information you need: How much energy was used (i.e. the amount
of work done), and how long did it take. Then you can calculate "power"

All the "power station" is doing (viewed as a black box) is changing
energy from one form to another.


--
Cheers,

John.

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

"Set Square" wrote:

A given size of pipe will deliver a
certain amount of energy *per unit time* - in other words, a certain amount
of *power*. So your units need to be kW - *not* kW/hr or even kW-hr.

[And yes, I *do* have a degree in Physics]

You forget that these are plastic pipes connected with the
revolutionary copper free brass compression fittings referred to by
Dribble the other day. :-)

On Planet Zog the impossible happens all the time and normal earth
physics are a thing of the past. For example combi boilers actually
manage to fill a bath with lukewarm water before the boiler needs
another annual service.


--

"dennis@home" wrote in message
.uk...

"Doctor Drivel" wrote in message
eenews.net...

It operates at a wider temperature differential.

But the temperature differential is determined by the size of the
radiators
and the flow rate and not by the boiler.
I still don't see why there is a difference between the two types.


You can increase the efficiency of a non-condensing boiler. Insert a
blending valve on the boiler return set to 60C (it doesn't go below
dew-point inside the boiler). This is common practice with commercial
boilers using a motorised mixing valve. This mixes system return water
with
flow water from the boiler. Design the system to run at 80C flow and
60C
return, and balance the system to achieve 20C across the heat loads. I
would only do this with a one-piece heat exchanger. You can then
downsize
the pipes. Note: the makers would always say runs at 80C flow and 10C
temp
differential. If you know what you are doing you can greatly improve
efficiencies



Increaseing the temperature difference reduces the efficency of the
radiators.
(The top would be at 80C the bottom 60C assuming no losses in the pipework
(insulation).)

No, not at all. The radiator has to be sized for that room though at 80 -
60C..

Incidently mine runs at 85C flow and 75C return but its sized to maintain
temps down to -15C not -1C like most are.

Don't do this with normal radiators they will burn at that temperature.
(Skirting heating works well at that temperature.)

I think you will find that is the reason they use mixing valves and low
tempreture flows in business.
It is better to have large radiators at 60C than be sued by running them
at
80C+.

Nothing at to do with suing. It is to do with efficiency. Scandinavian
countries have had 60-40C for many years.

"Dave Plowman (News)" in a haze of senile flatulence
wrote in message ...
In article ws.net,
Doctor Drivel wrote:
A powers station takes energy, water, oil, or coal, burns the energy to
make power, which turns the generator which produces energy, which goes
down a cable to your house and turns an electric motor and produces
power.

So a hydro-electric station burns the water?

Yes, just for you.

"Set Square" wrote in message
...
In an earlier contribution to this discussion,
Doctor Drivel wrote:

"Set Square" wrote in message
...
In an earlier contribution to this discussion,
Doctor Drivel wrote:


11C Temperature Difference Between Flow and Return
(81C flow - 70C return)

Pipe Size (mm) - approx kW/hour

15 - 6.0
22 - 13.4
28 - 22.5

What the hell's a kilowatt per hour? [Bearing in mind that a
kilowatt in its own right is a measure of energy consumed/delivered
per unit time]

BTU/hr & kW = power

Correct

kW/hr & BTU = energy


WRONG!

It is?

Well, actually, BTU is energy

So, it's not wrong.

but kW/hr isn't. kW-hr would be - but
that's different because it's power *multipled* by time rather than
*divided* by time.

But even if you (incorrectly!) believe kW/hr to be a measure of energy,

It is because we buy out electrical energy using that.

your
pipe capacity heading is *still* wrong! A given size of pipe will deliver
a
certain amount of energy *per unit time* - in other words, a certain
amount
of *power*. So your units need to be kW - *not* kW/hr or even kW-hr.

[And yes, I *do* have a degree in Physics]

Get your money back.

"Matt" through his brainache spat forth in
message ...
"Set Square" wrote:

A given size of pipe will deliver a
certain amount of energy *per unit time* - in other words, a certain
amount
of *power*. So your units need to be kW - *not* kW/hr or even kW-hr.

[And yes, I *do* have a degree in Physics]

You forget that these are plastic pipes connected with the
revolutionary copper free brass compression fittings referred to by
Dribble the other day. :-)

On Planet Zog the impossible happens all the time and normal earth
physics are a thing of the past. For example combi boilers actually
manage to fill a bath with lukewarm water before the boiler needs
another annual service.

"John Rumm" wrote in message
...
Doctor Drivel wrote:

In relation to what a pipe can deliver in heat. The boiler took energy
(gas
or electricity) and turned it to power - or did it?

No it took fuel, and released the potential energy from it.

So energy. A tank of diesel is a tank of energy.

This heat is fed to
radiators. The heat travelling to the rads in the pipes is now energy
as
far as the rads or fan convector heaters are concerned.

I think you will find that "heat" is energy as far as anything (or one)
is concerned.

Yep.

A powers station takes energy, water, oil, or coal, burns the energy to
make
power, which turns the generator which produces energy, which goes down
a

No, power does not come into it. power
is a measure of the rate of doing
work.

