Water Pressure

Gus1949 · Senior Member

Water Pressure

Roving-Dutchy · Guru

The water heater will be rated to a maximum recommended pressure and some parks have a low pressure and some a very high pressure, so the water pressure limiting valve ensures that the pressure in the piping and appliances is below the maximum rating.
The flow of water is governed by the size of your piping and if there are any restrictions such as kinks etc that will also reduce the flow.
Cheers
David

Baz421 · Guru

Gus

If you have one of these they have a pressure regulator/reducer built in, see link

http://caravansplus.com.au/catalog/product_info.php?products_id=5608

Flow and pressure are 2 different things.

You can have high flow and low pressure OR

You have high pressure and low flow.

Things that effect the 2 are hose pump output, diameter and length of pipes/hoses and any restriction/reduction devices built into the system.

My 12V Shurflo pump put a higher pressure into the lines BUT I have a lesser flow than when connected to mains.

I hope this makes sense.

Cheers Baz

KevinC · Senior Member

Our 2013 Sterling suffered this problem. The cause was the pressure limiting valve, a brass bodied device fitted to the inlet pipe under the van. It's a tubular object about 150mm long. It wasn't blocked with debris, so it couldn't be cleaned. It was one of a faulty batch. The local dealership replaced it for us, and I think they used an aftermarket one. Anyway, solved the problem.
Don't be tempted to remove it, or drill through it. The whole system is designed to run at limited pressure and without this device you'll probably find your tanks overflowing when you're connected to town water.

Baz421 · Guru

KevinC wrote:

Don't be tempted to remove it, or drill through it. The whole system is designed to run at limited pressure and without this device you'll probably find your tanks overflowing when you're connected to town water.

I don't understand how the water from a mains supply to the van will overflow water tanks. They are separate systems with separate fillers are they not????

graeme c · Senior Member

Had a problem with my mains supply overfilling tanks during my trip around the block, lived using the tanks, as it was under warranty when I got back had the van serviced and they replaced a faulty pump, when I reverted to mains pressure I was only a dribble, replaced pressure limiting valve and now all is good

Delta18 · Guru

As Kevin said there will be a tubular brass fitting where the mains hose connects to the van. Remove this and with a couple crescents take it apart. There is a spring inside but it is not under pressure, don't be scared of doing this.

Ideally use a pressure hose to blow any crud out but just mouth pressure will help.

Reassemble and enjoy a good shower again.

Cheers Neil

Stl · Senior Member

Hi, first up I would check to make sure your in line filter or strainer is clean If you have one. Mine is straight behind where the hose connects onto the van. If you don't be extra careful rolling your hose up may end up with bits of sand etc which will limit flow. Don't get confused with the hot water Temperature regulating valve.

And I'm another one that doesn't understand how your tanks overflow when connected to mains re pressure limiting valve? There should be 1 way valves to do this not pressure limiting valves or pumps?

For the record I have a 2011 van , no pressure limiting valve, an inline strainer with no spring which I have had to clean. I have also had to adjust my hot water valve as I would only get warm water out of the hot tap no loss of pressure though.

Hopefully it's just a blocked strainer, that's an easy fix. 5 mins max.

Cheers. Len

KevinC · Senior Member

Tanks can and do overflow. (If your van has separate taps for tank or mains, then read no further ... this doesn't apply to your van. But if you have sink, shower, basin taps that deliver water from both tanks or mains, then this could be your next van problem).
The two apparently separate systems come together at the pump. On the delivery side of the pump, the pipes are pressurized either by the pump or mains pressure. The pump has a non return valve, otherwise the pressure from the mains would force water back through the pump and into ... the tank. Simple. If you suffer the indignity of your tanks overflowing onto the ground through the breather when you're in a caravan park, as indeed I have, then you can replace the pump, (or claim it under warranty if you're lucky), or cut into the hose that delivers water from the tank to the pump and fit an external one way valve there. But make sure if this becomes a DIY project, that you put the valve on the inlet side of the pump.

Baz421 · Guru

KevinC wrote:

The two apparently separate systems come together at the pump. On the delivery side of the pump, the pipes are pressurized either by the pump or mains pressure. The pump has a non return valve, otherwise the pressure from the mains would force water back through the pump and into ... the tank. Simple. If you suffer the indignity of your tanks overflowing onto the ground through the breather when you're in a caravan park, as indeed I have, then you can replace the pump, (or claim it under warranty if you're lucky), or cut into the hose that delivers water from the tank to the pump and fit an external one way valve there. But make sure if this becomes a DIY project, that you put the valve on the inlet side of the pump.

Now I agree with this statement Kev, as this is how our van is set up. Yes if non return valve fails, but you were referring to something else before hence may query how your post related to the OP.

Cheers Baz

EDIT

PS I must have ben having a blonde moment when I wrote my other post Kev

-- Edited by Baz421 on Thursday 12th of November 2015 09:43:11 PM

KevinC · Senior Member

Sorry Baz, what I was trying to say was the pressure regulating devices can be faulty and reduce town water pressure even when they're clean. The reason the device is there in the first place is because excess pressure in the system can overcome the non return valve in the pump. And just to make things worse, the non return valve in the pump can fail even without excess pressure. So even if your pressure regulating device is good, the associated pump problem can still occur. I've been seeing this as one problem because the two issues are so closely related, and I've had both.
Maybe I've made this more confusing.
I'm hoping the OP gets back to us with some feedback.

PeterD · Guru

KevinC wrote:
If you suffer the indignity of your tanks overflowing onto the ground through the breather when you're in a caravan park, as indeed I have, then you can replace the pump, (or claim it under warranty if you're lucky), or cut into the hose that delivers water from the tank to the pump and fit an external one way valve there. But make sure if this becomes a DIY project, that you put the valve on the inlet side of the pump.

The non return valve should be on the discharge side of the pump.The diagram of how water systems below was taken from this link.

KevinC · Senior Member

Yes Peter, I've also heard that, but I've chosen the delivery side. The reason is that if the valve is on the inlet side, the pump will never want to turn on because the switch will always detect pressure. If the valve is on the discharge side, as some suggest, then the pump must be turned off so it won't periodically turn on to maintain pressure, and pumps aren't perfect so this could happen. And it will probably happen just after midnight.
I think it's a minor point, and it's certainly not something I would get undone about. I can't in all honesty recommend something I haven't tried myself and my installation is working well (so far at least.)

Greg9 · Veteran Member

I have done the spring stretch and it works well.

Have a look at the post on my blog.

http://wanderingoap.blogspot.com.au/2016/02/water-pressure.html