Combi Boiler with 2 heating zones

[beats]

Evening all,
Tomorrow i've got to 2nd fix a combi boiler with 2 heating zones and hot water, but i haven't really done many heating systems!

So is there a certain plan(s plan, Yplan etc ) to connect it all together.

Any help appreciated

chris

 

[Amp David]

With it being a combi, then you'll be looking toward creating a custom system, as your standard plans are for conventional heating systems.

Have done it once when a landlord wouldn't put a boiler in each flat.

IIRC then you will need 2 room stats for the individual temp control and then 2 2 port valves positions according to the layout of the property.

Its not the best idea, but thats a way to do it so it all works

 

[Guest123]

I suppose technically you could call it an 's' plan as you have 2 zone valves, albeit both for heating zones instead of 1 for heating & 1 for hot water.

As it is a combi, no additional controls for hot water will be needed as the combi deals with that 'on demand'

Double channel clock & 2 roomstats for the heating zones, the diagrams in the stickies will show you the connections required. Usually the SL to the boiler from the zone valve oranges, terminates into terminal 4 at the boiler.

If you can find the 's plan plus' diagram and ignore the hot water part of it, this will show you how 2 seperate heating zones are connected.

You will need to check pump overrun control requirements, some boiler models need to control the pump directly (if it is external to the boiler).

 

[beats]

Thanks for the replies
The system is wired and there are 2 x 2port valves installed and the pump isbuilt into the boiler.

Any ideas where i can find a s plan plus diagram.
thanks

 

[Guest123]

Honeywell Heating Schematics.

 

[beats]

Thanks again massive help. Saved for future reference.
ta

 

[a12jpm]

Honeywell site is great. Good app for the iPad/iPhone as well which I use a lot.

Sounds like you need a S plan plus, diagrams on the Honeywell site.

 

[bkh]

Very helpful also, thanks

 

[grandfortune]

yep its a s plan, getting more and more common, they also seem to put a pressurised water tank in also, cant seem why they dont use a system boiler, always seems to be a combi, anyone know why?.

 

[Geordie Spark]

yep its a s plan, getting more and more common, they also seem to put a pressurised water tank in also, cant seem why they dont use a system boiler, always seems to be a combi, anyone know why?.

I'm guessing here because in all honesty I don't know, but maybe the combi is connected direct to the kitchen hot tap & the shower, whilst the storage tank is connected to the bath hot tap & everything else.

My reason for thinking this is that combis are notoriously slow at filling baths & using this method offers the best of both worlds: almost instant hot water in the kitchen & shower & a quickly filled bath - if there's any hot water in the storage cylinder of course.

 

[EH58 ARC]

beats. which S plan plus plan did u use? i have exactly the same system to do, what did you run between the wiring center and the boiler? cheers

 

[FrankUK]

The pressurised tank is called a 'buffer tank'
When you have more than 1 heating system served by a common boiler/heat pump, this setup works best.
Basically, the boiler/heat pump will control via timeclock, on what's called a 'shunt circuit' to ensure that the buffer vessel is up to temperature and then the heating circuits draw from the buffer. This setup stops the boiler 'hunting' on individual thermostat signals.
Hot water demand is piped directly from the boiler.

 

[mccant]

You need 5 cores between the boiler and the wiring centre . Live , neutral , earth and a supply to the valves and a switch wire back from the valves . These last 2 just come from where the room stat link is fitted in the boiler , the link may not be mains voltage but this does not matter as it is only being switched by the valves.
Basically from the spur you need a supply to the 2 channel clock and a supply to the boiler , the live out of channel 1 on the clock should go to the brown of the first valve and the supply out of channel 2 should go to the brown on the other , (after going through stats) , the blues are neutral and cpc is green yellow .
Where the link on the boiler for the stat was removed you need a pair from there , 1 side going to both greys from the valves and the other going to both oranges from the valves .
That's it, when you turn a channel on , on the clock it will power up whichever valve and open it closing the micro switch inside and connect the grey to orange and fire the boiler as it would do if the link was still in the boiler.
(Some boilers do not have a link to remove , most do ) this should get you sorted anyway , if your still unsure just let me know what boiler it is and ill tell you where to connect it .

 

[mccant]

I think it's more of a space issue , with the combi boiler there is no need for a separate tank , don't quote me on this tho I just wire them up , I'll ask one if the heating engineers when I go back to work

 

[BrianDB9]

Reason for 2 zones is Part L of building regs watch this space it may change in April - seems nonsense to split a 1 bed flat into two zones but they who write the regs know best !

 

[chris murphy]

Reason for 2 zones is Part L of building regs watch this space it may change in April - seems nonsense to split a 1 bed flat into two zones but they who write the regs know best !

"Hello BrianDB9",

Please don`t be offended by this - I just want to clarify something that You wrote - from a Heating Engineer`s point of view - in case other Members / Readers get the wrong impression.

Also I have worded My message and highlighted words for the benefit of possibly `Non Technically minded readers`:

The 2 Zone Valves in this enquiry are not necessarily related to the Zoning requirements of Part L of the Building Regulations.

The 2 Zones requirement in Part L of the Building Regulations regarding Domestic Heating Systems for Homes with Floor Plans of `Up to 150 Square Metres` is for a Heating Zone with Thermostatic and Timed Control and a Hot Water Zone with Thermostatic and Timed Control.

The Heating System design and Installation can satisfy the `Thermostatic Zoning` of Bedrooms and other Living Areas with the use of Thermostatic Radiator Valves AND a Room Thermostat - for `Boiler Interlock`.


There is NO requirement for Homes with Floor Plans of LESS than 150 Square Metres to have 2 HEATING Zones controlled by Zone Valves and individual Room Thermostats - although the Heating must have both Thermostatic Control - including usually Thermostatic Radiator Valves and a Room Thermostat [ideally a Programmable Room Thermostat] and Timed Control.


There will never be a requirement to split a Home such as a One Bedroom Flat into 2 Heating Zones using 2 Zone Valves and the associated Pipework circuits - plus 2 Room Thermostats - it is simply not practical.


Regards,


Chris - Heating Engineer - Registered Gas Engineer - Plumber / Heating, Plumbing and Gas Contractor