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Combi - 2 heating zones



 
 
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  #11  
Old February 16th 05, 11:00 AM
Doctor Evil
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"Andrew Gabriel" wrote in message
...
In article ,
John Stumbles writes:
pauliepie wrote:
Is it possible to have the heating circuit off a combi split into 2
zones, one for a ground floor the other for upstairs.
If so, what controls are required, etc,etc?


2 * 2-port valves etc, but you'll also need a bypass (e.g. pressure
relief bypass) so when the last valve turns off and tells the boiler to
stop theres somewhere for water to go while the boiler keeps the pump
running as it cools down


I did it using a mid-position valve, so there is no mode in which
there's no flow path, without needing a bypass. I did however
design a circuit to drive the mid-position valve and boiler demand,
using two stats as input controls.


Good idea if the boioer has an auto heat disipation function. But two 2-port
valve are a lot simpler and more reliable than one mid-position 3-way valve.

If you have TVRs on all rads and close the pump will be pumping nothing. So,
it is wise to have the rads where the stat or programmers stats are with no
TRVs fitted.


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  #12  
Old February 16th 05, 12:00 PM
Christian McArdle
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Is it possible to have the heating circuit off a combi split into 2
zones, one for a ground floor the other for upstairs.
If so, what controls are required, etc,etc?


No problem at all. Wire up as S-Plan. This is compatible with all types of
combi. Some won't handle Y-Plan without external relays, as they often
expect "volt free" contacts on their room thermostat input.

You will need for each zone a 22mm 2 port spring return zone valve and a
programmable room thermostat of your choice.

Simply plumb each zone valve into the circuits for each zone. Obviously, the
feasibility of this will depend on your existing layout. If the upstairs
radiators come of a central trunk, with the downstairs dropping from the
same, you are unlikely to have a suitable layout. The ideal situation is if
near the boiler, the pipework splits into two, with two pipes going up to
the upstairs rads and two pipes going down to the downstairs rad.

Wiring up is simplicity itself. Wire a permanent live (fused at the same
point as the boiler, and preferably using a live out from the boiler, if
available) through the terminals of the room thermostat into the motor
terminals of the appropriate zone valve. Then, take the contact terminals of
all the zone valves, parallel them together and attach to the "room
thermostat" terminals of the boiler.

You may need an automatic bypass valve as well. This will depend on the
model of boiler. They're not expensive.

Christian.


  #13  
Old February 17th 05, 10:55 PM
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Posts: 20
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Sorry to complicate things but....

If a combi is used with a vented cylinder, then 2 zone valves are required, one for the heating and one for the hot water, BUT what if I want to split the downstairs heating from the upstairs heating....

Can this be done, the only problem is the heating in the house is existing on a semi gravity system.

Is it best to use the honeywell cm67 wireless package!!!!!!

cheers guys
  #14  
Old February 18th 05, 10:16 AM
Christian McArdle
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If a combi is used with a vented cylinder, then 2 zone valves are
required, one for the heating and one for the hot water, BUT what if I
want to split the downstairs heating from the upstairs heating....


The hot water cylinder forms a zone, just like a radiator zone. Each zone
needs a 2 port valve and a thermostat, whether it be a cylinder thermostat
or programmable room stat. If you had a cylinder and 2 heating zones, you'll
need three 2 port valves. The existing pipework will determine if it is easy
to divide into upstairs and downstairs zones.

Is it best to use the honeywell cm67 wireless package!!!!!!


It is very well regarded, but a little ugly, and very pricey if you start
having multiple zones.

Christian.



  #15  
Old February 18th 05, 12:07 PM
Doctor Evil
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"Christian McArdle" wrote in message
. net...
If a combi is used with a vented cylinder, then 2 zone valves are
required, one for the heating and one for the hot water, BUT what if I
want to split the downstairs heating from the upstairs heating....


The hot water cylinder forms a zone, just like a radiator zone. Each zone
needs a 2 port valve and a thermostat, whether it be a cylinder thermostat
or programmable room stat. If you had a cylinder and 2 heating zones,

you'll
need three 2 port valves. The existing pipework will determine if it is

easy
to divide into upstairs and downstairs zones.


If heating a low pressure vented cylinder, run the showers off the combi for
high pressure performance.

Is it best to use the honeywell cm67 wireless package!!!!!!


It is very well regarded, but a little ugly, and very pricey if you start
having multiple zones.

Christian.





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  #16  
Old February 18th 05, 02:10 PM
Tim S
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On Fri, 18 Feb 2005 10:16:46 +0000, Christian McArdle wrote:

If a combi is used with a vented cylinder, then 2 zone valves are
required, one for the heating and one for the hot water, BUT what if I
want to split the downstairs heating from the upstairs heating....


