What temp should I set the CH on our condensing boiler?

[Axel]

I had been led to believe that a condensing boiler will only work at the fantastic advertised 90% efficiency when it is in condensing mode, which is when it is running at a lower temperature?

 

[Leesa1966]

You beat me to it! I was going to ask why our condensing boiler (and others) have the option of a wide range of CH temperature settings when only max is recommended?

 

[D_Hailsham]

You beat me to it! I was going to ask why our condensing boiler (and others) have the option of a wide range of CH temperature settings when only max is recommended?

The efficiency figures you find quoted by manufacturers and in the Sedbuk database are annual averages, calculated according to a set formula. It takes into account the fact that the boiler will not always be condensing.

To give just one example, the Remeha 18V quotes the following spec:

Input: 18kW
Output at 80/60: 17.6kW
Efficiency at 80/60: 98% (not condensing)
Output at 50/30: 19kW
Efficiency at 50/30: 106% (condensing)
Sedbuk Efficiency: 90.5%

For a boiler to condense, the return temperature has to be below 55°C. (approx).

 

[Axel]

You had better explain Gross and Net heat inputs; the concept of 106% efficiency will may not be grasped by OP and others.

 

[D_Hailsham]

You had better explain Gross and Net heat inputs; the concept of 106% efficiency will may not be grasped by OP and others.

I don't thinks an explanation would help too much - it might send some to sleep!

I suppose choosing a continental boiler was a bad idea, as they test according to the DIN standard, which gives the over 100% efficiency figure- perpetual motion anyone!

To quote a "british" boiler -Ideal Icos HE18

Power Input: 20.7kW
Output at 70C mean temp: 18.2kW
Efficiency at 70C mean: 87.9%
Output at 40C Mean: 19.2kW
Efficiency at 40C: 92.8%
Sedbuk Efficiency: 90.3%

 

[Leesa1966]

You beat me to it! I was going to ask why our condensing boiler (and others) have the option of a wide range of CH temperature settings when only max is recommended?

The efficiency figures you find quoted by manufacturers and in the Sedbuk database are annual averages, calculated according to a set formula. It takes into account the fact that the boiler will not always be condensing.

To give just one example, the Remeha 18V quotes the following spec:

Input: 18kW
Output at 80/60: 17.6kW
Efficiency at 80/60: 98% (not condensing)
Output at 50/30: 19kW
Efficiency at 50/30: 106% (condensing)
Sedbuk Efficiency: 90.5%

For a boiler to condense, the return temperature has to be below 55°C. (approx).

Err this is all getting very techincal for a mum trying to set the temp with one hand and hold back a hyperactive toddler with the other!

 

[ManxPlumber]

So how does an 18 month old baby reach the controls on a boiler?

 

[Axel]

He first gets qualified and registered with GasSafe, and by age 3 should be developed enough to tackle any boiler installation or repair.

 

[Gasman77]

Toddler was up late! said 10:51 pm on the post!

 

[Leesa1966]

So how does an 18 month old baby reach the controls on a boiler?

It is 6 inches or so off the ground in the corner of the kitchen. Much to his delight the display panel lights up when he plays with it. For 6 months or so he had been fooled by a piece of paper sellotaped over the display panel it but now he has worked out that he can rip it off and have his own personal light show when my back is turned.

 

[Axel]

Then I would suggest you let the toddler decide on the settings of the boier controls. Some modern units have complex and sophisticated sub-menus and programmes / parameters to play with.