Boiler Short Cycling

[bagaceratops]

What status codes "S" and "D" are displayed during this cycling?.

Hi,

There is nothing on the display other than the flow temp and burner flame.
or do you mean the state list of this boiler, which I have not worked out how to access.

Thanks

 

[John.g]

Presume you got the boiler return temp from d.41? through Diagnostic menu Level 1 so you should be able to access the S parameters by selecting d.99, this should give all the S parameters?

 

[bagaceratops]

Presume you got the boiler return temp from d.41? through Diagnostic menu Level 1 so you should be able to access the S parameters by selecting d.99, this should give all the S parameters?

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Ah yes D99 - It is showing S04 and then when it cuts goes straight to S03 and then S04
I did try reducing pump speed again today to PPA curve. It is still cutting out, but stays on longer and lets the flow/return differential go much higher, circa 25 degrees

 

[John.g]

So only 2 of S codes, S.03 & S.04 which are ignition on and burner on, a bit strange that no other S code up when the burner stops, normally if the burner cuts out on say the boiler flowtemp exceeding its SP by 5C (where the boiler min output is greater than the heating demand) then you will get a S.08, the anticycle time.
You might look for a F (fault) code when next it stops, one would think though that if a fault code is flagged that you would have to reset the boiler?.

Not sure if available at your boiler output but you might try setting d.0, Heating Part Load, to say 10 or 12kw and see if any difference.

Where do you get these settings? "pump speed again today to PPA curve"

 

[bagaceratops]

So only 2 of S codes, S.03 & S.04 which are ignition on and burner on, a bit strange that no other S code up when the burner stops, normally if the burner cuts out on say the boiler flowtemp exceeding its SP by 5C (where the boiler min output is greater than the heating demand) then you will get a S.08, the anticycle time.
You might look for a F (fault) code when next it stops, one would think though that if a fault code is flagged that you would have to reset the boiler?.

Not sure if available at your boiler output but you might try setting d.0, Heating Part Load, to say 10 or 12kw and see if any difference.

Where do you get these settings? "pump speed again today to PPA curve"

Thanks, No F codes and just S03 and S04.
Will try the d0 setting, it is set to max at present

My pump is a Lowara Ecocirc L-plus 25-8/130 which has 3 fixed speeds, 3 constant pressure curves, 3 proportional pressure curves and an auto adapt curve

 

[ShaunCorbs]

Why such a big pump how many rads ?

 

[John.g]

Does that pump display the head(M), flowrate(m3/hr) and power(W)?, if and if d.0 is settable then if the max output is set lower than the heating demand then we can calculate the dTs etc from this and compare them with the boiler readings.

 

[bagaceratops]

Does that pump display the head(M), flowrate(m3/hr) and power(W)?, if and if d.0 is settable then if the max output is set lower than the heating demand then we can calculate the dTs etc from this and compare them with the boiler readings.

Hi,
Thanks for the continued responses.
Yes the pump does display all of that and yes according to the manual d0 is a writable value - Given this is a large house though what should I set to?

Boiler is a 30kw boiler.
I have 8 radiators which are each circa 4000 BTUs each at delta T 20.
I have 2 underfloor manifolds - each manifolds supports 7 pipe runs that are each circa 80 metres.
One manifold is fed with 28mm pipes as it is a long run
The other manifold is fed with 22mm pipes
The UFH is set at 45 - 50 degrees on the mixers
Plus DWH with a 250 litre tank.

Thanks

 

[John.g]

Just now, if (when) running continuously, note those pump values and also d.40 & d.41 and we can compare them.
Preferably with rads only on.

 

[ShaunCorbs]

Are the ufh manifolds got there own pump set ?