Poor water pressure from hot water outlets?
Due to our historical reliance on gravity fed hot water cylinders heated by ‘system’ boilers it’s not uncommon to find UK residents complaining about the low hot water pressure and poor flow at hot water outlets around a house. This becomes more prevalent as kitchens, bathrooms and ensuites become upgraded with more modern taps and shower valves.
These newer taps and valves tend to be designed on the basis of the water to both hot and cold parts of the taps and valves being supplied at somewhere between 1 and 2.5 bar typically. The simple fact is that in a standard UK house a kitchen outlet will develop about 0.6 bar pressure at the outlet at best. This is due to the limited ‘head’ from the outlet to the cold water cistern in the loft.
Trying to find taps and valves that will work on this sort of ‘low pressure’ system severely restricts the choices available.
So what are the options?
(1) Installation of a whole house 2.5 bar hot water pump
The main draw-off from the top of the existing vented gravity fed hot water cylinder is interrupted and the pump inserted in line with the pipework. Any hot water outlet that is opened will trigger the pump to activate and the pump will provide increased pressure hot water through this outlet, be it tap or shower valve. Certain technical features of the installation need to be observed and I wont go into these here. But the main drawback of this solution is the noise generated by the pump. The pumps are much quieter now, but they are still noticeable. Especially if you have early rising visitors staying that like to rise at 06:30am and grab a quick shower!
I have installed pumps from Stewart Turner and Salamander, both are reputable firms and experts in their field.
(2) Installation of an unvented hot water cylinder
Well one option is to replace the gravity fed hot water cylinder with an unvented (pressurised) hot water cylinder such as an Albion or Heatrae Sadia stainless steel unit. This can be placed in any location in the house (such as a garage), possibly freeing up an airing cupboard for other uses such as a shower cubicle. These cylinders tend to be more cost effective the more bathrooms and ensuites exist. Although, I had one client that had one main bathroom and one ensuite and declared the installation a raging success due to fantastic water pressure provided in both showers, and the increased flow at the kitchen sink, which used to take an age to fill from the hot water tap.
The key benefit of the unvented hot water cylinder over the pumped scenario is that there is no noise generated. The cold water cistern in the loft is no longer required.
(3) Installation of a Combination Boiler
This is indeed a drastic step to take to increase the pressure and flow to your hot water outlets, but if you have an older system boiler and are looking to gain savings by installing a more energy efficient boiler AND you have a problem with poor flow at outlets it could address both issues. Consideration needs to be given to the distance from the boiler to the hot water outlets to avoid wastage. Ideally the boiler should be sited as close as practically possible to all hot water outlets.
The benefits are: efficiencies gained, low noise, no stored water. The main disadvantages would be: no stored water (could heat a cylinder with an immersion heater) and in larger properties with a number of occupants the challenges on demand of say two bathroom outlets and a kitchen outlet being open at the same time. So probably more suited to small to medium sized properties.