Hi all,

How quickly do thermostatic valves adjust to a sudden loss in pressure
in one pipe?
Let me explain-
In my flat I have a combi boiler for the hot water, mains pressure CW
for the kitchen *but* a CW storage tank for the bathroom (apparantly
first thing in the morning the pressure was very poor). Unfortunately
the ceilings are very low so the head between the top of the CW in the
tank and the shower head is at best around 50cm. Not exactly great
then.
I'm in the process of fitting a single vane booster pump to the bath /
shower CW supply.
However, my worry is this: if the water pressure really is rubbish I
run the risk of using up all the water in the cold water tank and
getting scalded.
If I upgraded (from a standard mixer)would this help- would a
thermostatic shower unit (like the Pegler Fanfare sold in Screwfix)
adjust in time or would I be better with a hot water isolation valve
(electrically switched) run off an electronic float switch in the cold
water tank.
Thanks for any advice,

Ben

"Ben" wrote in message
om...
Hi all,

How quickly do thermostatic valves adjust to
a sudden loss in pressure in one pipe?

Not that quick. You need a pressure equalisation valve on the hot and cold
pipes to the shower.
http://www.plumbworld.co.uk/344-0000

Let me explain-
In my flat I have a combi boiler for the
hot water, mains pressure CW
for the kitchen

Sounds normal.

*but* a CW storage tank for the bathroom (apparantly
first thing in the morning the pressure was very poor).
Unfortunately the ceilings are very low so the head
between the top of the CW in the
tank and the shower head is at best around 50cm. Not exactly great
then.

Use the shower via the combi whoch will be from the mains. The combi, and
mains pressure, should be good enough for one shower.

I'm in the process of fitting a single vane
booster pump to the bath / shower CW supply.
However, my worry is this: if the water pressure
really is rubbish I run the risk of using up all the
water in the cold water tank and getting scalded.
If I upgraded (from a standard mixer)would this help- would a
thermostatic shower unit (like the Pegler Fanfare sold in Screwfix)
adjust in time or would I be better with a hot water isolation valve
(electrically switched) run off an electronic float switch in the cold
water tank.
Thanks for any advice,

Ben,

I;I'm not sure how your system is configured. Do you have a hot water
cylinder? What does the cold tank supply? Is the combi off the mains? Is
the mains pressure that poor you can't have a decent shower off the combi?

"IMM" wrote in message ...
"Ben" wrote in message
om...
Hi all,

How quickly do thermostatic valves adjust to
a sudden loss in pressure in one pipe?

Not that quick. You need a pressure equalisation valve on the hot and cold
pipes to the shower.
http://www.plumbworld.co.uk/344-0000

Aha! I wondered as much, thanks for the update!


Let me explain-
In my flat I have a combi boiler for the
hot water, mains pressure CW
for the kitchen

Sounds normal.

*but* a CW storage tank for the bathroom (apparantly
first thing in the morning the pressure was very poor).
Unfortunately the ceilings are very low so the head
between the top of the CW in the
tank and the shower head is at best around 50cm. Not exactly great
then.

Use the shower via the combi whoch will be from the mains. The combi, and
mains pressure, should be good enough for one shower.

I'm in the process of fitting a single vane
booster pump to the bath / shower CW supply.
However, my worry is this: if the water pressure
really is rubbish I run the risk of using up all the
water in the cold water tank and getting scalded.
If I upgraded (from a standard mixer)would this help- would a
thermostatic shower unit (like the Pegler Fanfare sold in Screwfix)
adjust in time or would I be better with a hot water isolation valve
(electrically switched) run off an electronic float switch in the cold
water tank.
Thanks for any advice,

Ben,

I;I'm not sure how your system is configured. Do you have a hot water
cylinder? What does the cold tank supply? Is the combi off the mains? Is
the mains pressure that poor you can't have a decent shower off the combi?

There's no hot water cylinder and the combi boiler is a non storage
type. The cold tank just supplies the bathroom fittings (toilet, sink
and bath / shower). The combi meanwhile is off the mains and seems to
always give a nice powerful flow. So really it's the opposite of
normal- high pressure hot water and low pressure cold (at least as far
as the shower is concerned).
Thanks for the info,

Ben

"Ben" wrote in message
om...
"IMM" wrote in message
...
"Ben" wrote in message
om...
Hi all,

How quickly do thermostatic valves adjust to
a sudden loss in pressure in one pipe?

Not that quick. You need a pressure equalisation valve on the hot and
cold
pipes to the shower.
http://www.plumbworld.co.uk/344-0000

Aha! I wondered as much, thanks for the update!


Let me explain-
In my flat I have a combi boiler for the
hot water, mains pressure CW
for the kitchen

Sounds normal.

*but* a CW storage tank for the bathroom (apparantly
first thing in the morning the pressure was very poor).
Unfortunately the ceilings are very low so the head
between the top of the CW in the
tank and the shower head is at best around 50cm. Not exactly great
then.

Use the shower via the combi whoch will be from the mains. The combi,
and
mains pressure, should be good enough for one shower.

