Sunvic motorised valves for domestic central heating.
A selection of emails received by the SeeRed author, reproduced without comment.
Hi Steve, just wanted to drop you a mail to say, thanks for the information on your website, superb. I have a SDM1901 not yet 2 years old and it's basically decided to stay in the mid-position regardless of what the CH or DHW are demanding. Marvellous! So I used to be into electronics and of course, you always have a tendency to take things apart (as you do). First obvious problem, one of the "after thought" diodes isn't even soldered on at one end and is merely making electrical contact, by touching the solder terminal on the PCB... Nice... Not sure if that is the problem/only problem just yet, but hey ho. Then I thought I'd search the web and here I am. So just thought I'd show my appreciation by dropping you a mail.
Kind Regards, Mark
16 Feb 2008
Hi Steve
Fascinated by your website which I discovered from a Google search on Sunvic.
I thought you might be interested in a problem I have had with my Sunvic SDM1901 3-way valve actuator (a couple of years old). My problem has been excessive hot water temperatures, and I tracked it down to the valve actuator stopping slightly off position when CH but no HW was demanded. This leads to hot water from the boiler leaking into the hot water circuit even when the boiler thermostat is switched to 'satisfied'. I worked through the electronic issues you described on your Sunvic pages, but I could find nothing wrong. The relays/microswitches seem to work as designed. (Incidentally I think that the Sunvic MoMo design is, in principle far superior to the traditional spring return design for these valves).
As far as I can tell, the problem seems to be that the actuator motor rotates randomly in the wrong direction. When the actuator rotates anti-clockwise (looking from top) all is well, but when the motor rotates clockwise, it stops in the wrong positions. This would seem to be a result of the asymmetric design of the cam (depression actually - is this a cam?) acting on the two lower microswitches.
I'm not familiar with these synchronous motors. I would not expect much of a response from Sunvic so I wondered whether you had any thoughts? Have you seen this before? Should they rotate unidirectionally? What causes the motor to rotate in one direction of the other? Does this just sound like a new motor job? Can they be sourced or would I need need a complete new actuator?
I appreciate that you probably get loads of email generated from your website, but any thoughts much appreciated.
Kind regards, Andy
Nice to see you sticking it up Sunvic, I have replaced the capacitors in mine & all is ok, very informative website, good luck from Paul in Hull.