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TMV servicing and in‑service testing
Mixing valves drift, clog up and wear out, usually without anyone noticing. A proper service catches that early. We test every valve, fix what needs fixing and leave you with records that make sense.
- Typical interval6 or 12 months
- ValvesTMV2 & TMV3
- Healthcare guidanceHTM 04-01
- You getCertificate + register
What we check on every valve
Here's what a standard service covers. If we find something that needs a part or extra time, we'll tell you what and why before we go ahead.
Find it and log it
We confirm the valve's location, make and model, and tag it if it hasn't got an ID yet. Hidden valves behind panels get noted so the next visit is quicker.
Supply temperatures
We measure the hot and cold supplies feeding the valve. If the hot isn't hot enough or the cold's too warm, the valve can't do its job, and that's worth knowing.
Mixed outlet temperature
With the outlet running, we take a stable reading with a calibrated thermometer and compare it with the right set point for that outlet type.
Fail-safe (isolation) test
We isolate the cold supply to the valve. A healthy TMV should shut down or reduce to a trickle within a few seconds, so nobody gets a blast of hot water.
Strainers and check valves
Debris and scale build up in the inlet strainers and non-return valves. We clean them, and replace any that are damaged or sticking.
Descaling
In hard water areas, scale is the main reason valves stop responding. We strip down and descale the valve body and internals where needed.
Recalibration
If the mixed temperature has crept up or down, we reset it to the correct maximum and re-test to make sure it holds.
Cartridge replacement
When a thermostatic element is worn out, cleaning won't save it. We fit a new cartridge (with your go-ahead) and re-commission the valve.
Re-test and record
Every valve gets a final temperature and fail-safe check, with the readings written up against that valve.
Certificates and logbook
You get a certificate for the visit, logbook entries and an updated asset register showing what passed, what we fixed and anything still outstanding.
Annual or six-monthly servicing
Most TMVs need servicing at least once a year. In care homes, hospitals and anywhere with vulnerable people, six-monthly is common, and some sites go more often based on how their valves behave.
New valves are best checked within the first few months after commissioning. If those early readings are stable, the interval can be set from the results. If a valve keeps drifting, it needs looking at more often (or replacing).
Your Legionella risk assessment and written scheme should set out the frequency for your building. See our TMV compliance guide for how HTM 04-01 approaches in-service testing.
- Day 1
Commissioned and recorded
- First weeks
Early in-service check
- A few months
Second check confirms it's stable
- Then 6–12 mo.
Ongoing interval set from results
Not sure where you stand? Send us what records you've got and we'll suggest a sensible schedule.
Don't wait for the annual visit if you notice these
Water too hot or too cool
If people are complaining the shower's lukewarm, or the basin feels hotter than it used to, the valve has probably drifted.
Temperature swings
Water that surges hot then cold when someone else uses a tap suggests the valve isn't reacting to pressure changes as it should.
Weak flow
Reduced flow is often blocked strainers or scale. It's quick to fix, and it stops a valve from failing to safe for the wrong reasons.
A failed fail-safe test
If hot water keeps flowing when the cold is isolated, take the outlet out of use until it's sorted. That's a priority job.
Overdue records
If you can't find the last service date, assume it's due. Gaps in records are one of the first things an inspector notices.
Older, obsolete valves
Some older valves can't get parts any more. We'll tell you honestly whether repair or replacement makes more sense.
TMVs and Legionella control go together
A TMV means the water downstream of it sits at a temperature Legionella likes. That's why valves should be fitted close to the outlet, little-used outlets should be flushed, and strainers kept clean.
We keep your TMV servicing in step with the Legionella control measures in your written scheme under ACOP L8 and HSG274, so the two don't work against each other.
- Supply temperatures recorded at each valve, useful evidence for your monitoring
- Long pipe runs after a TMV flagged so you can deal with them
- Little-used outlets noted for your flushing regime
- Clear notes you can hand to your Legionella risk assessor
Questions about TMV servicing
How long does a TMV service take?
It depends on access and condition. A straightforward valve that just needs testing is fairly quick. One that needs a strip-down, descale and new cartridge takes longer. We'll give you a realistic idea for your site when we quote.
Will the water be off while you work?
Only at the outlet we're working on, and only for as long as it takes. We work room by room so the rest of the building carries on as normal. In care settings we fit around residents' routines.
Can you service any make of TMV?
We work on TMV2 and TMV3 valves from the common manufacturers. If a valve is obsolete and parts aren't available, we'll explain your options.
What happens if a valve fails?
If it fails the temperature or fail-safe test, we try to put it right there and then, usually by cleaning, descaling or recalibrating. If it needs a part we don't have on the van, or a replacement, we make the outlet safe, tell you straight away and quote for the fix.
Do you provide certificates?
Yes. You get a certificate for the visit with the readings for every valve, plus an updated asset register and logbook entries.
Related articles
Hard water and TMVs: limescale, strainers and descaling
Limescale is the number one reason TMVs stop working properly. How it gets in, the signs to look for, and what regular descaling actually involves.
Read the articleWhy TMV outlet temperatures drift (and how to stop it)
Your valve was set to 41°C. Now it's giving 43°C, or 38°C. The usual reasons a TMV's outlet temperature drifts, and what actually fixes it.
Read the articleYour TMV failed its fail-safe test. What now?
A failed fail-safe test is the one result you can't sit on. What it means, what to do with the outlet today, and how the valve usually gets put right.
Read the articleBook your TMV service
Tell us how many valves and where. We'll quote a fixed price and get you booked in.