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  #1   Report Post  
Simon Hawthorne
 
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Default What type of central heating system is this?

Hi

I am in the process of fitting TRVs to all my rads (except the two in
the rooms where the room stats live) - and wondered if you could help
with a question about my current boiler. I thought it was a 'gravity'
system.

I have put some photos of it here (when the server will let me upload
them anyway!)

http://www.thehawthornes.org/the_lodge/boiler_room.htm

The system is set up in such a way that I can eithe rhave hot water
on, or heating and hot water - I can't just have heating. I have also
noticed that when the room stats have reached the set temperature, and
close the zone valves, the pump still works. Is this normal? Where
is the water going?

There is also green marks on nearly all the soldered joints between
pipes - is this normal?

I am in the process of designing a new CH system - but in reality, it
is probably 6 months away yet - one that will cope with a loft
conversion, and about 10Kw of extra rads (in a barn that is attached
to the house) - so am not about to do anything drastic.

Thanks in advance

Simon
  #2   Report Post  
IMM
 
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"Simon Hawthorne" wrote in message
...
Hi

I am in the process of fitting TRVs to all my rads (except the two in
the rooms where the room stats live) - and wondered if you could help
with a question about my current boiler. I thought it was a 'gravity'
system.

I have put some photos of it here (when the server will let me upload
them anyway!)

http://www.thehawthornes.org/the_lodge/boiler_room.htm

The system is set up in such a way that I can eithe rhave hot water
on, or heating and hot water - I can't just have heating. I have also
noticed that when the room stats have reached the set temperature, and
close the zone valves, the pump still works. Is this normal? Where
is the water going?

There is also green marks on nearly all the soldered joints between
pipes - is this normal?

I am in the process of designing a new CH system - but in reality, it
is probably 6 months away yet - one that will cope with a loft
conversion, and about 10Kw of extra rads (in a barn that is attached
to the house) - so am not about to do anything drastic.

Thanks in advance


Simon,

It almost certainly has gravity hot water with an old cast iron boiler like
that. At least it has zoning of upstairs and downstairs.

What are you future requirements? How many baths, showers, etc?



  #3   Report Post  
Simon Hawthorne
 
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Default

On Sat, 20 Nov 2004 17:13:56 -0000, "IMM" wrote:

It almost certainly has gravity hot water with an old cast iron boiler like
that. At least it has zoning of upstairs and downstairs.


Thanks IMM

Should the pump always run then - even when the room stats have closed
the zone valves?

Cheers

Si
  #4   Report Post  
Lurch
 
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Default

On Sat, 20 Nov 2004 17:00:57 +0000, Simon Hawthorne
strung together this:

I am in the process of fitting TRVs to all my rads (except the two in
the rooms where the room stats live) - and wondered if you could help
with a question about my current boiler. I thought it was a 'gravity'
system.

It is, on the water side anyway. Gravity sytems are generally pumped
heating and gravity hot water.

The system is set up in such a way that I can eithe rhave hot water
on, or heating and hot water - I can't just have heating. I have also
noticed that when the room stats have reached the set temperature, and
close the zone valves, the pump still works. Is this normal?


Well, it's one way of doing it.

Where
is the water going?

Don't know, can't see the piping that well in the pics, it's probably
pumping against the closed valves, unless there is a bypass between
the pump and valves. You should be able to spot this yourself, it'll
be a pipe between the flow and return with a valve on it.

There is also green marks on nearly all the soldered joints between
pipes - is this normal?

Yes.

I am in the process of designing a new CH system


Good idea!
--

SJW
A.C.S. Ltd
  #5   Report Post  
Lurch
 
Posts: n/a
Default

On Sat, 20 Nov 2004 17:13:56 -0000, "IMM" strung
together this:

It almost certainly has gravity hot water with an old cast iron boiler like
that.


WTF are you banging on about? I've seen plenty of old cast iron
boilers on Y plans.
Don't know if you know, but it's the way the pipes and controls are
connected to each other that determine the type of system, not the
compound of metal used in the boiler manufacturing proccess.
--

SJW
A.C.S. Ltd


  #6   Report Post  
Set Square
 
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Default

In an earlier contribution to this discussion,
Simon Hawthorne wrote:

Hi

I am in the process of fitting TRVs to all my rads (except the two in
the rooms where the room stats live) - and wondered if you could help
with a question about my current boiler. I thought it was a 'gravity'
system.

I have put some photos of it here (when the server will let me upload
them anyway!)

http://www.thehawthornes.org/the_lodge/boiler_room.htm

The system is set up in such a way that I can eithe rhave hot water
on, or heating and hot water - I can't just have heating. I have also
noticed that when the room stats have reached the set temperature, and
close the zone valves, the pump still works. Is this normal? Where
is the water going?

