Browse Forums DIY, Home Maintenance & Repair 1 May 04, 2015 9:57 am New member here, and I have a problem with which I hope somebody can help. I've done a renovation, carpentry, plasterboarding, painting, etc., for a friend, and during the work, she told me of the following problem. When a shower is in operation (or any other tap is on) and a second tap is turned on elsewhere in the house, e.g., toilet flushed, the flow in the shower (or to other tap) drops, resulting in the shower becoming excessively hot....or cold. The problem is with both hot and cold water. Before the current HWS was installed, there was an electric gravity fed unit in the roof space, 1" line out, and the problem was also evident then. The gravity fed unit has been removed from the system. There is a 3/4" main from the meter to the house. Where the main enters the house, a 1/2" line goes to the electric hot water system, and a 1/2" line comes out. For the problem to be affecting both hot and cold water, my analysis is that both hot and cold water pipes must be reduced too early in the network, and that's evident with the hot water line, 1/2" in and out, which then goes to the rest of the house, but the cold water continues under the house as 3/4". I'm unable to determine at what point it is reduced because there is insufficient space to crawl under the house. My view is that for this to happen with both the hot and cold water, both lines are reduced to ½” too soon, and they should continue as 3/4" for as far as possible. Either that, or there is a pinched cold water line causing the reduced flow in the cold water side, and the 1/2" to/from the HWS is the cause of the problem on the hot water side, which would mean that there are two independent problems, and that seems unlikely??? The home was owner built about 30 years ago, but one would assume that the plumbing was done by a licensed plumber, so also assuming that he was competent (??), the lines should be the correct diameter, but when the new HWS system was installed by a licensed plumber about 7 years ago, using only 1/2" to/from it would seem to be an issue to me. I’d be interested in any input. Re: Plumbing problem 2May 04, 2015 10:33 am Yep. 3/4" copper pipe should have been used all through the house as the main feed then into each room only dropping down to 1/2" to each tap/appliance. It may be more of a pressure problem too which can also be a result of the plumber having to install a pressure limiting valve necessary for some fittings. Stewie Re: Plumbing problem 3May 04, 2015 11:56 am Thanks Stewie. I can fix the line in and out of the HWS, but how far downline I can get with that I'm not sure. I hadn't considered the pressure limiting device, but would tapware requiring limited pressure, e.g., ceramic disc taps, have been available 30 years ago? I have one installed at my place, but there is very high pressure here, and I do have much more modern tapware. Re: Plumbing problem 4May 04, 2015 3:32 pm Probably. I find that HWS cylinders, certain dishwashers and washing machines, some shower mixers plus the occasional kitchen mixers are the ones mostly needing a limiting valve. Some of these have been around a long time so... your guess is as good as mine as to which ones would have needed it originally. Your friend may also just have to live with the fact that only one tap can be used at a time if all else fails. We have a similar problem here ( old house + old pipes )with an instant gas HWS and 3/4" pipes into the bathroom and toilet where it drops down to 1/2". We've just accepted the fact that if anyone is in the shower nobody is allowed to use another tap for a short time. No biggie in my book but it would drive some people nuts. Stewie Re: Plumbing problem 5May 05, 2015 9:40 pm There would be a reason for this. When more than one tap or outlet is opened the pressure will be reduced. That's just a given. The question is really how much is acceptable drop in pressure. You say it got worse when the roof mounted unit was removed. I assume it was a mains pressure unit installed? This will be cutting into the water inlet at a different point in the queue and the pressure from the HWS would have changed. Usually the first water points in the length of the main 3/4 pipe aren't as affected as the later points when it comes to pressure drop. This would take a bit more investigating but I'm going to take a guess that when taps closer to the start of the line are turned on, the shower goes cold and the taps to the end of the line are turned on the shower goes hot (or vice versa depending on where the HWS inlet lie in the queue) I don't think upgrading to 3/4 outlet on the HWS would solve it because if the shower goes hot then there seems to be enough hot water arriving. Most HWS's Ive seen on houses are 1/2 inch, and the older ones use to use only 3/8 See if you can find a relationship between where the water steals hot or cold and where the offending taps lie. Re: Plumbing problem 6May 06, 2015 3:59 pm Thanks for your input 33amc. A point of clarification though, the problem was evident before the electric HWS was installed also. I'm not familiar with exactly how it was before, versus how it is now, but I'm assured it was 'exactly the same' by the owner. I'll do a bit more research using your tips, and get back in a few days. In my experience roof is essential element of the building envelope and hence a common property and should be covered by owners corporation however a detailed review of… 3 6140 For anyone that comes across this issue in the future - Just did what aussieta said and found a plumber to inspect it and sign off on it. Was difficult to find someone to… 3 6963 5 3742 |