My Grohe mixer is fed from a hot/cold pump. The cold is mains pressure and
the hot is fed from a loft tank so the head is around 4 feet. The pressure
at 38C temp was very acceptable when new 8 years ago but now the pressure is
too low at this temperature. If I reduce the temeperature by rotating the
mixer the pressure returns to normal but the temperature is too low.

I have changed the shower head and flexible tube but this does not improve
the pressure. I also tried lifting the hot tank temperature but this did
not improve the pressure.

There is a maximum temperature limit adjustment on the mixer accessed by
removing the knob and rotating a inner knurled knob but this just sets the
temperature higher before the knob stop position is reached.

There is no air in the pump so can anyone advise why this is happening and
how I can fix it?

regards,

"nobody"

nobody wrote:
My Grohe mixer is fed from a hot/cold pump. The cold is mains
pressure and the hot is fed from a loft tank so the head is around 4
feet. The pressure at 38C temp was very acceptable when new 8 years
ago but now the pressure is too low at this temperature. If I
reduce the temeperature by rotating the mixer the pressure returns to
normal but the temperature is too low.
I have changed the shower head and flexible tube but this does not
improve the pressure. I also tried lifting the hot tank temperature but
this did not improve the pressure.

There is a maximum temperature limit adjustment on the mixer accessed
by removing the knob and rotating a inner knurled knob but this just
sets the temperature higher before the knob stop position is reached.

There is no air in the pump so can anyone advise why this is
happening and how I can fix it?

regards,

"nobody"

I don't understand where the pump comes into the picture if the cold is
mains pressure and the hot is gravity fed, and why isn't the hot water also
mains pressure. Most mixers require hot and cold pressures to be close to
equal. If it is a pressure control mixer that adjusts the water pressure to
keep the temperature reasonably level, it will have problems with unequal
supply pressure. A temperature control mixer which a Grohe probably is,
would be better but probably age, wear and with possibly some particular
matter in the works is now hampering performance. Have you tried a new
cartridge in it?

"EXT" wrote in message
anews.com...
nobody wrote:
My Grohe mixer is fed from a hot/cold pump. The cold is mains
pressure and the hot is fed from a loft tank so the head is around 4
feet. The pressure at 38C temp was very acceptable when new 8 years
ago but now the pressure is too low at this temperature. If I
reduce the temeperature by rotating the mixer the pressure returns to
normal but the temperature is too low.
I have changed the shower head and flexible tube but this does not
improve the pressure. I also tried lifting the hot tank temperature but
this did not improve the pressure.

There is a maximum temperature limit adjustment on the mixer accessed
by removing the knob and rotating a inner knurled knob but this just
sets the temperature higher before the knob stop position is reached.

There is no air in the pump so can anyone advise why this is
happening and how I can fix it?

regards,

"nobody"

I don't understand where the pump comes into the picture if the cold is
mains pressure and the hot is gravity fed, and why isn't the hot water
also mains pressure. Most mixers require hot and cold pressures to be
close to equal. If it is a pressure control mixer that adjusts the water
pressure to keep the temperature reasonably level, it will have problems
with unequal supply pressure. A temperature control mixer which a Grohe
probably is, would be better but probably age, wear and with possibly some
particular matter in the works is now hampering performance. Have you
tried a new cartridge in it?

The pump is a dual circuit rotary one which pumps hot and cold separately.
I have not tried a new cartridge as with all Grohe items this is expensive.
It has a strange pin in its center which can be easily lifted out vertically
but there is no mention of this in its installation instructions. Perhaps
its to insert lubricant for the mechanism? I agree that the pressures
should ideally be equal but they are both within the mixer's spec.

regards

nobody wrote:
"EXT" wrote in message
anews.com...
nobody wrote:
My Grohe mixer is fed from a hot/cold pump. The cold is mains
pressure and the hot is fed from a loft tank so the head is around 4
feet. The pressure at 38C temp was very acceptable when new 8
years ago but now the pressure is too low at this temperature. If
I reduce the temeperature by rotating the mixer the pressure returns
to normal but the temperature is too low.
I have changed the shower head and flexible tube but this does not
improve the pressure. I also tried lifting the hot tank
temperature but this did not improve the pressure.

There is a maximum temperature limit adjustment on the mixer
accessed by removing the knob and rotating a inner knurled knob but
this just sets the temperature higher before the knob stop position
is reached. There is no air in the pump so can anyone advise why this is
happening and how I can fix it?

regards,

"nobody"

I don't understand where the pump comes into the picture if the cold
is mains pressure and the hot is gravity fed, and why isn't the hot
water also mains pressure. Most mixers require hot and cold
pressures to be close to equal. If it is a pressure control mixer
that adjusts the water pressure to keep the temperature reasonably
level, it will have problems with unequal supply pressure. A
temperature control mixer which a Grohe probably is, would be better
but probably age, wear and with possibly some particular matter in
the works is now hampering performance. Have you tried a new
cartridge in it?

The pump is a dual circuit rotary one which pumps hot and cold
separately. I have not tried a new cartridge as with all Grohe items
this is expensive. It has a strange pin in its center which can be
easily lifted out vertically but there is no mention of this in its
installation instructions. Perhaps its to insert lubricant for the
mechanism? I agree that the pressures should ideally be equal but
they are both within the mixer's spec.

Have youy discussed this question with Grohe?

nobody wrote:
"EXT" wrote in message
anews.com...
nobody wrote:
My Grohe mixer is fed from a hot/cold pump. The cold is mains
pressure and the hot is fed from a loft tank so the head is
around 4 feet. The pressure at 38C temp was very acceptable
when new 8 years ago but now the pressure is too low at this
temperature. If I reduce the temeperature by rotating the mixer the
pressure
returns to normal but the temperature is too low.
I have changed the shower head and flexible tube but this does not
improve the pressure. I also tried lifting the hot tank
temperature but this did not improve the pressure.

There is a maximum temperature limit adjustment on the mixer
accessed by removing the knob and rotating a inner knurled knob
but this just sets the temperature higher before the knob stop
position is reached. There is no air in the pump so can anyone advise
why this is
happening and how I can fix it?

regards,

"nobody"

I don't understand where the pump comes into the picture if the
cold is mains pressure and the hot is gravity fed, and why isn't
the hot water also mains pressure. Most mixers require hot and cold
pressures to be close to equal. If it is a pressure control mixer
that adjusts the water pressure to keep the temperature reasonably
level, it will have problems with unequal supply pressure. A
temperature control mixer which a Grohe probably is, would be
better but probably age, wear and with possibly some particular
matter in the works is now hampering performance. Have you tried a
new cartridge in it?

The pump is a dual circuit rotary one which pumps hot and cold
separately. I have not tried a new cartridge as with all Grohe items
this is expensive.

Grohe is a high end product, most high end products have a lifetime
guarantee on their cartriges, call them they may ship one out at no cost
with instructions on replacing it. I have done it with other better brands.

nobody wrote:
My Grohe mixer is fed from a hot/cold pump. The cold is mains
pressure and the hot is fed from a loft tank so the head is around 4
feet.

Just out of curiousity, why is the loft tank not pressurized? It seems to me
kike this complicates the tank system immensely.