Which is the most cost effective?

wittynamegoeshere

tux900 said:

Besides which, ever heard or tea urns and boiling water taps? They are intended for regular draw off and would be a much more relevant comparison to make. 

Not saying you're conclusions wrong though; just the premise! ;-) 

Tea urns and boiling taps really do use lots of energy, regardless of whatever the pseudo-scientific claims and marketing waffle for these things state.

The only reasons to heat your house when you're not there is if it's sub-zero outside when there's a risk of damage from pipes freezing.

Reed_Richards

It comes down to two questions:

Does the house lose less heat when it is cooler?
Is a boiler working hard to warm up the house less efficient than a boiler just keeping the house at a constant temperature?

All conventional wisdom is that the answer to the first question is Yes.  That is why you are advised to turn down your room thermostat to save energy.  I don't believe condensation inside the walls will make them less thermally insulating, even if it did occur.

Generally the answer to the second question is No.  However if you have a condensing boiler and working it hard caused the return water temperature to be higher than that which is needed to achieve condensation then the boiler efficiency would be reduced.

Personally I allow my house to cool at night but set a "backstop" temperature of 1.5 C less than my desired daytime temperature so it never gets too cold.  


  

Aylesbury_Duck

tux900 said:

Aylesbury_Duck said:

I agree.  I've often thought of it like a kettle.  No one would keep their kettle simmering away all day so they save energy compared to heating it from tap to 100 Celsius when they need it, no matter how well-insulated the kettle might be.

I don't know how good that analogy is. You drink tea at discrete points in time, and in between you don't. It's very unlike heating a home.

Besides which, ever heard or tea urns and boiling water taps? They are intended for regular draw off and would be a much more relevant comparison to make. 

Not saying you're conclusions wrong though; just the premise! ;-) 

I suppose it could be in the case where the home is empty from say, 8am to 6pm.  It wouldn't be sensible to leave the heating on between those times just so it doesn't need to heat a cold house to 20 celsius in time for arrival at 6pm.

If you're home, then a permanently simmering kettle or urn is at least contributing to warming the house, even when you're not needing a hot drink 

wittynamegoeshere

Aylesbury_Duck said:

If you're home, then a permanently simmering kettle or urn is at least contributing to warming the house, even when you're not needing a hot drink 

Fine IF it's winter AND you're still paying the higher cost of electrical heating for that bit of heat rather than the lower cost of gas, heat pump, oil or whatever else!

A condensing boiler should work at higher efficiency if the house is cold.  Then the water returns at a lower temperature.  When it's maintaining temperature the returned water will be warmer so the boiler will run less efficiently, as more heat will go out of the flue as it doesn't get transferred into the water.

jimjames

GrubbyGirl_2 said:

QrizB said:

GrubbyGirl_2 said:

I would appreciate views

There's an official MSE article on exactly this subject:
https://www.moneysavingexpert.com/utilities/energy-saving-myths/

Having now read it I see it's not conclusive!!  I guess I should try one week each way and see what the smart meter says

Logically if you only need to put the heating on an hour before to get the right temperature it makes no sense to keep it on all the time. Otherwise the heating is on for 8 hours (for example) rather than one and you're heating a house with no one in it.

victor2

Don't forget this epic thread, which gets updated every year as the weather turns cold...

https://forums.moneysavingexpert.com/discussion/4327195/energy-myth-busting-is-it-cheaper-to-have-heating-on-all-day/p113

wittynamegoeshere

It's the most cost-effective to put a jumper on.

Streaky_Bacon

As has been said, the laws of physics, with regards to maintaining a temperature or allowing it to cool and then reheat, are pretty clear on this one. It takes more energy to keep things hot.

That said, there are specific issues with the workings of boilers which may mean that may muddy the picture.

Certainly, every time I have tried it, I have found that, in terms of gas usage, I have used the same when maintaining or cooling and then reheating, but it is impossible to get exactly the same variables.

The truth is that you could become a world expert on thermodynamic theory, but that would never be a substitute for actually trying it out with your boiler.

Reed_Richards

Streaky_Bacon said:

The truth is that you could become a world expert on thermodynamic theory, but that would never be a substitute for actually trying it out with your boiler.

Trouble with that is that you need exactly the same outside temperature (actually the same temperature profile for the day) two days running to make a proper comparison.  How often does that happen?  

Petriix

Streaky_Bacon said:

As has been said, the laws of physics, with regards to maintaining a temperature or allowing it to cool and then reheat, are pretty clear on this one. It takes more energy to keep things hot.

That said, there are specific issues with the workings of boilers which may mean that may muddy the picture.

Certainly, every time I have tried it, I have found that, in terms of gas usage, I have used the same when maintaining or cooling and then reheating, but it is impossible to get exactly the same variables.

The truth is that you could become a world expert on thermodynamic theory, but that would never be a substitute for actually trying it out with your boiler.

It's actually the opposite. You can use uncontrolled anecdotal 'tests' to attempt to demonstrate your erroneous belief that it could possibly lose a similar amount of energy while having a higher temperature differential for longer. But you'd still be objectively wrong. The only thing that would 'muddy the picture' would be the near infinite uncontrollable variables.