Sunvic MOMO 3 port problem

[RickO]

I have a problem with a fairly new Sunvic SDMV2304 Motorised Mid Position 3-Port Valve (MOMO).
It won't completely shut off the DHW and consequently the cylinder water is too hot. I have checked for complete rotation and this is fine. If I switch on the valve to make a complete rotation it then works until the next time.
System is Bosch Worcester 12Ri standard Y plan. Has been working fine for a year and has only recently developed this fault. Heating water is clean.
I like the idea of a MOMO valve but??? Should I change to and S plan?
Thanks,
Rick

 

[ShaunCorbs]

Best to change for an s plan (2 x 2 ports)

What cylinder do you have ?

 

[RickO]

Thanks for the reply. Normal 117 litre cylinder, open vented, loft cistern feed.
Probably best to change to an S plan as you say.