Low hot Water Pressure Upstairs With Gravity-fed Vented System All aspects of plumbing questions and answers, help, tips and information

[Alanterego]

Hi - I have an old two-storey house, gravity-fed vented system, two tanks in the loft, oil fired boiler and indirect cylinder in a boiler room on the ground floor, two bathrooms upstairs, positive head. One of the bathrooms is quite new with copper piping and the pressure is OK. The other is older, fed by galvanised pipes. Cold pressure is fine (probably mains direct) but hot water to the basin and bath starts fine when the taps are first turned on but soon fades down sometimes as low as 4 litres a minute. This is OK for the basin but the bath takes ages to fill and the shower attachment only works full hot or full cold. I have changed the bath mixer tap and put in a full turn low pressure mixer - doesn't help. Part of the problem is the head, only 3 metres above the baths, but we live in a hard water area - is this likely to be scale or debris buildup in the pipes and if so, can we fit a pump in the bathroom itself, just for this bathroom? There would be room to box one in. I don't want to increase the pressure for the whole system - there are several basins in upstairs rooms with old piping and I don't want to risk leaks all over the place. Thanks for your help with this.