Hot water pressure too low & I have received expensive quote

fit a negative head shower pump, to pump hot and cold to whole house,these work on pressure drop and not flow valves.

Hello, as D & R says, you can get whole house pumps and this can be the cheapest option in your case but there are stipulations in the pump's manuals about how large the cold tank in the loft is and where pipes are taken from etc. The second option is a large unvented hot water cylinder. In a 5 bedroom newbuild you would likely see a 300l unvented cylinder in the airing cupboard. These give very good hot water flow rates (provided your incoming mains from the street is good enough). Combi boilers - I'd say that's a no-no. Combi's were originally designed for flats and small properties where there was no loft space or limited cupboard space and no taps are that far away from the boiler. A combi boiler for a 5 bed detatched is bad practice as there will be long pipe runs to all the different taps and bathrooms in a large property and the flow rate isn't that good unless you get the largest and most expensive combi's with built-in cylinders. Note: these have potential for more complicated and costly maintenance over the years. The last option which is still very good but less popular now is a 'thermal' store cylinder. These provide very good hot water flow rates but again, some have circuit boards etc. and their own components which can go wrong later. In short - a booster pump or unvented cylinder are probably your best long term solutions, in my opinion.