Hive wired wrong?

[CalzorSuzay]

Ok having been out to he shops there's a Maplins 5 minutes down the road so I popped in and bought that linked capacitor whilst out, it has "LCR, MKP/SW/WF, 100nF 5% 500 VAC 13-24" written on it before I find out the Maplin guy gave me the wrong one and blow something up

It's quite big and has plenty of wire so will easily bridge from the blue wires in top 2nd from left to orange in top 3rd from right, is this ok? I can add protective sleeve on the bare wire.

And just to clarify besides hopefully stopping the boiler running permanently it will close the 3 port valve to the CH?

 

[jackthom]

That sounds like the right one, it is a fair size. Adding protective sleeve is a very good idea and assuming the boiler is firing because of electrical leakage through the 3 port valve it should help stop that.

The 3-port valve won't necessarily close back to the DHW-only position after each period of supplying central heating but that's normal and shouldn't cause the boiler to fire if there's actually no demand from the DHW or Heating thermostats.

 

[CalzorSuzay]

With the port open though if there's a call for the HW won't that then pump hot water round the heating as well or is this what I see when I make an on or boost to the HW the valve closing like it should do?

 

[Agile]

The capacitor makes no difference to the operation.

It just reduces the stray voltages coming from the valve when its off.

Tony

 

[jackthom]

With the port open though if there's a call for the HW won't that then pump hot water round the heating as well or is this what I see when I make an on or boost to the HW the valve closing like it should do?

As soon as there is a demand for 'hot water only' the valve should spring back to the correct position, if it isn't already there.

 

[CalzorSuzay]

Ok a quick multimeter test

Power cut and it back on as a reset...
From blue wires in top 2nd from left to orange in top 3rd from right

With nothing running I get
3v across the two

With HW running I get
247v-248v across the two

With CH on it goes from 3v
to 139v
I hear the motor move slowly there's two clicks at the 3 port valve which I guess are the micro switches then voltage fluctuates a bit then goes to a constant 245v-246v

with the heating then turned off/satisfied it then falls to
136-137v and stays there, also the valve doesn't move

Unless I call the HW at which point the 3 port valve resets and the voltage drops to the standby 3v

I guess it's the 136-137v heating off/satisfied state we're trying to remove here which is keeping the boiler going?

 

[jackthom]

Yes that's right.

When DHW is satisfied there is 230V on the grey wire which passes through a couple of resistors (total around 300k Ohms) inside the 3-port valve and a fraction of that voltage comes out on the orange wire while the valve remains locked in the Heating Only position.

http://www.diyfaq.org.uk/plumbing/controls/midpositionvalve.htm

The capacitor should drop that voltage considerably, probably to less than 30V

 

[CalzorSuzay]

Well I fitted it and with the valve open heating turned off/satisfied voltage fluctuates between to 11v-19v and stays there between the Orange & Blue neutral.

Initially I thought I wired it wrong as I turned it back on again, called the HW and nothing happened, eek! Then realised it was probably a tank full so turned the thermostat requirement up on the cylinder and it all kicked in.

I guess the next few days will tell if it works.
I've insulated the bare wires from the capacitor and pulled all the others away from it, does/will it get hot in use, I haven't put the cover back on yet but don't want a house fire caused by it overheating etc?

 

[jackthom]

No the capacitor won't get even warm if it's working as it should.

Had a resistor been used instead that would have warmed up, although using only a fairly small amount of power.

 

[CalzorSuzay]

Well a few days on and all seems good so far so thanks to all
I also had a concise email back from Glow Worm also explaining the same thing with a part number for the capacitor and boiler fitment. I looked the part up and it was about £75 odd!

 

[jackthom]

Thanks for reporting back. I love how they want £75 to fix what looks like their own design problem.