Header Tank Questions

[gme106]

Hi, could someone please answer a few questions I have about header tanks.

1. Does the header tank have to be placed above the cold water storage tank or is it ok to be on the same level?
2. What is the normal litre/gallon capacity of a header tank?
3. What is the smallest recommended size of tank you can fit?

Many Thanks.

 

[jobloggs]

What is important is the relative levels of the water in each tank.

They should be arranged so that the water level in cold water storage tank is higher than that in "header" (flow & expansion) tank This ensures that if the indirect coil in the cylinder fails that water will flow from CWST to F&E and overflow hence be noticed. Other way round means you are cleaning your teeth with diluted CH water and fault may not be noticed as CWST is drawn down by use of taps, toilet etc and may never overflow.

Typical size is of the order of 30-50 litres capacity.

 

[masona]

Other way round means you are cleaning your teeth with diluted CH water and fault may not be noticed as CWST is drawn down by use of taps, toilet etc and may never overflow.

Isn't it only on the hot water side?

 

[jobloggs]

Masona. My bathroom cold tap is supplied from the CWST rather than the mains. Is this not usually the case where a vented CH system is used so that both feeds to mixer taps are at similar pressures.

 

[JohnD]

It seems to vary by local practice. in London it is usual to use stored water for everything except the kitchen tap (used to be by bye-law as in the early years of piped water, supply was not continuous so the more water that was stored in the house, the better, and they didn't have DHW systems*).

Here in Hampshire plumbers expect all cold water to be off the mains.


* If I remember rightly, Jonathan Swift, author of "Gulliver's Travels" complained in his diary that he did not get a reliable water supply in his London house, even though he'd paid the extra for a pressured supply to the upper floors (!) as well as the extra for continuous supply. This would have been before 1750.

 

[masona]

Masona. My bathroom cold tap is supplied from the CWST rather than the mains. Is this not usually the case where a vented CH system is used so that both feeds to mixer taps are at similar pressures.

Ahh, I see where you're coming from, so the central heating water could contaminated the CWST? I have the same system as you but the sink/basin are from the rising mains except the bath taps for drinking water or cleaning your teeth as I thought you shouldn't use CWST for drinking or cleaning your teeth etc?