3 port valve (DM 5651 Actuator) Sunvic. 8 years of confusion

[Hugh Jaleak]

I would consider changing the valve to a Honeywell. The Sunvic valves dont seem to last very long, as I found out....

 

[spiceman]

Afraid it gets quite complicated. When HW is called for alone the boiler is supplied with power from the cylinder stat. The valve does not play an active role.
If CH is also called for while HW is still called for, the room stat supplies power to the valves white wire. This powers the motor until microswitch is triggered at mid position. There is no power on the 'grey' or 'yellow' in your case, so the valve stays at mid position. Boiler still being supplied power from cyinder stat.
When HW is satisfied (or turned off) the cylinder stat is out of action in supplying power. Two actions are required for the sysytem to continue.
First the valve must move from mid position to CH only and power must be supplied to the boiler.
The cylinder stat is of a two mode, so power that was going to boiler is diverted to the valves 'grey' and when this is live it takes over from the white and moves the valve over the final stage. This diversion wont work if HW was never on, so alternative is introduced coming direct from the programmers HW switch (another two way). The wire coming from the OFF terminal. It does not matter if this wire is fixed direct to the valves 'grey' or the cylinder stat terminal fixed to the 'grey'.
During the valves travel over this stage a 2nd microswitch is triggered which allows power supplied from the room stat out through the valves 'orange' wire to power the boiler.

The usual problems associated with 3 ports are (a) the valve not moving beyond mid position or (b) it does move correctly but boiler fails to light

Erm.... So are you saying my system will not work if I copy the Sundial honeywell y plan. Now Im really confused....lol

 

[wetshoes]

Sounds like you have a Duoflow system (grey metal control box ?)
If you have this the easiest thing to do is fit new wiring centre and swap existing sunvic valve for a honeywell (or similar) valve.

regards

 

[MANDATE]

No I'm not saying it won't work. hopefully it will if wired correctly.
I was explaining how the valve operated in two distinct stages and the importance of the power to be supplied to the 'grey' wire in order for the valve to move beyond mid position.
If valve does not operate over the final stage then boiler cannot light, because it no longer depends on the cylinder stat. It now depends on a microswitch within the valve head.
Don't think that by selecting both CH and HW that the valve takes up the mid position and stays there. It doesn't. It stays only until either becomes satisfied. HW will usually become satisfied first and when this occurs the 'grey' becomes live. The valve moves over final stage and boiler re lights due to valve microswitch.

 

[spiceman]

Hi, thought I would have a go at rewiring my heating system tonight and here are the issues im having regarding Duoval Actuator DM5651 sunvic 3 port valve.

Ok, here goes.... Wired the heating system exactly the same at the Honeywell Y plan wiring diagram but obviously using the 3 port sunvic duoval. Here are my results.

I unbolted the actuator from the valve so I could see what was happening when I applied power.
On the time switch/controller I set it to call for hot water and heating and set all stats to max... All the actuator done was continuously went round and round never stopping. I tested with meter and had 240v from the cylinder tank stat going to the orange core,
and 240v from room stat going to white core on the actuator. The yellow core was placed in a connector block on its own just for temp, this also had 240v on it all the time (normally hot water off).

I don't have a clue now. Please does anybody have anything I could try next.

Thanks

 

[spiceman]

Please anybody?

 

[MANDATE]

i'm not familiar with your valve, but I understand they all work on the same basic principle.
Don't know what is meant when you say actuator went round and round never stopping.
Within the actuator should be a geared quadrant. The motor having only about 8 gear teeth engages with the quadrant. Therefore the motor only actually turns about 2 or 3 revolutions, then the quadrant comes up against a stop at CH only position. The motor has to remain energised for the quadrant to stay there. If and when the power is removed the motor unwinds due to the force of the return spring.

If there is a demand for both CH and HW then power on the white wire will take the quadrant/valve to mid position where there is no 'stop'.
What happens here is that a separate 'modified voltage' produced by a pcb in the actuator head is applied along with the 240v. When the 240v on the white is dropped it leaves the 'modified voltage' which is designed to hold the valve. It's not strong to move it forward, but strong enough to hold against the return spring. Again the motor is energised but it's not actually turning.
The only way the motor could turn continuosly was if teeth on motor or quadrant were broke.

 

[spiceman]

Thank you for your quick reply. Not sure what is happening but I dont think its working correctly.

When I say it goes round and round I mean.

I remove the actuator from the body of the valve so I can see what is happening to the centre rotating inner part of what the shaft of the valve spindle fits into.

With calling for hot water and heating, so that means 240v are applied to the white wire and orange. all the inner part does is keep on turning clockwise, never stopping.

If I do buy a new valve and actuator can you recommend me the correct one I need please. Thank you so much for your help.

 

[Agile]

I think, but could be wrong, that this valve DOES rotate to the appropriate next position but always in the forward direction.

Regardless, the simplest solution would be to replace it with a Honeywell which is guaranteed to operate correctly as long as its wired up properly.

Very unfortunately most heating engineers have to make a bodge because the customer does not want to pay for outdated parts to be replaced to restore correct operation. They all want the simplest solution to get it going!

Tony

 

[spiceman]

Hi, Just spoke to Technical guy at Sunvic and told him my model.

He has just informed me that it cant be done without a additional relay box, No wonder I couldnt get it to work correctly. He said that I have to remove the whole unit, valve too.

Thanks for everybody's input. Now im on the hunt for a normal mid position y plan honewell vavle. What model number would I require please?

 

[Agile]

VA 4073 A

Usually a 22 mm three port valve. Far better to get a Honeywell rather than a cheaper plastic version which cannot be repaired easily or at all.

Tony

 

[spiceman]

Thanks Agile

 

[Hugh Jaleak]

I think, but could be wrong, that this valve DOES rotate to the appropriate next position but always in the forward direction.

Tony, that was my experience when I removed mine and tried it. They seem to be a different design to others, as the water enters a central 'tube' which then rotates to align the outlet ports cut in the tube with the appropriate output, be it HW, CH or both.

Honeywell Mid position is the V4073A, 22mm compression. Got mine from these guys: http://www.heatingcontrolsonline.co.uk/

I am happy to recommend them, ordered my valve just after 3 p.m., it was at my door via courier 11a.m. following day.

 

[boabcelt]

Just had a quick scan through this post and thought I'd point out that your system might not have been wired up incorrectly at all. Many older three port valves were of the diverter type i.e they could allow hot water, or heating but not both at the same time. For heating and hot water simultaneously you would need a mid position valve. Just so you dont think you have wasted time or money,I agree that an upgrade is probably best though.