ch header

[evdama]

Do you HAVE to put the boilers header tank in the loft.
I have to repace the entire system soon and as the boiler lives in its own apartment built on an outside wall I wondered whether I could put the tank in the loft of the boiler room which is about 3'x7' by 9ft high.
The water supply is nearby and it would simplify the feed arrangement as
the supply and feed pipes are currently doing a victory lap of the property quite unnecesarily.
The boiler room is fitted with a stat and obviously there would have to be some good tank insulation.

 

[breezer]

i am not a plumber or heating engineer, but i think the reason the header tank goes in the loft is to give enough pressure to get a shower / tap working in the bathroom which is usually in the floor below the the loft.

so if you put your header tank where you say it will run the downstairs taps ok but not the upstairs ones as the tank will be lower than what the taps are.

This is because the header tank supplies water to your copper cylinder (what you have in an airing cupboard) and the boiler heats water which flows through a coil in this cylinder heating the water up. when you turn on a hot tap you take hot water from the top of the cylinder which is replaced (or forced due to pressure of header tank) at the bottom with cold water
so if your header tank is too low it wont work.

on the other hand i could be wrong

 

[COG]

If by header tank you mean the feed and expansion tank for your boiler then you will have to check with your manufacturers instructions but it is usually with at least 300mm head (base of tank to top of system) and if it has a combined feed and exp pipe it must rise continous with NO valves

 

[MANDATE]

The water cistern does not have to be in the loft.
My cistern is in the bathroom directly above the hot water cylinder with a space between them of approx 600mm.
The higher the cistern above the hot water tap the higher the pressure. Although my layout is ok for the taps, there is insufficient pressure to operate a shower which would be positioned higher than the taps so I have the choice of raising the cistern into the loft space or install a electric shower using mains pressure which is considerably higher

 

[Gees]

Are we talking open combi or a "conventional" system here?

 

[breezer]

should it not be conventional as a combi does not require a tank

 

[Gees]

I had a myson Gemini boiler that was an open system and had a feed/expansion tank in the loft.....

 

[COG]

A combi can have an expansion tank if it was designed for use on an open vented system , not all combis are seald systems only. The tank connected to and above a cylender is a feed tank not an expansion tank. As a heating system warms up the volume of water expands,into the expansion tank which is why the pipe must rise continous with no valves and min of bends to reduce resistance etc.

 

[evdama]

Im talking of a conventional boiler feed expansion.
Surely the gravity aspect wouldn't count as the CH water is electrically pumped around the circuits?

Id still be tempted to put a sevice valve at the tank outlet for sevicing-X100 insn't cheap!

 

[COG]

There are two ways to install an expansion tank,the first has 4 pipes,overflow,cold main,feed to boiler and vent pipe(the one that goes over the top. The second way is with 3 pipes overflow,cold main and a combined feed and expansion pipe this is the pipe you must not valve, if the valve shut there would be no room for expansion BANG. ON THE FIRST TANK YOU CAN VALVE THE FEED PIPE AS IT CAN EXPAND UP THE VENT IF IT HAS TO,