Cleaning cold water tank in loft?


C

Colin Brook

Hello,
During the addition of more insulation in loft and around tank, I
noticed that there was some rather nasty looking in scum on the water
surface (brownish rather than green). I haven't felt the need to do
anything about maintaining cleanliness of tank over last 25 years so am
not rushing now but this does prompt me to ask whether it's a good idea
to carry out some regular cleansing and if so what to use and how often
might be appropriate? Tank is obviously going to be warmer than ever for
the summer months and this could I suppose promote growth.

Any suggestions?
 
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A

Aidan

Colin said:
Hello,
During the addition of more insulation in loft and around tank, I
noticed that there was some rather nasty looking in scum on the water
Best to put in a new Bylaw 30 compliant tank, with a tight-fitting lid,
insulation, filtered air vent, overflow screen, etc. Probably less work
than bringing an existing tank up to current standards. Tepid water and
any contaminants will encourage the growth of bugs. Lofts can get very
hot.

You can clean it out by siphoning out the contents. A 20ft drop will
generate a powerful suction and you can hoover up any debris in the
bottom of the tank with the hose end. You can start the siphon by
connecting the lowest end of the hose to a mains tap, open the tap to
send water up the hose to the tank & so getting all the air out of the
hose, then disconnect from the tap & siphoning will start. Clamp the
hose flat if you need to take the end outside. Works best with a
helper. A properly installed tank will have no dirt in it, except maybe
for some limescale.
 
J

John Stumbles

Best to put in a new Bylaw 30 compliant tank, with a tight-fitting lid,
insulation, filtered air vent, overflow screen, etc. Probably less work
than bringing an existing tank up to current standards.
If you're lucky you may find a correct sized close-fitting lid for your
existing tank.
You can clean it out by siphoning out the contents. A 20ft drop will
generate a powerful suction and you can hoover up any debris in the
bottom of the tank with the hose end. You can start the siphon by
connecting the lowest end of the hose to a mains tap, open the tap to
send water up the hose to the tank & so getting all the air out of the
hose, then disconnect from the tap & siphoning will start.
What a palaver! Run your hose from somewhere outside (where the water can
discharge to) up into the attic. Dunk several feet of it into the
tank keeping it sloping down to the open end so that it fills with water
as you go. Then block the open end (with your finger or fold the pipe or
whatever works) and pull back most of the pipe and let it hang over the
side of the tank, so that the several feet of water you've got trapped in
the pipe is mostly outside the tank. Unblock the end and the syphon will
start.
Works best with a
helper.
Easily do-able by one person!
 
A

Aidan

John said:
If you're lucky you may find a correct sized close-fitting lid for your
existing tank.
For a 25+ year old tank? I once tried finding a lid for a tank that
was 6 or 7 years old.
Complete waste of time, no lid available would fit; it needs to be
within a couple of mm to get the snap-on tight fit. Tried the makers,
they said the lid supported the tank sides and they would have
distorted. If I'd found the right lid ( tank was no longer made) it
wouldn't have fitted. I'd been asked to investigate problems with
blocked water pipes, turned out to be bits of loft insulation that had
got into the tank and were plugging the pipes at the reduced-bore
service valves.
What a palaver! Run your hose from somewhere outside (where the water can
discharge to) up into the attic.
Worked for me, dear.
 
A

Aidan

Chris said:
He could also *make* one.... DIY it...
Considered that.

A pukka lid is an ornate moulding with a continuous lip inside the
tank edge to shed condensation. A flat sheet of say perspex would sit
neatly on the tank, but the condensation would would make contact with
the tank and would escape, saturating the insulation. This had caused
the problems with the tank I referred to. A flexible sheet of
polythene, say, might fall towards the centre of the tank and so avoid
the escaping damp problems, but you would have an unpleasant job trying
to make it airtight (gaffer tape, bungees?) in a restricted loft space.
The splashing around the float valve will find any opening. The first
time someone removes it, to service the float valve, it will get
chucked in a corner; lazy plumbers do that with proper tank lids
anyway.

