I’m looking for some advice on modifying an old gas boiler – specifically an Immergas Eolo Mini 24.
I’m trying to reduce the delta T from 20K down to around 5K–10K to simulate heat pump operation (i.e., lower the flow temperature and ΔT). Since the boiler doesn’t have a display, I’m wondering if anyone has tried using a variable resistor or a triac controller for this purpose.
DT is important for main old DN20 PEX pipe limitation( in a 80m2 house /5 rad and 35 m2 UFH with 8 loops total =6.7KW ).
Has anyone managed to tweak the control settings or implemented any trick to achieve a lower ΔT safely?
What is max kw for DN20 ?
Any suggestions, tips, or experiences would be really appreciated!
On a heat only boiler you just need to increase the flow rate, the magic of Q = dm/dt x cp x deltaT will reduce the deltaT, double the flow rate, halve the deltaT.
In the instructions for your boiler …
“The boilers are supplied with a built-in circulation pump with
three-position electric speed control. The boiler does not operate correctly with the circulation pump on first speed. To ensure
optimal boiler operation, in the case of new systems (single pipe
and module) it is recommended to use the pump at maximum
speed. The circulation pump is already fitted with a condenser.”
So if you are lucky, the pump is not set on maximum speed and it could be as simple as turning the pump up to maximum. The boiler will try to control to the set flow temperature, so deltaT will naturally reduce.
In the UK it is definitely illegal to modify a gas boiler for all the obvious reasons.
