TMV questions, answered
The things London landlords, managers and estates teams ask us most. If yours isn't here, ring us. We like a good question.
What TMVs are and why they need looking after
What is a TMV?
A thermostatic mixing valve blends hot and cold water to a set, safe temperature before it reaches a tap, shower or bath. It reacts to changes in the supply temperatures and pressures, and if the cold supply fails it should shut off the flow so nobody gets a blast of scalding water.
Why do TMVs need servicing?
They drift over time, and scale and debris build up inside. In London's hard water that happens faster than in many parts of the country. A neglected valve may deliver the wrong temperature or fail to shut off when it should, which is exactly when you need it to work.
How often should TMVs be tested?
New valves are usually tested at around 6 to 8 weeks and 12 to 15 weeks after commissioning, following HTM 04-01. After that, the interval depends on how much the valve drifts. Most London sites end up between six-monthly and annual servicing, with hard water and vulnerable users pushing towards six-monthly. See our TMV servicing page.
What's the difference between TMV2 and TMV3?
Both are approval schemes. TMV2 covers valves for domestic-type use, tested to BS EN 1111 or BS EN 1287. TMV3 covers valves meeting the higher NHS performance specification for healthcare and care settings. Our compliance guide explains more.
What temperature should a TMV be set to?
It depends on the outlet. Healthcare guidance commonly uses maximums of about 41°C for showers and washbasins, 44°C for baths and 38°C for bidets. Your written scheme may set specific figures, and we'll work to those.
Visits, coverage and paperwork
Which parts of London do you cover?
All 32 London boroughs plus the City of London. We're based in Chiswick, W4, and we only work in London. Have a look at areas we cover for every borough and postcode district.
Do you work outside London?
No. We're London-only on purpose. It keeps our engineers close to your building and our time spent on valves rather than motorways.
How much does TMV servicing cost?
It depends mostly on how many valves you have, how easy they are to reach, and whether parts are needed. We give fixed quotes, so tell us the building type, rough valve count and postcode and we'll price it.
I don't know how many TMVs we have. Is that a problem?
Not at all, it's really common. We can survey the building and build a TMV asset register, often on the same visit as the first service.
Can you work out of hours?
Yes. Early mornings, evenings, weekends and school holidays can all be arranged where the building needs it. We'll agree timing when we plan the job.
What about parking?
We check the parking situation before the visit, including controlled parking zones and loading rules, and let you know early if we need a permit or bay. More on how we plan London jobs.
What paperwork do I get?
A service certificate for each valve with before and after readings, logbook entries for your Legionella records, an updated asset register and a priced list of any further work.
Do you do Legionella risk assessments too?
Our focus here is TMVs. Your TMV records feed into your Legionella risk assessment and written scheme under ACOP L8 and HSG274, and we'll flag anything we spot, such as hot or cold supplies out of range, so your assessor or Responsible Person can act on it.
Let's get your TMVs tested, tuned and on record.
Tell us where you are in London and roughly how many valves you've got. We'll come back with a fixed quote and a visit plan that suits your building.