Flow temp vs power rating

[John Smith Esq.]

Hi all,

I have my greenstar 25i combi set to 9.1KW and 53C flow temp. With the outside temperatures falling I want to know what would have the biggest effect on warmth indoors:

- increasing the rating to say 10.5kw
- increasing the flow temperature by 1 or 2 degrees
- increasing the amount of time the heating is on

However, I want to change the one that will increase warmth in the most efficient and economical way. I assume the last option will be effective but most costly. Which would win out of the first two?

There isn't much I can do to improve other factors like insulation.

Thanks

 

[Johntheo5]

Hi all,

I have my greenstar 25i combi set to 9.1KW and 53C flow temp. With the outside temperatures falling I want to know what would have the biggest effect on warmth indoors:

- increasing the rating to say 10.5kw
- increasing the flow temperature by 1 or 2 degrees
- increasing the amount of time the heating is on

However, I want to change the one that will increase warmth in the most efficient and economical way. I assume the last option will be effective but most costly. Which would win out of the first two?

There isn't much I can do to improve other factors like insulation.

Thanks

Increasing the rating will have no effect except that its present rating is stopping boiler flow temperature from reaching its set point so forget about that as a economy measure, it should be set to the max rating of your radiators, maybe something like 15kw or so, the boiler will use the exact amount of fuel necessary to satisfy the flow temperature SP set by you, no more and no less.

Adjusting the flow temperature is the most convenient and easiest way of getting the optimum performance.

For every 1 DegC rise or fall in the OAT (outside air temperature) then the Boiler flow temperature should be decreased or increased by around 2 DegC which will result in ~ 4% increase/decrease in the power required or if you want to increase the room temperature (with no change in OAT) then use the same method, if, say you wish to increase the room temperature by 2 DegC then increase the boiler flow temp by 4C which will result in ~ a 8% increase in power demand.