Intergas HRE X-Plan & ACV Smart Green 160 - poor recovery time

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Hi everyone. Happy reading. Any advice / suggestions would be greatly appreciated.

Project Goals

Replace an S Plan setup and old cylinder with Intergas X plan and high gain cylinder. Giving a very rapid cylinder reheat time (circa 12 minutes) and embrace OpenTherm control from the Nest

Issues

The boiler seems to reach temp too quickly but doesn’t correlate to flow emp of 85 degrees, as expected

System equipment and setup

Intergas HRE 40 SB
ACV Smart Green tank-in-tank 160 cylinder
(131l stored domestic hot water, 31KW heat absorbtion
Intergas NTC cylinder stat
Intergas outside sensor

Nest (OpenTherm for heating, on/off for hot water)

28mm flow and return to primary flow and return of ACV cylinder
22mm flow and return to heating, via fernox TF1 filter (on the heating return)

Intergas x-plan

Parameter 1 - 1
Parameter a - 6
Parameter 4 - 75 (31kw)
Parameter n - 85 degrees (flow temperature in DHW mode)
How water set point 65 degrees (maximum I can set)

I have two external sensors on the flow and return (DS18B20 to an ESP32) and another inside the drypocket (along with the intergas NTC)

My issue is that when heating the DHW store, with parameter 4 matched to the cylinder at 75%, the boiler soon ‘reaches temperature’ (state 1) sits there for about 30second to 1 minute then starts again.

The flow temperature I have on the DS18B20 is only around 61 degrees yet it keeps ‘reaching temperature’


To rule out any problem with circulation, the original flow and return in 22mm was replaced and upgraded to 28mm in the description above, but it’s made no difference.


If i drop parameter n to say 45% (19kw) the flow temperature I read gets up to 72 degrees. I believe it would keep rising but by that point, the set point on the DHW store is reached

What I don’t understand is why the boiler is ‘reaching temp’ very rapidly running at 31KW. I am not getting and because of the constant cycling, I am not getting the low time spent in DHW mode

I don’t yet have an IDS cable, I may buy one as I am intrigued to see what the boiler things S1 S2 readings are at that point


(pipework drawing to help clarify)
pipework.png
 
Last edited:

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