Pressure relief valve

[Buckman]

Are there really any people who believe such a claim that flooding a caravan for several hours" cause minimal damage"?
It was in the forenoon of a first of April surely to be spun that one.

Our caravan was flooded after a pipe burst in it. It was flooded for about 3 hours, but it happened in the summer. We tilted the caravan to allow the water to run out of any vent holes. We then mopped up the balance and removed all the wet carpets.

About a month later a damp test was done on the caravan by an AWS professional and all readings were as normal. The caravan was not submerged in water, but had some water internally for about 3 - 4 hours.

 

[JTQ]

Technically there is no reason why functionally you need a caravan market pressure relief valve, in that any water relief valve would achieve what is needed, a means to vent excessive pressure.

A bit of a challenge seems to be in finding low enough pressure reliefs in the readily available domestic plumping market, but 2 bar pressure, 1/2" size units do exist at modest pricing. RWC in their 100 range have one LINK.

If I was tasked with supplying such a direct water feed, I would source both the reducer and its companion relief from the domestic market and definitely locate both outside the van in the immediate supply hose. I personally have way more faith in products source from reliable makers in that market than the leisure industries offerings.

 

[JTQ]

About a month later a damp test was done on the caravan by an AWS professional and all readings were as normal. The caravan was not submerged in water, but had some water internally for about 3 - 4 hours.

In respect to that, you clearly have more confidence in what someone finds with just a damp meter, than I have in what the whole raft of implications of flooding a caravan could have had. At best a damp meter only finds the present moment's water content, and that in what it looks at, not elsewhere nor importantly any other sort of incipient issue caused by water where it should not have been.

 

[Dustydog]

I understand all the PRV comments but surely it won’t stop water flowing into the caravan if the internal plumbing fails?
Why not use a domestic style automatic shut off valve which detects irregular /excessive / pre set flow times ?

 

[Buckman]

I understand all the PRV comments but surely it won’t stop water flowing into the caravan if the internal plumbing fails?
Why not use a domestic style automatic shut off valve which detects irregular /excessive / pre set flow times ?

It seems that some cannot grasp this little snippet of information as that is more likely to happen than any pressure reducer failing or the float in the aquaroll going faulty.

No matter what you are using and how it is being used to get water into the caravan, if an internal pipe comes adrift you are up the creek without a paddle or a lifebuoy. 🤣

 

[JTQ]

No matter what you are using and how it is being used to get water into the caravan, if an internal pipe comes adrift you are up the creek without a paddle or a lifebuoy.

Not necessarily so; if you had a system refreshing the water container, eg an Aquaroll, used in conjunction with a van using a faucet switched water control system, as many do, then with a pipe coming off, water will only be pumped into the van whilst a demand is being made.

You are hardly up the creek without a paddle, for most needs you can decant any needed water.

Where it has the potential to go wrong, big time, are cases where people have vans they connect to sustained pressurised water feeds, be that directly or in cases with pressure switched systems, indirectly.

 

[Ukdave2002]

I was the OP mentioned in #6 where this topic was discussed, somewhere in that thread I suggested a suitable Pressure Relief Valve, that could be easily installed in a caravan .

When we went to France a couple of weeks ago on a fully serviced pitch we used the aqua roll float valve system, one thing that stuck me, given the quite high temperatures how warm the aqua roll got, even in the shade, ideal breeding conditions for any bacteria! Whilst I had cleaned the aqua roll prior to our trip, I made sure that if anyone wanted to drink some Corporation Pop, they got it directly from the site tap.

Certainly one advantage of the direct feed would be a fresher water supply in the van

 

[otherclive]

I was the OP mentioned in #6 where this topic was discussed, somewhere in that thread I suggested a suitable Pressure Relief Valve, that could be easily installed in a caravan .

When we went to France a couple of weeks ago on a fully serviced pitch we used the aqua roll float valve system, one thing that stuck me, given the quite high temperatures how warm the aqua roll got, even in the shade, ideal breeding conditions for any bacteria! Whilst I had cleaned the aqua roll prior to our trip, I made sure that if anyone wanted to drink some Corporation Pop, they got it directly from the site tap.

Certainly one advantage of the direct feed would be a fresher water supply in the van

Good point, and in all our visits to France we never had any problems using water from the aquaroll, but like you if it was very hot we generally fetched water for drinking from the taps on site using a 10 litre container that stayed in the van.

 

[Dustydog]

Only 3% of French mains water has natural fluoride salts. The remainder throughout France is fluoride free. So good point on bacteria. However in normal use I doubt there would be sufficient time for bacterial growth?

