Finding the chase and cutting to it

Can I be honest, here? I love data: I am a bachelor of science even though I did maths and computer science, and some of my natural scientist friends do look down on that “type of degree”. Can I be honest, I do think maths is more of an arts subject, as we don’t tend to do experiments.

Computer science is arguable. Yes, it is language based, but the vast majority of coders do test their code to ensure it is doing what it should be doing…

That’s not why I’m writing this piece. This is all about getting an infra-red camera.

Why, oh why, would you bother writing about that?

Well, because it’s kind of fascinating. We all know what we learnt at school and from the various adverts and articles discussing how to save energy at home by “keeping the heat in” – that’s insulation to you and me.

But as a mere human, it’s very hard to know if the measures you are taking are making any difference.

Without measuring, of course. I could have bought a dedicated unit: instead I bought a dedicated charge-coupled device that doesn’t have a filter to cut out infra-red rays. It plugs into the USB C port on my phone which launches the app which can display the data (image) being captured by the camera.

It came first thing this morning and I had a busy day at work, so I wasn’t able to play with it until my afternoon tea break. Oh my, it is amazing.

Downstairs, we don’t switch off the heating during the day, turning down the thermostat to 16°C. Internally, where we get thermal gain from our windows, the floors and furniture are warmer than their surroundings.

Externally, that heating effect is heating bricks that take much longer to cool down – so taking pictures at 7pm, 2 hours after the sun has set is probably showing heat coming off the bricks that is completely expected! If I’m keen I will get up early tomorrow when that effect will be minimal. Then I should be able to see if our insulation is being effective.

Some things are really interesting – if we don’t wear slippers, the camera picks up where we have just walked. Our footprints glow white then fad to yellow, orange, red, then fade completely.

We can see the heat conducting and convecting off our radiators or pouring through the underfloor pipes. We now have a means to see where our heating pipes are, so long as we’re pointing the camera at them when they first come on.

Outside, we can see the heat pour from the air vents in our walls and windows. The garage is particularly lossy, not least because it is very difficult to make it air tight. It also has the pipe work for the heating and hot water. We, and the previous owners, had lagged much of the pipe work in there as a result, but of course we can see if that is being impactful. The gaps are obvious.

But mostly, it looks like it is all working reasonably well.

So, how do you make use of the camera, and understand the results?

Good question. The camera calibrates itself to the surroundings, which means the scale is shown each and every picture.

Take this one of the lounge floor just starting its heating cycle just after tea.

The dark areas are cooler than the white areas but scaled for the image in question. Another picture will be at a completely range.

You know that advice to not dry items on radiators. This is why:

The radiator is nice and warm, but the towels are just soaking up all that heat and not distributing it around the room.

The tiles are colder, 21.2°C – the dark colour is not a good sign. It means we’re probably losing heat through this interior wall.

This picture shows that little heat is being lost through this external wall. While the window vents and wall vents are leaching heat through them. My beloved is glowing bright, as his body temperature is about 36°C – it was a little cold out in the dark that night and his clothing is shielding it a little.

OK, so now what? What are you going to do with this “knowledge”?

Well, nothing today, per se. But, it has spurred us into getting a blind for the last uncovered window in the house – a thermal black out one, of course.

I am very tempted to get something for our internal doors – it’s frightening how much of a rooms heat pours into the hallway.

We also seem to have some gaps in our roof insulation. We need to ensure this is breathable insulation but it’s tempting to pull our finger out and close those gaps.

Of course, that will all help to reduce our carbon footprint and save some money. It’s been a cold autumn. Even so, we are using dramatically less electricity to heat our house than we used gas – how can I say that? Well, a low usage year for our gas consumption was 13 MWh, where-as we have only used 3.97 MWh last year.

Of course, now the windows have been installed, I am looking forward to seeing the new results.

The results with the new windows.

What else can we do with this kind of knowledge?

Of course, this is not the only thing we can do with the camera.

The temperature measurement means I have been able to tune our heat pump to run really efficiently.

Heat pumps are basically mecahnical compressors taking heat from their inputs and use an exchanger to heat the water for your hot water supply and radiators and/or underfloor heating circuits. Compressors work efficiently (both economically and in terms of longevity) if they run gently, running at a constant rate and temperature.

So, ideally your input flow to your radiators is hitting about 35°C-50°C. By the time it hits the last radiator in your run, you shouldn’t be losing more than 5°C – you can only know that by measuring it or painstakingly working out the gradient from the radiator thermostat graphs and deriving the differences between each of your radiators…

Anyway, I used the camera to see that we were dropping about 10°C across our upstairs run, meaning our last radiator is struggling to get up to temperature with a input flow temperature of 42°C. Looking up how this works (Google or Gemini are your friends here), our strategy has changed.

First, change the temperature levels.

Our pump has three settings. Reduced will be set to 22°C, Normal to 23°C, and comfort to 25°C.

Next, look at the heat curve.

Our pump was originally set to “0.7”. That works really well for our underfloor heating circuits, but the radiators did not get up to temperature unless our temperature levels were set to 23°C, 25°C, and 27°C!

I have reset the curve to “1.1”, this changes the flow temperature that is set once the outside temperate (the ultimate input for the heat pump, the air temperature is where the heat is being extracted from). With a curve of “1.1”, the flow temperature going in to the radiators is set at 50°C when the outside temperature is below 1°C. At 10°C, the flow temperature is 40°C, and 20°C when the outside temperature is 20°C.

Finally, timing which radiators come on when.

Our ensuite tado radiator needs to be on most of the time, as that means the radiators in the 2nd ensuite and the bathroom are on. So, during our heating window (when we’re making the most of our solar generation), it comes on for an hour longer than the other rooms.

So far, it seems to be making a difference. Our electricity usage curve has smoothed out. Of course, I am mucking about with this on the coldest day of the year!

Now, what you are looking to do is keep your rooms at a reasonably constant temperature during the peak times and let them gently cool down when electricity is at its peak charge rate.

During the summer, we will be using our solar panels to heat our water completely, but spring and autumn will see us use the house as a thermal store, so we can move off using the grid as much as possible.

The winter is all about being comfortable. Last year, January saw us using 1,327.00 kWh, with 926 kWh being used by our heating.

Now, there are some things we need to consider. Our radiators worked well for a high output boiler, but we have to tune our heat pump to suit them. Ideally, three of our radiators would be swapped out. Looking at the camera and the electricity usage, it would be worth doing that for the bathrooms. Next week I will be looking at some tuning we can do for our heat pump, given these insights!

Hope this gives you some thought on your planned setup for your heat pumps or boilers!