Relay or contact or available?
- Thread starter coopersim
- Start date
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it is but vaillant didn’t know what I was trying to achieve and therefore stated their kit was not compatible hence me trying to find a solution to positively isolate their kit when the occupancy sensor kicks in.
What pump is it? Does it use under 5 amps?
Two of these would do it if you want to go that way.
https://www.amazon.co.uk/gp/product/B00GN7OQH2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Wire the Vaillant into one relay coil. Wire the motion sensor into the other relays coil.
Wire the pump so its feed goes into both relay contacts in parallel.
If its was mine I would just wire it up without the relays as long as the Vaillant and motion sensor had the same point of isolation.
Two of these would do it if you want to go that way.
https://www.amazon.co.uk/gp/product/B00GN7OQH2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Wire the Vaillant into one relay coil. Wire the motion sensor into the other relays coil.
Wire the pump so its feed goes into both relay contacts in parallel.
If its was mine I would just wire it up without the relays as long as the Vaillant and motion sensor had the same point of isolation.
Always best to buffer your inputs- avoids any arguments if their expensive box does throw a wobbly.
If you want to wire it right now and the plan is either source going high activates the pump then you could get away with your single relay;
Coil L goes to PIR output.
Coil N goes to neutral.
Contact COMMON goes to pump LIVE.
Contact normally closed goes to the Vaillant output.
Contact normally open goes to a permanent LIVE from the heating system.
States:
Relay passive (detector not triggered) Vaillant runs pump as normal
Relay active (detector triggered) pump runs until detector goes passive then switches back to Vaillant.
If you want to wire it right now and the plan is either source going high activates the pump then you could get away with your single relay;
Coil L goes to PIR output.
Coil N goes to neutral.
Contact COMMON goes to pump LIVE.
Contact normally closed goes to the Vaillant output.
Contact normally open goes to a permanent LIVE from the heating system.
States:
Relay passive (detector not triggered) Vaillant runs pump as normal
Relay active (detector triggered) pump runs until detector goes passive then switches back to Vaillant.
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The problem with that concept is that if one of the systems is powered via a transformer then phase changes occur which will tend to 'upset' things
But, as suggested very early on, a pair of simple isolation relays is all that's required.
Who knows. Use isolation relays as exhaustively described to buffer the inputs and you won't have to care
It's not a transformer feeding the pump that's the problem.
Take a mains supply and split it into two circuits. If one of the circuits then runs through an isolation transformer, the transformer output will be out of phase with respect to the other circuit (by about 20 to 30 degrees) If you then connect the two circuits back together, there will be high circulating currents due to the phase mismatch.
So are we saying the pump or PIR are run via a transformer....Seems oddly complicated for a boiler / PIR.
But yes have a relay run a relay. It will be fine either way...
But yes have a relay run a relay. It will be fine either way...
No, all I was pointing out was that a common supply rail, split into 2 circuits, one of which contains an isolation transformer, cannot have the circuits rejoined without experiencing problems.
It may not be as simple as some seem to think.
I had a situation with 2 boilers, to run as main / standby. The boiler installers simply connected the 2 pump outputs together.
When the building works were completed and people moved in it was discovered the boilers were not big enough so the system reconfigured to main/boost. Unfortunately part of the boiler lockout system was detecting electrical conditions on the pump circuit and whenever the second boiler tried to fire it went through its test sequence and seeing 230V it went into lockout.
I added a pair of relays, only to discover the boiler also monitored the pump current (>1/4A or thereabouts IIRC). I have no idea if the Vaillant have anything similar.
I had a situation with 2 boilers, to run as main / standby. The boiler installers simply connected the 2 pump outputs together.
When the building works were completed and people moved in it was discovered the boilers were not big enough so the system reconfigured to main/boost. Unfortunately part of the boiler lockout system was detecting electrical conditions on the pump circuit and whenever the second boiler tried to fire it went through its test sequence and seeing 230V it went into lockout.
I added a pair of relays, only to discover the boiler also monitored the pump current (>1/4A or thereabouts IIRC). I have no idea if the Vaillant have anything similar.
Personally I'm still trying to understand why there is a requirement to run a heating pump under room occupancy control without a heat source.
I'm convinced OP's requirement is to add a heating override to the existing (time controlled?) heating system which may be a far simpler option.
I'm convinced OP's requirement is to add a heating override to the existing (time controlled?) heating system which may be a far simpler option.
Many boilers use a triac to control the pump.
If your boiler REALLY does use a relay contact effectively directly between live supply and pump output without any of the voltage/current sensing mentioned earlier - then there is no identifiable reason at this distance why another relay contact cannot be added in parallel with it. BUT this depends entirely on your ability to assertain the exact circuitry within the boiler.
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