Gas on constantly or on and off...?

aelitaman

ixwood wrote: »

Sorry, but never allowing the house to cool, so that the boiler doesn't have to "work really hard" to warm it up is just ridiculous.

Boilers are most efficient when going flat out. If anything, as you have the heating on longer, then your boiler will be under more strain as it's on for a longer period overall.

Heating an empty house will never save money. That really shouldn't be hard to understand. Maybe you're just trolling.

If you're still adamant that it will, then obviously you must leave your kettle on 24/7 to make savings there too.

Why dont you measure the gas useage of your boiler. When you know you are going to have the heating on for 4 or 5 hours. Take the gas reading every hour from just before the boiler starts or you turn it on manually and then every hour afterwards. So you know how much gas is used to get the bolier and water up to temp and then howmuch it uses to tick over. You never know you may have a 100% efficient system, then again you may burn a heck of a lot of gas in the first hour compared to when the rooms are upto temp and the water temp just being top up.

Post the results, I am genuinely interested and it is the only way we can move on from equating central heating systems (designed to be run for long periods of time as effciently as posible) to boiling kettes (designed to heat and then VAPOURISE water quickly ineffciently).

Same argument as does a fiat panda use less petrol going 100 miles at 30 mph than a Formula one car doing 100 miles at 200mph.

SuzieSue

ixwood wrote: »

Sorry, but never allowing the house to cool, so that the boiler doesn't have to "work really hard" to warm it up is just ridiculous.

Boilers are most efficient when going flat out. If anything, as you have the heating on longer, then your boiler will be under more strain as it's on for a longer period overall.

Heating an empty house will never save money. That really shouldn't be hard to understand. Maybe you're just trolling.

If you're still adamant that it will, then obviously you must leave your kettle on 24/7 to make savings there too.

But my house isn't empty at night so why is "never allowing the house to cool, so that the boiler doesn't have to "work really hard" to warm it up" ridiculous?

ixwood

aelitaman wrote: »

Why dont you measure the gas useage of your boiler. When you know you are going to have the heating on for 4 or 5 hours. Take the gas reading every hour from just before the boiler starts or you turn it on manually and then every hour afterwards. So you know how much gas is used to get the bolier and water up to temp and then howmuch it uses to tick over. You never know you may have a 100% efficient system, then again you may burn a heck of a lot of gas in the first hour compared to when the rooms are upto temp and the water temp just being top up.

Post the results, I am genuinely interested and it is the only way we can move on from equating central heating systems (designed to be run for long periods of time as effciently as posible) to boiling kettes (designed to heat and then VAPOURISE water quickly ineffciently).

Same argument as does a fiat panda use less petrol going 100 miles at 30 mph than a Formula one car doing 100 miles at 200mph.

That would be even more of a waste of time than joining this thread.

Show me one link that says the efficiency of the boiler is lower when it's working hard and then I may take your point seriously. I think that's the key misunderstanding you're making

And anyway if it was somehow lower when working hard, it would still have to be enough difference to make up for all the unnecessary heat losses suffered from pointless heating.

Let's test your theory then... Say I run the heating for an hour in the morning and and 5 hours in the evening, that gives 6 hours in total. That's 1/4 of a day. If instead, I run the heating 24/7, that's 4 times as long, so in order for your magical less efficient when working harder theory to stack up the boiler would need to be over 4 times less efficient when it's running flat out. Do you think that's the case?

ixwood

SuzieSue wrote: »

But my house isn't empty at night so why is "never allowing the house to cool, so that the boiler doesn't have to "work really hard" to warm it up" ridiculous?

You're in a warm bed asleep, but that's not really the point.

The thread is about whether it's cheaper to only have the heating on when you're there, or just leave it on all the time (that's bound to work!). There is no doubt whatsoever that heating the house when you're not there is wasteful and inefficient.

aelitaman

ixwood wrote: »

Sorry, but never allowing the house to cool, so that the boiler doesn't have to "work really hard" to warm it up is just ridiculous.

You do not understand how a boiler works. If the water in the system is left to get to the temperature of the rooms overnight or during the day then the water may be 15C. If you have the temp on the boiler set to say 80C then the boiler will go flat out from start to heat all the water in the system from 15C to 80C. This will require a lot of energy to achieve. a temperature rise of 65C. When this temp is acheived the boiler will switch off the heating process but still pump water around (unless a thermostat is controlling the system). When the temp of the water entering the boiler has dropped to a certain level (depends on boiler but on some it is about 10C) then the boiler kicks in and heats the water again. But in this case it only has to raise the temperature from 70C to 80C a rise of 10C. So in this operation it will require 6.5 times less energy than when doing the initial get the water and boiler components up to temp.

