Lost pressure control switch

Been searching for the pressure control switch in my 2019 Nuevo ES as I need to adjust it. Looked everywhere for it but couldn't find it & eventually phoned AS service dept. at first they didn't know where it was but eventually told me it's in the electrical box under the seat. There is no way I can get to it without stripping out the seat. Has anyone else encountered this problem & how did you resolve it. My only hope is that I can remove the panel at the rear of the seat & access it from there.

If you have a vent grill on the electrics box, if you remove it by the 4 screws you should be able to see it and adjust it.[You must be registered and logged in to see this link.]

Thanks Casion, I do indeed have a vent like that, it's very close to the battery & it would be difficult to get 3 of the screws out & perhaps impossible to get the 4th out if fitted. Presumably you have had similar problems to me.

Been thinking that it may be an idea to fit another vent on the front of the box. This will give better & easier access if I need to adjust when in the middle of nowhere.

The AS Service Centre moved mine outside of the vent and electrics box to make it accessible.

Thanks Caraman, I wrote the the service centre last night & will await their reply but I would like mine moved. Did you pay for it to be moved ?
I will be annoyed if I have to pay to correct their design fault.

Flash.  I took it in last week for some warranty work which among other things required a new pressure switch.  When they fitted the new switch they moved it to its new location.  They quite rightly said that the pressure switch has to be accessible and where it was fitted was not accessible.  They said they had discussed it with Auto-Sleepers’ R&D which is across the road from the service centre.  There was no charge.

With the risk of appearing a total ignoramus, what ,in layman's terms, does this pressure switch adjust? What "pressure" are we talking about?

jetty wrote:With the risk of appearing a total ignoramus, what ,in layman's terms, does this pressure switch adjust? What "pressure" are we talking about?

The Whale in line pressure switch is adjustable, the adjustment sets the pressure at which the pump turns on and off. Set too high, fully clockwise, the pump runs all the time, adjustment too far anticlockwise will introduce clicking on and off when you close the taps. The setting is very variable depending on the Battery Voltage, level of water in the tank, cooling of the hot water overnight and even atmospheric pressure I think although that needs more proof.

You may like to view this video [You must be registered and logged in to see this link.] but beware you won't see an LED, they forget to tell you that does not exist other than on their demo version.

It is difficult access (through the brown vent) in the End Kitchen version too, a real pain.

Caraman has an EK version like mine, here is a picture of the modified installation (with permission from of Caraman).

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Thanks Marconi.  The in-line pressure sensitive switch is also a non return valve (NRV) for the whole water system which should stop pressurised water from flowing back through the submersible pump into the fresh water tank.  I believe it should also stop non-pressurised water from doing the same i.e. under thecweight of gravity if the pump is switched off and there is a leak in the system or a tap is left open.  In my case the NRV holds the water under pressure but not when the pressure is released.  The NRV can become contaminated with debris and cause water to flow back through it in which case the pump will come on intermittently to restore the water pressure without a tap being opened.  The NRV can be dismantled for cleaning which is another reason for the switch to be accessible.

I would love to get my nose inside that R&D department does it stand for Ruin and Destroy.

Seeing the photo from Caraman made me think, I didn't really recognise things. Likewise that from Caslon, I don't know what year that Nuevo is, what I do know is, the pressure switch is in a very different location to mine, I had to dig mine out from among some very heavy bulky wiring looms which I thought at first could well be moving the adjuster on the Pressure Switch (PSw), which in mine is well over on the left behind my Magic Box which saves me lots of twiddling of the PSw adjuster. The Magic Box is an on test item at present so the mounting is very temporary, but it is secure.

What I also notice is the difference in several places of layout and even the wiring colour scheme of the external pump. There seems to be no consistency in the design, a case of "stuff that in there will you Fred" and "find some wire and wire up one of those Jim" our vans are only a couple of months apart in production. No wonder Flash says "I eventually phoned AS service dept. at first they didn't know where it was but eventually told me it's in the electrical box under the seat".

