Thermostatic shower heats 3 or 4 minutes and starts to go cold or does not heat enough

Thermostatic shower runs hot and then cold If your thermostatic shower keeps going from hot to cold there’s only one way to resolve this issue. It’s very annoying to get into the shower in the morning this time of year only for the Shower to go straight from hot to cold. This usually happens the minute you put shower gel into your hair. There’s no need disassembling the Mixer Valve and looking into the filters for dirt, 9 out of 10 this is not the cause. Please check your boiler to see if the Hot water is warming up enough, simple way of doing this is running your hot tap in the kitchen to see if it’s getting hot. If it is then it’s not your boiler. The shower could get cold if you have a heat only boiler with a water tank in the airing cupboard or loft and a few people in the household had showers before you. But majorly intermittent hot and cold shower is caused by a thermostatic mixing valve. Installing a new mixing valve in the shower can reduce or eliminate the temperature fluctuations. Thermostatic mixing valves automatically balance the amount of hot and cold water being mixed, which will prevent drastic fluctuations in shower temperature. But you do not have to as this can be expensive, the best way and value for money method is changing the Diverter Cartridge and this will be resolved for you. Whether you have a Bristan shower, Ideal Standard Shower, Armitage Shanks, Grohe, Porcelanosa, Noken Shower you can find the Thermostatic Cartridges/Diverters and Mixer Valve spares here, if in doubt about the correct replacement