Water systems

[Zcars]

Hi . I the process of converting a house for HMO. Im a bit concerned about water supply so i am thinking of a gravity system with storage tanks in the roof, as opposed to a mains pressure system. What are peoples thoughts regarding Legionella, and suitability. It will be a completely new system with no deadlegs etc?

[Kape65]

You will still need mains water (fresh) for drinking supply. You would need a separate tank for each room or at least one huge tank which could mean strengthening the roof space.

[Zcars]

Hi Yes standard system would include kitchen drinking water supply. And fortunately there are two supporting walls that form the stairwell that will be able to support a tank stand. Im reckoning about 300 ltrs of water storage..so two 50/70 standard tanks should be ok at 590 and a 300litre hot cylinder...

[Waterboy]

With regards Legionella, the general rule is that if you don’t need stored water, then don’t store water. Direct mains cold and a mains fed combi-boiler are the ideal
set up in small to regular sized domestic dwellings. It really just depends how many rooms with water facilities and how many occupants there are in the property whether you need cold and/or hot water storage tanks.

[baldelectrician]

A pressurised cylinder would be possible, there could be oodles of hot water and as you are buying from new you could get one that has a coil in it to heat from gas / oil / air source as well as immersion heaters as a back up (these could use off peak or solar panels)

If you have a decent roof then you could have PV saving you a fair bit of electricity.

A combi may not cope with the demand

You may want to get the heating split in to zones (floors) then if the top floor is warm it will shut off, this will also help if it is not fully occupied.

[andybenw]

If I was starting from scratch I'd go with baldelectricians advice of megaflow or equivalent. Gravity fed will give you rubbish hot water pressure (which makes it a lottery when buying taps). You'd still need a hot water cylinder, and (unless of course you are going for mains fed electric showers) you would also need to factor in pumps for showers..