help with satchwell 2 port valve

[bikerblue]

Hi All,my first post so please be kind.I have a rather elderley heating system using 2 motorised 2 port satchwell valves type sd2301 i think (identified from google images).The problem im having is the radiators get very hot when i put the hot water on but not when i set the programmer to heat radiators.I think i have deduced that the motorised valve for the radiators is not working( i can see the hot water valve indicator on the top rotating) but the radiator valve just buzzes slightly but dosnt seem to turn.Is there a direct replacement? and also does the plastic cover come off to try and see whats going on.Does it clip off i dont want to break it.
I Hope this makes sense and thanks in advance for any replies

 

[Boilerman2]

Satchwell Valves are now marketed as Sunvic, there will be a straight swap head availible (SD****) The last 4 numbers have changed over the years as models have been improved, but if you ask a Heating spares Stockist for a Sunvic SD Head, you'll get what you want.
Before fitting the head make sure that the valve spindle is not leaking, and not seized.

 

[bikerblue]

Hi Thanks for the reply,Ah so the motorised bit is seperate from the metal valve and can be purchased seperate then.I didnt see an easy way to split the 2 but the underneath is a bit inaccesable to see so are there a couple of screws or clips underneath that i cant see.I will have a go at fixing the motorised part if i can.Im competent electricaly but less so when it comes to plumbing,but im learning ? thanks

 

[Boilerman2]

If you look from the top of the valve actuator, you will see 2 screws in opposing corners, older models have a loose nut on the underside of the screws, the newer valves have captive nuts pressed into the valve face plate. the important thing to remember is that these valves are "Power open, Power closed" which means that you have 2 lives, and a neutral, it is important to get the two lives (open/close) the right way round!

 

[bikerblue]

Thank you again

 

[bikerblue]

just to update i stripped it all down and the plastic piece that operates the valve had cracked,i repaired with epoxy resin and it seems as sound as a pound now all working if it cracks again i will replace it.

 

[45yearsagasman]

You should ask yourself why it broke in the 1st place. These valves are notorious for seizing and the internals should be replaced with a service kit.

 

[bikerblue]

Hmm point taken,the valve was difficult to turn with my fingers but easy with a small pair of pliers.Should it be relatively easy to turn by hand ?
I wasnt aware the there was a service kit available so i guess that will be cheaper than replacing the valve itself.Thanks for the info