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..