(Hot) Water pressure question

whosedaddy?

Hi,

my average SemiD 3 beedroom house has the following hot water "problems".

Just running gravity fed system (no power / electic shower).
When turning hot water on in the morning , the first 10sec the water is ice cold, not room temp, freezing. The pipes to the hot water tank should be about 3 meters (haven't ripped up floorboards to see where exactly the pipes run) .
If it was the water in the pipe, shouldn't it be at least room temp?

Or in case cold water pipes and warm water pipes are touching somewhere, could that cause such a dramatic temp reduction (cold water from attic is rather chilled)?

The other issue is in a way even more annoying.
The downstairs kitchen is an extension (build be previous owner), when turing on the hot water donwstairs, hot water upstairs stops running almost altogether. Is there anything that can be done to control the hot water distribution?

Last but not least, at the moment my cold water tank in attic sits about 50cm above the joists. I'd like to move it under the eaves. How much of a water pressure drop would that cause? I don't want to move it and then have to install power shower to top up the pressure.

TIA
WD

Reyman

whosedaddy? wrote: »

Hi,

Last but not least, at the moment my cold water tank in attic sits about 50cm above the joists. I'd like to move it under the eaves. How much of a water pressure drop would that cause? I don't want to move it and then have to install power shower to top up the pressure.

TIA
WD

If you lay the attic tank just on the joists you really won't be able to have a shower. I have found the tank really needs to be about 3 ft above the joists for a reasonable pressure (upstairs).

You can do a simple flow rate check if you one of those removable showers attached to the hot tap or mixer. Measure the time it takes to fill a 5 litre bucket with the shower head at a particular level. Then raise the shower head 50cms and repeat the measurement. This will give you the approximate flow reduction from putting the tank on the joists.
I'd guess you''ll lose 30-40%

(This method is also handy if you're thinking of raising the tank and want to know what difference it will make)

youtheman

1. I can only assume that your hot water pipe has no thermal insulation (as would be required under the current building regulations). So when you open the hot tap you have to wait until you flush the cold water out of the system. The floor is essentially a huge 'heat sink' that is taking the temperature out of the system.

2. It would also appear that you have a common hot water feed (to upstairs and downstrairs) that is undersized (i.e. diameter is too small). This is why one system (downstairs) takes preference over the other (upstairs). Of course there could be an isolation valve that is partially closed.

3. If you raise the tank (as you seem to be suggesting) then you'll raise the pressure. 70 cm of height will equal one pond per square inch (psi). You'd have to raise or lower the tank by a huge amount to make any appreciable difference to the pressure. If you move it horizontally then there will also be a pressure loss associated with a longer pipe run. Again, it would have to be a signifiant distance to make a real difference. You could counteract this by putting in a larger bore pipe.

JamesM

whosedaddy? wrote: »

Hi,

Just running gravity fed system (no power / electic shower).
When turning hot water on in the morning , the first 10sec the water is ice cold, not room temp, freezing. The pipes to the hot water tank should be about 3 meters (haven't ripped up floorboards to see where exactly the pipes run) .
If it was the water in the pipe, shouldn't it be at least room temp?


The other issue is in a way even more annoying.
The downstairs kitchen is an extension (build be previous owner), when turing on the hot water donwstairs, hot water upstairs stops running almost altogether. Is there anything that can be done to control the hot water distribution?

TIA
WD

In most cases the hot water pipe does not run under the floor. It goes up to the attic and then comes down to the bathroom - quite a long run of pipe.
Then it splits and goes down to the kitchen - naturally if you turn on the kitchen tap it will cut the flow to the bathroom.
Jim.

whosedaddy?

Thanks all.

Deffo not running through attic. Doing conversion job up there at the moment...
Although the water temp is as low as the cold water from attic.

I accept some drop in pressure / flow, but not it all going completely. How many ppl out there jump in the shower if someone turns on tap in the kitchen... some sort of valve as flow control for downstairs, would that work?

Have got insulation for the pipes, need to trace the pipes next.

looks like moving the cold water tank will not work (remove pedestal and put on joist level.) Unless I get coffin tank and a cut the hight of the pedestal so the tank sits further under the eaves. But cost vs. space benefits are also questionable. Need to think about this more.

Reyman

whosedaddy? wrote: »

looks like moving the cold water tank will not work (remove pedestal and put on joist level.) Unless I get coffin tank and a cut the hight of the pedestal so the tank sits further under the eaves. But cost vs. space benefits are also questionable. Need to think about this more.

I think you're saying that you'll get the tank closer to the eaves if you replace it with a lower and longer tank.
I'm afraid that won't work, because the 'head' is measured from the top of the water in the tank. If you reduce the height of the water in the tank by say 1ft you reduce the head to the shower by 1 ft.

whosedaddy?

Reyman wrote: »

I think you're saying that you'll get the tank closer to the eaves if you replace it with a lower and longer tank.
I'm afraid that won't work, because the 'head' is measured from the top of the water in the tank. If you reduce the height of the water in the tank by say 1ft you reduce the head to the shower by 1 ft.

Yes, that was my thinking. thanks for the clarification.

JamesM

whosedaddy? wrote: »

Thanks all.
Deffo not running through attic. Doing conversion job up there at the moment...
Although the water temp is as low as the cold water from attic.

I'm "Old School" Certainly 20 / 30 years ago that was the standard run.
Jim.

davidoco

whosedaddy? wrote: »

The other issue is in a way even more annoying.
The downstairs kitchen is an extension (build be previous owner), when turing on the hot water donwstairs, hot water upstairs stops running almost altogether. Is there anything that can be done to control the hot water distribution?WD

See first item on this page http://www.heatweb.com/products/pumps/pumps.html Set it to auto for your hot taps (not shower) and you can have some decent pressure at both hot water taps.


Move the header tank whereever you want and buy an all in one shower/mixer/booster like the Mira Event XS which runs on a normal power circuit (230V, 3 Amp double pole switched connection)

whosedaddy?

davidoco wrote: »

See first item on this page http://www.heatweb.com/products/pumps/pumps.html Set it to auto for your hot taps (not shower) and you can have some decent pressure at both hot water taps.


Move the header tank whereever you want and buy an all in one shower/mixer/booster like the Mira Event XS which runs on a normal power circuit (230V, 3 Amp double pole switched connection)

Thanks. I'll have a look how the pipes run and where shower branches off and where the taps. didn't really plan/budget for pumps and booster showers.