Poor water pressure in extension

[tigerjimbo]

Evening. A friend has a two storey house which has the kitchen and living room on the first floor and a bathroom and bedrooms on the ground floor.

He's also had a two storey extension added which now houses a further bedroom with en suite bathroom and a utility room which backs onto it, both on the ground floor with a lounge directly above.

The water/heating consists of a system boiler in the kitchen, cold water tank f and e in the loft and a HW cylinder on the first floor landing.

The problem is that he that the cold water pressure in the extension is awful. So bad in fact that it wont fill the washing machine properly and the machine shows an error message "insufficient pressure"!

The cold water supply to all of the extension is rubbish and yet the hot is fine. Toilet takes forever to fill and is amazingly quiet !!!
There are no problems with the hot or cold in all other (original) parts of the house, including the original downstairs bathroom.

My mate seems to recall that the original plumber (2 years ago when the extension was added) saying that the cold water pressure in the extension would never be as good as the hot water...but he can't remember the reason.

To my mind, the cold water pressure in the extension should be as good, if not better than the other draw off points upstairs, given that, I assume the supply was tee'd off the existing supply pipes and would therefore originate from the cold water tank, and the draw off points in the extension are even further away, gravity wise, from the CW storage tank.

My only thought at the moment is that there is some sort of restriction or partial blockage on the cold feed supply to the extension....and finding that could be a nightmare, given that all the pipes are in the stud walls and under floors etc.

Any help/advice greatly appreciated

 

[BoxBasher]

and the draw off points in the extension are even further away, gravity wise, from the CW storage tank.

You will friction loss along the pipe and across fittings too though.

Am I right in saying that it is definitely gravity fed for both H&C?

 

[tigerjimbo]

Yes, both hot and cold are gravity fed as far as I can tell.

I understand about the friction loss, but surely as the hot and the cold will be running very similar distances with similar bends etc there shouldn't be a reason for the hot to be so much better than the cold, should there?
Although I haven't checked it with a pressure guage, the hot in the extension seems very similar to the hot draw off in the rest of the house. Certainly not hugely different like the cold.

 

[BoxBasher]

What pipe material/size for H&C? Are they the same?

 

[tigerjimbo]

I can only see where the hot and cold pipes materialise out of the wall and yes, all of the pipes are the same, 15 mm copper. The only ones I cant see are the on suite shower pipes as they are buried.

 

[tigerjimbo]

Has anyone else got any thoughts or does anyone agree with my initial idea?

Cheers

 

[gas4you]

Could a couple of ball-o-fix isolators have been used to shut off hot an cold? These only have an internal bore of about 6mm maximum, so could reduce the flow on a gravity supply.

 

[tigerjimbo]

Not that I know of but I'll check. I would assume that if they have been used then they would more than likely have been used on both hot and cold so the "restriction" should be similar, but it's only the cold that's affected.

I even checked the gate valves to see if the spindles had broken in a half closed position, but they were fine and in any case the rest of the house is unaffected.

Thanks for the interest. I'll check for the isolating valves. Any other ideas?

 

[Bahco]

I would look into supplying the cold off the mains instead of supply from tank.

Good idea if there are no mixer taps or gravity shower.

 

[tigerjimbo]

Yes, good idea. It may well come to that! I dont think there will be a simple solution because even replumbing the cold will mean teeing off the cold main...which is on the first floor in the kitchen and then routing it to connect the extension, no doubt through walls and under floors etc.

Hey ho, if that's what it takes. It's just really annoying that there doesn't seem to be an obvious reason for it not to work properly.

Thanks for the suggestion