Gas Boiler Efficiency Study - October 2022

[Deleted User]

The Salford University study found that:

• Lowering the boiler flow temperature reduced space heating gas use e.g. lowering from 80 degrees to 60 degrees saved 12% of gas used to heat the house
• However, it also slowed heat-up rates and lowered internal air temperatures e.g. when lowering from 80 degrees to 60 degrees, heat up times in the morning went from 23 minutes to 37 minutes.
• The reductions in gas use measured are primarily due to increased boiler efficiencies rather than reductions in internal air temperature.

https://www.nesta.org.uk/report/salford-energy-house-boiler-flow-temperature-testing-initial-report-october-2022/

https://media.nesta.org.uk/documents/UoS_Nesta_Energy_House_Initial_Report_-_FINAL_2022-10-08.pdf

http://www.moneysavingboilerchallenge.com/

For those with System boilers, turning down the boiler flow temperature only works provided your cylinder temperature is below the boiler set temperature. If not, your boiler will just cycle when hot water re-heating is required. I am running my system boiler at 55C and then turning up the boiler flow temperature when I want cylinder heating (usually when there is no sun and solar re-heating). I then turn the boiler flow temperature down again.

[Deleted User]

Oops - MODs please move to correct forum. 

QrizB

In case anyone missed this thread:

• Lower boiler temperatures work, they reduce gas use;
• Cooler radiators might mean it takes longer for your house to warm up from cold, but that doesn't mean more gas use; just a longer, lower burn.

I would add that in really cold weather you might need to turn your flow temperature back up as the reduced output from your radiators might not be enough to keep your home warm.

BUFF

It's certainly interesting especially for those of us that live in Victorian/Edwardian terraces.
If they could replicate the tests with a Class IV & a modulating thermostat it would be even more useful data.

NannaH

You will also prolong the life of your boiler by having a lower flow temp 😉
Our combi is 5 years old,  the CH system is 30+ years old.  
DH put chemical system cleaner in last Saturday ( Adey MC3, you just pour it into the filter chamber) after servicing our boiler and cleaning out the magnetic filter which was full of crud.
Today he drained down the system, flushed through with fresh water then refilled + added new inhibitor ( Adey MC1 for anyone curious)   He checked the filter again and OMG it was even more cruddy than last week.
Anyone slightly competent can do this ( apart from Boiler service obvs. )  you just need a hosepipe and jubilee clip.  

 Plenty of youtube videos for guidance on rebalancing rads etc. 😉
honestly I’ve never seen anything like it! 

Systems are only usually flushed on installation of a new boiler but he’s going to recommend his customers have it done every 3 years, especially those with older boilers that don’t have an added filter.