Negative Head Pump

joxer1

Folks,

I moved my water tank in my attic to allow more space for an attic conversion, but ever since my hot water pressure has been terrible. My tank has droped by about 1.3m and is about 3m higher than the bottom of my hot cylinder, most of the pipework is nearly on the same level unfortunately. The flow(3/4") runs from the cold tank to the bottom of the cylinder and the return then comes from the top (with a vent pipe in the attic) to a tee to feed a mira pumped shower (1/2" hot and cold) and the other side of the tee (3/4") feeding down to my bathroom and my kitchen. Pressure is not bad in kitchen but is absolutely rubbish in the bathroom. I am wondering would I have to fit a pump to the system, where would I put this on the system (after the vent pipe I presume),and what type of pump would be suitable, not to noisy I hope.
Any advice appreciated.
Regards.

Ging Ging

If it worked before and the cold is still working you shouldnt need a pump. May be an air lock in bathroom hot line. Try opening the hot taps in bathroom, then by putting your hand over the tap nozzle at kitchen sink and setting the mixer to mid position, the mains cold water will be forced through the hot pipework and it may clear it. if it doesnt work, you may need someone in attic to put their hand over hot water vent pipe at tank to stop mains water flowing into tank through it.

joxer1

Ging Ging wrote: »

If it worked before and the cold is still working you shouldnt need a pump. May be an air lock in bathroom hot line. Try opening the hot taps in bathroom, then by putting your hand over the tap nozzle at kitchen sink and setting the mixer to mid position, the mains cold water will be forced through the hot pipework and it may clear it. if it doesnt work, you may need someone in attic to put their hand over hot water vent pipe at tank to stop mains water flowing into tank through it.

Thanks for your help, Ill give that a go and see what happens...

ART6

If you reduced the tank height from 4.3 metres above the hot tank to 3 metres you will have reduced the available head pressure from 6.12 psi to 4.27 psi, or by approximately 30% in upstairs taps. Downstairs ones would not be as significantly affected as the remaining head is still much greater than the amount by which you lowered the cold tank. A lower pressure upstairs could make airlocks more likely and the solution is as posted by the previous poster.

AckwelFoley

ART6 wrote: »

If you reduced the tank height from 4.3 metres above the hot tank to 3 metres you will have reduced the available head pressure from 6.12 psi to 4.27 psi, or by approximately 30% in upstairs taps. Downstairs ones would not be as significantly affected as the remaining head is still much greater than the amount by which you lowered the cold tank. A lower pressure upstairs could make airlocks more likely and the solution is as posted by the previous poster.

Exactly what he said ^

cnocbui

Gravity fed water systems suck. "power" showers even more so.

If you don't have any luck with finding and eliminating an airlock, get a Stuart Turner twin pump and get decent pressure everywhere. No more waiting 20 minutes for a toilet cistern to refill.

smooth operater

I reckon ART is right, specially as the shower outlet is going to be mounted about 2m above finished floor level.
If its not possible to mount the tank higher well then you'll need a pump...Located on the (3/4") flow from the tank as that'll serve both your hot and cold water services.
But try the air lock solution first anyway

Conor