Basically, the pump is running because you're not telling it not to! The
pump is not a positive displacement device, and will simply run "stalled" if
the water can't go anywhere. You really need a room stat in each zone, in a
room which *doesn't* have a TRV - and use this to close the respective zone
valve, and turn the pump off when both valves are closed.

You do indeed have a gravity hot water and pumped heating system. The
problem with this setup is that you can't have CH without HW because the
boiler needs to be on for the CH and, whenever the boiler is on, you get
gravity HW circulation.

In some cases, you can improve this by converting it to a C-Plan system - by
putting a zone valve driven by a cylinder stat in the gravity circuit. See
http://content.honeywell.com/uk/homes/systems.htm
This provides a "boiler interlock" which turns the whole lot off when both
HW and CH demands are satisfied.

Your system is a bit more complicated though, because you've got *two* CH
zones. You could probably devise some sort of combination of a C-Plan and
S-Plan system - but it would need a bit of thinking about.

There is also green marks on nearly all the soldered joints between
pipes - is this normal?

It's probably a bit of corrosion caused by the flux used in the soldering
process rather than indicative of a leak. Clean it up with wire wool, and
only worry if it quickly re-appears.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.


  #7   Report Post  
Simon Hawthorne
 
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Default

On Sat, 20 Nov 2004 18:09:59 -0000, "Set Square"
wrote:

You really need a room stat in each zone, in a
room which *doesn't* have a TRV - and use this to close the respective zone
valve, and turn the pump off when both valves are closed.


Hi SS

I do have this - two zones, two room stats - and when both stats close
the zones, the pump continues to run. There are no TRVs in the rooms
with stats - and won't be.

Do you think it could just be a simple wiring fix?

Thanks
  #8   Report Post  
Simon Hawthorne
 
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Default

On Sat, 20 Nov 2004 18:09:59 -0000, "Set Square"
wrote:

You do indeed have a gravity hot water and pumped heating system. The
problem with this setup is that you can't have CH without HW because the
boiler needs to be on for the CH and, whenever the boiler is on, you get
gravity HW circulation.



Ahhh.....I see...... makes sense.....
  #9   Report Post  
Set Square
 
Posts: n/a
Default

In an earlier contribution to this discussion,
Simon Hawthorne wrote:

On Sat, 20 Nov 2004 18:09:59 -0000, "Set Square"
wrote:

You really need a room stat in each zone, in a
room which *doesn't* have a TRV - and use this to close the
respective zone valve, and turn the pump off when both valves are
closed.


Hi SS

I do have this - two zones, two room stats - and when both stats close
the zones, the pump continues to run. There are no TRVs in the rooms
with stats - and won't be.

Do you think it could just be a simple wiring fix?

Thanks


Yes, but unless you also put a zone valve in the HW circuit, you can'e
achieve a boiler interlock - so the boiler will continue to cycle on its own
stat, and waste energy.

To fix the pump problem (i.e. simple fix without boiler interlock), it needs
to be wired thus:
The CH ON terminal on your programmer needs to be connected to the input
side of both room stats. The output side of each stat needs to connect to
the motor feed in its respective zone valve. The other side of the zone
valve motors should be connected to neutral.

Each zone valve should have a pair of "volt-free" (i.e. not connected to the
motor) contacts which close when the valve is in the open position. The COM
terminal on these contacts on both valves needs to have a permanent live
feed - or at any rate, a feed from CH ON on the programmer. The NO terminal
of both sets of contacts needs to be connected to the pump's live terminal.

The pump will then only run when either or both valves are open - which will
only happen when either or both room stats are calling for heat.

Hope this makes sense!
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.


  #10   Report Post  
logized
 
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Default


"Simon Hawthorne" wrote in message
...
On Sat, 20 Nov 2004 18:09:59 -0000, "Set Square"
wrote:

You really need a room stat in each zone, in a
room which *doesn't* have a TRV - and use this to close the respective
zone
valve, and turn the pump off when both valves are closed.


Hi SS

I do have this - two zones, two room stats - and when both stats close
the zones, the pump continues to run. There are no TRVs in the rooms
with stats - and won't be.

Do you think it could just be a simple wiring fix?

