Can you feel / measure the temps on the flow and return? Do they feel like they are 4 degrees apart? If the return is cold then the bypass is letting by inside the boiler. Happened on mine when the UFH circuit was on so I put the bathroom rad on the same circuit which cured it.
Valliant Boiler ecotech 832- Heating Partial Load
- Thread starter tommys1985
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Maybe wrong but I'm thinking my issue is too little pressure / flow too fast so radiators are not taking enough heat out the water hence dT too low.
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I can say for sure that the lower the dT for any given flow temperature and required room temperature then the greater the rad output, basically because the mean rad temperature is greater with a lower dT, so gretaer rad output.
Few examples below,
1.0kw (T50) rad.
20C required room temperature.
Flow.DegC/Return.degC/dT.deg.C/flowrate.LPM/Radoutput.kw
75C/65C/10C/1.433LPM/1.0kw
75C/55C/20C/0.625LPM/0.87kw
60C/50C/10C/0.902LPM/0.63kw
60C/40c/20c/0.367LPM/0.51kw
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I can say for sure that the lower the dT for any given flow temperature and required room temperature then the greater the rad output, basically because the mean rad temperature is greater with a lower dT, so gretaer rad output.
Few examples below,
1.0kw (T50) rad.
20C required room temperature.
Flow.DegC/Return.degC/dT.deg.C/flowrate.LPM/Radoutput.kw
75C/65C/10C/1.433LPM/1.0kw
75C/55C/20C/0.625LPM/0.87kw
60C/50C/10C/0.902LPM/0.63kw
60C/40c/20c/0.367LPM/0.51kw
Have you tried are are you running in temperature spread mode dT172, where, I think, the dT can be set between 10C & 20C. a friend of mine tried this but it didn't seem to work, he couldn't achieve a dT of 20C, but maybe he didn't set up all the parameters correctly.
Taking your second pair of readings with 60C boiler output while a 10C dT gives a greater heat output as I understand with 50C return the boiler will only be just be into the condensing zone while at 20C dT it will be well into the zone so will, or at least should be, more efficient.
This does of course presume that the lower output from the radiator is adequate.
This is how I have currently set my boiler with dT at 15C. I can only get a dT of 10C though.
I maybe wrong but am presuming this is because as I interpret the boiler will only run in dT control if dP is greater than 100mbar but as set my system has dropped to 100mbar dP.
As I posted already to try and prove this given time I will close the lockshield valves more to increase both dT across each radiator and the system dP. The opportunity may not be until between Christmas and New Year. I accept the heat output may well be too low. If so this points to needing larger / greater output radiators. As I stated above non of the installers who visited and quoted mentioned / suggested replacing the radiators.
Replacing the radiators of course has a cost. If the cost was £1000 I wonder if this would this be paid back over time by the boiler running more efficiently and / or working better so increasing reliability and lifespan.
With my previous system of a simple boiler delivering around 12kW or nothing set by the cut-out and cut-in temperature thresholds of the the control board and a pump with two fixed speeds and set to the lower one I could never achieve more than around 8C despite the ideal being 10C - 12C.
I have now found this.
Once in Installer mode the first menu is ' Data overview '. After selecting this and scrolling through ' Target Modulation ' is shown. When I looked it was 18%.
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Can you have a look at the attached and say what settings you are using, for example if you want temperature spread, dT, you might set D.170 to 3?, which presumably will cause the pump to ramp up and down to give the desired dT ( temperature spread), yet, D.172, Target Pressure is settable as well??( is it??) this seems illogical to me and the pump should be able to ramp up between its set limits of 100mbar & 400mbar, D.173&D.174?.
What does D.175 mean/read.
Now, because pump head is proportional to speed squared, then If the pump head is 100mbar (1.0M), it means that the pump speed will have to be 38% if the max pump head is 7M or 41% if the max pump head is 6M.
Can you please note the pump speed in those set of parameters, the pump speed is shown in d.15
Also show your requested dT (temperature spread) in D.172, (it was set to 15C?)
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D.170 is set to 3
D.172 is set to 15
D.173 is set to 100 mbar, lowest as recall if try to set lower it rolls over to 400mbar.
I need to check D.174 but 99% not changed so 400mbar
' which presumably will cause the pump to ramp up and down to give the desired dT ( temperature spread) '
.... so long as dP => 100mbar.
To get dT up to 15C the pump needs to run slower so water is in the radiators for longer and looses more heat.
As I keep saying I think to achieve this as the system is now dP would have to be <100mbar hence pump runs just fast enough to achieve dP of 100mbar.
If there was a reading of actual dP I could confirm this.
If I can finely close the radiator lockshield valves to further restrict / reduce the flow without the radiators giving out too little heat then my thinking is dT will increase.
I will look at the readings and record when I have time.
Was it in D.171 that you saw the 100mbar?? "my system has dropped to 100mbar dP."
D.173&D.174 are just low& high pump dP limits, so no problems there as the default settings of 100mbar to 400mbar cover the full operating range.
The actual pump speed D.15 will be one of the most important readings of all.
As I said above, if you had, which you did, the dT, D.172, set to 15C but only achieving 10C then the pump speed should definitely be down around 40% and should show that in D.15.
"If I can finely close the radiator lockshield valves to further restrict / reduce the flow without the radiators giving out too little heat then my thinking is dT will increase"
IMO there should be no need to do this unless the pump dP is 100mB just 1.0M which should in most cases be well more than adequate to give a dT of 20C, obviously if the room temperature is 20C then the rad return temp cannot be lower than 20C so the target flowtemp shouldn't be set lower than 40C, and preferrably say 45C, you are only looking for a dT of 15C so a flowtemp of 35C minimum and certainly there shouldn't be any problems if its 40C or greater.
