Low water pressure


21 Jun 2004
Reaction score
United Kingdom
just had Vaillant 824 combi fitted replacing old Potterton floor standing boiler. Water pressure on old sytem was good - could run taps/shower together no problem. Now opposite - low pressure and reduces to trickle if using hot/cold simultaneously. Shower pressure also low. any suggestions?
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Previous Potterton system presumably included hot water cylinder fed from a cold water storage tank.
Combi is supposed to be fed with cold water at mains pressure.
What's the pressure / flow like on your kitchen tap - this should be direct from the main?

It's possible that you have a situation where the mains PRESSURE is OK but only at low flow, so formerly the cold tank only filled slowly but it didn't matter. Now, there's not enough mains flow available to drive hot and cold taps directly. Installers of Combi should have spotted the problem and either fixed it or advised against a Combi.
Think you might be right - no kitchen taps to test yet (no kitchen as such!) but tap in garden fed from mains and flow on that should be better. Water company have suggested upgrading ancient pipes outside to 25 or 32mm but can't guarantee it'll fix problem. At same time they say there is a "problem in the area" and they will sort it some stage.

worth upgrading pipes now? any other fixes?

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