When I was 15 years old straight from school in my first job I changed the whole Electrical department methods of working, introducing standardisation which saved hours of production time and some big flashes, sparks and bangs from some of the old boys duff workmanship. AS could do with some similar standardisation.

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Caraman wrote:In my case the NRV holds the water under pressure but not when the pressure is released.

Hi Caraman

Looking once again at your photo. Since modification by AS Service Center and in view of your continuing problem, I can't be sure, but do you now have 3 maybe even 4 NRV's in series on the feed side of your set up from the pump an no NRV on the Cold Feed to the Hot water system. The NRV's not counting the Pressure Switch one, are white and have an arrow indicating direction of flow, there 3 suspect white dollops on the pressure switch side and nothing after the drop valve.

Marconi,

Yes on my photo you can see three white dollops (excluding the pressure switch).  The white dollop to the right of the Truma drop valve (inlet side) is a NRV.  This is the NRV recommended in the Truma Combi-E installation instruction to separate the hot water from the cold water which you have and Marquis moved not knowing what it was for.  A new NRV was fitted back in its place by Willersey last week. The white dollop to the right of the pressure switch (inlet side) is where Marquis moved the NRV to, not knowing that the pressure switch had a NRV let alone one that was spring assisted and could be cleaned.   Willersey decided to leave it where it was as it was doing no harm.  Excluding the pressure sensitive switch NRV, this gives me two NRVs where you only have one.  The white dollop to the left of the pressure switch (outlet side) is not a NRV.  It is a ‘T’ piece allowing the cold water to go directly to the three mixer taps and the toilet flush.

Peter Brown - thanks.  If it becomes a problem I’ll take it out.

Caraman wrote:Marconi,

The white dollop to the left of the pressure switch (outlet side) is not a NRV.  It is a ‘T’ piece...…..

Ah that is what was worrying me, I can see now that it is a 'T' piece, I was going to add, have they split the hot and cold after the drop valve under the electrics where we can't see it, you have explained that. Which leaves us with the Hot system NRV on the 'wrong' side of the drop valve, Marquis will have moved it from the same place as mine I would have thought, unless its AS non standardisation.

Now then will it make a difference, err the cold system won't drain down will it, who decided to put it there the Ruin and Destroy dept. wait a minute though yes it will in fact it makes more sense than where mine is really although when there is no pressure on either side that type fall open I think.

Marconi,

I think yours and mine are the same it’s just that the water is flowing in opposite directions.  On mine it flows from the the cold water junction (‘T’piece) through the NRV past the Truma drop valve into the Combi and then to the three hot water mixer taps.  The NRV is where it should be according to the Combi installation instruction.  If the NRV was the other wrong side of the Truma drop valve, opening the valve would only allow the cold water to drain.  The hot water would be trapped in the system as the NRV would not allow it to reach the drop valve.  With the NRV in the correct position opening the drop valve will allow both the cold water and hot water to drain through it.  The situation may be different if the taps are opened after turning the pump off as this will depressurise the system.  Water may then flow back through the NRV as it requires pressure on it’s outlet side to work, at least that is my understanding.  As you have discussed with me off-line, the pressure switch NRV should be different because it’s spring assisted.  It should prevent water flowing back through it regardless of the water pressure. As you know, this has been confirmed by Whale which concerns me because my pressure switch NRV, unlike yours, does not behave in this way.  Once the pressure is taken off the outlet side it allows water to flow back through it into the fresh water tank as of course does the redundant NRV, which isn’t spring assisted, that Marquis through their lack of understanding placed in series with the pressure switch NRV.

I shall probably take up a suggestion from ASOC technical to replace the screws with neodymium magnets so the vent can easily be pulled off if required

Caslon wrote:I shall probably take up a suggestion from ASOC technical to replace the screws with neodymium magnets so the vent can easily be pulled off if required

Oh very technical, not bad idea though better than constantly having to remove the screws.

