Radiator temperature setting on combi boiler

NewEdition

Frequent Poster
Messages
205
I got a combi boiler fitted in the summer.
Its obviously getting some use now.
What is the rad temperature setting on the boiler?
Is that the temperature that the boiler heats the water to which will obviously be higher than the rads themselves?

What do people have this set to usually?
I am setting it to 45 degrees but have had to increase that now.

What temperature should I not go above?
I dont want to cause damage to the boiler or my wallet!

Does the temperature I set the boiler to cost proportionately more in line with the temperature, for example is 44 degrees 10% more expensive than 40 degrees?
And is 45 degrees 10% cheaper than 50?

I heard some of those energy saving ads on tv say by turning down by a couple of degrees can save a lot of €€'s but is there much savings made by a couple of degrees?

Thanks
 

Leo

Moderator
Messages
10,417
What make / model of boiler? What does the manual say? See here for an example where they recommend 75 degrees for the radiator setting.

When they talk about turning the heating down a couple of degrees, it is the room thermostat they are referring to. If you set your radiator temperature too low, it may struggle to bring the rooms up to the temperature set at the room thermostat, and so be extremely inefficient. A boiler constantly firing on and off to hit a lower temperature will always be less efficient than one running at full blast for a time to hit a higher temp. The increased cycling of the lower setting is also harder on the boiler.
 

Alkers86

Registered User
Messages
69
Also, the heat transfer between the radiators and the room is proportional to the temperature difference. If the rads are only a small bit warmer than the temperature you want the room to be, they will take very long to bring the room to that temperature. If the rads are very hot, much more heat transfer occurs.
 

NewEdition

Frequent Poster
Messages
205
@Leo Its a Logic Combi C35.
I understand the above.
I should have the boiler higher.

I usually turn off the rads in rooms that are not used for periods of time. It seems that is a bad idea.
Some of the rads have the thermostat ranging from 1-5 but for unused rooms that just have the old valves, should I leave them partly open? 25%? 50%?
It seems a waste having the rads on full in guest rooms.
 

NewEdition

Frequent Poster
Messages
205
In fact.. whats the point of those old valves?
Its just restricting flow rather than temperature.
I dont understand any advantage in having it 20% open vs 80% open. The rad will still get as hot as the others right?
 

Leo

Moderator
Messages
10,417
I usually turn off the rads in rooms that are not used for periods of time. It seems that is a bad idea.
Balancing a system is done with the main valves all fully open. It is the lockshield on the other connection that is adjusted to ensure that the system as a whole operates efficiently, and that every rad in the system can get sufficient flow.

I dont understand any advantage in having it 20% open vs 80% open. The rad will still get as hot as the others right?
Once the system is balanced, you can then adjust the main valves to suit your usage patterns. It's usually a good idea to keep some heat in unused rooms so you don't end up with condensation and issues as the warmer air from heated rooms hits cold surfaces in unheated rooms.

Some of the rads have the thermostat ranging from 1-5
These are almost certainly thermostatic valves, and the numbers refer to the temperature range. As the temp approaches the set value, the valve will start to restrict the flow of water to that rad.
 
Top