Small cottage, single story, vented direct hot water system and wood stove
with back boiler.

Friend reports that prior to this week

Bathroom wash hand basin hot tap was working well, kitchen hot tap OK, but
bath hot tap tended to "Air Lock" so bath not used for three years as
Electric Shower available and after the bath taps were used it needed the
owner to connect the wash hand basin taps together with a hose to get any
hot taps working again.

Back boiler in stove springs leak it is carbon steel and connected to the
120 litre direct, vented hot water tank. I volunteered to replace boiler
that was Thursday morning.

Boiler replaced in stove. Water turned on. Hot tank fills no problem. Goes
up to loft to see how storage tank is getting on. Finds it is 30 year old,
galvanised and is very rusty. I'm not happy but it fills up.

Without heating the hot water, tests tap. Very very low flow. Connects
washing machine pipes together as advised here. Puts thumb on vent pipe
after letting it flow for a while and water starts to come up outlet of
storage tank. So assume no large blockages.

One thing after then turning of the washing machine link and waiting a few
moments there is the sound of what appear to be air in the system moving
about!!

Now test hot water taps again. Wash hand basin about Ok but not as good as
before boiler replacement! Kitchen tap not wonderful but it is a mixer tap
and may not be suitable for a gravity system. Bath tap flow very poor. So go
into loft and the bath tap appears to start by draining the overflow pipe
and it appears there is not enough water rising from the hot tank below to
keep it running.

Cold storage tank in loft with it's outlet some 600mm above the level of the
loft floor. The outlet pipe drops to the loft floor, runs two metres
horizontal and then drops through ceiling, then 1.5 metres drop to the
bottom of the hot water tank. There are two pipe bends and a stop valve and
two tees in the run one for the boiler and a final one for a drain. Remove
stop valve it is opening fully with a small amount of gunge. Clean and
replace in system

From the top of the hot water tank the pipe work goes horizontal say 400mm,
90 elbow and rises say 500mm then through ceiling. ( That 90 elbow between
the horizontal and vertical pipe had gunge in it now cleaned but I'm scared
to remove top connection from cylinder as I may rip the top of the tank it
is ten years old.), then runs some 10 metres horizontal. then down through
ceiling two metres to the bath. On the way it goes through 3 off 90 elbows,
two 90 bends, a tee for the overflow and then gets to the bath. All these
pipes are 22mm.

Can anyone advise if this run is just too long and complicated for a gravity
system to run properly. I realise that a nasty old storage tank and steel
boiler are not helping either.

I have just ordered a few plastic storage tanks as the loft opening is tiny
and the storage tank needs replacing.

9100DN OWNER wrote:

....
Now test hot water taps again. Wash hand basin about Ok but not as good as
before boiler replacement! Kitchen tap not wonderful but it is a mixer tap
and may not be suitable for a gravity system. Bath tap flow very poor. So go
into loft and the bath tap appears to start by draining the overflow pipe

how do you know this?

Cold storage tank in loft with it's outlet some 600mm above the level of the
loft floor. The outlet pipe drops to the loft floor, runs two metres
horizontal and then drops through ceiling, then 1.5 metres drop to the
bottom of the hot water tank. There are two pipe bends and a stop valve and
two tees in the run one for the boiler and a final one for a drain. Remove
stop valve it is opening fully with a small amount of gunge. Clean and
replace in system

Is there much difference in behaviour if you almost close the valve in
the pipework feeding cold water to the bottom of the cylinder?


From the top of the hot water tank the pipe work goes horizontal say 400mm,
90 elbow and rises say 500mm then through ceiling. ( That 90 elbow between
the horizontal and vertical pipe had gunge in it now cleaned but I'm scared
to remove top connection from cylinder as I may rip the top of the tank it
is ten years old.), then runs some 10 metres horizontal. then down through
ceiling two metres to the bath. On the way it goes through 3 off 90 elbows,
two 90 bends, a tee for the overflow and then gets to the bath. All these
pipes are 22mm.

Can anyone advise if this run is just too long and complicated for a gravity
system to run properly. I realise that a nasty old storage tank and steel
boiler are not helping either.

Is it a hard water area?

Could it be that the top outlet of the hot water cylinder is scaled up
and letting little water through? That could explain the vent pipe
draining and air consequently being drawn into the system. Also, since
it's about the one part of the system you haven't opened up to check,
Sod's law dictates that that's the culprit :-)

Can you cut the pipework (assuming it's copper not steel) close to the
cylinder connector and investigate?

Now test hot water taps again. Wash hand basin about Ok but not as good
as before boiler replacement! Kitchen tap not wonderful but it is a mixer
tap and may not be suitable for a gravity system. Bath tap flow very
poor. So go into loft and the bath tap appears to start by draining the
overflow pipe

how do you know this?

