Ideal logic Combi, weather management & OpenTherm question

[RobTi]

Hi so I have just had a logic Combi 30kw fitted and the above 2 items have been mentioned, so question is is it cost effective for me to fit them, 3 bed flat with 2 showers?
Thanks

 

[shambolic]

Why didn’t you get the 35 if you have 2 showers?
Do you understand weather comp and opentherm?
Both reduce the boiler flow temp to radiators, one depending on outside temperature and the other depending on room temp of sensor.
So If system fitted and sized correctly it should reduce bills.
If not you may feel that rooms don’t get hot enough.

 

[RobTi]

I got the boiler through a grant scheme and had to push for the30 they wanted to fit the 24. What I was trying to fathom out was what happens to the boiler in condensing mode if these products drop the temps

 

[D_Hailsham]

What I was trying to fathom out was what happens to the boiler in condensing mode if these products drop the temps

Simple answer: It condenses even more.

Condensing starts when the return temperature is about 55C. As the return temperature drops the amount of water condensed out of the flue gasses increases so the efficiency of the boiler improves. Weather comp reduces the flow temperature, and consequently the return temperature, as the outside temperature increases. This results in less fuel used and an increase in the percentage of water vapour condensed. Meaning the boiler is more efficient.

If both Opentherm and weather comp are installed the OT thermostat uses the outside temperature data to determine the required flow temperature.