I will post some of my friend's readings when I find them.
D.173&D.174 are just low& high pump dP limits, so no problems there as the default settings of 100mbar to 400mbar cover the full operating range.
The actual pump speed D.15 will be one of the most important readings of all.
As I said above, if you had, which you did, the dT, D.172, set to 15C but only achieving 10C then the pump speed should definitely be down around 40% and should show that in D.15.
"If I can finely close the radiator lockshield valves to further restrict / reduce the flow without the radiators giving out too little heat then my thinking is dT will increase"
IMO there should be no need to do this unless the pump dP is 100mB just 1.0M which should in most cases be well more than adequate to give a dT of 20C, obviously if the room temperature is 20C then the rad return temp cannot be lower than 20C so the target flowtemp shouldn't be set lower than 40C, and preferrably say 45C, you are only looking for a dT of 15C so a flowtemp of 35C minimum and certainly there shouldn't be any problems if its 40C or greater.
I will post some of my friend's readings when I find them.
I am only presuming this as unless you can tell me where there is not a readout of the actual dP.
As I interpret D.171 is a dP target value setting.
On reading the MIs again, D.171 is not active when the hydraulic (pump) settings are set to 3. temperature spread, dT, so should have no effect in this mode?.
Right, the one year old boiler is a Vaillant EcoTec Plus 630.
The best result (briefly) was, on CH only, a dT of 17C with flow/return temps of 64C/47C, pump speed 58%, next best gave 64C/50C, dT 14C, pump speed 64%, (taken only 10 minutes after the first) and on HW (cylinder), 64C/60C, dT 4C, pump speed 80%. D.170 was set to 3 with D.172, dT, set to 20C in all 3 cases.
The best result (briefly) was, on CH only, a dT of 17C with flow/return temps of 64C/47C, pump speed 58%, next best gave 64C/50C, dT 14C, pump speed 64%, (taken only 10 minutes after the first) and on HW (cylinder), 64C/60C, dT 4C, pump speed 80%. D.170 was set to 3 with D.172, dT, set to 20C in all 3 cases.
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sorry, the thread seemed to have been hijacked here 
I still have same issue, did a factory reset on the boiler. delta is always about 5c and no more. Pump is always running at 15% when on auto.
I still have same issue, did a factory reset on the boiler. delta is always about 5c and no more. Pump is always running at 15% when on auto.
I can only find the Mis for a Ecotec PLUS 832, Is this your boiler?, if not post any link you have to a EcoTec 832.
Where are you seeing 15%, is it in d.015 parameter, if it is actually running at 15% speed then the pump head is only ~ 0.16M, you will circulate absolutely nothing at that head, normally head would be ~ 300mbar or 3.0M with a pump speed of around 55% to 65%.
Check the pump speed when running HW.
If you have the Plus boiler check D.170, D.171, D.172, D.173 & D.174
You said "I have reduced D014 pump speed to 53% and it has not done anything. What else can I do to increase efficient of the boiler?" Is d.015 still reading 15% at this setting? or is it reading 53%??.
As I said previously a actual speed of 53% is fairly normal, if it is running at this speed then if you measure the flow/return just before the boiler and it gives says a dT of 10C then the internal bypass is causing the 4C boiler dT.
Where are you seeing 15%, is it in d.015 parameter, if it is actually running at 15% speed then the pump head is only ~ 0.16M, you will circulate absolutely nothing at that head, normally head would be ~ 300mbar or 3.0M with a pump speed of around 55% to 65%.
Check the pump speed when running HW.
If you have the Plus boiler check D.170, D.171, D.172, D.173 & D.174
You said "I have reduced D014 pump speed to 53% and it has not done anything. What else can I do to increase efficient of the boiler?" Is d.015 still reading 15% at this setting? or is it reading 53%??.
As I said previously a actual speed of 53% is fairly normal, if it is running at this speed then if you measure the flow/return just before the boiler and it gives says a dT of 10C then the internal bypass is causing the 4C boiler dT.
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Please see page 54, there are no D.170, D.171, D.172, D.173 & D.174 codes, and I have also checked myself.
Mine is Ecotec Plus 832 as you pointed out rightly.
I have no issues with hotwater or radiators warming up, everything is working fine...but just not sure why it is showing 15% speed in D14 when in heating.
DHW is showing pump speed as 53%
Ok got it now, its a older version?.
From what I can see, the lowest pump speed you can set in manual is with D.014 set to 1 = 53% and D.015 reads the same? but it Auto D.014 set to 0, then D.015 reads 15%, is that correct?
Can you check D.17, D.18 & D.19
So if the minimum speed is 53% and you are getting a boiler dT of 4C but a rad dT of say 10C then you might be able to adjust the internal bypass close to minimum and see how you get on, you might have to balance the rads but but the easiest "overall" method is just reduce the target temp to say 40/45C and see if you still have sufficient heat.
From what I can see, the lowest pump speed you can set in manual is with D.014 set to 1 = 53% and D.015 reads the same? but it Auto D.014 set to 0, then D.015 reads 15%, is that correct?
Can you check D.17, D.18 & D.19
So if the minimum speed is 53% and you are getting a boiler dT of 4C but a rad dT of say 10C then you might be able to adjust the internal bypass close to minimum and see how you get on, you might have to balance the rads but but the easiest "overall" method is just reduce the target temp to say 40/45C and see if you still have sufficient heat.
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