Can Running Your Gas Boiler at 50°C Simulate an Air Source Heat Pump?

With rising energy prices and growing interest in low-carbon heating, many homeowners and heating engineers alike are asking a brilliant question:

“If I run my gas boiler at 50°C, will it work like an air source heat pump (ASHP)?”

The short answer is: Sort of. It’s not a perfect match, but it’s a handy way to test whether your current system is compatible with the lower flow temperatures that a heat pump relies on. Let’s break it down—and if you fancy trying it, I’ll walk you through a simple way to test and log how your home performs. What’s So Special About 50°C?

Traditional gas boilers often run at flow temperatures of 70–80°C. In contrast, ASHPs work most efficiently at low flow temperatures—typically between 35°C and 50°C. The lower the temperature they have to produce, the more efficient and cost-effective they become.

So, if your home can stay comfortable with your boiler set to 50, it’s a good sign that a heat pump might work for you with minimal upgrades. What’s Similar to an ASHP at 50°C?

Running your boiler at 50°C lets you test a few key things:

• Heat distribution: Will your radiators or underfloor heating still heat your rooms properly at a lower temperature?

• Comfort levels: Do you feel warm enough, especially in colder weather?

• Room performance: Are there any areas that struggle to heat up?

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It’s Not a Perfect Simulation

There are some significant differences:

So, while it’s a good approximation, don’t expect it to feel the same.

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How to Test Your Home for Heat Pump Readin Here’s a simple DIY test to see how your current setup handles a 50°C flow temperature.

Step 1: Set Your Boiler

• Drop your central heating flow temperature to 50°C using your boiler controls.

• Leave the hot water settings as they are.

Step 2: Choose a Cold Day

• Pick a day when outdoor temperatures are 7°C or lower for a more realistic test.

• You can use a weather app or an outdoor thermometer.

Step 3: Log Your Room Temperatures

Create a  table to log what temperatures your rooms get to:

Use these titles.

Room Name, Start Temp, Target Time, Time to Reach, Notes (cold spots, comfortable, etc)

• First thing in the morning, take a temperature reading before heating.

• Then, switch the heating on and time how long it takes to reach a comfortable level (e.g. 20°C).

• Note how warm the rooms feel and whether they all get there.

Step 4: Observe & Reflect

Ask yourself:

• Did all rooms reach a comfortable temperature?

• Did any take too long or not get warm enough?

• Any noticeable cold spots, draughts, or uneven heating?

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What the Results Tell You

• If your home gets comfortably warm at 50°C, your radiators and pipework are likely suitable for a heat pump.

• If not, you may need:

  • Larger or additional radiators

  • Better insulation

  • Or consider a hybrid setup or slightly higher flow temp (e.g. 55°C)

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Conclusion: A Smart First Step

Testing your system at 50°C is a cost-free, practical way to assess whether you’re heat pump ready. It won’t precisely replicate an ASHP, but it gives real-world data about your home’s performance—and helps you plan upgrades if needed.