Smart thermostat costs

What it costs

Item	Typical cost
Single-zone smart thermostat (unit)	£100–£220
Professional installation	£60–£120
Smart thermostatic radiator valve (each)	£50–£70
Multi-zone system (whole house)	£300–£600+

If you are replacing an existing wired room thermostat on a like-for-like basis, a competent DIYer can sometimes avoid the installation cost — but heating wiring varies, and for a heat pump you should always use the installer-specified control.

The payback maths

The saving is the Energy Saving Trust's ~10% on heating — and only if you currently lack effective controls. Worked through:

• A home spending £1,000 a year on heating saves roughly £100 a year from a full, well-used set of controls.
• A £150–£300 setup therefore pays back in roughly two to three years.
• If you already use a programmer, thermostat, and TRVs well, most of that 10% is already banked — the upgrade is comfort and convenience, not savings, and payback may never arrive.

This is the part the marketing leaves out: the saving is against having no controls. Be realistic about your starting point before you spend.

When zoning is worth it

Smart TRVs and zoning pay back fastest in larger homes with rooms used intermittently — a home office empty at weekends, bedrooms unused during the day. In a small, always-occupied home the per-radiator cost rarely earns its keep on savings alone. Many people still choose it for the comfort of room-by-room control, which is a fair reason — just not a savings one.