Would it really cost more to always keep the heating on?

[HumanBehaviour]

My husband has the habit of turning the heating on for an hour in the morning and an hour in the evening, each time turning the thermastat to 25C. This means that each time we turn the heating on the radiators has to heat a cold house.

Would it really cost that much more to keep the heating on 19C all the time? If it is kept at a constant temperature it will not have to work as hard each time, IYSWIM?

How do you heat your houses?

We've got conventional gas central heating, well insulated house. If we put the thermostat at 19C it would keep the temperature of the house at 19C (at least where the sensor is).

Why on earth does he turn the heating up to 25C? Surely even if you were to put it on for an hour at 21C it would still heat the house through - turning the thermostat up higher doesn't warm the house up any faster.

We do find that if the heating has been off for a really long time the whole structure of the house gets too cold and it's hours before it'll warm up again.

In ours we have the heating on for a couple of hours in the morning (as we tend to get up early) and then again from 5:30pm to 9pm, but it doesn't always click on as the house stays warm enough.

The whole point of a thermostat is to set it at a sensible temperature and then bloody leave it alone

Jareth: What is your reason for not leaving it alone then?

Sorry, I'm not sure what you're asking?

Haha, very apposite nickname, HumanBehaviour!

Your DH's behaviour is exactly why some advise leaving heating on low all the time.

There have been very good explanations on some threads of why, in physics terms, it is cheaper to only have heating on when necessary.

However as soon as you introduce humans, they come in, whack the thermostat up to 25 C and then go out just as the house is reaching temperature.

The true best way to do it is to set the thermostat for the desired temperature with the timer to come on 30 mins before you wake/get in (or however long your house takes to warm).

You can also set the timer to switch off 15 mins before you go out, if you don't mind the house cooling slightly before you're actually out of the door.

I was told many years ago that the most cost effective way of keeping the house warm in Winter is to keep the heating on at a constant temperature.

That way the house always maintains the heat eg 21C instead of having to try to bring the temp up from whatever to 21 every few hours.

Obviously it hasnt been horrendously cold so far this year, well in SE England it hasnt, so our heating is on but turned down lower than usual, when it gets 'properly' cold it will be set a bit higher.

Jareth: You wrote "The whole point of a thermostat is to set it at a sensible temperature and then bloody leave it alone" But you also said that you got the heating on timer to switch it on and off. IN that case you're not leaving it alone, are you? You're doing the same thing as my husband but at a lower temperature.

Tianc: I'm a SAHM so we don't turn it on just to leave as soon as it gets warm, I'm in most of the day. Do you know what the explanations in physics terms are? Would love to hear them.

I have to add that I have recently moved to the UK from Sweden (where we always keep the heating on at a constant temperature) which is why I am puzzled with this phenomenon of only turning the heating on when it feels cold.

Try this one: Probably stupid question about this keeping the heating on constantly at 16 degrees thing

But the short answer is, cos the UK housing stock is crap. Insulation and air-tightness on older houses are rubbish, and on new-builds still greatly inferior to many northern European countries.

So the house loses heat very quickly.

If you have a well-insulated house, I can imagine the discussion of constant temp vs reheating comes down to the most efficient working conditions for your boiler. Here, iiuc, it's usually over-ridden by the heat loss factor.

If you're in all day, I don't understand why your DH is switching it on and off.

Switching on/off is for people who'd otherwise be heating an empty house all day.

Definitely bonkers to sit in the cold all day and then heat to a high temp in the evenings to make up for it - heat loss is proportional to temp difference!

It gets warm during the day anyway without heating, so far its only been cold at night.

To phrase it better: If we left the heating on all day it would not be kicking in during the day when it's warm so it shouldn't matter.

In the mornings though, had we kept the heating on all night we would not have to "start from scratch" and heat the whole house as it would never get really cold. This is basically what I am wondering, would we use more energy if we had it on all night at a reasonable temperature than if we heat it up from cold every morning.

Yes, I said I leave the thermostat alone. Of course we have a timer for the heating - we don't want it on all day when we're not here, or all night, do we?

Stop being bloody picky

wow, that was stroppy!

anyway.. I just meant that we let the thermostat control the temperature in the house and we don't need to worry about it. It works for this (slightly drafty house)

I don't get the 25C though - do you actually want your house to be that warm, or is it an attempt to warm the house through faster?

Sorry Jareth, I wasn't clear to start with. The thermostat is set at 25 he doesn't actually turn it, but that is what comes on when he turns the heating on.

But anyway, that is beside the point. Let's say he turns it on to 20C, stil asking the same question.

I've lost track of the question.

HumanBehaviour, can you say what temperature you would like yourself and the people in your house to be experiencing:
a) first thing in the morning
b) during the day
c) in the evening?

d) During the night?

I would like it comfortable (say 19C) at all times but not at night. At the moment it does not get cold indoors with heating off.

This is basically what I would like to compare the use of kWh when:

A - thermostat set at 19C with heating on constantly where it only have to cover the buildings heat loss as it happens

B - thermostat set at 19C with heating on twice a day for two hours having to increase the buildings temperature from (say) 16C to 19C and therefore using higher kW when it is turned on (but for shorter period)

At the moment it does not get cold indoors with heating off during daytime

I think you need:

C - thermostat set at 19C with timer (or manual switching) set for heating on all day and off at night.

As you correctly say, the heating will work harder for a short period to raise the temp from say 16C to 19C. You can then allow the thermostat to click the heating on and off when necessary to maintain the 19C. You can happily leave it on this setting all winter (tho you may need to arrange night-time heating at some point.)

Your (rather, DH's) current method is using the timer to overshoot the 19C and then letting the house cool, then hitting it with 25 degrees in the evening. So you're hotter than you need be in the morning and evening, and when the weather turns you'll will be colder than you'd like during the day.

So you are basically saying that we will use less energy by turning the heating off at night and on all day compared to always keeping it turned on?

Arrrggghhhhh! How long is a piece of string?

Your heating bill will depend on
how long the heating is on
how high the heating is on
your habits like leaving windows open

Your human comfort will depend on
how warm the house is
when the house is warm
your habits like when you're in the house

Only you can decide how to join the dots for your max satisfaction.

No one can give you a fixed rule, because as your DH shows it's possible to apply the rule so that it's wrong for your situation.