keeping boiler on all time saves money

loates123

What do u think does this really work with a system boiler http://www.telegraph.co.uk/property/propertyadvice/jeffhowell/8214378/Home-improvements-how-to-heat-the-house-this-winter.html

rogerblack

loates123 wrote: »

What do u think does this really work with a system boiler http://www.telegraph.co.uk/property/propertyadvice/jeffhowell/8214378/Home-improvements-how-to-heat-the-house-this-winter.html

It's at best confusing.
It is not actually saying 'keep your heating on 24 hours'.
It's saying 'keeping your boiler running at 25% 24h, not turning on and off at 100% output for 6h total a day will save money,'.
In short, if you have a boiler with a variable output, and want to keep the home at a constant temperature, adjusting the output down, so the loop temperature of the water stays in the condensing range is a good plan.
Many boilers do this anyway, and the improvement will be small - 10% tops.
Varying the temperature of the house so iit's as low as is possible throughout the week will save more.
Though the boiler may be less efficient, it is running at a lower total kWh output' so saves money.

macman

No, it doesn't apply to any boiler. The more you run it, the more gas it burns and the more it costs you.
The advice to keep both CH and DHW on 24/7 is uterly nonsensical.
It defies the basic law of physics.
PS: this question is asked about 5 times a week once the weather gets colder-but the answer does not change.

rogerblack

macman wrote: »

No, it doesn't apply to any boiler. The more you run it, the more gas it burns and the more it costs you.
The advice to keep both CH and DHW on 24/7 is uterly nonsensical.
It defies the basic law of physics

Not quite true.
Boiler on 100% for 15 min/hour, input power 30kW, radiator return temp 60c, efficiency 80%, heat output 24kW, total used at the end of the day 180kWh.
(6h*30).
Boiler on at 20% constantly, heat output 6kW, return temp 40c, efficiency 85%, gas input 7kW, gas use 168kWh.

The advice to keep it on all the time is mislead, but there is a core of truth there.

HappyMJ

rogerblack wrote: »

Not quite true.
Boiler on 100% for 15 min/hour, input power 30kW, radiator return temp 60c, efficiency 80%, heat output 24kW, total used at the end of the day 180kWh.
(6h*30).
Boiler on at 20% constantly, heat output 6kW, return temp 40c, efficiency 85%, gas input 7kW, gas use 168kWh.

The advice to keep it on all the time is mislead, but there is a core of truth there.

In your first example you need to divide by 4 as the boiler is running at max for 15 minutes every hour (1/4 of an hour) so the total usage over 6 hours would be 45kWh per day.

In your second example you could also say the boiler is running for 6 hours and uses 42kWh per day.

So the saving by having the boiler set to a low temperature over 6 hours would be 3kWh but it would take longer to heat up the house. Maybe an hour instead of 15 minutes.

Wywth

loates123 wrote: »

What do u think does this really work with a system boiler http://www.telegraph.co.uk/property/propertyadvice/jeffhowell/8214378/Home-improvements-how-to-heat-the-house-this-winter.html

Thank you for posting that article from 2 years ago.

I remember reading it at the time and have followed the advice to the letter, particularly this part:

Think of the motoring analogy, where everyone agrees it is more fuel-efficient to drive at a steady speed, rather than continually stopping and starting.

I've been running my car engine at a constant 5000rpm ever since it was first published and not stopped it once (apart from it's annual services), even at the filling stations ... which I appear to be visiting far more often than previously all in the same of moneysaving :money:

Toxteth_OGrady

Wywth wrote: »

I've been running my car engine at a constant 5000rpm ever since it was first published and not stopped it once (apart from it's annual services), even at the filling stations ... which I appear to be visiting far more often than previously all in the same of moneysaving :money:

If you put a money saving end stop on your accelerator you could stop it idling above 4500 rpm. That would save you a few bob.

oldskoo1

I was in the 24/7 camp for a long time, you will see the threads i posted on here about it from my post history. However, i've just moved into a 5 bed, 3 storey house which is substantially more expensive to heat. With the 25% rise in prices plus the fact we underpaid due to a £50 credit our bills are higher, so i'm trying to tune our G.CH system to be efficient and comfortable.

Luckily i have had a week of stable weather conditions. I have taken daily readings running different settings which at micro level does have a high margin of error. But i need a best estimate result to put in place for the winter.

Same temperature 24/7 v timed (6am-9am, 12pm-2pm, 5:30pm-11pm) - you save at least 10% on gas using timed. On average you save 15% (there is a 5% swing each way to account for the margin of error). The savings maybe further exaggerated at different outside temperatures.


Now my biggest problem is trying to decide on what temperature to set the thermostat. I have TRV's on all rads above the ground floor, the ground floor is just normal open valve. I also need it on in the day as i work from home.

Problem is my thermostat is in the hall, outside the kitchen door and the kitchen is very cold due to gaps behind the kitchen cabs. So the CH is constantly clicking on. A hall temp of 16c translates to 21c in the lounge and 18c-19c upstairs (all bed rads have a TRV setting of circa 19c).

I'm not sure whether to have it timed longer at 16c or to cut the timings by 1hour in the morning, day and evening and have it at 18c in the hall, let their TRV's do their job but build up more residual heat downstairs but more importantly have the boiler running at high output which i thought was more efficient for an older non-condensing boiler. I will need to test it with meter reads as i dont know the technicals behind the boiler efficiency.

rogerblack

HappyMJ wrote: »

In your first example you need to divide by 4 as the boiler is running at max for 15 minutes every hour (1/4 of an hour) so the total usage over 6 hours would be 45kWh per day.

In your second example you could also say the boiler is running for 6 hours and uses 42kWh per day.

So the saving by having the boiler set to a low temperature over 6 hours would be 3kWh but it would take longer to heat up the house. Maybe an hour instead of 15 minutes.

15 minutes an hour, for 24 hours a day - 6 hours.

The saving from the above is small in comparison to other measures, like setting the thermostat down a degree, or adjusting temperature throughout the day and week to keep it at a minimum.

There is some efficiency gain from keeping the loop temperature low - but many boilers will do this automatically.
If your boiler is condensing, and not running fully in condensing mode due to high return temperature, then it's worth investigating if you can fix this.

Pincher

The Telegraph answer has an extra angle. It is saying if you wear a dry sweat-shirt it keeps you warm, but if it's wet it will drain heat from you. This makes it necessary to keep the sweat-shirt dry. In the case of a house, this means keeping the heating on at a minimum level.

My programmer has no OFF mode. I am running the programmer with two temperatures: 18 and 16 degrees. I used 124 imperial units in 27 days up to today, so it's about £5 a day for recent weather, including hot water. Five bedroom semi, two storeys, with outdoor sensor for weather compensation.

Cardew

I am a little puzzled by the advice in the articleabout heating unoccupied rooms to prevent mould.

If an unoccupied room becomes damp it is because there is an inherent problem. All heating a room achieves is for the air to hold more moisture and initially mask the problem.

Indeed mould is a far bigger problem for properties in sub-tropical/tropical climates.

If there is a problem of dampness in an unoccupied room that cannot be cured, it would be better to use a small dehumidifier than keep it heated.