Energy myth-busting: Is it cheaper to have heating on all day?

QrizB

I'm convinced the creator of those videos is wrong.

Explaing why is tricky, but in essence his models are over-simplified.

richardc1983

QrizB said:

I'm convinced the creator of those videos is wrong.

Explaing why is tricky, but in essence his models are over-simplified.

He has many other videos but he is trying to explain this to end users like you and me. They have some very in depth videos with data but for the end consumer this would not make any sense. 

There are many others who are also saying the same though. Heat Geek also do an advanced engineering course in this area which is a recognised qualification for installers as this is the way things are going now. It's about understanding the thermal mass of a property but of course it's a balance between cost and comfort. Like he says in the videos each property is different and usage pattern. If you are home all day it's best to use low and slow rather than timed bursts of high inefficient heat (where the boiler is not condensing) .

For me at home my system is set to 19c 24/7 and on an evening bump it to 20c because the house thermal mass never really drops we are comfortable at those temps. I have tried setting it back to 16c overnight and then on an evening say 22c because at 20c the house felt cold. at 22c the house felt warm and the rads were hot but the boiler spent more time at an inefficient flow temp. It uses more energy in a sharp high burst of heat in  MY HOME. Everyone will be different though. 

BUFF

He's right in that it's a grey/blurry area & that the balance between comfort/convenience & cost will be different for every house/heating system & person. (especially if you also consider potential damage to the fabric of the house through not heating properly).
A lot of it chimes with where I have evolved to what suits me over the last 13 years in the same house with same heating system.

Northern_Wanderer

richardc1983 said:

There's the reasoning behind that as well. Another good video for consideration... 

Oh god! That vid is a bit much for me but I get the gist of it (kinda?) lol. I'd not thought about "zoning" before but I can see how my cold unused room is now like an added external wall in terms of heat loss? So, if I were to also have the TRV on it at 2, my system might be more efficient and save fuel? I might test this theory although waether variables would make that hard.

I just don't want to have bedrooms with the max setting for TRV, prefer a cool bedroom. I don't heat overnight as I don't want the boiler noise or get hot in bed. If I turned down the stat over night then the house wouldn't be warm enough in the morning when I get up.

I also wouldn't want my stat in the living room as I don't think the rest of the house would get warm then. I suppose we all have to work out the best way to use our own system as there are so many variables.

richardc1983

Northern_Wanderer said:

richardc1983 said:

There's the reasoning behind that as well. Another good video for consideration... 

Oh god! That vid is a bit much for me but I get the gist of it (kinda?) lol. I'd not thought about "zoning" before but I can see how my cold unused room is now like an added external wall in terms of heat loss? So, if I were to also have the TRV on it at 2, my system might be more efficient and save fuel? I might test this theory although waether variables would make that hard.

I just don't want to have bedrooms with the max setting for TRV, prefer a cool bedroom. I don't heat overnight as I don't want the boiler noise or get hot in bed. If I turned down the stat over night then the house wouldn't be warm enough in the morning when I get up.

I also wouldn't want my stat in the living room as I don't think the rest of the house would get warm then. I suppose we all have to work out the best way to use our own system as there are so many variables.

You have zones already, each room that has a TRV has a zone.

Think of your house as one big room but you have a number of rads to heat that big room. You shut off rooms you don't use but they are still part of the same house, even with doors closed heat will leach into them from the thin door, walls and floors which means the remaining rads are heating a larger space. 

Having less rads to heat means your boiler when modulating low is unlikely to be able to ramp down low enough to satisfy the few rads left on which means it cycles. When a boiler cycles you don't want this because you end up with unburnt gas in the chamber that is purged at the start and end of each cycle. 

I am like you, I prefer a cooler bedroom so our bedroom is turned down but not off, the remaining spare room though is left on full but then I leave the internal doors open as I use it as my office. 

It is a very personal preference on your lifestyle, your home etc but it's about being considerate of what works for others doesn't work for some folk etc. 

What do you run your boiler flow temp at? The idea is to get that down as low as possible but while being able to have all the other zones open so that the house is comfortable. My boiler uses opentherm which can mean the rads have water as low as 30c flowing through. 

wild666

After April we could see homes not being heated as much and a rush on hot water bottles. I have a hot water bottle that I use most days in winter. I heat my property once per week, when the daughter is down, other times it's a hot water bottle. 

richardc1983

wild666 said:

After April we could see homes not being heated as much and a rush on hot water bottles. I have a hot water bottle that I use most days in winter. I heat my property once per week, when the daughter is down, other times it's a hot water bottle. 

Before winter we opened up the fireplace again and put a log burner in. 

Ultrasonic

richardc1983 said:

Ultrasonic said:

One thing I do often forget is that many have thermostats fixed to the wall in unhelpful places like hallways. My thermostat is wireless so I can have it in the room I want (my lounge) whilst my hallway can remain much cooler.

yeah it was designed to be in the cooler room so that it didn't shut off too early. I had my thermostat moved from my hall into my living room for the reason you say above BUT I moved it back. The radiator in the lounge is bigger and thus the room warmed up quicker and then meant that the heating shut off to the rest of the house. Having it in the hall means the room warms slower due to a smaller rad but the heating stays on that little bit longer before modulating down or going off. 

Whether the point in bold is an issue depends if this results in the rest of the house being heated less than needed or not. In my case it doesn't.

For context, I've just checked and over the exact period 04/03/21 through 04/03/22 I've used a total of 3202 kWh of gas for heating and hot water. This is as a single occupier of a three bedroom detached home (about 25 years old), and generally being at work rather than home on weekdays.

QrizB

Northern_Wanderer said:

richardc1983 said:

There's the reasoning behind that as well. Another good video for consideration...

Oh god! That vid is a bit much for me but I get the gist of it (kinda?) lol. I'd not thought about "zoning" before but I can see how my cold unused room is now like an added external wall in terms of heat loss?

That's one of the things he's simply wrong about.

But I am not prepared to spend the time and effort it would take to debunk his errors; I have better things to do.

richardc1983

QrizB said:

Northern_Wanderer said:

richardc1983 said:

There's the reasoning behind that as well. Another good video for consideration...

Oh god! That vid is a bit much for me but I get the gist of it (kinda?) lol. I'd not thought about "zoning" before but I can see how my cold unused room is now like an added external wall in terms of heat loss?

That's one of the things he's simply wrong about.

But I am not prepared to spend the time and effort it would take to debunk his errors; I have better things to do.

He’s a fully trained heating engineer who’s passion is for people to save money and run their systems efficiently. He does advanced installer training courses that are government recognised qualifications that are based around what he is saying. He isn’t wrong but like everything it’s very specific to peoples homes just like he says at the beginning. There are many videos on his page and youtube that provide data to back up what he is claiming. 

I’ve mentioned above if you have a large room such as a lounge with two rads, would you turn off one half of the room as you only use half of it or would you have both turned on? The rest of your house is the same and connected via the same structure and fabric. Unless it is an extension annex or mainly separate from the rest of the home. It’s the same thermal mass. It doesn’t suit everyone but a heat pump for example would use more energy having 2 timed periods a day at 60c flow temp than low and slow all day. It’s no diff for mains gas boilers if you run them in the same way, you will save energy although gas is cheaper per unit of electricity so the savings are less substantial.