Need help with S plan with a 3rd zone for under floor heating!

[Sparkydan]

Hi i am wiring up an S plan heating system tomorrow which has a 3rd 2 port valve with separate controls for underfloor heating, does anybody know how to wire these as i am thinking i will end up with 2 switch lines at the boiler witch will back feed to either one that is not activated.

Thanks

 

[Guest123]

As it has it's own zone valve then there wont be a problem. An S plan already has 2 valves anyway......1 for DHW & 1 for CH, adding another is fine. In theory you could keep on going with additional zones as long as they have their own zone valve.

You may need to use a 3 channel timeclock depending on what controls come with the underfloor kit.

 

[Lofty]

Hi All,
As Lenny says you may need to have either a 3 channel T/clock or add a single channel one for the UFH.
What you actually have is an 'S' plan + (plus) the schematic for this can be found on the Honeywell website. If i have one I'll dig it out and post it on here.

Cheers,
Lofty.

 

[Guest123]

There's diagrams in the 'stickys' at the top of this forum.

 

[thewetspark]

The zone valves all have their own switch to give your boiler switched live, it only close when the valve is activated so there is no feedback to other parts of the circuit. Use a programmable roomstat for the underfloor and feed that direct from the supply to the heating circuit.

 

[Lofty]

Hi, heres the Honeywell UK link.
Honeywell United Kingdom Heating Controls

Simply register with them and you can then get all the diagrams form their downloads tab.

In addition to the 'extra' timeclock it will need it's own stat but I think that you have this already for the UFH. All switch lines from all three valves, i.e. the orange, are connected together to call the boiler for which ever reason DHW,CH or UFH.
Hope this helps.
Cheers,
Lofty

 

[Spudnik]

Must admit i would go for the programmable rooms stats on each zone.

Done this many times and works a treat.

 

[Sparkydan]

Thanks Lads

Connected it all up today but when i went to test it the wiring centre to the S plan was popping fuses but that might be the printed circuit board so im going to take it off and use 10 connector blocks, here is a diagram of the underfloor heating centre, I spoke to there tech today and they said its fine to take S/L from both center's to the same terminal in the boiler but this still dont seem right to me because of back feeding the unused S/L?

 

[Guest123]

Thanks Lads

Connected it all up today but when i went to test it the wiring centre to the S plan was popping fuses but that might be the printed circuit board so im going to take it off and use 10 connector blocks, here is a diagram of the underfloor heating centre, I spoke to there tech today and they said its fine to take S/L from both center's to the same terminal in the boiler but this still dont seem right to me because of back feeding the unused S/L?

The backfeed isn't an issue as it will only back feed on the orange wire as far as the microswitch in the closed valve.

 

[Sparkydan]

Ok cheers Lenny

 

[Lofty]

Hi Sparkydan,
Happy to help. Hope you are sorted mate.

Cheers,
Lofty

 

[judgeelectrical]

just wire a normal s plan and treat the under floor heating as a seperate entity, with its own controls stat and valve, the boiler will fire and not open the other valves.

You could also use the existing clock to control the underfloor, just connect the heating on button to the common of your room stat for the underfloor and then onto the valve and orange wir to the boiler live, then you need only set the one 2 chanel clock and the stat will contol the seperate vale to the underfloor

 

[Gazzdid]

Thanks Lads

Connected it all up today but when i went to test it the wiring centre to the S plan was popping fuses but that might be the printed circuit board

can i suggest double/treble checking your connections. sounds very unlikely to be a fault of the pcb, probably something shorting somewhere due to wrong connections. easy mistake to make considering the amount of cables/connections

Gazz

 

[Gazzdid]

Must admit i would go for the programmable rooms stats on each zone.

Done this many times and works a treat.

have to agree with you there jason, that will give more control over the system especially with the 3rd zone being underfloor heating. it can take alot longer to get to temperature, being on a seperate programmer to the rest of the system gives the user the option of having it kick in earlier. or a 3 zone programmer as mentioned earlier would do the job but programmable room stats tend to be a little bit easier for most customers to set up/understand

Gazz

 

[feebs73]

Hi There
just read through your post did you get it sorted, i have a simalier problem i have a s plan plus system and an UFH system aswell, i have wired it as i thought it would be correct.
It is a three storey house
ground floor, ufh polypipe system, with its own wiring center pump, zone valve
1st floor 1 zone valve
2nd floor, 1 zone valve
I have a three channel programmer, 1 ufh (ground flr), 2 heating (1st & 2nd Flr), 3, ho****er
valiant boiler
the plumber today has told me the ufh heating only works when channel 1& 2 are on together. he said that it did not fire the ufh on its own, so just woundering about the s/l to the boiler, it is in with all the orange cores from the zone valves in the wiring loom.