Caraman

Yes I have considered that maybe flow is reversed due to the layout and I do have pipework and T junction which are in the box buried in cable harness etc so I can't trace it. However there will be a clue, the arrow on the Hot Feed NRV which I have used to envisage my installation. You can see the NRV in my photo on the left of the drop valve, the arrow points away from the drop valve toward the viewer and the flow which is in the long curving pipe.
I suspect in your installation the arrow points away from the pressure switch toward the drop valve ?

I must check the Combi installation instructions. However in the past I have considered it correct to have the hot feed NRV as close to the boiler as possible, some instructions show it there and that system worked fine in vans that have had it. Other instructions say the NRV should be fitted after the pressure switch and before the drop valve. Confused, we should be.

Marconi,

My arrow is as you suspect pointing away from the pressure switch towards the Truma drop valve.  If it was pointing the other way, no water would get to the Combi and hot water taps.  From what you have said about your installation, the NRV is the wrong side of the Truma drop valve.  This will mean that unless you open a hot water tap no water will drain from your hot water system when you open the drop valve.  The big concern here is that your hot water system is not being protected as it should be from frost.

Caraman

The first thing I did this morning was to double, triple, quadruple check the arrow on the NRV it is as I remembered it, which is how I drew it out on paper in order to visualise the system to help with the discussions about your water problems.

Yes indeed, the drop valve is Auto Frost Protection and should open automatically when the temperature is low and drain the hot tank to protect it and the rest of the system from damage, under these circumstance no taps will be open and the protection will be negated with the NRV as fitted in mine.

Non standardisation and incompetence is rife at AS it seems. The Truma installation instructions are clear enough :-


When using pressure pumps with a high switching hysteresis, hot water can flow back via the cold water tap. We recommend installing a non-return valve (22, not included with the delivery) between the outlet to the cold water tap and safety/ drain valve as a return flow inhibitor.

Surely they have produced enough vans to get it right. All it needs is a standard layout per model with a drilling template for mounting and sizeable drawing of the connections. Our vans have been produced on the whims and fancies of individual operatives it seems, including the one who fits wardrobe drawers 'with a hammer'.

There is a disadvantage with the Auto Frost Protection in that if it is too sensitive (they operate at 5 deg C) then it can ditch a whole tank of hot water in the night for no real reason or advantage.  I have not experienced this in other vans but you do hear from people who have had it happen but that is no excuse for not following manufacturers instructions.

I can understand your point about standardisation, but I suspect that the problem A/S face is that the motorhome market requires that a manufacturer brings out a "new model" every year, or they are considered to be getting left behind, out of date, etc.

There comes a point where the cost of maintaining "standard templates" for all installation actions costs more than it gains - and I think that A/S has production numbers that are so low (for a model before it gets changed) that the cost simply can't be justified. Hence, their installation workers really are more or less making it up as they go along (or you can interpret it differently: each van is unique and bespoke to its owner!).

Roopert wrote:I can understand your point about standardisation, but I suspect that the problem A/S face is that the motorhome market requires that a manufacturer brings out a "new model" every year, or they are considered to be getting left behind, out of date, etc.

There comes a point where the cost of maintaining "standard templates" for all installation actions costs more than it gains - and I think that A/S has production numbers that are so low (for a model before it gets changed) that the cost simply can't be justified. Hence, their installation workers really are more or less making it up as they go along (or you can interpret it differently: each van is unique and bespoke to its owner!).

Yes I understand what you are I saying but there can't be that many changes in the water system under the bench on a Nuevo, making it up as they go along on each one of a run leads to errors like they have made on mine, and maybe the weird fault that Caraman has. And where and when do QC and inspection come in, never it seems.

I don't envisage intricate expensive templates and laser cutting of holes just a bit of hardboard, or MDF these days, with hole centres drilled, diameters in felt tip plus traces for pipes and fittings etc. Like the ones the boy just out school  that I mentioned previously introduced. No one had thought of it among all the time served electricians, works manager etc. With a few bits of wood, pegs and drawings we were able when pushed and other departments were slack to get painters and glass workers to produce error free wiring looms ready for installation.
Storage on a shelf somewhere, labelled. KISS engineering.