H/W and H/W with C/H together but NO C/H ON IT'S OWN - HELP!

[Wildeman]

I am hoping that someone will be able to help me with the problem I am experiencing with my Central Heating system.

I moved into the house (4 bed Detached) 6 years again and the system has never worked properly.

I have a Glow Worm Ultimate 60BF boiler, Wilo Gold 50 Pump, Honeywell Cylinder Tank stat, Sunvic SD2701 3 Port Diverter Valve, Sunvic Select 207XLS 2Channel Programmer and a Sunvic TLX6501 Programmable Room Stat. Everything with the exception of the boiler has been replaced in the last 6 months (including the 3 Port Diverter Valve body) and the system has been rewired to a Y-Plan following the replacement of a Danfoss 103E programmer (with the Sunvic Select 207XLS) to allow independant control of C/H and H/W. The radiators are connected via Microbore and all of them have been removed and flushed out.

The problem I have is a 'weird' one, when no H/W or C/H is demanded the grey wire from the valve actuator is the only wire of the 4 live which is normal. When H/W is demanded the boiler fires, pump starts and hot water is passed through the Hot Water cylinder via the Diverter valve which is normally in the H/W only position and heats the tank. The orange wire from the actuator becomes live and grey is NOT live.

If C/H is then demanded together with H/W the valve moves to the Mid Position and there is power on White and Orange, pump spins and boiler remains lit the water is heated and the radiators get hot.

If H/W is no longer demanded (the cylinder stat has reached its temp) but there is still a demand for C/H the valve moves to the H/W position, when it starts to move from the Mid Position the pump stops (not sure about boiler as cannot be in too places at once - boiler in garage and valve in airing cupboard upstairs!!) then the actuator moves the valve to the final C/H only position there is a click of the microswitch in the actuator and the pump fires up again (power on white, grey and orange actuator wires). The main problem I am experiencing then happens whereby within a few seconds the pipe from the boiler to the pump and subsequent pipes after the pump and diverter valve on the C/H side become cold and the boiler is not fired up (only pilot light lit)

This problem is also apparent if I try to fire the system up from cold onto C/H only the pump starts, valve moves to correct position (power on White, grey and orange) but boiler does not fire and no heat to radiators even though the room stat is turned up and calling for heat.

So to conclude I can only get the radiators to remain on by turning the cylinder stat up to max (90 degrees) and have the H/W and C/H on together at the programmer which is a waste of energy and I have Franke taps with cartridges in them that cannot exceed 60 degrees water temp.

Can someone please help me with this puzzle as I have spent a lot of time and money in investigating myself, plumbers, electricians not to mention the cost of the replacement parts??

I am technically able so any assistance will be gratefully received.

Thanks

Andy

 

[doitall]

Have you fitted the valve the right way round

That would be port A&B common. Port A to heating and Port B to the cylinder.

Is there 240v on the white in the heating only mode.

 

[Wildeman]

Thanks for the reply doitall

Yeah the valve is fitted the correct way round, AB to the Pump, A to the heating and B to the cylinder

When the valve is in heating only mode there is power to Orange, White and Grey. I have not tested the voltage value just the fact that there is power using a neon mains tester screwdriver.

Should I test the voltage on the white wire in Heating only mode and should it be 240v or some other value?

 

[doitall]

Need a multimeter really.

If there's power on the white, grey and orange the boiler should work.

Where/what is the pump connected too.

 

[Wildeman]

I have a multimeter so can test the values on each wire if that will give more of a clue to the issue, really want to get it resolved and working.

When the valve is in Heating only mode the Live feed to the boiler is Live (again tested with Mains Tester neon screwdriver but not tested voltage)

The Pump is connected to the 10way junction box as per the Y-plan diagram, Live is in 8 connected to orange from valve and feed to boiler and neutral/earth connected to the relavant terminals in the junction box.

Pumps runs in all modes H/W only, H/W and C/H and C/H only.

Could it be a voltage issue?

 

[doitall]

As I said it there's 240v on the white and orange it should work.

The grey is connected to the cylinder stat sat ?

 

[Wildeman]

Yes the grey lead is connected the cylinder stat but cannot remember the terminal number off the top of my head will check later

I will check the voltage on the White and Orange wires - any other ideas if they are both 240v?

 

[kevplumb]

ive got the fault finding in a pdf if it will help
if you e mail me adress in profile

 

[Wildeman]

Thanks KevPlumb, emailed you at the address in your profile

If you could send me the PDF that would be great, will it help me solve the issue?

 

[MANDATE]

In hw or hw/ch mode the power to light boiler comes from the cylinder stat.
In ch only mode the stat is no longer live and the power comes from the 'orange' wire of the valve.

In the terminal box the wire from the stat and the orange from the valve must be connected together to allow boiler to work from either source.

So check to see its connected correctly and to ensure there is 240 volts.

If the valve has moved across to the ch only position, then it proves the room stat and the white wire are working ok

 

[kevplumb]

Thanks KevPlumb, emailed you at the address in your profile

If you could send me the PDF that would be great, will it help me solve the issue?

sent

 

[Wildeman]

Thanks for the docs Kev, I will look at the troubleshooting flow chart although our boiler does not have a fan and no circuit boards in the main controller.

Will let you know what I find.

 

[Wildeman]

Thanks doitall and Mandate,

All the wires are connected correctly as you suggest and to the Y-Plan diagram. I have today had an electrician test all the voltages and I am getting 240v at all points and even getting 240v to the Boiler live feed when in CH only mode or HW/CH and the HW cylinder stat is satisfied. The electrician has confirmed all wiring is to Y-Plan and the thermostat/control valve on the boiler appear to be working.

I have tried removing the head from the valve and manually moving the valve, when I move it to the CH only position with the programmer set to HW & CH and the cylinder stat calling for heat I still get no heat in the radiators and notice the feed to the pump and from the pump go 'cold'. I am now starting to wonder if it is the plumbing. I can see a feed pipe and return pipe from the boiler (which is in the garage) disappearing into the ceiling and in the airing cupboard I can see a pipe coming up into the pump (presumably the feed from the boiler) and then the pipe from the HW side of the valve goes into the cylinder and the feed out of the cylinder disappears under the floorboards and the CH side of the valve goes straight down under the floorboards.

The radiators are on micro-bore and I am wondering if there is a lack or return pipe to the boiler on CH only, if I manually move the valve from CH only to the mid positon I can hear a "whoosh" of water the pump seems to speed up and hot water flows (the pipe to the pump gets hot and so does the CH&HW pipes from the valve. I can never recall the heating working independantly from the HW as I used to have the cylinder stat on 90 degrees but now I have new tapes they advise not to have the hot water above 60 degrees.

Can anyone help me any further, if see all the pipework is a nightmare as the house does not have old-style floorboards but large chipboard sheets which need to be cut to be lifted.

Surely this must be something simple if the electrics are ok and a blocked pipe would mean no heating in any mode!!

HELP!!!

 

[Wildeman]

Thanks Kev for the troubleshooting diagrams but all tested and OK as checked by a qualified electrician.

 

[doitall]

The boiler and the pump should be connected to the orange wire.

There's nothing to stop it working, only installer error, or air.

Do you have a by-pass valve.

Can we have some pics.