Reduction in water pressure a couple weeks later?
 

Hi folks. I'd appreciate some opinions.

We've recently had a loft conversion done, and at the start of the
construction we had a main fed hot water system put in (Megaflo).
Immediately after that was put in, I noticed a fantastic increase in
the water pressure in the shower and all the taps around the house.
The shower was barely useable at full blast.

Strangely, a couple weeks later the pressure dropped again. It was
still pretty good but no where near as it was before, but it was
useable so I didn't think twice about it.

Now that our loft conversion is finished, the water pressure up there
is pretty poor, and downright unuseable if someone has a cold/hot tap
on downstairs.

Unfortunately the plumber who put the original Megaflo system in has
left now (went to Poland), so I can't ask him what he might have done
to cause the reduction in pressure. We had another plumber come in and
check it, and he says it's because of the 15mm copper piping we have
from the mains (and wants us to spend a couple thousand upgrading
that). That doesn't make sense to me because the pressure /used/ to be
great for a couple of weeks.

I've checked the mains stop cock in the house and that's open fully,
and I'm out of ideas now, other than consulting yet another plumber.

Could there have been something else during the construction that may
have affected the water flow? Or what else can I try to find the
bottleneck?

Thanks a lot,
James

JT wrote:

We've recently had a loft conversion done, and at the start of the
construction we had a main fed hot water system put in (Megaflo).
Immediately after that was put in, I noticed a fantastic increase in
the water pressure in the shower and all the taps around the house.
The shower was barely useable at full blast.

Strangely, a couple weeks later the pressure dropped again. It was
still pretty good but no where near as it was before, but it was
useable so I didn't think twice about it.

Well, if it was formerly OK and suddenly dropped, then surely you're
looking at a physical blockage somewhere, eg a bit of debris (left in
the pipework by the plumber) having detached itself and migrated to
somewhere critical. Is it just the loft shower that's got the problem?
The shower valve is likely to have a filter on the incoming pipes; can
you remove the valve and check that there's nothing in there?

David

I noticed a drop in pressure in all taps around the house. A blockage
somewhere would make sense, but if it's affecting all the taps, then
it must be a blockage nearer the mains source. It seems a bit rubbish
that our plumber that came to have a look didn't suggest that as a
problem and just said 'nah, you've got to replace all the 15mm'.

The other thing is that it was good for a couple of weeks first. Is
there a chance that some kind of debris could have broken off from
somewhere inside the pipework?

Cheers,
James

On Wed, 28 Sep 2005 13:15:31 GMT, Lobster
wrote:

JT wrote:

We've recently had a loft conversion done, and at the start of the
construction we had a main fed hot water system put in (Megaflo).
Immediately after that was put in, I noticed a fantastic increase in
the water pressure in the shower and all the taps around the house.
The shower was barely useable at full blast.

Strangely, a couple weeks later the pressure dropped again. It was
still pretty good but no where near as it was before, but it was
useable so I didn't think twice about it.

Well, if it was formerly OK and suddenly dropped, then surely you're
looking at a physical blockage somewhere, eg a bit of debris (left in
the pipework by the plumber) having detached itself and migrated to
somewhere critical. Is it just the loft shower that's got the problem?
The shower valve is likely to have a filter on the incoming pipes; can
you remove the valve and check that there's nothing in there?

David

JT wrote:
I noticed a drop in pressure in all taps around the house. A blockage
somewhere would make sense, but if it's affecting all the taps, then
it must be a blockage nearer the mains source. It seems a bit rubbish
that our plumber that came to have a look didn't suggest that as a
problem and just said 'nah, you've got to replace all the 15mm'.

The other thing is that it was good for a couple of weeks first. Is
there a chance that some kind of debris could have broken off from
somewhere inside the pipework?

Erm - that's what I suggested last time! But less plausible I suppose
given that all the taps are affected; any blockage would be most likely
to be at a bottlneck, ie a valve or tap.

David



JT wrote:

We've recently had a loft conversion done, and at the start of the
construction we had a main fed hot water system put in (Megaflo).
Immediately after that was put in, I noticed a fantastic increase in
the water pressure in the shower and all the taps around the house.
The shower was barely useable at full blast.

Strangely, a couple weeks later the pressure dropped again. It was
still pretty good but no where near as it was before, but it was
useable so I didn't think twice about it.

Well, if it was formerly OK and suddenly dropped, then surely you're
looking at a physical blockage somewhere, eg a bit of debris (left in
the pipework by the plumber) having detached itself and migrated to
somewhere critical. Is it just the loft shower that's got the problem?
The shower valve is likely to have a filter on the incoming pipes; can
you remove the valve and check that there's nothing in there?

David

JT wrote:
There's a strainer/ filter on the inlet to the multi-function valve
(strainer, reducing valve & check valve); I'm not certain that the
Megaflo's got a PRV but you'll see at a glance. The strainer may have
got blocked with crud left in the pipes. Check the pressure reducing
valve (if there is one) is set at the correct pressure.

It should have been fitted by a registered installer, if not the
warranty will be void. Read the installation manual ensure it's been
installed correctly.

Aidan wrote:
JT wrote:
There's a strainer/ filter on the inlet to the multi-function valve
(strainer, reducing valve & check valve); I'm not certain that the
Megaflo's got a PRV but you'll see at a glance. The strainer may have
got blocked with crud left in the pipes. Check the pressure reducing
valve (if there is one) is set at the correct pressure.

But that wouldn't affect the cold mains pressure all over the house??