I'm in the process of fitting a single vane
booster pump to the bath / shower CW supply.
However, my worry is this: if the water pressure
really is rubbish I run the risk of using up all the
water in the cold water tank and getting scalded.
If I upgraded (from a standard mixer)would this help- would a
thermostatic shower unit (like the Pegler Fanfare sold in Screwfix)
adjust in time or would I be better with a hot water isolation valve
(electrically switched) run off an electronic float switch in the cold
water tank.
Thanks for any advice,

Ben,

I;I'm not sure how your system is configured. Do you have a hot water
cylinder? What does the cold tank supply? Is the combi off the mains?
Is
the mains pressure that poor you can't have a decent shower off the
combi?

There's no hot water cylinder and the combi boiler is a non storage
type. The cold tank just supplies the bathroom fittings (toilet, sink
and bath / shower). The combi meanwhile is off the mains and seems to
always give a nice powerful flow. So really it's the opposite of
normal- high pressure hot water and low pressure cold (at least as far
as the shower is concerned).
Thanks for the info,

The hot and cold to the shower should be both off the cold mains. they must
be approx the same pressure. Any slight fluctuation sin either pipe, the
equalisation valve will take care of. Remove the shower pipe off the tank.

"IMM" wrote in message ...
"Ben" wrote in message
om...
"IMM" wrote in message
...
"Ben" wrote in message
om...
Hi all,

How quickly do thermostatic valves adjust to
a sudden loss in pressure in one pipe?

Not that quick. You need a pressure equalisation valve on the hot and
cold
pipes to the shower.
http://www.plumbworld.co.uk/344-0000

Aha! I wondered as much, thanks for the update!


Let me explain-
In my flat I have a combi boiler for the
hot water, mains pressure CW
for the kitchen

Sounds normal.

*but* a CW storage tank for the bathroom (apparantly
first thing in the morning the pressure was very poor).
Unfortunately the ceilings are very low so the head
between the top of the CW in the
tank and the shower head is at best around 50cm. Not exactly great
then.

Use the shower via the combi whoch will be from the mains. The combi,
and
mains pressure, should be good enough for one shower.

I'm in the process of fitting a single vane
booster pump to the bath / shower CW supply.
However, my worry is this: if the water pressure
really is rubbish I run the risk of using up all the
water in the cold water tank and getting scalded.
If I upgraded (from a standard mixer)would this help- would a
thermostatic shower unit (like the Pegler Fanfare sold in Screwfix)
adjust in time or would I be better with a hot water isolation valve
(electrically switched) run off an electronic float switch in the cold
water tank.
Thanks for any advice,

Ben,

I;I'm not sure how your system is configured. Do you have a hot water
cylinder? What does the cold tank supply? Is the combi off the mains?
Is
the mains pressure that poor you can't have a decent shower off the
combi?

There's no hot water cylinder and the combi boiler is a non storage
type. The cold tank just supplies the bathroom fittings (toilet, sink
and bath / shower). The combi meanwhile is off the mains and seems to
always give a nice powerful flow. So really it's the opposite of
normal- high pressure hot water and low pressure cold (at least as far
as the shower is concerned).
Thanks for the info,

The hot and cold to the shower should be both off the cold mains. they must
be approx the same pressure. Any slight fluctuation sin either pipe, the
equalisation valve will take care of. Remove the shower pipe off the tank.


Aha! That's where the problem lies.... The water supply to the house
is pretty pathetic, consequently in the mornings there is limited
flow. I think the person who installed the plumbing thought putting
all the incoming water to the combi with a tank for the CW was a
better idea. Then again, the ball cock will come making the pressure
still drop... Confusing!!!
Sometimes I think it would be easiest to take the water to the
bathroom straight off the mains and scrap the tank!!! Any obivous
disadvantages????
What kind of pressure differential will a pressure equalising valve
manage? The plumbworld one says it prevents scalds- I'm assuming a
100% differential therefore. Anyway, I'm hoping a 1.5bar shower pump
will roughly equal the pressure coming out of the combi boiler and all
will be good! We'll see!
Is it still a requirement to fit flap valves or will the PEV
effectively do this automatically.
Thanks for the info- I'm more a sparky person myself, plumbing is a
new field for me.... Very confusing!

Ben

On 12 Oct 2004 13:13:15 -0700, (Ben) wrote:


Aha! That's where the problem lies.... The water supply to the house
is pretty pathetic, consequently in the mornings there is limited
flow. I think the person who installed the plumbing thought putting
all the incoming water to the combi with a tank for the CW was a
better idea. Then again, the ball cock will come making the pressure
still drop... Confusing!!!
Sometimes I think it would be easiest to take the water to the
bathroom straight off the mains and scrap the tank!!! Any obivous
disadvantages????
What kind of pressure differential will a pressure equalising valve
manage? The plumbworld one says it prevents scalds- I'm assuming a
100% differential therefore. Anyway, I'm hoping a 1.5bar shower pump
will roughly equal the pressure coming out of the combi boiler and all
will be good! We'll see!
Is it still a requirement to fit flap valves or will the PEV
effectively do this automatically.
Thanks for the info- I'm more a sparky person myself, plumbing is a
new field for me.... Very confusing!

Hi,

Have you measured the CW flow in the morning to see what it is? It may
be that the boiler needs a minimum pressure and the separate tanked CW
supply helps maintain this.

Try running the shower hot in the morning while all the cold taps in
the kitchen are open. If the combi doesn't cut out and the flow is
satisfactory just take the shower cold off the mains.

cheers,
Pete.