The hot water cylinder forms a zone, just like a radiator zone. Each zone
needs a 2 port valve and a thermostat, whether it be a cylinder thermostat
or programmable room stat. If you had a cylinder and 2 heating zones, you'll
need three 2 port valves. The existing pipework will determine if it is easy
to divide into upstairs and downstairs zones.

Is it best to use the honeywell cm67 wireless package!!!!!!


It is very well regarded, but a little ugly, and very pricey if you start
having multiple zones.

Christian.


I've been planning a multi zone setup for some time, due to never being
very satisfied with single zone setups.

I was considering wireless once. My conclusion:

X10: would do quite well in theory, nice DIN rail contactors available.
But not much in the way of timer-thermostats. Would end up being very
kludgy. This system is really geared to the US with some European
penetration (slow). For example, if you want to install an X10 filter at
the supply then the biggest single phase filter available is 63A, so a
100A supply would need the 3-phase 200A massive filter block. Or hope
no-one in the wrong third of households down the road decide to play with
X10 too...

Wireless: Better. But I need in some cases, 2 contactors remotely
positioned on each channel/zone. One to control a fan-convector or rad
valve and the other to contribute to a demand signal centrally. Apparantly
possible, but only 2 makers sell the receivers as separate items: Siemens
and Danfoss (and the latter do do multi-channel receivers). But as you
say, very pricey and having a bank of 100x80mm receivers commoned up at
the boiler end looks hideous.

Other systems: www.smartkontrols.co.uk produce a very nice modular system,
but I haven't the balls to ask how much it is! They don't appear to sell
parts either, preferring to offer a one-stop consult+install service.
Mucho wonga without much doubt.

So eventually, I thought, if I'm going to run light duty signal cable
everywhere for something like the smartkontrol system, why not go back to
basics and make something custom.

Essentially, a central relay box (using DIN rail for ease and neatness),
24V DIN PSU, bit of cat5 (have loads and it's fairly tough) to remote room
programmer/thermostats and wire all the relays in common for the demand
signal. Tee off to remote relays in nice tidy little boxes for
fan-convector or electric rad-valve control.

I like this solution. I have to run wires, but not heavy ones and the
system is mains-isolated and fused low so I can string the cables
anywhere I like. DIN gives neatness, wide variety of modestly priced
components and enough ease to wire a safe (mains one half, 24V other half,
proper DIN connector blocks to present the external wiring to) neat little
unit which is easy to maintain and expand.

Plus, I'm not tied to anyone proprietry set of thermostats.

Can't think of a better way. But I'm always open to more ideas.

Tim
  #17  
Old February 19th 05, 09:46 AM
Ed Sirett
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On Fri, 18 Feb 2005 10:16:46 +0000, Christian McArdle wrote:

If a combi is used with a vented cylinder, then 2 zone valves are
required, one for the heating and one for the hot water, BUT what if I
want to split the downstairs heating from the upstairs heating....


The hot water cylinder forms a zone, just like a radiator zone. Each zone
needs a 2 port valve and a thermostat, whether it be a cylinder thermostat
or programmable room stat. If you had a cylinder and 2 heating zones, you'll
need three 2 port valves. The existing pipework will determine if it is easy
to divide into upstairs and downstairs zones.

Is it best to use the honeywell cm67 wireless package!!!!!!


It is very well regarded, but a little ugly, and very pricey if you start
having multiple zones.

..... and only needed if the hassles/costs/disruption of running a wire
makes it attractive.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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  
Old February 19th 05, 10:38 PM
Andrew Gabriel
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Posts: n/a
Default

In article ,
"Doctor Evil" writes:

"Andrew Gabriel" wrote in message
...
In article ,
John Stumbles writes:
pauliepie wrote:
Is it possible to have the heating circuit off a combi split into 2
zones, one for a ground floor the other for upstairs.
If so, what controls are required, etc,etc?

2 * 2-port valves etc, but you'll also need a bypass (e.g. pressure
relief bypass) so when the last valve turns off and tells the boiler to
stop theres somewhere for water to go while the boiler keeps the pump
running as it cools down


I did it using a mid-position valve, so there is no mode in which
there's no flow path, without needing a bypass. I did however
design a circuit to drive the mid-position valve and boiler demand,
using two stats as input controls.


Good idea if the boioer has an auto heat disipation function. But two 2-port


Also, for pump run-on, and boiler auto-start for frost protection,
and daily pump exercising.

valve are a lot simpler and more reliable than one mid-position 3-way valve.

If you have TVRs on all rads and close the pump will be pumping nothing. So,
it is wise to have the rads where the stat or programmers stats are with no
TRVs fitted.


Indeed, the radiators in the rooms with the stats have lock shield
valves at both ends, i.e. no TRV and no hand operated valves.

--
Andrew Gabriel
 




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