header distance central heating

[mini1000]

I have currently involved mself once again in a nightmare situation!

It looks like i am going to have to move my cw tank(coffin) and ch header tank to the top of my loft as the new hw cylinder (indirect) i have bought is too large to fit in the cupboard.

i am using a surrey flange going into a twin impellor pump for the shower.

So my question is how much head do i need between the bottom of the cw tank and the top of the hw cylinder?

and are there any unwritten rules to watch out for????

i had a builder come round and he thought it was a 12 inch gap but someone else has told me its 1metre whereas others have pointed to the cylinders with the header tanks on top!!!!

any help would be greatly appreciated.

Many thanks

Peter

 

[MANDATE]

It will be of interest to see the replies you get.
I would say there is no minimum distance. the pressure created at a tap/shower outlet is based on the vertical distance between outlet and the level of water in the tank( not the bottom of tank) and not the top of the cylinder.
It is obvious the the tank could not be lower than the cylinder or the cylinder would never be full so as long as the water level is above the cylinder outlet pipe it will function, but the pressure at shower will be very low and there is always the problem of using water at a fast rate and having a supply to replace it quickly. so a adequate size tank as high as possible would give the best result.
I think you already had the answer to your query when you mentioned cylinders with header tanks on top.

 

[MANDATE]

Just to add another point, you could have the bottom of the water tank below the top of the cylinder and the system will function providing the water level remains above the top outlet.Of course you wouldn't do it in practice as there is nothing to gain.
Anyone disagree?

 

[masona]

The only thing I can see the hot tap water pressure will be low,I say higher the tank the better,including the F & E tank.

 

[mini1000]

cheers

i am going with the mount it high principle at least it will be out of the way.

 

[COG]

As Masona said there is no min distance between the cyl and the cold water tank, but you said expansion tank ,which should have at least 300mm head above the primary coil on your cylender,from the rest of your txt i assume you meen the cold water tank so the higher the better .

 

[masona]

As Masona said there is no min distance between the cyl and the cold water tank, but you said expansion tank ,which should have at least 300mm head above the primary coil on your cylender,from the rest of your txt i assume you meen the cold water tank so the higher the better .

Yes, you're right Got carried away