Boilers & Heating
TRV fitting
TL;DR
Fitting TRVs to every radiator (except the room with the wall thermostat) is the cheapest single upgrade you can make to a UK heating system — usually £45-£75 per valve fitted, and Building Regs Part L has required it on all new/replacement radiators since 2018. Add smart TRVs at £55-£85 fitted per rad and you unlock true room-by-room zoning.
A thermostatic radiator valve is a small brass valve on the flow side of the radiator with a temperature-sensing head. When the room hits the set number, the valve closes and the radiator cools; when the room drops, it opens again. Done properly across the whole house, TRVs cut fuel bills 10-15% on their own — and they're a Building Regs requirement on every new or replaced radiator in England and Wales since 2018 (Part L).
This page covers when TRVs are worth fitting, the difference between manual, smart and lockshield ends, and the Part L rule that catches a lot of DIYers out.
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When do you actually need TRVs?
Any radiator that is not in the room with your wall thermostat should have a TRV. The stat sets the whole-house call for heat; the TRV lets each other room tune to its own preference. Without TRVs, every room heats to whatever the thermostat room decides — which is usually a hall or landing, and always wrong for a bedroom.
- Bedrooms — set 1-2 numbers cooler than living areas
- Bathrooms — quick warm-up on demand, cool between
- Kitchens — often need less because of appliance heat
- Spare rooms and dining rooms — turn down when empty
- Room with the wall stat — leave on a plain lockshield or wheelhead (do NOT fit a TRV here)
Manual TRVs vs smart TRVs — which is worth it?
Manual TRVs (Drayton TRV4, Honeywell VT100, Danfoss RA) are cheap, reliable, and last 20 years. Fit-and-forget. Smart TRVs (Tado, Hive, Wiser, Netatmo) add per-room scheduling, geofencing and app control — but they're 3-5x the price and the batteries need replacing every 18-24 months. Our advice: if you're doing the whole house, fit manual TRVs everywhere first for Part L, then upgrade to smart TRVs only in the rooms where scheduling actually matters (bedrooms, home office, spare rooms).
How long does a whole-house TRV upgrade take?
For an average 3-bed house with 8 radiators, expect half a day (4-5 hours) including draining down, refilling, bleeding and re-adding inhibitor. Single valve swaps take 30-45 minutes each. If any valves are seized (a common issue on 15+ year-old systems), we bring compression adaptors so we don't have to cut the pipework.
Part L Building Regs — what's the rule?
Since June 2018, Approved Document Part L requires a TRV to be fitted every time a radiator is replaced or added in a domestic property in England (Wales followed shortly after). The one exception is the room containing the room thermostat — that radiator should have a lockshield, not a TRV, so the stat can still get an honest reading. If you're replacing radiators, this isn't optional.
Do TRVs need setting up after fitting?
Yes — this is where most DIY fits fall down. After all TRVs are fitted, we balance the system by adjusting the lockshield valve at the other end of each radiator, so the return temperature is consistent (usually a 10-11°C differential). Without balancing, the radiators closest to the boiler steal all the heat and the far ones never warm up. Balancing takes 30-45 minutes and is included on every whole-house TRV job.
Typical prices
Real-world ranges from recent Northwest jobs. Your final price is confirmed in writing before any work starts.
| Item | Typical price | Notes |
|---|---|---|
| Single manual TRV — supplied & fitted | 55 – 85 | Isolate, drain, fit, refill, bleed |
| Whole-house manual TRVs (8 radiators) | 340 – 480 | Includes drain-down and balancing |
| Smart TRV — supplied & fitted | 55 – 85 | Per radiator, needs existing hub |
| Smart TRVs whole-house (8 radiators) | 440 – 620 | Labour only if you supply valves |
| Lockshield only replacement | 35 – 65 | Cheap fix for a leaking end cap |
| Whole-house balance & inhibitor top-up | 95 – 145 | Fitted at the end of any TRV job |
| Seized valve removal with compression adaptor | 45 – 75 | Per valve if pipework can't be cut |
| 12-month labour guarantee | included | 10-year mfr warranty on Drayton/Honeywell heads |
Which brand should you fit?
For manual TRVs we fit Drayton TRV4 and Honeywell VT100 as standard — both are BS EN 215 compliant, replaceable heads, 10-year manufacturer track record. For smart TRVs we fit Tado, Hive, Drayton Wiser and Netatmo depending on your existing smart heating hub. We install and service Worcester Bosch, Vaillant, Ideal, Baxi, Viessmann and Alpha — none of them pay us commission and we don't push a "boiler of the month".
Our promise on this job
Flat £50 diagnostic — deducted in full from any work booked. Fair, transparent quote before we start. If we can't fix the fault we diagnosed, we refund the diagnostic. All gas work is signed off by a Gas Safe registered engineer.
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