Space Heating

Introduction

Upgrading to a heat pump was the key step in modernising my existing electric panel heating system. With rising energy costs, I wanted a solution that was both cost-effective and environmentally friendly. This page documents the entire process—from evaluating different options to final installation, testing, and improvements.

Rejected Options

There were a few options I considered, each varying in convenience, flexibility, installation cost, efficiency & running cost, environmental impact, durability and performance.

The easy-to-reject options:

1. Gas boiler - Setting aside the fact that this was never an option due to the building having no gas supply, gas boilers are outdated technology. Even if their phase-out doesn't happen as quickly as planned, reliance on fossil fuels leaves homeowners vulnerable to price fluctuations and contributes to the geopolitical risks of foreign suppliers.
2. Electric storage heaters - Off-peak electricity rates make this a cheaper alternative to direct electric heating, but it relies on storing heat overnight and slowly releasing it through the day, which often doesn't align with actual heating needs. Don't need the heat from 8am til 5pm? Tough. You can't stop it. This leads to overheating in the morning and underheating in the evening. Additionally, they're very bulky.

The first viable option was an air-to-water heat pump, which, in itself, has two further options: underfloor heating or radiators.

Radiators were quickly ruled out—they are bulky, create uneven heating (with a hot side of the room), and to work effectively with a heat pump, they either need to be very large (larger than the gas boiler equivalent) or run at temperatures higher than a heat pump can efficiently provide.

Underfloor heating (UFH) is the more suitable choice. UFH is highly efficient, typically achieving around 300% efficiency (a Coefficient of Performance, or CoP, of 3). It provides a gentle, even warmth across the entire room, improving comfort. However, it comes with a key challenge: thermal inertia.

The floor itself has high thermal mass, meaning it heats up slowly (taking hours) and cools down just as slowly. This makes traditional on/off thermostat control, as used with a gas boiler and radiators, impractical. Instead, the heat pump should ideally run continuously at a low temperature, with weather compensation adjusting output based on outdoor conditions in advance.

The installation and labour costs for this option were simply too high. Underfloor heating is inefficient beneath carpet and wood, so installing it would mean replacing my current flooring with tile, even though the existing floors are in excellent condition and I prefer carpet in bedrooms. All-in, without even considering labour, my early cost estimate was 7-to-8 times more expensive than an air-to-air heat pump. Investing in an expensive system that requires replacing flooring I like with a finish I don’t simply didn’t make sense.

As a final note, had I had fewer rooms to heat, I would have chosen multiple air-to-air split systems like this one.

Chosen Solution

Thankfully, the most cost-effective option, most practical option, and most efficient option are all the same: air-to-air heat pump.

An air-to-air heat pump provides:

1. Lower installation & labour cost - No need for new hot water pipework, radiators or flooring replacement.
2. Higher efficiency - Delivers heat directly into the air, avoiding heat loss through water circulation, giving a CoP of around 4.5.
3. Fast response time - Heats up quickly and can be adjusted in real time.
4. Cooling capability - Provides air conditioning as well as heating.