This country has a long tradition of grotty water storage tanks with
grotty pikey lashed-up lids. Most people wouldn't leave a saucepan
uncovered in their kitchen for fear that dust would settle in it, so
why be any less hygenic with the water? A proper tank with a proper
lid; there's a satisfying clunk as the lid snaps securely into place.
 
T

Tim Hardisty

What a palaver! Run your hose from somewhere outside (where the water can
discharge to) up into the attic.
<snip>
Am I missing the point here? Why not tie-up the ball-cock or, if
won'es fitted, turn off the ervice valve in the cold water feed to the
tank (unlikely to be there for an old insallation of course) and then
drain the tank through a tap that's connected to the tank?
Tim Hardisty.
Please remove HAT before replying by email.
 
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A

Aidan

Tim said:
Am I missing the point here? Why not tie-up the ball-cock or, if
won'es fitted, turn off the ervice valve in the cold water feed to the
tank (unlikely to be there for an old insallation of course) and then
drain the tank through a tap that's connected to the tank?
Could do, but there are disadvantages;

1) The outlet connections are usually through the side of the tank and
25 or 50mm above the bottom. Heavy particles (limescale, rust,) settle
to the bottom of the tank and won't get into the outlet pipes. Floating
particles (dead insects, leaves, etc) will go down the outlet pipes.
2) The resistance may be high (due to bends, elbows, tap outlet
resistance, etc.,) and it probably won't generate flowrate & the mount
of suction that a vertical, unobstructed hose will. Also you can't use
the outlet pipes to suck up muck in the corners of the tank.
3) You do not want the muck in the distribution system. It will get
into taps, mixer valves, washing machine & dishwasher solenoid valves,
etc.. These things don't like solids; even if there are any strainers,
designed to catch solid particles, you'd have to dismantle it to clean
it out. It will also settle at the bottom (coolest part of cylinder and
lowest water velocity in the piped system) of the DHWS cylinder, where
it will stay and provide nutrients for any resident bugs, or provide
them with a shelter from high pasteurising temperatures.
 
A

Aidan

Chris said:
A sheet of WBP is a good start.... it doesn't need to be airtight,
just to stop "dust" getting in.
BTDT. Unlikely the tank, and the lid, will be exactly level.
Condensation droplets & splashes on the underside of the lid runs down
the sheet of WBP until it reaches the tank/lid junction. Capilliary
action draws some of it through the joint, saturating the tank
insulation and making a damp patch below.

New tank; £60? Less work involved in fitting a new tank than in
flaffing about with it. WBP probably not permissible under the Water
Bylaws.
 
A

Aidan

Chris said:
It shouldn't be far enough off to matter. The tank should sit on
a flat base.
No one's going to check it's level, but just whack it onto a base of
WBP on 3x2's on the joists. You can get something like 1/2 pt of water
running off the underside of a tank lid when you open it. A WBP lid
would probably be bowed one way or another and you'd probably get some
water leakage.
Sounds as though the tank or weren't installed properly in the
first place.
It wasn't; they hadn't fitted the lids that had come with the tanks.
New houses, I think all were like that; probably they'd mixed mortar in
the lids. The loft space was restricted (roof trusses) & me a bfg. It
was a virtual avalanche of unpleasant jobs caused by the omission of
the tank lids some years previously.
Nevertheless, it works well (in most cases).
Certainly better than nothing. Having done it once, I'd just get a new
tank if I had to do it again.
 
C

Colin Brook

In message said:
does prompt me to ask whether it's a good idea to carry out some
regular cleansing and if so what to use and how often might be
appropriate? Tank is obviously going to be warmer than ever for the
summer months and this could I suppose promote growth.

Any suggestions?
Just a quick thanks for all suggestions. I think the new tank will
probably be the best solution but I may need to clean the existing one
as an interim.

Regards, Colin
 
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J

John Stumbles

For a 25+ year old tank? I once tried finding a lid for a tank that
was 6 or 7 years old.
Yeah I know it's a long shot (I did say "If you're lucky") but worth
checking. I actually found one that fitted a tank I needed a lid for the
other day - that was sweet!
 
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