Underfloor Heating With a Heat Pump: Does It Work and Is It Worth It?

If you are thinking about swapping a gas boiler for a heat pump, sooner or later someone will tell you that it works best with underfloor heating. They are right, but the full story is a little more nuanced than that. Pair them well and you get a quiet, efficient, comfortable home. Pair them badly and you can end up with cold rooms and a bigger bill than you expected.

In this guide we explain how underfloor heating with a heat pump works, why the two suit each other, what you need to get right at the design stage, and how to decide whether it is the right choice for your own home. It is written for homeowners, self-builders and renovators across Hampshire and the south of England who want straight answers before they commit.

Does underfloor heating work with a heat pump?

Yes, and it is widely regarded as one of the best combinations available. A heat pump takes heat from the air, the ground or water and uses it to warm your home. It is most efficient when it does not have to work hard, which means delivering heat at a lower temperature than a traditional boiler.

That is exactly where underfloor heating shines. A conventional boiler might send water at 60 to 70°C to radiators. A wet underfloor heating system typically runs at much lower temperatures, often somewhere between 35 and 45°C, because the heat is spread across the whole floor rather than a few small panels. The lower the water temperature a heat pump has to produce, the less electricity it uses for each unit of heat it delivers.

In short, the floor does the job of a very large, gentle radiator, and the heat pump is happy because it is not being pushed.

Why heat pump underfloor heating is such a good match

There are several reasons the two work so well together.

Efficiency. Heat pump efficiency is usually described by a figure called the coefficient of performance, or COP. The lower the flow temperature, the higher the COP tends to be. Underfloor heating lets the pump run at the lower end of its range for much of the year.

Even, comfortable heat. Because the whole floor surface gives off a mild warmth, rooms feel evenly heated from the ground up. There are no hot spots near radiators and no cold corners, and the warmth sits at foot level where you feel it most.

Steady running. Heat pumps work best when they run gently for long periods rather than blasting on and off. A floor full of warm screed or a well-designed floor structure holds heat well, which suits that style of running.

More usable space. With no radiators on the walls, you gain space for furniture, and the room looks cleaner and more modern.

Quieter, fresher air. There are fewer draughts and less dust movement than with a convection-heavy system, which many people find more comfortable.

Wet or electric: which type goes with a heat pump?

This is a common point of confusion. A heat pump heats water, so it connects to wet, or hydronic, underfloor heating, where warm water circulates through pipes in the floor. Electric underfloor heating, which uses cables or heating mats, does not connect to a heat pump at all. It runs on electricity directly, and works independently.

If you are planning a heat pump, wet underfloor heating is the natural partner. Electric systems still have their place, for example in a single bathroom or a small extension, but they will not use the efficiency that a heat pump brings. For a full comparison of the two types, see our guide to wet vs electric underfloor heating.

What you need to get right at the design stage

A heat pump and underfloor heating system only performs well if it has been designed properly. This is not a job to guess at. The key points are below.

A proper heat loss calculation. Every room needs to be assessed so that the system delivers the right amount of heat at a low flow temperature. If a room loses more heat than the floor can supply, you will either have a cold room or need to push the water temperature up, which costs efficiency.

Good insulation. Heat should go up into the room, not down into the ground. Quality insulation beneath the pipes makes a big difference to performance and running costs. It is particularly important in new builds and renovations where the floor is being replaced anyway.

Pipe spacing and layout. Closer pipe spacing gives the floor more output at a lower temperature. The layout should be planned room by room, taking account of furniture, doors and fixed units such as kitchen cabinets.

Zoning and controls. Separate zones and room thermostats let you set different temperatures in different spaces, and weather compensation controls adjust the flow temperature to match the weather outside. Used well, these keep the pump running as efficiently as possible.

The right floor covering. Tiles and stone conduct heat very well, so they are an ideal choice. Engineered wood and many vinyls also work well. Thick carpets and underlay slow the heat down, so they need to be taken into account when the system is designed. Our guides to low profile UFH systems and the basics of how underfloor heating works give more detail.

Is underfloor heating with a heat pump suitable for an older home?

It can be, but it needs more thought. Older properties often have less insulation, solid floors and higher heat loss, and these can make low temperature heating harder. That does not rule it out. It simply means the building should be assessed carefully, and improvements such as insulation, draught proofing and better glazing may be needed alongside the heating.

Low profile systems, which add very little height to the floor, can be a good fit when you cannot dig out the existing floor. If you are renovating, it is also the ideal time to plan the floor build up properly. We cover this in more detail in our guide to integrated floor heating systems.

How should you run it day to day?

This is where many people go wrong. Underfloor heating and heat pumps are both slow, steady systems, and they do not respond to short bursts of heat the way a boiler and radiator system does.

• Do not turn it right down and back up. Big swings in temperature force the system to work hard to catch up. Smaller, steadier adjustments are better.
• Set a comfortable base temperature. Allow the house to hold a gentle background warmth rather than expecting the room to heat in twenty minutes.
• Use schedules sensibly. A modest set-back overnight can work, but avoid dramatic drops.
• Trust the weather compensation. If your system has it, leave it to do its job instead of constantly overriding it.
• Look after the system. An annual check keeps filters, pressures and controls in good order.

What does it cost?

Costs depend on the size of the house, the type of floor and the heat pump chosen. The underfloor heating system itself is usually a smaller part of the overall budget than the heat pump, the pipework and the insulation work. Fitting underfloor heating during a new build or major renovation is almost always more cost effective than retrofitting it later, because the floor is already open.

Running costs are where a well-designed system pays back. Lower flow temperatures and steady running can reduce the amount of electricity needed for heating, though the saving depends on your insulation, your energy tariff and how you use the system. It is also worth checking whether any government grants or support schemes are available for heat pumps, as eligibility and amounts change from time to time. For a breakdown of what goes into the price of the floor itself, take a look at our guide to underfloor heating installation cost.

Common mistakes to avoid

• Choosing the heat pump and the underfloor heating separately, without one design covering both.
• Skipping the heat loss calculation and relying on rules of thumb.
• Under-insulating the floor, so heat disappears downwards.
• Laying thick carpet over a system that was designed for tiles.
• Expecting instant heat, and then turning the thermostat up and down all day.
• Using an installer with no experience of low temperature systems.

Is it right for you?

For most new builds, extensions and major renovations, underfloor heating with a heat pump is an excellent choice. It is comfortable, quiet, efficient and tidy, and it gives you a heating system that is ready for the future. For smaller changes, or homes with very high heat loss that cannot be improved, it is worth getting advice before you decide.

The best next step is to talk to someone who designs and fits both. DUO Systems installs underfloor heating across Hampshire and the surrounding counties, and can look at your plans, explain the options in plain English and give you a clear quote. Get in touch and tell us about your project.