Commander Posted November 28, 2015 Posted November 28, 2015 I'm trying to convert a Danfoss Set2 to a Horstmann C27. The old unit only does HW or HW+CH while the new one supports independent control of both. Most of the wiring between the valves and the controller is hidden in the walls so I can't trace them and double check what goes where. I assume I need to re-do some wiring but I can't tell what. Also, they use different back plates. Any help?! Quote
Commander Posted November 28, 2015 Author Posted November 28, 2015 (edited) New: Old: Old: Edited November 28, 2015 by Commander Quote
Paul K Posted November 28, 2015 Posted November 28, 2015 From what I recall when I changed my controller over a few years ago. All of the cables for control etc are standardised colours. All of the stats etc and pump and valve cables should all go into a central terminal block. Sent from my iPhone using Tapatalk Quote
Paul K Posted November 28, 2015 Posted November 28, 2015 Ignore that. I thought you meant the stat/pump/valve connections Sent from my iPhone using Tapatalk Quote
Angrybiker Posted November 28, 2015 Posted November 28, 2015 Looks like red wire in connection 1 is your HW and 4 is your CH. I will say though that just because your new timer is set up to give independent heating and hot water doesn't mean that the system is piped to allow that. Sent from my iPhone using Tapatalk Quote
350zedd Posted November 28, 2015 Posted November 28, 2015 Can I ask what type of system you have, fully pumped or not, motorised valves, stats etc. It looks like the red wire on term 1 is going out to a boiler feed when t/s is on (gravity hot water?) and the black wire term 4 feeds heating pump via a room stat provided the controller switch is set to HW/CH ? Quote
Commander Posted November 28, 2015 Author Posted November 28, 2015 Gravity hot water 1 pump to push water through the radiators and through the heat exchanger in the tank. 2 electric valves (one for CH & one for HW) 2 Thermostats (one on the tank for HW, one in the hallway for CH) Quote
Commander Posted November 28, 2015 Author Posted November 28, 2015 Piping looks like it'll be fine for what I want, 'just' a question of getting the valves to work as required. Quote
350zedd Posted November 28, 2015 Posted November 28, 2015 You could use both channels if there are aux switches in each motorised valve to switch the pump and boiler. Quote
Commander Posted November 28, 2015 Author Posted November 28, 2015 I have no idea how to check? Each valve just does on/off and has multiple wires to it. Why the frig an on/off valve needs more than 2 wires I've no idea?! Quote
350zedd Posted November 28, 2015 Posted November 28, 2015 Take the lid off the motor housing and you should see a small microswitch. I've got Honeywell valves and the switch wires are orange and grey...6 in total. Quote
gsexr Posted November 28, 2015 Posted November 28, 2015 (edited) On your original there is a live link added which is common to see but the new one looks like its got a built in link. You might want to check and confirm this. The new one shows on and off because you can get motor open and motor closed valves but most domestic valves are motor open and spring return to close them. Just remember that all the time clock is doing is at the on time joining the incoming live to the switched live which is the one going out to your valve. The thermostat will also interface this live so that when its up to temperature it effectively cuts off the live supply to where ever its going. Room stat and tank stat do the same just different circuits. If you have two valves then one will be for heating and one will be for hot water. When the time clock comes on it just sends a live feed to the valve and the valve opens. When it gets to the end of its travel it operates a micro switch. Again all this does is join a live to a switched live which goes to the boiler/pump to come on and heat up with ever circuit that valve is on. Hopefully this explanation will help you look at what you have and understand how it works so you can replace the time clock. You usually can find a wiring diagram that shows you how to convert from one make of clock to another but this has to assume your original is wired in correctly.. Is your time clock faulty or do you have another reason for changing it. I ask because most problems if the heating/hot water io not coming on are caused by the valves failing. eg the micro switch not being operated due to the valve not fully opening and you can just change the syncron motor if thats failed. Happy to help if you want to ask more mate. Ex heating engineer This may help if you can follow a wiring diagram http://www.plumbcenter.co.uk/wcsstore7.00.343.53.04/ExtendedSitesCatalogAssetStore/images/products/AssetPush/DTP_AssetPushHighRes/std.lang.all/ti/on/Horstmann_C21-C27_Installation.pdf Edited November 28, 2015 by gsexr Quote
Angrybiker Posted November 29, 2015 Posted November 29, 2015 I wouldn't even bother checking valve end switches and whether or not they're wired in. Just wire the red wire in terminal 1 to the new timer connection 3 and the black in terminal 4 to 4 on the new timer. When you power the timer turn heating on by its self, if the boiler fires great, you're done, if it doesn't just take the timer back off and remove the little black jumper at the back of the timer, this will link the heating and hot water. Sent from my iPhone using Tapatalk Quote
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