Demand Side Response (DSR) is a concept we’re hearing more and more about in the heating industry. The idea is simple: run your heating during off-peak tariff hours when electricity is cheaper, then let the home’s insulation carry that warmth through until the next “cheap” window comes around. On paper, it sounds like a smart way to help both homeowners and the grid. But is it right for heat pumps?
For traditional boilers, this kind of approach makes sense. They’re designed to fire up quickly, run at high flow temperatures, and switch off once the temperature is reached. Savvy homeowners may already do this. Or like many of us, heating is timed to come on quickly in the morning and in the evening to ‘take the chill out’.
But for heat pumps, it’s a very different story. And that’s where the clash comes in.
Taking it “low and slow”
Heat pumps aren’t boilers and they don’t reach their full potential if you treat them the same way. The key to running a heat pump efficiently is consistency. Instead of firing in short bursts, heat pumps are designed to run for long periods at lower flow temperatures. They gently top up the home so that the space never really cools down.
Liken it to a car: you get better fuel economy by holding a steady, slower speed than you do by constantly stopping and accelerating. A heat pump works on the same principle. When it’s allowed to tick over steadily, it delivers the highest levels of efficiency and keeps the home at a comfortable, even temperature.
How much does DSR clash with heat pumps?
DSR encourages homeowners to let the house cool down, then switch the heating back on during the next tariff window. That might make sense when you’re thinking purely about the price of electricity, but it ignores how heat pumps actually function.
When a heat pump is asked to reheat a cooled space, it has to work much harder than it would if it had been left running steadily. Instead of maintaining a gentle background warmth, it’s suddenly being asked to pull the temperature back up quickly. That means longer run times at higher outputs, which in turn reduces efficiency. The result is that any perceived saving from the cheaper tariff could easily be cancelled out by the additional energy the system uses to reheat.
It’s not just about efficiency either. Frequent cycling also puts unnecessary strain on the components of a heat pump. Compressors, in particular, are built to run smoothly over extended periods. Forcing them to power up and down multiple times a day goes against the way they’re engineered to perform.
Over time, that can increase wear and tear, potentially shorten the lifespan of the system, and create more maintenance headaches for installers and end users alike.
All of this can feed into the narrative that ‘heat pumps aren’t efficient’. If a homeowner has bought into the idea of a heat pump expecting efficiency and low running costs, only to find it underperforms because it’s being run under DSR conditions, their confidence in the technology suffers. That’s not good for the installer, the manufacturer, or the wider push towards low-carbon heating.
So what do you do?
DSR and heat pumps both have an important role to play in the future of heating, but we don’t see them as natural partners. The “on/off” principle of DSR conflicts directly with the “low and slow” design of heat pumps.
Running them in this way is not only inefficient, it risks undermining consumer confidence and could compromise the longevity of the equipment.
The message is simple: understand the essential principles behind heat pumps. If you’re running a pump, go for the low and slow approach. If you’re still on traditional gas boilers, then DSR could save you money. Just don’t assume the same applies to heat pumps.
Until DSR evolves to account for technologies like heat pumps, we need to be honest about the mismatch and make sure expectations are set realistically.