Hi,

I may be attempting to fit a 2 port valve to my gravity hw this
weekend. However, placement of the valve may turn out to be a problem.

I know that the valve has to go after the venting pipe, so the options
are....

Between the venting pipe T and the cylinder - Impossible, as there is
only a few cm of space between the two.

On the return, after the cylinder, very difficult for a relatively
amature plumber like myself. Access at the bottom of the cylinder is
limited, and the return pipe comes out of the bottom of the cylinder
and bends all over the place to go through the floor and return to the
boiler.

I was wondering if an easier option would be to move the t fo the vent
so that its lower down, and then i can fit the valve above it.... for
example.. cue cruddy ascii art

Current system

_____ |vent
| |
cyl |---|
| |
| | flow

New layout

_____ |
| |vent
cyl |---| |
| | |
| V |
| |__|
| |

V is the 2 port valve
Is there any problem with the vent t being lower down the flow pipe?

Dont know what happenned to that ascii art. Suppose thats what you get
posting through google groups

In an earlier contribution to this discussion,
Mark Trueman wrote:

Dont know what happenned to that ascii art. Suppose thats what you get
posting through google groups

Yes, it's not easy to convey a clear picture with it!

Any chance you could stick a photo of your cylinder and its pipework on a
website somewhere, and post a link to it?

Is there room to extend the upper coil connection horizontally, to make room
for the valve but also to allow the vent to connect at the same level?

Does your boiler have an overheat cutout stat? If so, you may get away with
putting the valve in the return pipe on the boiler side of the feed pipe.
[There are others with more expertise than me on this - hopefully they will
chip in].
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

I might be able to put a photo up later when i get home.

There wont be room to extend the upper coil horizontally, as the
cylinder is in an airing cupboard that is only slightly bigger than the
cylinder itself. There is only about 1 inch of pipe visible between the
tank connector and the T for the vent, and then about 1 inch of space
between the T and the wall of the cupboard!! Needless to say, its a
pain to get in there - took me a whole day to fit a new cylinder a
while back which normally would have taken an hour at the most!!

Is there a reason why the vent has to connect at the same level as the
entry to the cylinder?

Not sure about the overheat cutout stat. I was under the impression
that 99% of the old gravity heating boilers did have this (its an old
baxi bermuda 401 back boiler)

It seems that C-plan conversions are your niche Set Square. Looking
through previous posts on the subject, your name pops up more than
most.

Cheers

Mark

In an earlier contribution to this discussion,
Mark Trueman wrote:


Is there a reason why the vent has to connect at the same level as the
entry to the cylinder?

I'm not absolutely sure. The default with gravity systems seems to be to
connect the vent pipe to the highest point - but I'm not sure whether it's
de rigeur. Others may care to comment.

On my fully pumped Y-Plan system, it certainly *isn't* connected at the
highest point - both the vent and F&E pipes are connected into the flow pipe
under the airing cupboard floor, just before the pump. But the requirements
for gravity systems may be different.

Not sure about the overheat cutout stat. I was under the impression
that 99% of the old gravity heating boilers did have this (its an old
baxi bermuda 401 back boiler)

If it's similar to 2 Baxi Bermudas which I have owned in the past, it
*won't* have one. The Bermuda has a large heat exchanger - which holds a lot
of water - and can take care of being able to operate with virtually no flow
without any danger of the residual heat causing the water to overheat.

It seems that C-plan conversions are your niche Set Square. Looking
through previous posts on the subject, your name pops up more than
most.

I have certainly suggested them several times since converting a gravity
system to C-Plan is often the simplest way of providing a boiler interlock
where there wasn't one before. I have a very good understanding of how they
work - but have never been in a position where I have needed to implement
one myself.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

"Mark Trueman" wrote in message roups.com...
Is there a reason why the vent has to connect at the same level as the
entry to the cylinder?

You have to have the vent at the top of the coil otherwise you have an
air lock and no way to vent it.
It is a problem in tight cupboards like this. All I can suggest is
that you turn the flow pipe towards the front of the cupboard, near
the floor, then up and back to the coil connection, move the vent to
the "front top corner" and put the valve on the horizontal bit between
there and the coil...