On 10 Nov 2004 15:52:28 -0800, (Andy Hide)
wrote:

I'm in the process of moving my hot water cylinder and cold water tank
to a new location. Things are going well but I have a couple of
questions:

1) Should the cold water tank be directly above the hot water
cylinder? It was in it's old position. In the new position it's nearer
to an outside wall and the loft has a pitched roof. This means the
tank will be about 1.5 metres to the left of the cylinder below. Will
this reduce the head from the tank if the 22mm output from the tank
takes a straight run across the floor before it drops down to the
cylinder ? My guess is it makes no difference. It's the distance
between the top of the water in the cold tank and the bottom of the hw
cyl that's important.

It won't make a huge difference, but since you are doing this
exercise, it's worth increasing the feed pipe size to 28mm to reduce
the effect of the extra length especially if you might run a bath,
shower and other services. I did this during a cylinder and tank
change and it made an improvement. For bends, I used pairs of obtuse
elbows with a short length of straight pipe between them. This gives
less flow resistance than elbows and saves getting a large pipe
bender. This approach also makes it easier to maintain slopes.



2) I understand the vent pipe must be on a continual upward slope to
work properly and prevent air locks. If it's a longer run to the tank
does this matter so long as it's sloping upwards?

Not really. THis length is OK. Try and slope it upwards by at least
50-70mm over the 1500mm length.


3) I've bought a Polytank PT2000 package from Screwfix and I need to
drill 27mm holes in the cold water tank. The adjustable tank cutters
i've found all say they make holes from 30mm upwards. I also have a
hole saw but the blades on this go up in 5mm increments (25mm, 30mm
etc). I've seen others in this forum have bought a Polytank. How did
you cut your tank holes guys ? I have the 25 gallon version of the
Polytank.

Don't use concentric bimetal hole saw cutter sets for this because
they are likely to wreck the tank unless you are extremely careful.
The separate cutter types tha screw onto a mandrel are much better and
you can certainly buy 27mm. B&Q have them as do the usual online
places.

I put a smear of clear silicone sealer on each side of the tank
connector fitting where it goes into the tank.



4) Any tips on tightening the hot water cylinder connections without
causing damage? It's foamed on the outside which makes gripping the
back of the connector with a second spanner (for the male connections)
just about impossible. I'm going to use PTFE on the threads. Do I just
do them up tightish without putting stress on the tank and that should
be sufficent ? I have no problem with the side of the connector that
has compression joints it's just the connections to the tank itself.

You can buy specific cylinder connectors (BES have them) but they
aren't absolutely necessary. Provided that you wrap about 5-6 turns
of tape along the thread neatly, you then screw the fitting on.
There is no need to go mad with tightening it against the end limit
because that doesn't make the seal anyway.



--

..andy

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