It does come into it. A tank of diesel to intents is a tank of energy. It
is used to create power which charge the energy from one state (oil) to
another heat. It took power to do the state change.

It is not until you use the energy that you can ascertain the two
bits of information you need: How much energy was used (i.e. the amount
of work done), and how long did it take. Then you can calculate "power"

All the "power station" is doing (viewed as a black box) is changing
energy from one form to another.

And uses power to do it. So, power comes into the reckoning.

A boiler: The output is in "power". Yet the boiler just converts one energy
state (oil) into another (heat). Yet the output is rated in "power". It
takes power to do the state conversion.

In an earlier contribution to this discussion,
Doctor Drivel wrote:

"Set Square" wrote in message
...

But even if you (incorrectly!) believe kW/hr to be a measure of
energy,

It is because we buy out electrical energy using that.


Oh no we don't! We buy it in kilowatt-hours - not kilowatts *per* hour.


[And yes, I *do* have a degree in Physics]

Get your money back.

I can't - it was so long ago that the state paid! g

But even though I've forgotten a lot, I can still remember more Physics than
you'll ever know!
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

In an earlier contribution to this discussion,
Doctor Drivel wrote:


A boiler: The output is in "power". Yet the boiler just converts one
energy state (oil) into another (heat). Yet the output is rated in
"power". It takes power to do the state conversion.

Yet another travesty of the facts! The power rating of a boiler is simply
the *rate* at which it can convert the energy in the gas or oil into heat
and impart it to the circulating water. This is measured in energy per unit
time - whether it be BTU per hour or kilo-joules per second (better known as
kW).

The only power used to do the conversion is that due to the *inefficiency*
of the process - so if a boiler is (say) 90% efficient, 10% of the energy in
the fuel ends up heating the neighbourhood or whatever rather than your
house!
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

"Set Square" wrote in message
...
In an earlier contribution to this discussion,
Doctor Drivel wrote:

"Set Square" wrote in message
...

But even if you (incorrectly!) believe kW/hr to be a measure of
energy,

It is because we buy out electrical energy using that.


Oh no we don't! We buy it in kilowatt-hours - not kilowatts *per* hour.


[And yes, I *do* have a degree in Physics]

Get your money back.

I can't - it was so long ago that the state paid! g

But even though I've forgotten a lot, I can still remember more Physics
than
you'll ever know!

It is clear you forgot a hell of a lot. Alas I know all about life and
everything therein, and answer is not 42.

"Set Square" wrote in message
...
In an earlier contribution to this discussion,
Doctor Drivel wrote:


A boiler: The output is in "power". Yet the boiler just converts one
energy state (oil) into another (heat). Yet the output is rated in
"power". It takes power to do the state conversion.

Yet another travesty of the facts!

It is?

The power rating of a boiler

So, power in there somewhere.

is simply the *rate*

Which is time.

at which it can convert the energy
in the gas or oil into heat and
impart it to the circulating water.

Power = Energy x Time. So this energy and the rate (time) sounds like
power.

This is measured in energy per unit
time - whether it be BTU per hour or
kilo-joules per second (better known
as kW).

Which is power.

The only power

Power again.

used to do the conversion is that due to the *inefficiency*
of the process - so if a boiler is (say) 90% efficient,
10% of the energy in the fuel ends up heating the
neighbourhood or whatever rather than your
house!

So, this power is used to change one energy state to another then. Which is
what I said.

I fear taxpayers money was wasted.

"Doctor Drivel" wrote in message
eenews.net...

"Set Square" wrote in message
...
In an earlier contribution to this discussion,
Doctor Drivel wrote:



snip

Which is power.

The only power

Power again.

used to do the conversion is that due to the *inefficiency*
of the process - so if a boiler is (say) 90% efficient,
10% of the energy in the fuel ends up heating the
neighbourhood or whatever rather than your
house!


I'm afraid Set Square's description was entirely correct except that in his
last paragraph he said "The only power used..." when he meant "The only
energy used..." (which was about the only thing you didn't query). In a
previous post you claimed the power station "burned energy to make power".
One can neither "burn energy" (only convert it from one form to another) nor
"make power" (as it's a rate, ie so much of something per second). One can
convert energy at a certain rate (which is power). In a 100% efficient
boiler (using the commonly accepted definition rather than the
manufacturer's one) all the converted energy gets out into the water by
heating it up. Some energy is lost to the atmosphere however and the rate at
which it is lost compared with the rate it gets into the water gives one the
inefficiency. The use of the terms "power station" and "power supply" are
rather looser terms generated by the need to satisfy consmer "power
requirements" (ie the rate at which they wish to use energy).


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)

Doctor Drivel wrote:

A boiler: The output is in "power". Yet the boiler just converts one energy
state (oil) into another (heat). Yet the output is rated in "power".

You are falling into the trap of using "power" in a colloquial sense.
Power is not something you can consume in a strict sense. You can use
energy (you don't even consume that - just change its form), but you
don't use power - it is simply a measurement of the rate of energy use.

It takes power to do the state conversion.

No. In absolute terms no energy is gained or lost in the reaction.

--
Cheers,

John.

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