 

[feebs73]

very strange!!!
3rd channel is hot water

 

[thewetspark]

Hi feebs73.
Depends how the plumber has plumbed it!
If UFH is a complete separate zone with pump then it usually needs the heating pump to run as well.
You'll need the boiler switched live from the UFH system (if it has the Polypipe control then that has a boiler SL, if not the Orange wire from the zone valve gives it, neither will give unwanted feedback) to fire up the boiler & pump on the boiler system. Again there are numerous ways to achieve this and will depend how the plumber has plumbed it but the UFH pump is only for that zone, does not pump through the boiler usually, needs the system pump running.

If that doesn't help then I'll need more and precise info of how the system is configured.

I'm a plumber as well as a sparks and installed a lot of multi zoned systems and with mixed UF & rads.

It's about time the industry standard, (Honeywell) got away from the old S & Y plans and all the silly wiring needed for cylinder stats, they are a leftover from gravity systems, went to part pumped and then fully pumped so had loads of unnecessarily complicated ways to adapt the systems to work.
Best way now is programable roomstats and a single channel programer for the hot water.
Be nice if someone made a programable cylinderstat and then it would be real easy.

 

[i=p/u]

i myself have heating sytem to wire in new year, exisiting house, plus second floor extension heaters , hot water , and underfloor heating ground floor extension.

4 channel time clock with stats is what im thinking but im sure underfloor heating valve will be in completely differnt place from other valves which are beside burner. then manifolds and all,

lets face it havent a clue, so any tips on this 1?

 

[thewetspark]

Hi i=p/u

Programable room stats is the way to go, battery operated, just need a 2 core cable, each can be individually programmed. 1 in hall for downstairs, one on landing for up, 1 in the extension.
3 core and earth to the U/F setup, L / N / E & SwL return to the boiler. That programable roomstat is linked to the U/F setup direct.
If there is already a programmer use that for the hot water unless it's a combi.
If the system pump is big enough and the plumber uses 15mm Polypipe you'd get away with no second pump and manifold unless it's in a slab then you need the pump as you'd have to blend the water temp down.

I've done huge houses converted to bedsits / HMO's, you run a large flow and return pipe then stick a prog roomstat in each room, 2 port zone valve in a trapdoor under the doormat. Run a 3 core & E round in a loop to supply each room and send the SwL back to the boiler.
Dead simple, very efficient, gives you boiler lock out when no heat is required as required by the Building Regs. I've had 15 zones working perfectly like that, plumbing and wiring is simple so not much to go wrong, easy to see what is wrong if 1 zone plays up.

 

[i=p/u]

i know i need to meet with plumber to finalise, but i normal use a programable timeclock, then just stats as switches for the area, i.e in a office i programme from 8-5 and then stat does the rest..

im knew to this only done two heating systems... and as you say over time there is many ways to achieve whats needed..

 

[i=p/u]

easy when you know how

 

[Hants-Spark]

feebs73, hope this doesnt sound like a silly question but have you put a perm live on the UFH valve grey? Also does the valve actually operate when calling?

Sorry should have looked at all the replies and not just one page.

 

[feebs73]

Thanks guys for the replies,
i have had a nightmare of a day and just got in. As I mentioned before there is a 3 channel programmer, UFH system(poly pipe) all self contained pump, zone valve , manifold. The problem has been i have two heating channels, channel 1 ufh, & channel 2 radiators, channel 3 hot water.
the problem is the UFH works fine when channel one is on, but if I have channel 2 on aswell the UFH will not turn off unless channel 2 is off,
i have a back feed from the boiler s/l, when I spoke to poly pipe they informed me that there is a diode that stops feed back ( but it does not work )
I know the channel 1 will be on long than channel 2 but I would like it to work properly, what doe you think wetsparks.
it is probably something simple but I just can't see it!
thanks for reading this.

 

[feebs73]

Just read my last post, sorry my spelling was not great, but you should get the jist of it. Thanks

 

[thewetspark]

Wiring a standard S or Y plan the cylinderstat has to switch the hot water OFF not just have an ON (calling). As systems get more complex, heating only required at times, then you need to use the 'Hot Water Off' contact on the programmer.

Using programmable roomstats makes it all simple:

Heating zones;
Each roomstat has a live from the heating system isolator, it has it's own program so decides when heating is required occording to both time and room temperature.
It control a 2 port zone valve, calling or not.
The zone valve controls the boiler (and pump) via the microswitch.
You can common all the boiler SwL (Orange) wire if you have 2 or a hundred, the microswitch stops feedback.
No system water bypass is needed as the zone valve opens before the SwL is contacted so the boiler/pump always has somewhere for water to go.

Hot water;
Heating system isolator supplies the hot water timer, when 'On' a live goes to the cylinderstat, only use the 'calling' contact (NO HOT WATER OFF IS REQUIRED) which opens the zone valve for the hot water, it opens and the microswitch sends the SwL to the boiler. (Exactly like the heating zones.)

If a system your working on has a 3 port mid position valve then the hot water must be taken off that and a 'hot water off' taken from both the cylinderstat and the programmer or the valve won't move past the mid position to heating only and supply the boiler SwL via the orange wire.
Look on Honeywell's site and see how they are wired AND plumbed as you MUST use the correct port for the hot water, must use the 'Hot Water Off' if you want a heating only option.