Thanks


It may be because your zone valves do not incorporate a switch contact to
disconnect the pump when closed - you could probably tell by checking how
many wire connections to the zone valve.
Modern types have at least 5 connections (two for the valve motor, two for
the contacts and one for earth). e.g.
http://www.diyfaq.org.uk/plumbing/plumbingpage2.html
A typical wiring diagram is here -
http://content.honeywell.com/uk/homes/systems.htm

Dave




  #11   Report Post  
Ed Sirett
 
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Default

On Sat, 20 Nov 2004 17:22:55 +0000, Simon Hawthorne wrote:

On Sat, 20 Nov 2004 17:13:56 -0000, "IMM" wrote:

It almost certainly has gravity hot water with an old cast iron boiler like
that. At least it has zoning of upstairs and downstairs.


Thanks IMM

Should the pump always run then - even when the room stats have closed
the zone valves?



My guess is the CH timer drives the pump and boiler. The wall thermostats
drive the zone valves. The timer is probaby set so the HW heating is
always implied with any heating ("10" or gravity mode).

Very likely the flow to the HW coil is also the vent pipe pipe.
Likely with this type of installation the feed pipe (if it not combined
with the vent ) goes to somewhere near the boiler returns from the HW
coil.

With care it might be possible to make this system fully pumped using two
pumps and an extra zone valve. It shouldn't matter if a pump is running
in a stalled condition, but graeat care has to be taken to make sure that
pumping over or sucking air won't happen.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html


  #12   Report Post  
Keith G. Powell
 
Posts: n/a
Default


"Simon Hawthorne" wrote in message
...


I thought it was a 'gravity'
system.
.......................................

The system is set up in such a way that I can eithe rhave hot water
on, or heating and hot water - I can't just have heating. I have also
noticed that when the room stats have reached the set temperature, and
close the zone valves, the pump still works. Is this normal? Where
is the water going? ..............................................


This operation appears to be the same as my 1980s bungalow CH which it is
not a gravity system. It is fully pumped.

Below the thermostat set temperature, the 2- port valve is open, so water is
pumped to both radiators and the DHW coil.

When the thermostat set temperature is reached, the 2-port valve is closed,
so water is pumped to the DHW coil only.

That is the pump runs continuously. After the pump, the pipe Tees off to the
2-port valve and to the DHW coil(via a stop cock).

The DHW cylinder does not have a thermostat.

The timer also allows either DHW or DHW with CH or both off.

Hope that makes sense


Keith G. Powell





  #13   Report Post  
Lurch
 
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Default

On Sat, 20 Nov 2004 23:42:14 +0000 (UTC), "Keith G. Powell"
strung together this:

This operation appears to be the same as my 1980s bungalow CH which it is
not a gravity system. It is fully pumped.

Below the thermostat set temperature, the 2- port valve is open, so water is
pumped to both radiators and the DHW coil.

When the thermostat set temperature is reached, the 2-port valve is closed,
so water is pumped to the DHW coil only.

That is the pump runs continuously. After the pump, the pipe Tees off to the
2-port valve and to the DHW coil(via a stop cock).

The DHW cylinder does not have a thermostat.

The timer also allows either DHW or DHW with CH or both off.

That's not fully pumped, that's some lame attempt at plumbing. It's a
cobbled together hybrid system and should be discounted from any
country wide energy efficiency and heating type surveys.
--

SJW
A.C.S. Ltd
  #14   Report Post  
Keith G. Powell
 
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Default


"Lurch" wrote in message
...
On Sat, 20 Nov 2004 23:42:14 +0000 (UTC), "Keith G. Powell"
strung together this:

This operation appears to be the same as my 1980s bungalow CH which it is
not a gravity system. It is fully pumped.

Below the thermostat set temperature, the 2- port valve is open, so water
is
pumped to both radiators and the DHW coil.

When the thermostat set temperature is reached, the 2-port valve is
closed,
so water is pumped to the DHW coil only.

That is the pump runs continuously. After the pump, the pipe Tees off to
the
2-port valve and to the DHW coil(via a stop cock).

The DHW cylinder does not have a thermostat.

The timer also allows either DHW or DHW with CH or both off.


That's not fully pumped, that's some lame attempt at plumbing.


Why is "my" system not fully pumped? Both the CH and DHW circuits are
pumped. No gravity/convection circuits involved.


It's a cobbled together hybrid system and should be discounted from any
country wide energy efficiency and heating type surveys.


I illustrated "my" system to show one reason why a pump would be running
continuously - not to advocate it. I make no claims about efficiency. But if
a survey was held about efficiency of installed systems, and it was ignored,
it would be a misleading survey. Besides, all systems are not 100% energy
efficient.

Yes, it could be more efficient - just by adding a DHW cylinder thermostsat
and a bypass and a bit more wiring, etc, etc. But that was not my point.

