contactor for underfloor heating

[bennjy]

Hi
I've installed the electrics for an underfloor heating system. The system has 6 manifolds each with a small pump. There is then a primary pump that pushes hot water through the system from an aerobic digester next door. I have fitted 6 contactor each using a switch wire from the thermostat to energise terminal 1 of the contactor, I have then linked from terminal one to a of the coil. I've taken a neutral to all contactor in parrelal in terminal 2 then from 2 to a2 of each contactor. I've then connected in parrelal the primary pump to terminals 3 and 4. This works fine with one stat, when it calls for heat aswell as energising the secondary manifold pump it also energises the contactor and energises the primary pump. The problem is, is that when another stat calls for heat if the other stat goes off the contactor still stays energised until all stats are off. I don't think it's latching contactor I'm sure there non latching could be wrong tho. I'm sure it's a wiring fault so any help would be great .

 

[Leesparkykent]

I misunderstood in my post #5 I skim read the bit about 6 contactors, I thought you only had 1. Draw it out, it's not a difficult one.

 

[dansk]

OK - repeat this at each manifold.

From a local switch fused spur bring Live & Neutral into a JB (small adaptable box), connect live into "2" connect the primery pump/boiler enable to "1"

Connect A1 to Neutral.

The switch live from the thermostat connect to A2 and also connect the live for the local pump to A2.

Make sure all the electrical feeds to the manifolds are fed from the same heating circuit.

 

[bennjy]

Thanks for that. The way I've done it is to energise the coil with the switched feed then terminal 2 to primary pump but I guess that is enabling the contactors to stay latched once switched until all feeds are broken. I've mounted the time clock on a adaptable box so all cabling and contactors are in there. I've used 5 core tho so it's easy enough to do there

 

[Leesparkykent]

Thanks for that. The way I've done it is to energise the coil with the switched feed then terminal 2 to primary pump but I guess that is enabling the contactors to stay latched once switched until all feeds are broken. I've mounted the time clock on a adaptable box so all cabling and contactors are in there. I've used 5 core tho so it's easy enough to do there

Are there any valves?

 

[bennjy]

No valves

 

[Resu]

Might have misenterpreted the OP but are you sure the "small pumps" are not actuator heads? Not sure contactors are needed here...

Otherwise what type of stats are you fitting and what rating are the pumps?

 

[bennjy]

No its right as I just haven't wired them right for the job. There the same pumps as what you'd find in a domestic boiler install. It's one large area split into 6 zones. Each zone has a manifold and secondary pump. There is then a primary pump to get the water to all these pumps. I need it so when a stat calls for heat the primary pumps starts aswell as the manifold pump. It works but i wired the contactors wrong as they stay latched once another stat calls for heat. It's only when they all switch off that the contactors de-latch. Once the contactor is wired so there art any back feed to the pumps it will work fine.
Hope this makes sense

 

[bennjy]

There digital stats

 

[Resu]

Ignore this post just now!

 

[Resu]

Sw from each stat to a1 of each contactor, sw also straight to individual manifold pumps. Output of each contactor to main pump.

 

[dansk]

Well follow my advice then and it will work, otherwise get someone in who can help you.

 

[bennjy]

Same as dansk I think his/her name Ian's said then pretty much. Thanks for your swift response and help tho it's very much appreciated.

 

[bennjy]

Is not Ian's

 

[Resu]

Well follow my advice then and it will work, otherwise get someone in who can help you.

Just realised my response was the same as yours! Beaten to it!

 

[bennjy]

Thanks for the help. I understand how this should now be connected but because there wired in parallel at contact "1" will they not have a back feed and hold the other contras open once they have been enabled?