Navitron Renewable Energy and Sustainability Forum

WIND TURBINES => Direct Heating Systems => Topic started by: freddyuk on January 12, 2018, 10:27:19 AM

Title: Relay wiring questions
Post by: freddyuk on January 12, 2018, 10:27:19 AM
I am rewiring my S PLAN central heating system to separate the UFH and Radiator heating circuits. I have 3 radiator zones and 2 ufh zones with 2 cylinders for DHW.
All the radiator zones and DHW are in one wiring centre with UFH in a second wiring centre (too much for 1 centre!)
All zones controlled by programmable room stats. DHW by standard cylinder stats (with solar surplus diversion control).
I have a mixing valve for the UFH which uses boiler circuit water so this cools it down. You need to pull the UFH flow through this valve so a second pump is required. Pump 1 is standard S Plan feeding 5 wire motorised valves to each zone.
Pump 2 has 2 motorised valves which split the loops into 2 zones.

In standard S plan the pump and boiler are switched on by any of the valves energising the orange wire via any of the thermostats calling for heat and switching power through. The pump and boiler are common.
If I want to use 2 pumps and separate the zones for each pump I need to separate the pumps from the boiler power or otherwise both pumps will run.
I have a relay (8 pin) which I want to use to connect Pump1 for all the rads and switch over to Pump2 for just the UFH.
If both pumps are required then they must be able to run together. I think I need 2 relays to achieve this as one will switch on or off just one pump.
I have no idea how to wire this to make it work.
Has anyone done this?

Title: Re: Relay wiring questions
Post by: offthegridandy on January 12, 2018, 11:10:38 AM
A drawing would help Freddy but I think I get your drift.

I agree you will need two relays.

Live feed from boiler to relay 1 C and relay 2 C. Relay one gets signal from zone one to switch relay one, and pump one goes live. Relay 2 takes signal from zone 2 if zone 2 is calling then pump two gets switched as well. Or vice versa.


Title: Re: Relay wiring questions
Post by: martin W on January 12, 2018, 06:11:08 PM
Slightly off topic, as a drawing would help me understand the layout you've got...

Salus do a cracking wiring centre which is quite large, and very configurable..

usually about 15 from eBay, amazon, etc...

Title: Re: Relay wiring questions
Post by: freddyuk on January 13, 2018, 08:08:59 AM
Here is a standard S Plan layout. The pump and boiler are connected to terminal 10 so each valve can open and switch on both boiler and pump. Now add a new zone valve with it's own pump for UFH and you can see you cannot connect the new pump to the boiler as the boiler must be fired by pump 1 and if that boiler connection is live both pumps will come on. You have to separate the new pump from main pump and also connect to the boiler but be isolated from the other zones on terminal 10 and the main pump.

I ended up with 8 pin DPDT relays. I need to split the zone valves to there own switched terminal so UFH goes to one terminal and the other zones go to a separate terminal.

I power up relays through pins 1 and 7 to energise the coil from the switched terminals of the valves ie. orange wires (say terminal 11 and 12)) so any valve opening will power up the respective relay? I have live from terminal 11 going to pin 7 and a neutral going to pin 1. Valve opens and relay closes the NO contacts?
How do I wire the pumps and boiler to these. ? Is it just the live feed for pump 1 in and out with neutral picked up in wiring centre on one NO connection and boiler live feed to the same NO connection? Then do the same for the other relay with another common boiler live feed and live feed to pump 2.
Zone 1 calls for heat and boiler and Pump 1 switch on. Then UFH calls and boiler is already running so just pump 2 starts up. Then Zone 1 is satisfied so valve closes and Pump 1 stops but pump 2 and boiler keep going.......

Title: Re: Relay wiring questions
Post by: freddyuk on January 13, 2018, 05:19:59 PM
It does not work! Tried various ways to wire in the boiler via separate terminal but it still backfeeds to the relays. I can have one pump and boiler running OK. I then switch second zone with Pump 2 and both pumps run and boiler runs.
When I turn off either zone the relays remain energised so pumps run but valves are closed.

Commoning the boiler into relay backfeeds.
Using the other terminal NC to get a relay feed does work but as soon as both relays are on one or the other will not switch off due to the boiler which must power up the relay either terminal that is connected.

I am out of ideas?

Title: Re: Relay wiring questions
Post by: paul149 on January 13, 2018, 06:40:19 PM
PhotoBlockit strikes again, Brilliant, the death knell to all highly informative and enlightening forum threads!!!

Paul m.

Title: Re: Relay wiring questions
Post by: Antman on January 13, 2018, 06:50:58 PM
Can't see your diagram due to pbucket hosting restriction. Try uploading it to the Forum store.

I'm trying to get my head around the various posts. But have you tried separating the boiler CFH (Call for Heat) from UFH and S-Plan via two independant relay NO contacts? So...

  S-Plan valve runs main pump from term 10 (commoned Zvalve switches) as usual but also to coil of Relay1.  NO to Live and Com of relay 1 to boiler CFH.

  UFH valve runs UFH pump and coil of Relay2. NO of Relay2 goes to L and Com of Relay2 to boiler CFH.

This should isolate the CFH to boiler from respective sources. I am assuming that the primary S-Plan pump is directly connected to terminal 10 and not direct from the boiler via a pump over-run relay (within the boiler). That may give you unexpected results.
Also make sure there is no hidden/missed commoned connection link left in somewhere joining the pump or boiler connections.


Title: Re: Relay wiring questions
Post by: freddyuk on January 13, 2018, 07:24:33 PM
I think I have it sorted. There are a lot of permutations but I had switched lives when I could use permanent lives and also the boiler feeds were connected to a different pin. Andy was correct but there are a few other cables to get right!
I will do a drawing so it can be verified in case anyone else wants to do this. I feel a bit inadequate having not got this right first time.... banghead:

Title: Re: Relay wiring questions
Post by: offthegridandy on January 14, 2018, 09:26:17 PM
Sorry Freddy I can't see a diagram either so can't be of more help yet I'm sure it must be possible.

Good luck.