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Author Topic: Older Plumbing  (Read 5509 times)

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Offline si-dog

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Older Plumbing
« on: July 03, 2009, 01:22:29 PM »
Hi there. We have purchased an older house, built in 1940ish. At some stage, previous owners have redone the plumbing, no consent has been obtained for this. Black or gray 15 - 20mm plastic piping has been used, and it appears a plumber has done the work, as joints have been made with crimped copper clips (i could be wrong here of course).

So i have several issues, including whether the re-done plumbing meets the standards, and if it can be granted consent. BTW, we have also just had the HWC replaced by an equivalent low-pressure cylinder by a plumber.

One major issue is that the water pipe from the street has also been replaced at some stage, with black plastic tubing, 15mm. It comes into the house at the front, and makes it way to the back. Our house has a header tank in the ceiling. The shower pressure is also arse (I am about to check if the correct grade mixer/showerhead have been installed, cos in my opinion, these should be low pressure accessories).

The first of my questions is: the water main pipe from the street connects to the amenities on its' way to the header tank, in the ceiling right at the back of the house, ie connections are made to: the shower, bath, handbasin, toilet, laundry, kitchen - in that order, from front to back of the house.

The output feed out from the header tank only seems to be going to the input of the HWC, it is not connected to any other cold-water amenities. Weird - shouldnt the pipe from the street go straight to the header tank, THEN back to all the amenities? This seems backwards to me and could partially explain our arse water pressure (which is worst at the shower).

Your views and/or advice would be appreciated. This site looks like a great resource.

Linkback: https://www.plumbers.nz/ask-plumbers-public/2/older-plumbing/265/

Offline Grenville Ngatai

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Re: Older Plumbing
« Reply #1 on: July 05, 2009, 11:07:27 PM »
Hi si-dog all your cold feeds off the main 15mm pipe to you amenities are on town supply which could be anywhere from 300KPA - 1000KPA depending on the available pressure and the area you live in. The main 15mm pipe into the header tank after this is alright but not good. You do not mention any valves, if there was a limiting valve on the main 15mm supply pipe before entry to the house, say 350KPA- 500KPA will give good cold pressure, but the main coming out from the header tank and into the HWC could be 20KPA-30KPA depending on the height of the tank from the HWC. what you have now is unequal pressure. To get equal pressure you may need to lift the tank up to about 30- 50 meters, which could be difficult. The cold pressure is forcing the hot water out your vent pipe, if it is open vented, thru the tap fixtures, or you may have main pressure tapware, giving poor performance.
One option is to isolate the header tank all together, and have the main 15mm pipe supply go straight into the HWC, via a valve train, e.g isolation valve, non-return, filter, pressure reducing valve, isolation valve then into HWC, this will give you equal pressure and excellent pressure if the tapware is appropriate. Depending on the pressure reducing valve rating,  3.6-7.2KPA , a 350KPA-500KPA limiting valve on the main 15mm supply going into the house before the first branch off will remendy your problem.
The black pipe with copper fittings sounds like Quest pipe, which is about that time used in the 40,s. The grey pipe could be Dux or Polybute,which is commonly used today. Both pipes comply with industry standards.
The second option is to replace the low pressure cylinder with a mains pressure cylinder and also isolate the header tank.
I hope this helps.
 Grenville
Grenville Laurie Ngatai

Offline si-dog

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Re: Older Plumbing
« Reply #2 on: July 08, 2009, 08:39:18 AM »
Cheers for your reply Grenville. The main thing i take from that is that the current water hook-up in our house is OK, and that the pressure from the street is higher than i would have thought....

cheers


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