I have a large rectangular plastic storage tank in my attic which holds the
cold water to feed the (gravity fed) DHW system. [Fitted it myself some
years ago - replacing a circular one - in order to make space for a loft
ladder]

The tank was not supplied with a lid - but its predecessor didn't have one
either - so I didn't think a lot about it.

I have recently had to replace my hot cylinder - necessitating draining the
cold tank, which has accummulated all sorts of crud over the years. So I
need to clean it out and fit a lid.

What material should I use for the lid? It can't be very thick because part
of the tank is tucked under a purlin with only a few mm clearance. It
presumably needs to be impervious to water - condsensation at any rate - so
plywood, MDF, etc. probably wouldn't be much good. Maybe a thin sheet of
some sort of rigid plastic? If so, what, and where can I get some without
buying half an acre of the stuff? How do I hold it in place - should it have
something fixed to the underside to fit inside the tank to stop it moving
about? [It will obviously need a cutout to allow for the vent pipe].

What have others done in similar circumstances?
--
Cheers,
Roger
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On 11 May, 20:55, "Roger Mills" wrote:
I have a large rectangular plastic storage tank in my attic which holds the

Buy a new Byelaw 30 compliant tank and lid.
I spent a long time looking for a lid to fit a plastic tank, but it
was a complete waste of time.

You will find that the manufacturers don't make that tank anymore and
you won't get a snap-tight closure with anything you might fabricate.
It should also have a screened overflow and air inlet.

The proper lid should have drip mouldings adjacent to the side of the
tank; without these condensation or water splashes on the underside of
the lid will get under the lid.

On Sun, 11 May 2008 20:55:23 +0100, "Roger Mills"
wrote:

I have a large rectangular plastic storage tank in my attic which holds the
cold water to feed the (gravity fed) DHW system. [Fitted it myself some
years ago - replacing a circular one - in order to make space for a loft
ladder]

The tank was not supplied with a lid - but its predecessor didn't have one
either - so I didn't think a lot about it.

I have recently had to replace my hot cylinder - necessitating draining the
cold tank, which has accummulated all sorts of crud over the years. So I
need to clean it out and fit a lid.

What material should I use for the lid?

I would consider heavy-gauge polyethylene sheet, which you can get
from a rubber/plastics-type merchant in almost any size/gauge, and
anchor it with maybe a giant bungee cord around the tank.

--
Frank Erskine

On Sun, 11 May 2008 20:55:23 +0100, Roger Mills wrote:

What have others done in similar circumstances?

Estate agent's signboard plastic. (Assuming you can't get a pukka byelaw
30 compliant lid and aren't going to do it by the book and replace the
tank for one with a lid.)

--
John Stumbles

My karma ran over my dogma

Frank Erskine wrote:
On Sun, 11 May 2008 20:55:23 +0100, "Roger Mills"
wrote:

I have a large rectangular plastic storage tank in my attic which
holds the cold water to feed the (gravity fed) DHW system. [Fitted
it myself some years ago - replacing a circular one - in order to
make space for a loft ladder]

The tank was not supplied with a lid - but its predecessor didn't
have one either - so I didn't think a lot about it.

I have recently had to replace my hot cylinder - necessitating
draining the cold tank, which has accummulated all sorts of crud
over the years. So I need to clean it out and fit a lid.

What material should I use for the lid?

I would consider heavy-gauge polyethylene sheet, which you can get
from a rubber/plastics-type merchant in almost any size/gauge, and
anchor it with maybe a giant bungee cord around the tank.

Pond liner from a garden center might be easier to find. One advantage over
a rigid lid - it's bound to sag a bit, so condensation will run towards the
middle and drip back into the tank.

--
LSR

"Roger Mills" wrote in message
...
I have a large rectangular plastic storage tank in my attic which holds the
cold water to feed the (gravity fed) DHW system. [Fitted it myself some
years ago - replacing a circular one - in order to make space for a loft
ladder]

The tank was not supplied with a lid - but its predecessor didn't have one
either - so I didn't think a lot about it.

I have recently had to replace my hot cylinder - necessitating draining
the cold tank, which has accummulated all sorts of crud over the years. So
I need to clean it out and fit a lid.

What material should I use for the lid? It can't be very thick because
part of the tank is tucked under a purlin with only a few mm clearance. It
presumably needs to be impervious to water - condsensation at any rate -
so plywood, MDF, etc. probably wouldn't be much good. Maybe a thin sheet
of some sort of rigid plastic? If so, what, and where can I get some
without buying half an acre of the stuff? How do I hold it in place -
should it have something fixed to the underside to fit inside the tank to
stop it moving about? [It will obviously need a cutout to allow for the
vent pipe].

What have others done in similar circumstances?

I made a tank lid out of two sheets of 1 1/2" (or 2 ") polystrene sheet
glued together (use proper polystrene glue) wrapped on a large sheet of
black 500 gauge polythene. I melted holes on the sheet and tied back using
garden twine to hold it tight. This was to replace the existing lid that had
been snapped by previous house owners and had been propped up out of the
tank using a peice of wood that was completely black and mouldy and dripping
gunge into the tank.

Also glued a block of polytyrene in underside centre of my lid to form a
"drip centre". Worked fine for 10years odd till I moved.

Roger Mills wrote:

What material should I use for the lid? It can't be very thick because part
of the tank is tucked under a purlin with only a few mm clearance. It
presumably needs to be impervious to water - condsensation at any rate - so
plywood, MDF, etc. probably wouldn't be much good. Maybe a thin sheet of
some sort of rigid plastic? If so, what, and where can I get some without
buying half an acre of the stuff? How do I hold it in place - should it have
something fixed to the underside to fit inside the tank to stop it moving
about? [It will obviously need a cutout to allow for the vent pipe].

What have others done in similar circumstances?

Mine just has a slab of expanded polystyrene on top.

If you want perspex/acrylic etc, when faced with a similar
small-quantity requirement I recently bought a sheet about 300mm square
from an e-bay dealer for a couple of quid.

David

"LSR" wrote in message
...
Frank Erskine wrote:
On Sun, 11 May 2008 20:55:23 +0100, "Roger Mills"
wrote:

I have a large rectangular plastic storage tank in my attic which
holds the cold water to feed the (gravity fed) DHW system. [Fitted
it myself some years ago - replacing a circular one - in order to
make space for a loft ladder]

The tank was not supplied with a lid - but its predecessor didn't
have one either - so I didn't think a lot about it.

I have recently had to replace my hot cylinder - necessitating
draining the cold tank, which has accummulated all sorts of crud
over the years. So I need to clean it out and fit a lid.

What material should I use for the lid?

I would consider heavy-gauge polyethylene sheet, which you can get
from a rubber/plastics-type merchant in almost any size/gauge, and
anchor it with maybe a giant bungee cord around the tank.

Pond liner from a garden center might be easier to find. One advantage
over a rigid lid - it's bound to sag a bit, so condensation will run
towards the middle and drip back into the tank.

Air needs to be able to get in and out as the water level changes. Byelaw
compliant lids have an insect proof air vent for that purpose.

Colin Bignell

nightjar cpb@ wrote:

Air needs to be able to get in and out as the water level changes. Byelaw
compliant lids have an insect proof air vent for that purpose.

Insect proof is right :-) A girl at work recently had a major Ladybird
infestation in her home's water tank, and millions of gritty eggs that
did a good job of restricting water flow all over the house and causing
other issues ....

--
Adrian C