Keith G. Powell


  #15   Report Post  
Set Square
 
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Default

In an earlier contribution to this discussion,
Keith G. Powell wrote:


This operation appears to be the same as my 1980s bungalow CH which
it is not a gravity system. It is fully pumped.


No according to the OP's description! He said that the pipes to the right of
the boiler - which are *not* in a pumped circuit - go to the heating coil in
the cylinder, and that the two zone valves are for two different heating
zones. He also said that he can't have CH without HW. All this is consistent
with a gravity HW system.

Of course, he *could* have got it wrong. The pipes on the right *could* just
go to the F&E tank, and the zone valves *could* be one for CH and one for
HW. But that is *not* how he described it.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.




  #16   Report Post  
Simon Hawthorne
 
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On Sun, 21 Nov 2004 12:29:50 -0000, "Set Square"
wrote:

Of course, he *could* have got it wrong. The pipes on the right *could* just
go to the F&E tank, and the zone valves *could* be one for CH and one for
HW. But that is *not* how he described it.


The pipes on the right run straight to the cylinder. I also have two
CH zones (upstairs & down) - the valves are for each circuit....

Thanks SS for yout time in describing how, with some wiring, I could
stop the pump running. If I'm honest, I think it is beyond me........!
Think I'll wait until the summer - when I change to boiler..

Many thanks

Simon
  #17   Report Post  
Ed Sirett
 
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Default

On Sun, 21 Nov 2004 10:55:54 +0000, Keith G. Powell wrote:



Why is "my" system not fully pumped? Both the CH and DHW circuits are
pumped. No gravity/convection circuits involved.



Your system is fully pumped. What you don't have (like a great number of
older systems) is independant control of the heating and HW.

The system the OP showed us and described is a pumped 2 zone heating
system with gravity indirect HW.

There are scopes for energy savings to be made on these systems.
Whether or not this is worth doing will depend on many factors.

A large one will be how many years of life the existing boiler has left in
it. If it's up for replacment in the next few years it may well not be
worth trying to make improvements just yet.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html


  #18   Report Post  
Keith G. Powell
 
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Default


"Set Square" wrote in message
...
In an earlier contribution to this discussion,
Keith G. Powell wrote:


This operation appears to be the same as my 1980s bungalow CH which
it is not a gravity system. It is fully pumped.


No according to the OP's description! He said that the pipes to the right
of
the boiler - which are *not* in a pumped circuit - go to the heating coil
in
the cylinder, and that the two zone valves are for two different heating
zones. He also said that he can't have CH without HW. All this is
consistent
with a gravity HW system.

Of course, he *could* have got it wrong. The pipes on the right *could*
just
go to the F&E tank, and the zone valves *could* be one for CH and one for
HW. But that is *not* how he described it.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.




  #19   Report Post  
IMM
 
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Default


"Simon Hawthorne" wrote in message
...
On Sat, 20 Nov 2004 17:13:56 -0000, "IMM" wrote:

It almost certainly has gravity hot water with an old cast iron boiler

like
that. At least it has zoning of upstairs and downstairs.


Thanks IMM

Should the pump always run then - even when the room stats have closed
the zone valves?


Does it?


  #20   Report Post  
Keith G. Powell
 
Posts: n/a
Default


"Set Square" wrote in message
...
In an earlier contribution to this discussion,
Keith G. Powell wrote:


This operation appears to be the same as my 1980s bungalow CH which
it is not a gravity system. It is fully pumped.


No according to the OP's description! He said that the pipes to the right
of
the boiler - which are *not* in a pumped circuit - go to the heating coil
in
the cylinder, and that the two zone valves are for two different heating
zones. He also said that he can't have CH without HW. All this is
consistent
with a gravity HW system.

Of course, he *could* have got it wrong. The pipes on the right *could*
just
go to the F&E tank, and the zone valves *could* be one for CH and one for
HW. But that is *not* how he described it.


Agreed )

Thought I'd just give my example of continuous pump and where water was
going, just in case OP's sytem interpretation had got it wrong.

Keith G. Powell





  #21   Report Post  
Lurch
 
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On Sun, 21 Nov 2004 10:55:54 +0000 (UTC), "Keith G. Powell"
strung together this:

Why is "my" system not fully pumped? Both the CH and DHW circuits are
pumped. No gravity/convection circuits involved.


Erm, now I read it properly, I think you could be right. Some new
words seem to have come to light!

I illustrated "my" system to show one reason why a pump would be running
continuously - not to advocate it.


Fair enough, I misread your first post. Just 1 minor point that still
stands, the OPs system is gravity hot water, I can't be bothered to
write anymore.....
--

SJW
A.C.S. Ltd
url here when I get around to it
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