Dee Posted November 1, 2019 Share Posted November 1, 2019 Hi I have a Heatrea Sadia megaflo system installed with a Worcester Bosch Boiler and a Danfoss control unit. The issue seems to be that the heating seems to come on at random times and ignores the times set on the control panel. Another strange occurance is: If I turn off the heating on the Danfoss the numbers on the boiler display, (say from 63 to 76) increase....I would expect this number to fall ( is it a temperature gauge ?) Thanks Link to comment Share on other sites More sharing options...
ProDave Posted November 1, 2019 Share Posted November 1, 2019 A LOT more information needed. So you have a megaflow UFH system and a Worcester boiler. What is this "Danfoss control unit"? Is that a standard boiler programmer where you set the on and off times of the central heating or something more complicated like a programmable thermostat? What other controls are there, there will probably be some motorised valves. What type of boiler system or combi (i.e is there a hot water tank)? From what little I know so far my first guess is you might have a faulty motorised valve, quite likely if those are Danfoss as well as they have a regular habit of the microswitches failing that would then "call for heat" from the boiler even when the heating is off, and because the water has nowhere to go it just gets hotter and hotter until the boiler shuts down. Link to comment Share on other sites More sharing options...
PeterW Posted November 1, 2019 Share Posted November 1, 2019 13 minutes ago, Dee said: If I turn off the heating on the Danfoss the numbers on the boiler display, (say from 63 to 76) increase....I would expect this number to fall ( is it a temperature gauge ?) That is the correct behaviour. It’s the water flow temperature and when you turn the controller off, the pump goes off and the boiler heat exchanger transfers the residual heat to the water in the system. Having a pump over run would help - what Danfoss controller have you got ..? Link to comment Share on other sites More sharing options...
Dee Posted November 12, 2019 Author Share Posted November 12, 2019 I'll get back to you with the info @ prodave Link to comment Share on other sites More sharing options...
Dee Posted November 13, 2019 Author Share Posted November 13, 2019 No Link to comment Share on other sites More sharing options...
Dee Posted November 13, 2019 Author Share Posted November 13, 2019 Link to comment Share on other sites More sharing options...
Dee Posted November 13, 2019 Author Share Posted November 13, 2019 (edited) Edited November 17, 2019 by Dee Link to comment Share on other sites More sharing options...
Dee Posted November 17, 2019 Author Share Posted November 17, 2019 ANYONE?! Link to comment Share on other sites More sharing options...
dpmiller Posted November 17, 2019 Share Posted November 17, 2019 have you now checked the motorised valves and their switches for function? Might be worth looking next at the tank stat too? Link to comment Share on other sites More sharing options...
Temp Posted November 17, 2019 Share Posted November 17, 2019 Dee, silly question but how do you know it's heating when it shouldnt? The evidence you have for that may help diagnose the problem. When the heating comes on unexpectedly at the wrong time go to the controller and check if it's calling for heating or hot water or nothing. My guess it will be calling for hot water not heating and the diverter is sticking allowing hot from the boiler into the heating circuit instead. Link to comment Share on other sites More sharing options...
Dee Posted November 19, 2019 Author Share Posted November 19, 2019 @Temp..... The heating should turn off at 9pm just before I retire but it always remains on unless I physically turn it off either permenently or I knock the temp right down to 5 degees or so. Then the warmth in the bedroom wakes me up at silly o'clock (eg 2.30am ) this morning and I go down and turn it off again When I check the control it's calling for heat, the heating light is in not the Hw. Link to comment Share on other sites More sharing options...
Dee Posted November 19, 2019 Author Share Posted November 19, 2019 @dpmiller..... Where do I check the valve you mentioned? There is a small galvanised box with a sliding switch, manual and auto settings, is that it.?? Link to comment Share on other sites More sharing options...
JFDIY Posted November 19, 2019 Share Posted November 19, 2019 Did it ever work as expected? Perhaps it is wired in wrong or the time switch is kaput, and it is just reacting to the thermostat. Link to comment Share on other sites More sharing options...
Onoff Posted November 19, 2019 Share Posted November 19, 2019 3 hours ago, Dee said: @dpmiller..... Where do I check the valve you mentioned? There is a small galvanised box with a sliding switch, manual and auto settings, is that it.?? You get them in 2 and 3 way form. This is a (knackered) 3 way: This is the guts of a 2 way: I've two 2 ways and one 3 way. Not long replaced them all: How many do you have and what make? On the better (more modern?) ones you can swap out the motorised bit without affecting the plumbing. If the valve itself is all crudded up and stiff then you'll likely need to change that anyway. A picture of your valve(s) and the surrounding pipework might help. Link to comment Share on other sites More sharing options...
PeterW Posted November 19, 2019 Share Posted November 19, 2019 Not sure that this is a valve issue as the valve will be driven by the thermostat. @Dee is there a tank stat on the hot water tank...? I’m wondering if this is wired as W Plan but someone has wrongly wired the tank stat so it bypasses the time clock. how old is the installation ..? Link to comment Share on other sites More sharing options...
SteamyTea Posted November 19, 2019 Share Posted November 19, 2019 45 minutes ago, Onoff said: I have seen these, what happens when you manually slide the lever over? Link to comment Share on other sites More sharing options...
JFDIY Posted November 19, 2019 Share Posted November 19, 2019 There's more history and photos on Dee's other threads https://forum.buildhub.org.uk/topic/3850-balancing-system/?tab=comments#comment-61355 Link to comment Share on other sites More sharing options...
ProDave Posted November 19, 2019 Share Posted November 19, 2019 5 hours ago, Dee said: When I check the control it's calling for heat, the heating light is in not the Hw. Did you mean to type "The heating light is on"? If so that is your problem. Either the programmer is faulty or your times are set wrong. 1 Link to comment Share on other sites More sharing options...
Temp Posted November 19, 2019 Share Posted November 19, 2019 1 hour ago, ProDave said: Either the programmer is faulty or your times are set wrong +1 Link to comment Share on other sites More sharing options...
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