The shower mixer is either very hot or very cold. It's hard to find a stable in-between temperature.
In addition, when the showerhead is held low, the temperature gets really hot.
Are these obvious symptoms of a specific cause?
tygertung,
Mar 11, 2:46am
Yes, you have a large difference in pressure between your hot water and cold water supply.
You could get a plumber to fit a pressure regulating valve on the inlet to your house.
The neighbor below us has one. The filter on it got blocked up with debris when we had a broken pipe, but I was able to clean it out no worries.
trade4us2,
Mar 11, 3:50am
You could put a washer with a tiny hole into the cold feed. Because my cold pressure is incredibly high, I have put a pressure reducing valve into the main pipe for my house.
machinehead,
Mar 11, 4:14am
Unfortunate - I had a new PRV installed less than a year ago.
I'm not sure that the problem has been there since the install, but from what I can gather, it's a more recent problem.
I don't actually live there, I'm just trying to help a friend out.
gabbysnana,
Mar 11, 4:53am
your hot water cylinder is a low pressure and not mains. Need to upgrade to mains.
tweake,
Mar 11, 5:17am
the first thing is check the adjustment of the mixer. then i would get plumber and test water pressures. see what pressures your hot and cold actually are.
i'm wondering if they fitted a pressure regulator on the cold side and wound the pressure way down low to match the hot, plus probably didn't adjust the mixer. so when you reduce the shower height, which will give more flow, your getting more hot water flow than cold water flow.
tegretol,
Mar 11, 10:54am
Stick a $100 pump in the hot line as you obviously have a low pressure system with a header tank. Doesn't take much more hot flow (not pressure) to balance things up and produce a dramatic improvement. Been there done that more than a few times.
elect70,
Mar 11, 11:33am
^^ agree im on ntank water & hot pressure iwas low 100% improvement with pump
tygertung,
Mar 12, 4:23am
Mains hot water is a scam as you end up using way more hot water. The solution is to reduce the cold water pressure.
tweake,
Mar 12, 5:14am
that makes for a pretty lousy shower. if you have mains pressure hot water, you need to use a mains pressure shower head. that will reduce the water usage but give you a nice strong shower.
tonijo,
Mar 12, 5:38am
Something to be aware of with a pump is if you have an open vent, it may not work as you need it to. We installed a Grundfos pump on the hot water as part of bathroom renovations - which is apparently "designed for a system such as ours". Unfortunately the pump draws the water through and the level drops so we get a lot of air & bubbles through to the shower. Make sure you talk to a plumber who has done these pumps before if you decide to look at them.
tegretol,
Mar 12, 7:12am
If you have a header tank and were able to suck air out of it then there are two possibilities: 1. The tank is too small and your pump is so big as to be able to empty it, or 2. The supply/ballock into the header is not providing sufficient water to keep the tank topped up.
That said, hot water pumps are designed to increase flow and are normally switched by a series flow switch. They are low pressure/high flow devices and I wonder if the pump you have is a high pressure model which is cavitating and creating air bubbles on it's own? Don't suppose you could get the model number out of interest?
tweake,
Mar 12, 7:26am
+1 mine had the same issue. ended up fitting a relief valve on the vent. that also meant we could crank up the pressure a tad. but i still had issues. basically caused by the really high cold water pressure. fitted a pressure reg on the house supply and its a lot better. that also helps with the washing machine filling. using the taps you can't tell the pressure has been lowered.
tygertung,
Mar 12, 12:26pm
Only makes for a lousy shower if you have a lousy shower head. A good one will give an excellent shower without wasting loads of money on hot water.
trade4us2,
Mar 13, 1:45am
You need to be careful to not exceed the allowable pressure for the cylinder. Usually that is 7.6 metres of water from the BOTTOM of the cylinder.
tegretol,
Mar 13, 7:15am
Not legal to fit a PRV on an open vent. Read the Plumbing Regs.
tweake,
Mar 13, 7:58am
i didn't do it, the plumber did it.
tegretol,
Mar 13, 9:54am
Report him, he should be struck off and de-registered as that sort of action will kill someone.
trade4us2,
Mar 13, 10:27pm
What do the plumbing regs say? A plumber has done that for an elderly friend when his HW cylinder started leaking. It didn't seem right to me.
I have a pdf of the Plumbers,Gasfitters,andDrainla- yersRegulations2010 which is completely useless.
tygertung,
Mar 15, 8:25am
People have been doing fine with low pressure hot water systems for hundreds of years. Not sure why it isn't possible to have a shower without now?
tegretol,
Mar 15, 8:32am
Coz there seems to be some sort of thought that hi-pressure on both sides is the only say to go. 99% of the plumbing industry will convince innocent householders to convert for the sake of it. I have two dwellings both with low-p and both have water-blaster quality showers, both with $100 pumps on the hw side.
tweake,
Mar 15, 8:32am
they will need a weegee board if they want to talk to him.
tweake,
Mar 15, 8:38am
the thing for me was the difference in water pressure. which is why we fitted regulator to the cold supply to drop the pressure as well as the pump on the hot side. so its gone from touchy as hell adjustment to useable. the other i suspect is shower heads. this one is 2-3x the size of the one in the last house.
trade4us2,
Mar 15, 9:05am
Many years ago, shower mixers were either "equal pressure" or "unequal pressure". Unfortunately they were not marked to indicate that. I have a number of second hand mixers which are probably the wrong type. But I can make them work OK by adjusting the screws in the mixer. As long as the top of the hot water cylinder is not much lower than the shower head, you should never need a high pressure system or a pump.
I am still waiting for a sentence from the plumbing regs. "Not legal to fit a PRV on an open vent. Read the Plumbing Regs."
pauldw,
Aug 11, 5:12pm
It's in the Building Regs. You can't valve vent wetback systems. Valve vented systems are common.
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