 

[Buckman]

Not necessarily so; if you had a system refreshing the water container, eg an Aquaroll, used in conjunction with a van using a faucet switched water control system, as many do, then with a pipe coming off, water will only be pumped into the van whilst a demand is being made.

When a pipe comes off surely there is a demand as the pump tries to maintain the pressure?

 

[Ukdave2002]

When a pipe comes off surely there is a demand as the pump tries to maintain the pressure?

Agreed, if the pipe that fails is "north" of the pump its no different to opening a tap.

 

[JTQ]

You both missed reading or otherwise the pertinent technical bit, "used in conjunction with a van using a faucet switched water control system".
With a pipe coming off or any other leakage, that does not initiate the pump of that system to start; the faucet micro switches do that and leakage does not switch them. A design shortcoming of the alternative pressure switch based systems, by design they feed leaks.

 

[ProfJohnL]

I understand all the PRV comments but surely it won’t stop water flowing into the caravan if the internal plumbing fails?
Why not use a domestic style automatic shut off valve which detects irregular /excessive / pre set flow times ?

You are suggesting two approaches One is an excess pressure detection, and the second is to have preset time windows for operation.

In respect of excess pressure dump valves, I have not researched domestic fittings but my central heating does have one on the pressure tank, but I suspect that finding an pressure sensitive detection valve that will reliably operate at the comparatively low pressures (absolute max 2.5Bar ) is going to be difficult. JTQ seems to imply he has not found one. But it could work.

The other option you suggest only limits access to the water supply, it would not prevent an over pressure situation from possibly damage the caravan pipe work or fittings.

 

[ProfJohnL]

No matter what you are using and how it is being used to get water into the caravan, if an internal pipe comes adrift you are up the creek without a paddle or a lifebuoy. 🤣

Caravan water systems are designed to operate with pressures under 2.5Bar.
I totally agree that if you have a weak pipe coupling that leaks with normal caravan pressures then you have a problem, but that is not circumstances being discussed.

The concern I pointed out is if the water pressure delivered to a caravan exceeds 2.5Bar, then it is more than likely to cause fittings or appliances to fail. When a direct mains water system is used, the only thing between the mains pressure and the caravan plumbing is the Pressure Regulator built into the hose pipe, and if it should fail to do its job ( and a few have), then it is certain to apply mains water pressure to the caravan.

In the UK water mains pressure can easily reach and exceed a static pressure of 6Bar, that's over 2 times more than the caravans plumbing is designed to manage, but you also have to take into account the surge and inertial pulses that arise when water flows are turned off which can rise to much greater pressures.

If you use a direct mains system, that is an ever likely potential risk. I am not saying every pressure regulator will fail, far from it, but if they do the consequences are almost certain to damage the caravans plumbing system.

Whilst a Pressure regulator failure is rare, the consequences are usually severe, so to mitigate the risk (at little or no extra cost) them it is a perfectly reasonable to use the indirect mains approach.

 

[Buckman]

Hi All,

I'm planning to use mains water quite often and I am a bit concerned about pressure reducer failing so I'm thinking about installing a pressure relief valve which would automatically drain if the water pressure exceeds the acceptable level for caravans.

Does such thing exist for caravans, if yes - which one would you recommend?

Thanks!

As a matter of interest here is the original question in case anyone missed it!

 

[JTQ]

As a matter of interest here is the original question in case anyone missed it!

And your point is what?

I read it that the OP realised the potential risk that using mains pressure reducer feeds present and opened discussion on reliefs to mitigate these, IMO very wisely and exhibiting a sound understanding of the risks.
Thus, the ensuing conversations.

 

[Buckman]

And your point is what?

I read it that the OP realised the potential risk that using mains pressure reducer feeds present and open discussion on reliefs, IMO very wisely and exhibiting a sound understanding of the risks.
Thus, the ensuing conversations.

I think that question was answered many posts back so not sure about all the the indepth posts etc

 

[Ukdave2002]

A simple and cheap solution to protect against the fail of a pressure reducing valve or a sticking float valve would be to add a pressure release valve in the exterior pipework, down stream from the PRV/ Float valve.
Edit, It could also be fitted inside the caravan with an external drain.

Pressure Relief Valve 1-3bar 1/2" x 1/2" - Screwfix

Order online at Screwfix.com. To avoid over-pressure. Can be used on combi boilers, unvented systems and sealed systems. FREE next day delivery available, free collection in 1 minute.

www.screwfix.com

From the previous thread

 

[JTQ]

I think that question was answered many posts back so not sure about all the the indepth posts etc

Not that I see a problem with that; very often more informed understandings come from deeper debate of issues, and of course those not interested can simply not read further, nor is there pressure nor need for the uninterested to get further involved.

