S Plan Help Please

[gselectrical]

Evening all.

I am after some advice on a heating system we will be wiring in a few weeks.

Basically we have 2 boilers, 6 zone valves, 3x CH pumps, 1 dual channel programmer and a hot water circulating pump with its own programmer.

2 zones will share a pump. Each room stat will operate a zone valve. If we wire the system as a conventional "S plan system" then if one stat calls then all 3 pumps will run, which we want to avoid. So I thaught we could run each pump off the brown of each valve, the problem we have then though is that both valves on that pump will open even if only one stat is calling.

I hope this makes sense.

Any help/suggestions would be much appreciated.

GS

 

[NozSpark]

What make valves are you using?

 

[ProDave]

For a complex system like that, forget 3 port valves, your brain will melt trying to work it all out.

For each "zone" have it controlled by a simple 2 port valve, so its own thermostat and programmer drives the valve for that zone. That's true for heating and hot water circuits.

Then when any zone calls for heat, it will fire up the boiler(s)

The hot water circulating pump is a little different, have that on its own timer (probably the same timer as the hot water programmer) but it wants to pump all the time, even when the tank is up to temperature and not "calling for heat" so controll that directly from the programmer, not via the thermostat or zone valve.

Any more advice would require a plumbing and valve diagram of exactly what you have.

 

[gselectrical]

Not sure what meke valves the plumber will be installing. I'd imagine Honeywell.

Thanks Dave.

The hot water circulating pump is not a problem, we have wired them in the past.

2 port valves will be used.

My issue is with the CH pumps, the valves will be connected to something (I can't remeber what the heating engineer called it) that will balance the load between the 2 boilers. 3 pumps, 6 valves, 2 valves on each pump. I need to figure out how to wire the system so that when one zone calls, it does not run all three pumps, and does not open the other valve connected to that pump that is not calling.

Cheers lads.

GS

 

[steptoe]

I'll 2nd Dave there

I recently done something similar,

16zones, with overlapping pumps and simply used zone valves to control what zone actually needed heat,

BTW, this involved a combi boiler supplying a HW cylinder as well, so that was simply another zone,

use the stats to open and close what zone valve is required, and the 'fire wire' from each valve to operate the boiler/pump.

 

[NozSpark]

Just wire each pair of stats/valves and pump as a s plan, it will not actuate the other valves or pumps if done correctly

 

[Steve3948]

Was it an Optimiser.

 

[ProDave]

A neutraliser is often used to combine multiple heat souces into one, but that's a purely passive thing, and from what I hear doesn't work very well.

 

[wozz]

I think you will have to fire the pumps through 3 contractors to avoid them all coming on.

 

[gselectrical]

Just wire each pair of stats/valves and pump as a s plan, it will not actuate the other valves or pumps if done correctly

Cheers for the input guys.

If I wire it as a normal "S-Plan" where the orange's fire the boiler and pumps, then if one zone calls,  it will open that zone valve only but run all 3 pumps due to the live on the orange backfeeding to the other pumps.

GS

 

[wozz]

5 replies since the last one I read so my post may not make sense

5 replies since the last one I read so my post may not make sense

 

[NozSpark]

Cheers for the input guys.

If I wire it as a normal "S-Plan" where the orange's fire the boiler and pumps, then if one zone calls,  it will open that zone valve only but run all 3 pumps due to the live on the orange backfeeding to the other pumps.

GS

But you don't normally wire the valve to fire the boiler,, the boilers own stat maintains the jacket temperature,,, unless the boiler needs the pump to run on and the boiler is wired directly to it,, in which case the boiler is not really suitable for what for your needs

 

[steptoe]

Cheers for the input guys.

If I wire it as a normal "S-Plan" where the orange's fire the boiler and pumps, then if one zone calls,  it will open that zone valve only but run all 3 pumps due to the live on the orange backfeeding to the other pumps.

GS

it can be configured to NOT do that, but it starts getting complicated,

the EASIEST way of doing what you want is probably an UFH wiring centre, simply get one with enough zones [6 for the stats] , enough outputs [3 for your pumps], and a heating call for the boiler,

it doesnt matter if it exceeds those numbers, thats just the minimum you need, maybe another 200£ but it will save you a whole heap of time and trouble if you are slightly unsure of exactly just how to configure the wiring.

 

[wozz]

But you don't normally wire the valve to fire the boiler,, the boilers own stat maintains the jacket temperature,,, unless the boiler needs the pump to run on and the boiler is wired directly to it,, in which case the boiler is not really suitable for what for your needs

You have lost me there.

Stand by previous post three contractors and all will be fine.

 

[Steve3948]

I would think the boilers will have a master flow pump, the zones will then have their own pumps, so the stat would open the valve and pump, the aux would then fire the boiler and master pump.

With two boilers or more this may all be via an optimiser control panel with outdoor stat to determine when and what time boiler or boilers need to come on to achieve temperature.

 

[wozz]

A compensator wasn't mentioned and I think that will all be done at the programmer and of things rather than the boiler and pumps end.

 

[gselectrical]

But you don't normally wire the valve to fire the boiler,, the boilers own stat maintains the jacket temperature,,, unless the boiler needs the pump to run on and the boiler is wired directly to it,, in which case the boiler is not really suitable for what for your needs

The boiler will have a permanent feed (to allow overun pump etc) The ext controls will be wired through the relay within the boiler (Worcester)

I would think the boilers will have a master flow pump, the zones will then have their own pumps, so the stat would open the valve and pump, the aux would then fire the boiler and master pump.

With two boilers or more this may all be via an optimiser control panel with outdoor stat to determine when and what time boiler or boilers need to come on to achieve temperature.

This would be the case if we had 6 pumps (one for each zone) but we don't. Yes the boiler does have a "master flow pump" which will be wired directly into the boiler.

Have you got an expensive budget ?

Small IMO/Siemens /Allen Bradley PLC in a small Panel with motor starters for each pump and zones all wired back to the plc, small HMI for visuals and temperature display and off/auto/manual and tie clock and night setback etc

Can also incorporate VSD's on the pumps for flow control and energy saving

Just suggesting......

Good suggestion, however budnget is an issue. The most cost effective solution I can see is to inatall 6 pumps, one for each zone?

it can be configured to NOT do that, but it starts getting complicated,

the EASIEST way of doing what you want is probably an UFH wiring centre, simply get one with enough zones [6 for the stats] , enough outputs [3 for your pumps], and a heating call for the boiler,

it doesnt matter if it exceeds those numbers, thats just the minimum you need, maybe another 200£ but it will save you a whole heap of time and trouble if you are slightly unsure of exactly just how to configure the wiring.

Whats the complicated way steps!? Your suggestion of a UFH wiring centre is a good idea, that would work, and won't be too complicated.

Cheers lads.

GS

 

[steptoe]

pump overrun?

have you [the plumber] allowed for a seperate non-TRV rad for this I take it?

the complicated way is just that, well, trying to explain it is anyway, well for me,

but once you get your head around it its actually fairly simple [relatively]

its not something I could even contemplate typing out,

but I could try, [TRY], and explain it to you, dunno if it would help much though with the way i put things into English sometimes.

 

[Steve3948]

So 2 Zones share a pump, use a couple of relays with pump wired across N/O on both, with each coil fed from aux of each valve.

 

[ProDave]

Step's has it, an UFH controller.  Will open each zone only when that zone calls for heat, but will fire the boiler when ANY zone calls for heat.