shower flow problem


Postby tools1234 » Sun Mar 08, 2009 1:42 pm

Hi what is ment by neg or pos pump? I also am not sure what you mean by saying ten will give me five that the take off is from the vent pipe. What and where would the gravity loop be. The drawing down of hot water is a strong pos. thanks.
tools1234
Rank: Apprentice
Progress to next rank:
10.5%
Posts: 7
Joined: Sat Mar 07, 2009 3:42 pm

Sponsor

Simply Build It

Postby plumbbob » Sun Mar 08, 2009 9:51 pm

Not quite sure what all your questions mean, but a negative head is where the shower head is close to or above the water level in the header tank.

Normal pumps which require a positive head need a small natural flow of water to trigger the flow switch and start the pump. Negative head pumps get round this by pressurising the feed and the pump is activated by the fall in pressure when the shower is switched on.

See this post.

http://www.diydoctor.org.uk/forums/view ... hp?p=50186

What do you mean 10 will give 5?? Gravity loop???
plumbbob
Rank: Project Manager
Posts: 1873
Joined: Wed May 07, 2008 9:59 pm

Postby Dave From Leeds » Mon Mar 09, 2009 12:33 pm

Hi plumbbob,

I think tools1234's post here is referring to answers he got to his other thread entitled "shower flow to ensuit". In particular to a reply from rosebery which I am reproducing here.

"Negative head pump or positive?

If it's positive which I suspect ten will get you five that the take off for the shower is off the vent pipe of your cylinder and theres no gravity loop fitted.

I'll hazard another guess that the hot supply to the bathroom is teed of the same pipe that feeds the pump.

Air is being drawn into the pipework through the vent which is preventing flow to the pump. Flow switches on pump detect no flow so pump doesn't run.

Opening the hot tap is enough to draw water through which reaches the pump and then it runs.

In other words it sounds as though it's piped incorrectly.


I think the translation of this bit

"If it's positive which I suspect ten will get you five that the take off for the shower is off the vent pipe of your cylinder and theres no gravity loop fitted."

is "....which I suspect then will bet you five quid that........".


Guess that's what the reference to ten will get you five is. I also suspect that tools1234 didn't mean to start a new thread here, but to add this to his original one.
Dave From Leeds
Rank: Ganger
Progress to next rank:
86%
Posts: 179
Joined: Mon Nov 19, 2007 9:02 pm

Display posts from previous
Sort by
Order by



  • DIY How to Project Guides

  • DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!



 


  • Related Topics