Question about gravity fed system ?

Biggie

I have a gravity fed system and had the following queries :-

1) When the central heating is on does it heat fresh water and then pump to raditors or does it use hot water from the cylinder ?

2) Sort of related to the above question , would the electric immersion heater heat water for the central heating ?

3) My controls for hot water\central heating are sperate, if I switch ON CH would I also get hot water from the taps.

Geoff_W

A gravity fed system usually means that the hot water cylinder is not pumped; it relies on the hot water rising, whilst the cold water falls, thus creating a circulation which heats up the hot water.

In answer to 1) the central heating system will be a closed system, ie the same water is heated and pumped around the radiators; it is not taken from the hot water cylinder. There will be a small header-tank (probably in the loft) which supplies any top-up water the boiler needs.

2) No.

3) Only if there was already hot water in the cylinder. Normally, the central heating will not heat up the hot water. There is usually a valve, often controlled by a thermostat on the cylinder, which allows the boiler-heated water to reach the cylinder (but this part of the circuit is not pumped in your case).

Don't forget that the water being circulated around the boiler/radiators/hot water cylinder, is in a closed system - it is not physically the same water as comes out of your tap (it would be pretty mucky if it was!). Inside your hot water cylinder is a spiral of copper pipe, known as a heat-exchanger, which transfers the heat from the boiler to the water in the cylinder.

Apologies if this is teaching you to suck eggs!

Geoff

Biggie

Many thanks Geoff_W

that now makes perfect sense.

how do I Identify weather I have a direct or indirect water cylinder ?

my system apprently is about 10years old btw

Geoff_W

Biggie wrote: »

Many thanks Geoff_W

that now makes perfect sense.

how do I Identify weather I have a direct or indirect water cylinder ?

my system apprently is about 10years old btw

Direct Cylinder
A Direct Cylinder is heated by a source located within the cylinder - such as an electrical immersion heater. Because the Immersion Heater is heating the water 'directly' the cylinder is called a 'Direct Cylinder'. In a direct cylinder there are no other external heat sources.

Indirect Cylinder
Although heat is imparted to the cylinder by an internal heat exchanger, the heat source is actually remote - such as a gas boiler, solar panel, wood burning stove, Aga etc. etc.. It is therefore deemed that such a cylinder is 'Indirect'. Indirect cylinders may be fitted with immersion heaters as a supplementary heat source, but they are still known as 'Indirect'.

Geoff