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Discuss I only have heating if hot water on also ? in the Central Heating Forum area at PlumbersForums.net

Gally

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Hi,
I have a conventional Worcester Bosch condensing Boiler on ground floor- no problems.
Hot water tank (with tank stat) in bathroom where the pump and 3 port valve are situated (Danfoss Hsa3)
I have a Danfoss fp715 programmer which I have set to come on early morning (water and heating) and evening (water and heating). All good, room stat and tank stat working fine and switch on and off as desired temp is reached. In summer I just turn down the room stat and that works fine, no heating just hot water, perfect.
My problem is that occasionally I want heating only, I hit the '+1hr' button on the controller for heating only, the boiler kicks into action for about 4 seconds then shuts down !
If I hit both +1hr buttons I get heating and hot water so in every other aspect my system is running like a dream, just cant have heating on its own.
Any ideas.
 
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Gally

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More info -
If I turn the 3 port valve to manual from auto and hit the +1hr button for heating only then the boiler fires up and stays on but obviously it starts heating the water in the tank also which defeats the object.

cheers Mike
 

Riley

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Has it ever worked separately?? If yes I’d say it’s a faulty three port.
 
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Gally

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I changed the 3 port valve and actuator about 3 yrs ago and its always behaved like this since. How can I check to see if its a wiring problem ?
 
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Gally

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Quick update...
It turned out to be a wiring issue with the programmer.
The programmer connections were at terminals 2,3&4 instead of 1,3&4....but it took me all day identifying the cables in the junction box and consulting google for wiring diagrams.
My 3 port valve actuator is only four wire so that also threw me as most of the diagrams I found show 5.
Learned so much though and cost me nothing apart from my time.
wonder how much a heating engineer or spark would have charged ?

Mike
 

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