Boilers are most efficient when going flat out. If anything, as you have the heating on longer, then your boiler will be under more strain as it's on for a longer period overall.

Rubbish, see above the boiler may run for flat out for the first hour of being turned on and then run for less than 10mins an hour when water has been heated to operating temperature.

Heating an empty house will never save money. That really shouldn't be hard to understand. Maybe you're just trolling.

If you're still adamant that it will, then obviously you must leave your kettle on 24/7 to make savings there too.

See comments above.

SuzieSue

aelitaman wrote: »

You do not understand how a boiler works. If the water in the system is left to get to the temperature of the rooms overnight or during the day then the water may be 15C. If you have the temp on the boiler set to say 80C then the boiler will go flat out from start to heat all the water in the system from 15C to 80C. This will require a lot of energy to achieve. a temperature rise of 65C. When this temp is acheived the boiler will switch off the heating process but still pump water around (unless a thermostat is controlling the system). When the temp of the water entering the boiler has dropped to a certain level (depends on boiler but on some it is about 10C) then the boiler kicks in and heats the water again. But in this case it only has to raise the temperature from 70C to 80C a rise of 10C. So in this operation it will require 6.5 times less energy than when doing the initial get the water and boiler components up to temp.See comments above.

Thank you, this is the point I have been trying to make.

aelitaman

closed wrote: »

http://en.wikipedia.org/wiki/Calorie

You might want to expand on the point you are making.

Cardew

You do not understand how a boiler works. If the water in the system is left to get to the temperature of the rooms overnight or during the day then the water may be 15C. If you have the temp on the boiler set to say 80C then the boiler will go flat out from start to heat all the water in the system from 15C to 80C. This will require a lot of energy to achieve. a temperature rise of 65C. When this temp is acheived the boiler will switch off the heating process but still pump water around (unless a thermostat is controlling the system). When the temp of the water entering the boiler has dropped to a certain level (depends on boiler but on some it is about 10C) then the boiler kicks in and heats the water again. But in this case it only has to raise the temperature from 70C to 80C a rise of 10C. So in this operation it will require 6.5 times less energy than when doing the initial get the water and boiler components up to temp.See comments above.

I find all this incredible.

Of course the boiler will work harder initially to heat a cold house, that is not in dispute; but it is irrelevant in this discussion.

Switch on a kettle filled with cold water and it will use more energy initially. So using your argument, you should keep it simmering 24/7 as it is more economical.

Can you not appreciate that the kettle when simmering at 100C will lose lots of heat that needs to be replaced? The hotter the water in the kettle, the more heat it loses, allow it to cool and it loses less heat, until it reaches room temperature and it loses no heat.

Don't dismiss that analogy as silly, it is exactly the same as a house(or any other body) as it cools down it loses less heat until when it reaches the same temperature as the outside ambient temperature it loses no heat.

I gave the quote from the Energy Saving Trust in an earlier post, and that is quite specific.

Question.
Is it more economical to leave my heating on 24hrs in the winter?

Answer

No. It is a common misconception that it is cheaper to leave your hot water and heating on all the time. Boilers use more power initially to heat water from cold, however the cost of this is greatly exceeded by the cost of keeping the boiler running all of the time.
The best solution is to programme your heating system so that it comes on when you need it most (possibly early morning and in the evening), and goes off when you don't need it (when you are out of the house or asleep). There are a range of controls that can be used and your heating engineer will be able to provide you with the most appropriate solution.
Depending on your circumstances it may be necessary to keep the heating on all day during winter but it will cost more than if you turn the heating off when you don't need it.

The analogy I gave earlier about leaving the house for a year is still valid.

Surely you are not claiming that the boiler having to work hard to heat the water from xC to 80C justifies keeping the house at constant temperature for a year.

Quite seriously, if you concede it would not be sensible to keep the house heated for a year, how about a month? it really is exactly the same principle. A week? a day? 12 hours? 3 Hours? Just at what point do you think the laws of physics no longer apply.

aelitaman

closed wrote: »

The gram calorie, small calorie or calorie (cal) is the amount of energy required to raise the temperature of one gram of water by 1 °C.

Same old point, heating from cold costs more per hour than than heating from warm, but not as much as maintaining temp in a cooling body.

Out of interest what is the Physics Law that is used to prove this "more energy is required to maintain temp in a cooling body"

TIA.

PennyPinchingMiser

aelitaman wrote: »

Out of interest what is the Physics Law that is used to prove this "more energy is required to maintain temp in a cooling body"

TIA.

First Law of Thermodynamics.

HTH