The friend is a lady and she said so!!! for drop in performance recently.
Otherwisw this is from getting friend to open the hot water bath tap when I
am standing beside the cold water storage tank.

Is there much difference in behaviour if you almost close the valve in the
pipework feeding cold water to the bottom of the cylinder?

I will try that tommorrow. I know it stops the cylinder filling when closed.

Is it a hard water area?

No, very soft water area, Aberdeenshire

Could it be that the top outlet of the hot water cylinder is scaled up and
letting little water through? That could explain the vent pipe draining
and air consequently being drawn into the system. Also, since it's about
the one part of the system you haven't opened up to check, Sod's law
dictates that that's the culprit :-)

When I last filled the system with the hot water cylinder say 10% full, I
turned on the washing machine link and the water was comming in there at
what appeared to be with some force.

Can you cut the pipework (assuming it's copper not steel) close to the
cylinder connector and investigate?

Never though of that!

Eddie

9100DN OWNER wrote:
Now test hot water taps again. Wash hand basin about Ok but not as good
as before boiler replacement! Kitchen tap not wonderful but it is a mixer
tap and may not be suitable for a gravity system. Bath tap flow very
poor. So go into loft and the bath tap appears to start by draining the
overflow pipe

how do you know this?
The friend is a lady and she said so!!! for drop in performance recently.
Otherwisw this is from getting friend to open the hot water bath tap when I
am standing beside the cold water storage tank.

Sorry, I meant how do you know the bit about draining the overflow pipe
(since you can't see into it)?



Is there much difference in behaviour if you almost close the valve in the
pipework feeding cold water to the bottom of the cylinder?


I will try that tommorrow. I know it stops the cylinder filling when closed.


Is it a hard water area?


No, very soft water area, Aberdeenshire

I've seen an almost-blocked outlet from a cold water tank in a soft
water area (mid-wales, Elan Valleys supply, so I supose it must have
been reactions between different metals rather than anything in the
water itself). I wonder if the same could happen at the hot water
cylinder outlet?


Could it be that the top outlet of the hot water cylinder is scaled up and
letting little water through? That could explain the vent pipe draining
and air consequently being drawn into the system. Also, since it's about
the one part of the system you haven't opened up to check, Sod's law
dictates that that's the culprit :-)


When I last filled the system with the hot water cylinder say 10% full, I
turned on the washing machine link and the water was comming in there at
what appeared to be with some force.

Though with mains behind it you'd expect some force, even if the actual
flow wasn't up to much.

"9100DN OWNER" wrote in message
...
Small cottage, single story, vented direct hot water system and wood stove
with back boiler.

Friend reports that prior to this week

Bathroom wash hand basin hot tap was working well, kitchen hot tap OK, but
bath hot tap tended to "Air Lock" so bath not used for three years as
Electric Shower available and after the bath taps were used it needed the
owner to connect the wash hand basin taps together with a hose to get any
hot taps working again.

Back boiler in stove springs leak it is carbon steel and connected to the
120 litre direct, vented hot water tank. I volunteered to replace boiler
that was Thursday morning.

Boiler replaced in stove. Water turned on. Hot tank fills no problem. Goes
up to loft to see how storage tank is getting on. Finds it is 30 year old,
galvanised and is very rusty. I'm not happy but it fills up.

Without heating the hot water, tests tap. Very very low flow. Connects
washing machine pipes together as advised here. Puts thumb on vent pipe
after letting it flow for a while and water starts to come up outlet of
storage tank. So assume no large blockages.

One thing after then turning of the washing machine link and waiting a few
moments there is the sound of what appear to be air in the system moving
about!!

Now test hot water taps again. Wash hand basin about Ok but not as good as
before boiler replacement! Kitchen tap not wonderful but it is a mixer tap
and may not be suitable for a gravity system. Bath tap flow very poor. So
go
into loft and the bath tap appears to start by draining the overflow pipe
and it appears there is not enough water rising from the hot tank below to
keep it running.

Cold storage tank in loft with it's outlet some 600mm above the level of
the
loft floor. The outlet pipe drops to the loft floor, runs two metres
horizontal and then drops through ceiling, then 1.5 metres drop to the
bottom of the hot water tank. There are two pipe bends and a stop valve
and
two tees in the run one for the boiler and a final one for a drain. Remove
stop valve it is opening fully with a small amount of gunge. Clean and
replace in system

From the top of the hot water tank the pipe work goes horizontal say
400mm,
90 elbow and rises say 500mm then through ceiling. ( That 90 elbow between
the horizontal and vertical pipe had gunge in it now cleaned but I'm
scared
to remove top connection from cylinder as I may rip the top of the tank it
is ten years old.), then runs some 10 metres horizontal. then down through
ceiling two metres to the bath. On the way it goes through 3 off 90
elbows,
two 90 bends, a tee for the overflow and then gets to the bath. All these
pipes are 22mm.

