SUNVIC SD2701ACTUATOR & XL207 PROGRAMMER

[SWOLLENGLAND]

I have a problem with my CH whereby all of a sudden the heating wont come on at all when it should but the rads do get hot when the water heating is on .
The system is controlled by a combination of the above .
I changed the actuator because for a while the problem could be cured by giving it a good thump, but changeing didnt work so I changed the programmer ,which didnt help either .
Does the brass valve need changeing or could it jist be stuck and if so how can I tell?

 

[Gasguru]

The valve body spindle often sticks. Remove the actuator and you should be able to turn the spindle easily by hand.

I suggest you don't try it at this time of night since they have a tendancy to start leaking water.

Think about changing over to a Honeywell valve ....these are far more reliable.

 

[gas4you]

Could be the valve 'ball' has stuck. Has it been wired up correctly?

 

[SWOLLENGLAND]

Re wiring ,should be ,I just changed the controller 1 for one so didnt touch the wiring .
The house is about 12 years old and most people on the estate will tell you they have changed a couple of actuators at least ,this is my third !!!!
I have always suspected that the programmer gets damaged by the fault conditions that the actuator creates as I have had to change previous controllers as well which is why i changed the actuator first before the controller this time .

I dont think the spindle is hand loose ,should it be and if its not what amount of pressure should i apply to see if its stuck (dont worry ,wont do it tonight!!)

 

[gas4you]

Sunvic have never been one of my favourites. change to Honeywell as GG suggests. I fit loads of Danfoss and don't get any trouble.

 

[SWOLLENGLAND]

Beginning to think that but just laid out some hard earned cash and as a Yorkishire man that hurts !!

Just unscrewed the actuator and switched on the heating and the centre of the actuar moved round and the pump fired up which wasnt happening with actuator in place ,any ideas?

 

[gas4you]

To make the pump spin the actuator must have turned, operating the microswitch. Sounds more like the valve body jammed.

If I remember rightly the sunvic rotates 360D depending on what is called for. Try gently turning it with a pair of grips etc.

 

[Gasguru]

I fit loads of Danfoss and don't get any trouble.

Hmm... thats odd since the valve body is identical to the Sunvic. They use the PTFE/graphite spring loaded shoes. The O rings on the drive shaft leak or sieze. Nothing but trouble even on perfectly clean systems. And as expected Danfoss and just as bad.

Always fit Honeywell; refurb ball and plate is only a tenner and give 20 years service.




The actuator on this valve only turns 90 degrees. The brass spindle on the valve body should also turn 90 degrees from hot water only "mode" to ch "mode". I did warn you if it starts leaking though. If its ok you will be able to turn it with your fingers alone.

 

[gas4you]

I often think valves fail due to excess heat in the airing cupboards. Whats your opinion on this GG?

 

[SWOLLENGLAND]

That would make sense the way our lass cram stuff in the cupboard

 

[Gasguru]

Its all down to design - the O ring on the Honeywell valves undergoes far less rotation perhaps only 10 degrees of movement. Most other valve bodies have 90 degrees or in the case of MoMO valves continuous rotation.

Its only a matter of time before the O ring can take no more punishment

Plus the fact of material selection - O ring compression set due to system chemicals/ageing appears more of a problem with the Sunvics/Danfoss valves (when I've stripped them down).

In terms of actuators Honeywell were by far the best but since they have reduced the size/quality of the microswitches and use crimped pcb connections they don't last as long. I'm not sure if they still use quality Hansen motors (used to give 15 - 20 years service). For the price they charge (compare with an Orkli with 2 year warranty) a small heatsink could be fitted to the motor.

 

[SWOLLENGLAND]

Don't want to speak too soon but looks like you guys know your stuff!!!

Turned the spindle with my pliers and then put the actuator back on and it now seems to be ok .

Cant say for certain as the rads need to cool enough for me to know for sure that the wont get hot when the hot waters on but the heating is firing up on demand now which it wasn't before and I can here the spindle turning.

In anticipation of a success thanks to you guys for responding ,much appreciated.

 

[gas4you]

You should be able to feel the temp dif on the pipes each side of the valve almost straight away.

 

[gas4you]

GG; What sunvic valves am I thinking of then. Cant remember exactly but I'm sure there are some that go through 360 rather than being spring return valves

Or is it my bacardi clouded brain got it wrong again

 

[SWOLLENGLAND]

Hmmm
Spokee too soon its stuck again ,is there anything will free it up (WD40)or the like ? or perhaps just some gentle turning back and forth ?

If the brass valve needs changing is that a full system drain ?