Central Heating economy of running 24 hours

[JonathanM]

Yes, just write 2^2 into google search and you will get 4.

Thanks. I'd not seen this notation before. I'd only ever used a superscript for powers.

 

[RandomGrinch]

The problem is we get poor information. This report seems good, but it shows when my thermostat called for heat, not when the boiler was running, the same applies with a modulating boiler, it tells you how long it was running for, but not at what output it was running at.

Thanks Eric - just for comparison my call-for-heat time is substantially less:

But I have a non-condensing, non-modulating boiler, set continuously to 18°C. My boiler may be running continuously on full power for the entire time, whereas yours is modulating away happily!
As you say, these reports don't give adequate information.

...and heat loss wise, I am in an 1890's mid-terrace. Despite solid stone walls, with neighbours both sides, over 60% of my walls have perfect, or better than perfect insulation!

Calculating and comparing the economy of heating systems is complicated!

 

[Harry Bloomfield]

Vaillants are or were even worse, they maintain ignition conditions for 60 secs bvefore allowing any modulation so the boiler temperature has to be very low to avoid recycling.

I think I am correct in suggesting that was the case here, when simple basic controls were installed. Once I upgraded to Vaillant controls, my boiler seems to start up with a purge, then ignition - following which it seems to almost immediately modulate to a level to match the demand.

 

[fixitflav]

What does the ^ mean?

Is rad to room different because convection is higher when rad temperature is higher?

It's just an observed fact that for a rad the heat output by natural convection varies as ∆T^n where n is typically 1.25. For different configurations eg a horizontal surface n is different. For cooling by a strong draught heat loss varies as ∆T - Newton's law of cooling.

 

[fixitflav]

Thanks. I'd not seen this notation before. I'd only ever used a superscript for powers.

Superscript looks neater but no way of typing it on here (that I've found), so have to use ^

 

[JonathanM]

Superscript looks neater but no way of typing it on here (that I've found), so have to use ^

I don't think I've ever typed a power! The last time I did this sort of thing was over thirty five years ago so I've only ever handwritten them before. Presumably in the intervening years ^ has become the way to do it.

 

[Johntheo5]

Spreadsheets have always used ^ as the power to and * as multiply