David

Lobster wrote:

But that wouldn't affect the cold mains pressure all over the house??

If it's the usual multi-function valve with a balanced pressure
draw-off for cold, then yes it would affect everything served by the
hot & cold.

If not, or if it's not been piped correctly, then no. It's often a
PITA to properly connect the cold to the PRV outlet, which will
typically be above the ground floor. They often leave the cold
connected to the ground floor mains supply.

JT expressed precisely :
Could there have been something else during the construction that may
have affected the water flow? Or what else can I try to find the
bottleneck?

Could the problem be outside your property?

Our pressure sometimes varies between two levels, we put it down to the
water authority turning pumps on and off at the local water tower.

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.org

Thanks for all the replies!

Aiden, I cleaned the strainer, and also recharged the air volume in
the Megaflo, but that didn't seem to make much difference.

I suppose it /could/ be the water company changing something, and was
just an unfortunate coincedence that it was just after we got our
system newly setup!


On 28 Sep 2005 08:24:02 -0700, "Aidan" wrote:


Lobster wrote:

But that wouldn't affect the cold mains pressure all over the house??

If it's the usual multi-function valve with a balanced pressure
draw-off for cold, then yes it would affect everything served by the
hot & cold.

If not, or if it's not been piped correctly, then no. It's often a
PITA to properly connect the cold to the PRV outlet, which will
typically be above the ground floor. They often leave the cold
connected to the ground floor mains supply.

On Wed, 28 Sep 2005 18:53:14 +0100, "Harry Bloomfield"
wrote:

Could the problem be outside your property?

Our pressure sometimes varies between two levels, we put it down to the
water authority turning pumps on and off at the local water tower.

On Wed, 28 Sep 2005 15:47:59 +0100, wrote:

If it's /all/ taps, cold as well, it could be that the water authority has
introduced a programme to reduce leakage from its mains by pressure
reduction. Have neighbouring properties been affected?

JT wrote:
Thanks for all the replies!

Aiden, I cleaned the strainer, and also recharged the air volume in
the Megaflo, but that didn't seem to make much difference.

There is (should be) a pressure reducing valve on the Megaflo; it
should be factory set to deliver 3 bar outlet pressure. It won't do
this if the inlet pressure is less than 3 bar. Your problem is most
likely caused by a reduction in inlet pressure (i.e., reduced mains
pressure), or a defective or incorrectly set PRV. You'd need to get
hold of a pressure gauge to diagnose the problem.

If it had been a restriction, as I'd suggested, then the pressure would
creep up to the set PRV outlet pressure when there was no flow,
compressing the gas charge in the top of the heater. You'd then get an
initial 'burst' of flow at 'normal' high pressure, dropping off as the
air expanded and the flow rate from the mains declined. Sorry to
contradict myself.

You could check that neither of the 2 pressure relief valves are
discharging water. The discharge tundish (usually black plastic) should
be visible, so this should be immediately obvious.

If it's reduced mains pressure ( 3bar at the PRV inlet), you could
also contact the water supplier to enquire about the recent reduction
in pressure. They're not obliged to supply much pressure, so they may
have turned it down. It might also be caused by a large underground
leak and they'd want to know.

If it had been a restriction, as I'd suggested, then the pressure would
creep up to the set PRV outlet pressure when there was no flow,
compressing the gas charge in the top of the heater. You'd then get an
initial 'burst' of flow at 'normal' high pressure, dropping off as the
air expanded and the flow rate from the mains declined. Sorry to
contradict myself.

Sorry, I didn't entirely understand all that. However, when I do turn
on a tap or shower, there /is/ and initial burst of air/water coming
out. After a few seconds it stabilises at a slower rate. What did you
mean that this implies?

You could check that neither of the 2 pressure relief valves are
discharging water. The discharge tundish (usually black plastic) should
be visible, so this should be immediately obvious.

There isn't any sign of discharge.

If it's reduced mains pressure ( 3bar at the PRV inlet), you could
also contact the water supplier to enquire about the recent reduction
in pressure. They're not obliged to supply much pressure, so they may
have turned it down. It might also be caused by a large underground
leak and they'd want to know.

I think this might have to be my next step. Unfortunately it's
difficult for me to come up with specific dates that the pressure went
down because I didn't take much notice back then. I suppose I could
just get a reading from the water company and check that it's the same
as what's coming through to my house?

Thanks a lot,
James

JT wrote:
However, when I do turn
on a tap or shower, there /is/ and initial burst of air/water coming
out. After a few seconds it stabilises at a slower rate.

There will be, it is the nature of the system.

The question is whether the initital surge/burst is at the same sort
of pressure as the surge/burst was when the system was first installed.
If so, this would suggest a restriction, i.e., adequate static pressure
but inadequate pressure & flow rate when you're drawing off water.

If not, it suggests low pressure (less than 3 bar) at the inlet to the
heater/ outlet of the PRV. That would be low mains pressure or low
outlet pressure from the PRV; gauges are needed to determine which.

There isn't any sign of discharge.

Good.

I think this might have to be my next step. Unfortunately it's
difficult for me to come up with specific dates that the pressure went
down because I didn't take much notice back then. I suppose I could
just get a reading from the water company and check that it's the same
as what's coming through to my house?

I fear you'll probably get shunted from one useless minion to another,
but it's worth trying. You could ask your neighbours if they've noticed
a pressure drop. It won't much affect thoose with traditional tank-fed
systems, so they may not have noticed.

Thanks a lot,
James