hot water header tank sizing

[diy_dude]

I have a galvanised hot water header tank in my airing cupboard in my 1950s house. I think its about time to change the tank before it rusts through and fails in a spectacular way!!

I plan to install a new tank in the loft directly about the airing cupboard and simply extend the pipes down (15mm cold feed, 22mm to hot water tank).

My question is: How do I know what size of tank to buy / install?

The house is a 3 bed semi, 3 hot water taps (bath, basin and kitchen sink) if this makes any difference. Any guidance would be appreciated.

Thanks...

 

[corgiman]

just by a 7 gallon one from the merchants that;ll do you

 

[JohnD]

Is this the tank that supplies the water to fill your bath? Does it supply the cold too, or just the hot? Or is it the tank that provides feed and expansion to the central heating and boiler?

I fear a 7 gallon bath might not seem very fulfilling

 

[corgiman]

OOOOPPSSSS

LMAO

sorry had me heating head on

What a plum i am

cheers john

(hides head in shame)

 

[JohnD]

 

[diy_dude]

There is a header tank for the central heating in the loft already which I plan to leave.

All cold water in the house is mains fed and again I plan to leave it that way.

This new planned tank will feed the hot water to the bath, basin and kitchen sink only. Will the 7 gallon tank suffice?

 

[corgiman]

Nooooooooooooooooooooooooo


at least a 45 gallon

 

[diy_dude]

Screwfix sell a 50 gallon tank

http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=101561&ts=69138&id=10134

It is the largest they sell. Does it *really* have to be this big?

What support does a tank this size require. I'm guessing that I cannot just sit it on the joists!!

 

[corgiman]

i would say yes

unless you want short showers

 

[ollski]

The biggest one you can fit into your loft hatch.

 

[corgiman]

or that

 

[diy_dude]

my shower is electric and fed from mains water.

£70 seems a lot for a tank, or is this the going rate?

How much extra wood do I need up there to support the tank when full?

 

[JohnD]

You can lie three or four timber bearers (like joists but 70mm x 30 mm or so would do) across several of the roof timbers to spread the load, and put a piece of 18mm ply or chip under the tank as they only have soft plastic bottoms. If you can see a wall (preferably a brick one) under any of the roof timbers, place the centre of the cistern above it.

You might possibly find that in part of your loft you have the trusses doubled up next to each other, to make a stronger area for standing the cistern on. It might be near the loft hatch.

I like to put some Cuprinol Green on all the timbers under or near the cistern as a precaution against rot in case of leaks, and WBP ply will also stand up to wet better than chipboard.

 

[Nige F]

my shower is electric and fed from mains water.

£70 seems a lot for a tank, or is this the going rate?

How much extra wood do I need up there to support the tank when full?

£400 to move one from one end of loft by 8 feet Nice if you can get it 25 gall should historically do for hot only...

 

[chrishutt]

As Nige says, 25 gallons is normally adequate, unless you've got a pumped power shower.