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?

"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

"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.

"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:

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.

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

"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.

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

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.

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

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

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.

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
______
Please reply to newsgroup. Reply address is invalid.

"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.

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