Hi

I've got a problem with my hot water system and, having searched
through the posts and learned a lot, wondered if someone might have
some incite.

I've bought a 3 storey house (built 8 years ago) with the hot
water tank on the 3rd floor and cold storage tank in the loft. It's a
2 circuit system, one small cold tank for the central heating/water
heating circuit and one large tank for the cold supply to the taps and
the hot water cylinder.

We have bathrooms on the 2nd and 3rd level and have recently fitted
a shower tap in the 2nd and a power shower (using water from the hot
tank) in the 3rd.

I noticed that water pressure on the 2nd floor seemed to be
sometimes good, mostly bad and when we fitted the power shower it
started to play up when pressure was low, sounding like it was sucking
air (gets noisy and the motor seems to "rev" up). This would occur even
on it's lowest power setting.

We assumed an airlock, back flushed the system, and everything was
fine but over the following days you could see the pressure dropping in
the middle bathroom, eventually to the point where the power shower
plays up on the top floor. Every time we flush it it's prefect but
the pressure slowly dies over the following days and then problems
occur.

I've checked the cold water tank and it seems clear. Once the
system is flushed I can leave the power shower on 9 (at which point
flow is high enough that the bath starts to fill) for 5 minutes while I
go up and look at the cold water. The water is going down but there's
enough water going into the tank that I don't think the tank is
emptying.

I've now found I can flush the system by switching water off to
the hot tank and draining a few litres of hot water from the middle
bathroom, then switch the water back on, you can hear the water run
down the pipe, you get a couple of spurts of air when you switch the
tap back on and then it all fixed. I've now got this down to a 2
minute pitstop!

I'm assuming it must be air that's restricting the flow
somewhere if it can be fixed by flush/drawing water. I also assume
that, although I think when the pressure is low the power shower is
drawing air down the vent pipe when on power level 1, as it works fine
after flushing on power level 9 for 10+ minutes it's not the presence
of the power shower that causing problems. Also, as I have low pressure
in both bathrooms the blockage must be in the common pipe and before it
splits to the top floor bathroom.

I've yet to check which pipe water comes out of when I back flush
(the vent pipe or the bottom of the water tank). Maybe it's coming
out the vent pipe and I need to put my finger over it and back flush
the cylinder? I'm tempted to temporarily block the vent pipe (I've
seen the posts about the danger of fitting one values to the vent pipe
- I just mean for 5 minutes) and see if the power shower can draw the
blockage through.

I'm wondering if the problem comes back so quickly if I'm
actually fixing the problem or just moving an air bubble and then it
comes back? Any other tests I should do? Many thanks

Jason

On 16 Feb 2005 02:14:49 -0800, "jason" wrote:

Hi

I've got a problem with my hot water system and, having searched
through the posts and learned a lot, wondered if someone might have
some incite.

I've bought a 3 storey house (built 8 years ago) with the hot
water tank on the 3rd floor and cold storage tank in the loft. It's a
2 circuit system, one small cold tank for the central heating/water
heating circuit and one large tank for the cold supply to the taps and
the hot water cylinder.

We have bathrooms on the 2nd and 3rd level and have recently fitted
a shower tap in the 2nd and a power shower (using water from the hot
tank) in the 3rd.

I noticed that water pressure on the 2nd floor seemed to be
sometimes good, mostly bad and when we fitted the power shower it
started to play up when pressure was low, sounding like it was sucking
air (gets noisy and the motor seems to "rev" up). This would occur even
on it's lowest power setting.

We assumed an airlock, back flushed the system, and everything was
fine but over the following days you could see the pressure dropping in
the middle bathroom, eventually to the point where the power shower
plays up on the top floor. Every time we flush it it's prefect but
the pressure slowly dies over the following days and then problems
occur.

I've checked the cold water tank and it seems clear. Once the
system is flushed I can leave the power shower on 9 (at which point
flow is high enough that the bath starts to fill) for 5 minutes while I
go up and look at the cold water. The water is going down but there's
enough water going into the tank that I don't think the tank is
emptying.

I've now found I can flush the system by switching water off to
the hot tank and draining a few litres of hot water from the middle
bathroom, then switch the water back on, you can hear the water run
down the pipe, you get a couple of spurts of air when you switch the
tap back on and then it all fixed. I've now got this down to a 2
minute pitstop!

I'm assuming it must be air that's restricting the flow
somewhere if it can be fixed by flush/drawing water. I also assume
that, although I think when the pressure is low the power shower is
drawing air down the vent pipe when on power level 1, as it works fine
after flushing on power level 9 for 10+ minutes it's not the presence
of the power shower that causing problems. Also, as I have low pressure
in both bathrooms the blockage must be in the common pipe and before it
splits to the top floor bathroom.

I've yet to check which pipe water comes out of when I back flush
(the vent pipe or the bottom of the water tank). Maybe it's coming
out the vent pipe and I need to put my finger over it and back flush
the cylinder? I'm tempted to temporarily block the vent pipe (I've
seen the posts about the danger of fitting one values to the vent pipe
- I just mean for 5 minutes) and see if the power shower can draw the
blockage through.

I'm wondering if the problem comes back so quickly if I'm
actually fixing the problem or just moving an air bubble and then it
comes back? Any other tests I should do? Many thanks

Jason

Hi,

Did you back flush it in the following way?:

http://groups.google.co.uk/groups?q=back+flush+hot+water&hl=en&lr=&selm=36hp0 7F53b3htU1%40individual.net&rnum=3

How big is the supply pipe from the hot water tank, and does the
shower have it's own pipe teed directly into this?

cheers,
Pete.