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Discuss Most efficient settings for me in the Central Heating Forum area at PlumbersForums.net

Antonio01989

Messages
5
Hello,

I am new to this forum and I hope someone can help me find the most efficient settings for my boiler and radiators. I moved house and I have been using approx. 30% more gas in my first two months here if compared with my previous flat in the same period last year. The settings I am thinking to adjust are the water temperature at the boiler and the individual settings on the radiators.

I used to live in a one-bedroom flat of approx. 410 sq. ft. with a combi boiler (Worcester) and 4 average-size radiators (plus the one in the toilet). I used to have a digital thermostat with 6 different temperature settings for the day which was set similarly to my current one (below), perhaps 0.5°C lower than now.

I now moved in a one-bedroom flat of approx. 580 sq. ft. with a combi boiler (MAIN Combi 25 Eco Elite) and two large radiators: one in the bedroom and one in the lounge (plus the one in the toilet); these have settings 1-5. I have a digital thermostat with 5 different temperature settings for the day which I use as below:
  • 5:30 - 22.5°C (warming up before the alarm clock at 6:00)
  • 6:00 - 21.5°C (cooling down as I open the window to let some fresh air in)
  • 8:00 - 22°C (warming up gradually before I start working)
  • 9:00 - 22.5°C (warming up gradually to desired temperature for the day)
  • 23:00 - 21.5°C (cooling down for the night)
I am sharing the thermostat temperature settings in case they can be helpful for your answer, but I am not planning to change these as, from a temperature perspective, I feel comfortable with them.

The radiator water temperature in the boiler can be set from 25°C to 80°C. I have read that the “most efficient” temperature should be 60-75°C. The issue I have with this high temperature is that if I set the temperature at 60°C, when the radiators kick in the warmth generated is too strong, the air becomes heavy and the end temperature exceed the desired temperature as once the thermostat shuts the boiler the radiators are still very hot and keep warming up the environment. I tried to set the temperature at 60°C and reduce the settings in the individual radiators, but this is difficult to control.

At the moment the water temperature in the boiler is set at 45°C; this enables the temperature to raise gradually and the radiators do not become very hot; also once the thermostat shuts the boiler, the desired temperature is the one I chose, not any higher. The downside of this is that the boiler stays on for a longer periods of time and the temperature is lower than the recommended one which I think might cause excessive gas consumption.

I know there are several factors to consider such as:
  • My current house is 40% larger than my old one
  • The boiler is different
  • The temperature now may be 0.5°C higher than in the previous house
  • And many more

However, my question is: can anyone help me understand what most affects the gas consumption of the boiler in my circumstances? Is high temperature for a short time better than low temperature for a longer time? I would not like to change the temperatures I use during the day, but I am happy to adjust the water temperature in the boiler and/or the settings in each individual radiator.

Many thanks, Antonio.
 

ShaunCorbs

Staff member
S. Mod
Plumber
Gas Engineer
Messages
30,568
Solutions
2
Think it’s down to 3 rads and 40% bigger eg need more rads to evenly heat up the rooms as sounds like you need to have to nearly maxed out to fully heat them ?
 

Murdoch

Esteemed
Res.Electrician
Messages
979
Unless you compare the outside temperature, and November this year was much colder than last year, aren’t you over thinking this?
 

SimonG

Esteemed
Plumber
Messages
20,531
Are you looking at volumetric consumption or cost usage?

Been an increase in gas prices.

Only you can decide when you want it on and at what temperature.
 

king of pipes

Esteemed
Plumber
Gas Engineer
Messages
5,594
Do you have a dual smart meter which monitors your usage and costs ? Does your flat. temperature stay set at 21° through the night ?
 

Antonio01989

Messages
5
Think it’s down to 3 rads and 40% bigger eg need more rads to evenly heat up the rooms as sounds like you need to have to nearly maxed out to fully heat them ?
Yes, it could actually be down to the differences in the new house and I made it too complicated
 

Antonio01989

Messages
5
Unless you compare the outside temperature, and November this year was much colder than last year, aren’t you over thinking this?
Yes, you are probably right that I am overthinking it, but I posted this mostly because I wanted to understand more about what affects the boiler efficiency in my situation, but maybe it is not that stragihtforward
 

Antonio01989

Messages
5
Are you looking at volumetric consumption or cost usage?

Been an increase in gas prices.

Only you can decide when you want it on and at what temperature.
I am looking at volumetric consumption; I was trying to understand if having the water boiler so low is reducing the efficiency of the boiler or whether this is sensible to do from a gas consumption perspective
 

Chuck

Esteemed
Messages
2,365
I have a traditional meter and yes, my flat stays at the temperatyre I set through the night
Assuming that you are a reasonably healthy adult, set it to more like 17 or 18°C overnight and reduce it to 20 or 21°C during the daytime occupied period. At the temperatures and profile you've chosen you are not only overheating your own flat but you are probably paying a good chunk of your neighbours' bill as well.
 

king of pipes

Esteemed
Plumber
Gas Engineer
Messages
5,594
I tend to agree with Chuck cut back on your usage drop the temperature lower at night and 1-2 ° during the day
 

John.g

Messages
2,832
Also set the boiler temperature as low as possible as the really big gain in boiler efficiency is below 50C return temp as it starts to condense then, at 50C return the boiler efficiency is ~ 88% but at 35C return its 96%. Maybe try a boiler temp of 45C initially but bear in mind that this setting, if it results in a return temp of 35C means that your rads will (only) emit 30% of their rated output which will still more than likely give you sufficient heat especially if the heating is on 24/7.

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