As I said the standard sytem configiuration is outdated and needs scrapping, I have reels of five and seven core as you need it to make things work if existing systems keep getting added to, valves and pumps all over the place, standard roomstats that have been upgraded needing a 3c & E as they need a neutral for the compensation resistor.
In my experience it's far quicker and you get a very simple and reliable system if you just go the programmable roomstat route, each zone is fully programmable, each zone gives boiler lockout. (Required by the Building Regs so the boiler doesn't keep cycling on the boiler temp stat.) The client can easily program each stat so upstairs and down can be different, odd rooms or an extension different, the programer is on the stat so right there where the temperature is set so no confusion over which channel does what on a multi channel programmer.

 

[i=p/u]

so are you saying just take live to programable room stat and forget the time clocks?

- - - Updated - - -

if you have few zones.. last time clock was £180 and took an hour +to programme

 

[thewetspark]

Basically yes but good practice & Regs to have the heating system on an isolator, so the boiler and everything else is dead if you need to service it. Why I said supply from the heating isolator.

Programmable stats are around £50-£75 each, some are just 24 hrs, some 5/7 day and some 7 day. Most have an overide and/or 'extra hour'.
I personally like Drayton 'Digistats', they do several models.

Sorry, just read this again and maybe didn't explain well enough.

A programmable roomstat is a conbination digital roomstat and a programmer, it governs the heat of the room for set periods so makes a programmer obsolete for the heating. Most you set the maximum heat of the room for each period, some have five periods each day, there is no 'off' period just set the time when the room is not in use to a low level, could be so nothing freezes or warm enough to stop condensation and if you get into it (look at a few technical articles) then you don't use as much heat to get the room back up to 'living' comfort if it's not been allowed to go completely cold but maintained at a reasonable temperature.

 

[feebs73]

Hi wetsparks
the water channel does not affect the UFH system, the problem is the heating channel two( radiators over 2 floors ) each floor has a standard honeywell room stat, they work fine turning each zone valve off. What I can't get my head around is why the UFH system stays on when channel one is off ( UFH ) and channel two (1st & 2nd flr radiators ) is on, yet the hot water with the orange wire in with the others makes no affect on it.
I went back to the job today every thing is working fine, apart from the above situation but like I have said before, channel one is on long before and after channel two is finished.

And to top this off my own boiler has developed a fault and needs restarting every time I want it to fire.

 

[thewetspark]

Hi feebs73.

Zone valves are two ports, in & out, they have a microswitch that gives a SwL when they are open. They are either open or closed.
Mid position valves have three ports, one 'flow' (hot) from boiler, one 'flow (hot) to heating A, one 'flow' (hot) to cylinder B. Have the same microswitch to give a SwL to the boiler but need a 'hot water off' signal, on grey wire, (from cyl stat and maybe the programmer) to supply only the heating. - This gives a lot of wiring problems with feedback if you get it wrong and are often in a system that gets added to with an extra zone on a zone valve.
You can't just replace a mid position with two zone valves as sometimes the boiler needs an pump overrun to cool down so has to have a 'bypass' to pump the water round, a mid position valve is never closed, always one port open so is a built in bypass.

Supposedly impossible but when lots of boilers needed an overrun I used to cascade mid position valves to give me zoning instead of having a perminent bypass which made balancing the system impossible at times. Wiring is a little complex though.

So if you have a 'zone' that will not operate on it's own and the wiring is correct then make sure the original heating (rads) and hot water aren't on a mid position valve (3 port) as you need a 'hot water off' signal to make the mid position valve close the hot water down, the cylinder stat does it on temp rise but it won't go 'off' if the programmer doesn't also give 'hot water off' signal when the hot water is due off on the timer!

 

[thewetspark]

Hi feebs73

U/L needs to switch on it's own zone valve AND pump AND the boiler with the main system pump. The U/F controller,stat should switch the zone valve and pump, that zone valve will then switch the boiler and main pump on.
If you're using the U/F controller/stat to switch everything then you'll get feed back from the other zones, using the U/F zone valve to swith on the boiler will eliminate that feedback.

 

[i=p/u]

All oranges , greys , blues, green and yellows together, brown and black for each zone switching

 

[feebs73]

Ok will give that a go ta

 

[helloeddy]

hi,

I am just about to install a 2 zone s plan plus, one for rad's and one for UFH, both with separate stat/programmers, I have a vaillant ecotec plus 837 combi boiler, and have bought two NC honeywell port valve's, on the wiring do I wire the UFH pump to the call from the stat (brown) before the zone value so I don't get feedback from the rad's stat running the UFH pump?

also what do you recommend regarding pump overrun on the main boiler? I don't think it has the facility to have a direct input, so would need an external relay? and also for it to also hold the rad's port value open for the time also.

Cheers

 

[gnuuser]

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