Poor hot water flow from taps

[lucynliam]

Hi.

We've just moved into our first house and have realised poor flow from the hot water taps. C/H all ok and no issues from cold running taps.

After seeing the pipework near the h/w cylinder my dad says its wrong. I would just like to get other opinions on the best way to resolve this.

The cold storage tank is in the loft. The hot water pipework comes straight out of the top of the cylinder (no horizontal) and then goes into the loft where it then continue for the vent and t's off for the supply to the hot taps which all all ground floor at the back of the house (bathroom downstairs). The cold to the cylinder and the hot out from the cylinder pass eachother in the loft and is only 1" from the bottom of the cold water tank.

I think im sure that this is the problem, but can it be cured by raising the c/w tank by about 2 feet. Will this solve the issue or do we still need to rework the hot pipes.

I dont fancy lifting floors before Christmas but am struggling to get enought water to fill a kitchen sink.

Help is appreciated.

Untitled

• lucynliam
• 15 Dec 2009
• 1

 

[JohnD]

what is the height difference between the bottom of the cold tank, and the hot taps with poor flow?

Run each of these taps into a bucket, timing how long it takes to fill, and tell us how many litres per minute each delivers

Are the taps stylish new Italian ones? It often happens that continental taps designed for high pressure are fitted in the UK, where they deliver poor flow as their internals and connections are very small.

BTW are all the pipes, especially in the loft, encased in stiff plastic insulating foam as thick as your arm? This does not affect the flow, but will help you with heat loss, water temperature, energy saving and freezing.

 

[mikegm]

Lucy, I am no expert, but roughly how old is your property, the way you describe your hot pipework does'nt really sound right. For a start, there should be a horizontal from the top of your Hot water storage vessel of 400mm before it then straightens vertically again to your loft. (Expansion)

 

[powell30]

Well from the diagram the 'head' is in inches so i doubt your flow will be more than very poor.....

The only option is to raise the cws tank in the loft or preferably t into the hot water line on your first floor landing.......

 

[JohnD]

Well from the diagram the 'head' is in inches

no, cold-water tank is in loft and hot taps are on ground floor.

 

[powell30]

Nope......head is from bottom of cws to top of cylinder (assuming this is the highest water point and it isn't in this case)........the 'drop' to taps is immaterial.....pressure is created only on the distance from cws to top of cylinder (or high point)......this pushes the water out the cylinder......that is 'Head' pressure

 

[lucynliam]

Thanks for the replies.

Just to confirm all taps are downstairs.

Cylinder first floor bedroom.

Yes the hot pipe comes straight out vertical and carries on up into loft where it runs along the loft floor (so its pretty much level with the base of the cold storage tank) to the back of the property, drops down to the kitchen and bathroom on the ground floor.

Although there may be maybe 4 feet gap between bottom of cold tank and top of cylinder, the hot pipe goes up and is level with cold tank in loft.

Do we need to raise the tank AND put a horizontal on the outlet hot pipe from cylinder?

Regards

 

[jobloggs]

Where is your bathroom? Groundfloor or first floor? Is the problem at your kitchen sink, bath or washhand basin or all of them.

I would agree with JohnD that the problem is likely to be with your taps being of the high pressure variety. The effective head is the vertical distance from the water level in CWS tank to the taps, not CWS to top of cylinder. I'm assuming that most of the pipework is 22mm not 15mm.

 

[JohnD]

the horizontal from the cylinder does not affect flow, it is to reduce thermal wastage by convection currents within the vertical pipe.

put the thick insulation round that pipe, unless you are replumbing anyway, it will be quicker, cheaper and easier.

the pipe needs insulation even if it has a horizontal section.

the pipes in the cold loft need insulating even more urgently.

 

[lucynliam]

Where is your bathroom? Groundfloor or first floor? Is the problem at your kitchen sink, bath or washhand basin or all of them.


Bathroom on ground floor. Problem in all taps. If i turn on bath tap, then nothing will flow out of any others - even then the bath tap is only flowing slowly and will eventually stop

 

[jobloggs]

Could be air in the pipes. Probably in the hot water pipe running horizontally across the loft. How far is it from where it tees off the vent pipe until it drops down to the the ground floor? Is there any fall from the tee towards the drop down?

You could try connecting the cold mains supply to the hot water system and blowing any air back to the vent pipe. Details of how can be found on this forum
if you search for airlock.

A relatively simple permanent fix might be to cut the horizontalpipe just out from the Tee and cap the spur that's left. Then raise the end of the hoizontal pipe a few inches (to ensure that you have a small fall to the drop down pipe) and tee it back in to the vent pipe above the existing Tee.