I was not working on Christmas-eve but responded to a call. The timber floor in the bedroom above had been replaced well over a month ago. There was both plumbing and heating pipe-work.

The holly is the only festive thing about this image.

Some woodworm prompted replacement of the flooring in
the bedroom above. It was certainly well screwed down to
the pipes and joists.

An oil-based ceiling paint appeared to have held back water for some weeks until 9pm on Christmas-eve. It was probably escaping along the joists to the wall cavity.

This Christmas incident serves as a stark reminder to us all
that we should always clearly mark the position of pipe-runs on the walls or skirting when replacing flooring.I use pieces of brightly coloured pvc insulating tape and it never left a mark.

This perforated 1/2 pipe to a radiator was isolated
before the one below was noticed. .

Another very large screw through the heating main meant it would have to be drained. The temptation to tackle this from above should be avoided even if a circuit tester is used to pinpoint the offending screws.

The wetted timbers will have to be left exposed to dry out before being treated.

Surprisingly the householder was unable to get to speak directly with any of the emergency contractors listed with the insurers advice line. Are the new lower alcohol limits keeping plumbers off the roads at Christmas time. More on this later.

Using Jet-Freezer Jacket with CO2 liquid/gas
to replace a corroded pipe on a large heating system.

This corroding pipe was hidden by office furniture.
It was being wetted externally by a weeping radiator valve packing gland.

I wouldn't cut and thread a freeze off job unless
I have two threading tools and two bottles of CO2.

There is often not a lot of good pipe to work with.

I don't take chances when freezing and threading.
A relatively new tool is quickly cut to ensure a
rapid start on the pipe.The thinner tool enables me
to finish with a full thread.

An insulated glove was used to hold the jacket tight around the 1/2 branch pipe when the CO2 is injected into the insulated jacket.
A 14in Stilson works well on the grooves cut in the tool.

The teeth of a hack-saw blade are drawn across
the new threads to ensure that they retain the flax when jointed.

A valve is immediately fitted. I can breathe again
and finish the job at leisure.

The sonatest microgauge11 enables some quick
steel thickness tests. I have to allow for the many
layers of paint on this old Veha radiator.

Echo to echo mode also enables steel thickness to
be established without removing the original paint

The Institute of Plumbing and Engineering Services design guide. I recommend this book to designers and installers. It contains practical Health and Safety guidance on inhibiting legionnella growth. A stated key aim is to maintain cold water below 25degC .Other standards suggest cold water  be stored at or below 20degC.

This would not appear to be possible when the cold water storage cistern
 is fitted within the same enclosure as a hot water cylinder and exposed
 hot pipe-work.?

Apart from insulation on the cylinder there is little to prevent the cold
water storage temperature rising to an unsafe level.
The pump which is a necessary part of this installation increases the
possibility of any infected water being atomised and ingested into the lungs.

Lagging the cold water cistern, bottom of shelf and all pipes will reduce the
heat transfer rate. A foam seal could be added between the shelf and door.

Keeping stored cold water cool... If the entire plumbing installation is
to be within an apartment a separate, insulated cold water cistern enclosure
should be constructed. Perhaps architects should consider clustering cold water
storage and access around the cooler stairwell.

Surprisingly many local authorities continue to ignore this simple safer principle

Pump manufacturers advise that the hot water to the pump be
taken from the bottom of an inclined hot water / vent pipe.
This reduces the troublesome air that enters the pump and shower mixer.
Or the hot water can be taken from a patent surrey flange fitted to the top
of the hot water cylinder.

Once you own such an installation ask a plumber to check that the
water storage tank is clean. 
He  may have to cut access above the tank to do so.
He may even fit a proper plastic dust cover and lagging jacket.
A proper fitted dust cover helps a plastic storage tank retain its design shape.

He may also ensure that all trapped deposits are removed The filters are often accessed by isolating and pulling out the supply hoses. You may offer your plumber the loan of a large bath towel.

If a pump tends to run on your plumber may use a magnet detector to see if a magnetic float is sticking in the up position.   A common find in recently fitted tanks. Little plastic curly bits from tank and wrapping from a packet of woodbines?

Pump manufacturers ask that a  pump hose be bent  no more than 30 degrees. One like this bent through 90 degrees  may leak  or internally collapse. Especially on the suction side of the pump Your plumber may re-pipe the pump properly using a new hose.

Bath mixers are not immune to the plastic curly bits either. An enthusiastic DIYer would wipe out a plastic tank after cutting.

Hot and Cold storage sharing?
Not a good idea. Often found in the Dublin area.

Is there a presumption that regular use will keep the cold water tank cool and bacteria free?

Be careful if it has been un-used for a while like during a long holiday break or when you move into an apartment.
The cylinder should not have been left heating as the unused cold water tank may overheat and present a legionella risk.
The same precaution applies to the widely used combination cylinder.

All plumbing systems should be thoroughly flushed through after being un-used for a while.
Like during a long hot summer break. Especially before showering upon your return. 

Ask your local plumber for advice and tell him about the Fernox Sterox Chlorinating kit  and LP Sterox on the Home Page.

In a very hot London last summer.
An often used cold water storage cistern had risen to an unsafe 31 C.

 

The cold water storage cistern was un-insulated there was heat transfer from the hot water cylinder and pipe-work. Infrared thermometer with laser pointer from Maplins

Hubble Bubble! Found in an overheated roof space,
supplying a gravity shower

No it is not roof insulation floating near the surface..

A colourless mucus-like substance was present near the surface.
It had a yellow tinge where in contact with air.
The householder was fortunate
 that a pump had not been installed

 It would be risky to inhale water droplets from a tank like this.
Expert opinion will be appreciated.

See Legionnaire's disease.