Shower Temperature Fluctuating
The shower runs hot then cold when another tap or the toilet is used..
The shower runs hot then cold when another tap or the toilet is used.
What is actually going on
The shower runs hot then cold when another tap or the toilet is used.
The realistic causes, in order
A non-thermostatic mixer that cannot compensate when pressure changes A combi boiler modulating poorly at low flow, so temperature hunts Unbalanced hot and cold supplies, with one at mains pressure and the other gravity-fed
What we test on site
Whether the valve is thermostatic and whether its cartridge still responds Supply pressures on hot and cold at the valve Boiler modulation range against the actual shower flow rate
Safe checks to make with a shower that swings hot and cold
- Note whether it swings only when another outlet is used
- Check whether the shower valve is described as thermostatic
- Where a bath or shower is used by children or vulnerable adults, a thermostatic valve with a safe maximum setting is worth specifying rather than treating as optional.
Who does the work
- Gas Safe registered engineers — registration 554328
- Worcester Bosch accredited installer
- John The Plumb Ltd, company registration 10026483
Get a shower that swings hot and cold diagnosed properly
A thermostatic valve or a supply balance correction gives a stable shower — the right one depends on your system type.
Questions we get asked
What causes a shower that swings hot and cold in a bathroom?
A non-thermostatic mixer that cannot compensate when pressure changes
What normally puts a shower that swings hot and cold right?
A thermostatic valve or a supply balance correction gives a stable shower — the right one depends on your system type.
Is it safe to keep using the system with a shower that swings hot and cold?
Where a bath or shower is used by children or vulnerable adults, a thermostatic valve with a safe maximum setting is worth specifying rather than treating as optional.