Can anyone advise if this run is just too long and complicated for a
gravity
system to run properly. I realise that a nasty old storage tank and steel
boiler are not helping either.

I have just ordered a few plastic storage tanks as the loft opening is
tiny
and the storage tank needs replacing.



The part about the pipework coming from the loft to a downstairs hot water
storage tank, then rising back up through the ceiling to the loft before
coming back down to the bath, is the bit I don't get. The pipework will
fill with water alright, but it has lost all momentum in doing this dance
all around the house. You're only left with a pressure head height from the
last bend in the pipe down to the bath tap. I think this could be your
problem.

You say that the hot water vent pipe (overflow you're calling it) is also on
this part of the pipework, and that it drops its water level when the bath
tap is turned on. I'm not surprised by this because the head of water above
the bath tap will be the height of the water in the vent pipe, which should
become level with the water in the cold water storage tank. The pipework
then does this dance all over the place and will take ages to fill up again,
especially if the bath tap is still turned on.

Is there room in the loft for a hot water cylinder? Even if it lies on its
side? Lifting the hot tank in to the loft and dropping all the pipework
down from there will cure all your ills in this plumbing system.

You're only left with a pressure head height from the
last bend in the pipe down to the bath tap. I think this could be your
problem.

Agreed

You say that the hot water vent pipe (overflow you're calling it) is also
on
this part of the pipework, and that it drops its water level when the bath
tap is turned on. I'm not surprised by this because the head of water
above
the bath tap will be the height of the water in the vent pipe, which
should
become level with the water in the cold water storage tank. The pipework
then does this dance all over the place and will take ages to fill up
again,
especially if the bath tap is still turned on.


This was put in 30 years ago and it was a solution based on use of space and
you can't go wrong with a solid fuel back boiler if the electricity goes
off. It does here in the winter quite often. It was not based on the
dynamics of a gravity system.

Is there room in the loft for a hot water cylinder? Even if it lies on
its
side? Lifting the hot tank in to the loft and dropping all the pipework
down from there will cure all your ills in this plumbing system.

Max size of loft opening is 400mm and the useable height to the highest
point is less then 1.5 metres. Friend still wants to use back boiler in wood
stove. So need say 1 metre head above hot tank for it to work properly so
little chance of that!

Further she has to run off boiling water quite often as the water cannot be
used for a bath or shower, it is a one person household so no real use of
water as the bath taps do not work and she is a shower type person so uses
an electric shower!!!

My suggestion is to move the cold water storage tank above the bathroom and
the hot water cylinder to an airing cupboard next to the bath room. This
means no return trip to the loft for the hot water and to take the boiler
out the stove and replace it with a fire brick. I was rebuffed as it would
be loosing the advantage of the back boiler!!!!!!!!!!

So that was Thursday, Friday and Sunday lost but who wants the time off!

Eddie

Sorry, I meant how do you know the bit about draining the overflow pipe
(since you can't see into it)?

Basically hearing it.by standing beside the cold water storage

Though with mains behind it you'd expect some force, even if the actual
flow wasn't up to much.

I will try your suggestion of trying to cut this pipe near the joint at the
top of the cylinder and pushing a wire in to clear any possible blockage.

"9100DN OWNER" wrote in message
...
You're only left with a pressure head height from the
last bend in the pipe down to the bath tap. I think this could be your
problem.
snipped

My suggestion is to move the cold water storage tank above the bathroom
and
the hot water cylinder to an airing cupboard next to the bath room. This
means no return trip to the loft for the hot water and to take the boiler
out the stove and replace it with a fire brick. I was rebuffed as it would
be loosing the advantage of the back boiler!!!!!!!!!!


That all sounds like a good method to cure it, but you can still keep the
back boiler in place. I loved our old coal fired back boiler, and 'am sorry
we took it out now. I could have fitted a pump to the back boiler and used
an indirect cylinder to heat the water for our system, but I jumped in to
quick with one of these modern gas things that hang on the wall. :-)

You still have all the options open to make a bad job good here, so think
about what layout you'd need to heat the hot water tank from the back
boiler, and still keep the pressure to all the taps at an acceptable level
by re-arranging the pipework to suit.

A hot water cylinder doesn't have to stand upright if you seal all the
un-used holes. A cylinder lying on its side in the loft, with a coil inside
(indirect cylinder they're called) to heat the water from the back boiler,
will do the same job of supplying hot water well enough, and it doesn't need
to be too big. It also create space in its old postion for other things
like a new storage cupboard.

As long as you can get rid of the part of the system that rises above the
height of the bathroom floor, then you've got the job cracked.


So that was Thursday, Friday and Sunday lost but who wants the time off!

Eddie



LOL !!! Yeah !!! Who needs rest and relaxation. We're hard men !!!! :-)