We should not lose sight this is a "forum".
forum
/ˈfɔːrəm/
noun
1.
a meeting or medium where ideas and views on a particular issue can be exchanged.
"we hope these pages act as a forum for debate"

 

[Dustydog]

You are suggesting two approaches One is an excess pressure detection, and the second is to have preset time windows for operation.

In respect of excess pressure dump valves, I have not researched domestic fittings but my central heating does have one on the pressure tank, but I suspect that finding an pressure sensitive detection valve that will reliably operate at the comparatively low pressures (absolute max 2.5Bar ) is going to be difficult. JTQ seems to imply he has not found one. But it could work.

The other option you suggest only limits access to the water supply, it would not prevent an over pressure situation from possibly damage the caravan pipe work or fittings.

Nearly Prof.
I had more in mind the type of units which actually cut off the water flow when , the water continues to flow for longer than a preset continuous time, pre set pressure fluctuations arise..
It may help if we all understand what a pressure reducer unit is . My direct mains water feed pipe contains one .It is a simple archimedes screw thread which slows the water rate by reducing the volumetric space thus reducing the pressure. How that simple piece of kit could fail in service is beyond me.
PRVs.
I have 3,
Pump, Water heater and toilet waste container.

How does a PRV stop the water flow and avoid water damage.
This does https://www.checkatrade.com/blog/expert-advice/automatic-water-shut-off-valve-uk/

 

[JTQ]

Pressure reducers that modulate the flow will not necessarily "regulate" the pressure where there is no flow to "strangle".

The "Achillies heel" is this very point where there is no flow, the minutest leak across any restriction in the water feed will ultimately lead to the pressure downstream equalling the pressure before that restriction.
With minute leaks commonly encountered by debris, hair etc across even a pressure regulators seal, will take time for the downstream pressure to build up. Though the water itself can be considered incompressible, the plastic tubing we typically find in our systems does have a bit of compliance, "give", but ultimately the downstream pressure creeps up to the supply pressure.

This is well known and understood by those like myself who have practiced in these systems for capital high value kit, and there we compliment even the best of regulators with reliefs.
Elsewhere, where there is ignorance [in the true sense] or where the products being fed fluids are of more trivial value to those specifying the kit, it can go spectacularly wrong if such provision is overlooked.
The budget end products we see in this industry, operate way from best practice; that cost money even if only a few pounds.

You pays you money you take the gamble; as is so often pointed out we make our own choices. Here this bit of plastic we couple up with a hose, on multiple occasions, store where a spider might fancy using it as a home etc, so very prone to pick up spots of debris, could be considered at risk. However, one where the consequences could be huge, unless we buy tipping the van up to drain the water out some hours later, then means water flooding a caravan presents minimum consequences. As said each one their personal choices, use best practice or gamble on something falling short of it.

 

[Mr Plodd]

By the way I have been reliably informed that if for some reason a caravan did flood, if you tilt the caravan, a lot of the water would run out of the vents. The remaining water can then be soaked up with mop or rags and the caravan ventilated. Even if a caravan was flooded for several hours, damage should be minimal and a damp reading done a few days later may not show any trace of the flooding.

And what about the water that finds (found?) Its way between the vinyl floor covering and the caravan floor??

Having had an internal leak (whilst away in the caravan) a substantial amount of water did exactly that and I had to remove the vinyl flooring to mop up what was there (it was rather a lot) AND dry the floor out which took several weeks. So how did you dry your floor without removing the vinyl covering??

 

[Buckman]

And what about the water that finds (found?) Its way between the vinyl floor covering and the caravan floor??

Having had an internal leak (whilst away in the caravan) a substantial amount of water did exactly that and I had to remove the vinyl flooring to mop up what was there (it was rather a lot) AND dry the floor out which took several weeks. So how did you dry your floor without removing the vinyl covering??

A lot of the water was soaked up by the carpets. As said it was only a couple of hours and not days, weeks or months and it happened in the summer.

When the caravan was traded in several months later the dealer did another damp check and no damp. Who am I to argue with a dealer that is using a professional meter. As said I am only talking from experience, but I guess experience and facts do not count any more?

 

[JTQ]

As said I am only talking from experience, but I guess experience and facts do not count any more?

Not very convincingly, based here on only those ramifications that arose within a few months later.

 

[Shaino]

by the way are the pressure reducers sort of an intelligent devices or are they just built assuming they need to reduce the pressure from 6 to 2 regardless of the actual ingress pressure? If it's the latter I assume the egress pressure will be lower than 2 if the ingress is less than 6 (and vice versa)?