Hot & cold water supply

[adyt61]

Hello

I have an Adria Adora 613UT Thames, 2014, which we have had from new.

It is fitted with Truma Ultrastore Rapid GE water heater, with a Truma Ultraflow Compact Housing and a Whale pressure switch.

I have been having various problems with both the hot and cold water supply to all taps and shower over the last few months;

1. The system does not seem to have the pressure it used to, despite having adjusted the pressure switch many times.

2. The pressure in the system seems to fluctuate through the day.

3. When operating any cold tap, particularly first thing in the morning, hot water comes through first.

4. If I switch off the pump master switch before going to bed. There is a lot of air in the system, particularly the hot, which requires a good bleed to get things working.

Any advice very gratefully received.

Cheers

Phil & Lesley

 

[ProfJohnL]

Hello Phil & Lesley,

Firstly your experience of the hot water "coming through first" is a natural consequence of the way the water heater works. Basically when you fill it with first time with cold water and close the taps the water is trapped inside the heater. But for safety reasons there is a small amount of air also trapped at the top of the tank. This is to allow the water space to expand as it heats up. This compresses the air cap, and along with teh fact that if you heat up a volume of air it will also increase its pressure, it means the water in the heater is at a higher pressure than the the cold water in the rest of the system. So naturally when you open the tap, teh hot water will preferentially flow out until its pressure drops and matches that of the cold water system.

Only when the pressure in the cold system drops enough will the pressure switch turn on the pump. With some systems you can get also get a situation where the pump can deliver more water than the tap will let out, so when the pump runs it raises both the cold ad hot pressure enough to trip teh pressure switch, but becasue of teh air cap in teh hot tank the hot will continue to flow for a moment or two even though the cold has stopped. This gives you hot and warm cycling from some taps.

One solution is to make sure there is a surge damper on teh cold pipe work ( a plastic air tank basically) which helps to match teh air cap in the hot tank.

Th other symptoms you are describing of poor general pressure , and varying pressure are not quite so clear cut. especially as you have tried to adjust the pressure switch. Do check you have followed the pressure switch manufacturers instructions for doing it as that can have quite a noticeable effect on its performance.

Your description of air in the hot pipes, and it needing some time to bleed off, suggests you may have some leaks in the pipe system. You should trace all teh pipes back and look for any pipes or fittings that seem wet. but you can also get some internal leaks which you wont see. Within your system there will be a number of non return valves. Especially at the pressure switch, and on the inlet to the water heater. If these are compromised so they don't shut off properly then water will leak back past them and back to the cold water storage container. Equally if they have become compromised so they don't shut completely they also may not be opening fully which will restrict water flow.

This sort of damage can be the result of incomplete draining down over winter, or if some debris has got into the water form say perhaps a broken carbon filter.

Another possible concern could be if the water storage has emptied and the pump has run dry for any length of time. Some pumps only need a couple of minuets dry running or teh accumulation of several bouts of running dry to damage teh shaft seals which allows water into teh motor itself, which is not good news and such pumps rarely last long once damaged.

Sorry I can't be more specific, becasue I cant see your system.

 

[Woodentop]

Er, Prof, should there not be a directional flow valve between the cold supply and the input to the water heater tank? Mine has one.

There should be any way that heated water can get back into the cold supply system in a caravan, home, or anywhere else for that matter.

 

[Martin24]

Check the filters on your taps to ensure they aren't blocked with limescale and the like. Do the same with shower head. May improve flow from taps.

 

[ProfJohnL]

Er, Prof, should there not be a directional flow valve between the cold supply and the input to the water heater tank? Mine has one.

There should be any way that heated water can get back into the cold supply system in a caravan, home, or anywhere else for that matter.

I'm sorry Woodentop, you are correct for domestic systems and compliance with WRC regulations, but they don't cover caravans! but the principle should be the same. What you call a "directional flow valve" I call a "non return valve or NRV", and there should be one built into the input of every storage water heater used in caravans.

But if the NRV's on the inlet to the heater has been compromised then the pressure would certainly translate back through to the cold water.

But even if the NRV is working where the water mixes in a mixer tap there can be problems with pressure translation and water temperature. We had a number of caravanners a number of years ago who all complained the water at the kitchen sink and bathroom basin was only warm, We discovered that the caravan manufacturer had fitted a mixer valve for the shower but the water flow valve was on its output. s o even though the shower was not running. both teh hot and cold flows were meeting at the mixer valve, and given teh right conditions, the pressure of the hotwater back fed into the cold supply pipes to the basin and sink. You would be surprised how much effort was involved to get the caravan manufacture to understand why it was happening.

I should have added that when a mixer tap is opened, becasue once the hot water flows into the plenum. being a higher pressure it will resist increase the back pressure on the cold water keeping the pressure switch contacts open until the pressure is relieved from the hot tank.

 

[adyt61]

Hi Martin24

Many thanks for taking the trouble to help.
We regularly, about every 3 to 4 months since the caravan was new, use a tank cleaner/de-scaler through the system. Usually at shower heads and sprinklers on taps, the limescale shows as jets going off in different directions, and we have none of that.

So, we do not suspect any problems of debris in the system.

Happy caravanning

Phil & Lesley

 

[adyt61]

Hi Prof

Many thanks for a really helpful reply.

As per my reply to Martin24, our system is regularly cleaned, (and drained down for winter - although I could not guarantee completely). Also, in the two years we've had the pump, it's never been run dry for more than a couple of minutes, but I will borrow a friends to see if there's any difference.

So, because of the above, I'm going to focus on the NRV issue. I had a similar problem with the Carver Cascade in our other caravan which was resolved, with the help of this wonderful Forum, by replacing the non-return inlet valve. I can't find any NRV's in this Adria!

I'm assuming the Truma Ultrastore does NOT have an NRV at the tank cold feed, as per the Cascade, as the cold feed goes through the drain valve, there would be no way of draining the tank as there is no drain plug on the heater, as per Cascade.

The cold feed to the heater comes off a tee very close to the heater, goes through the drain valve, then into the Ultrastore. There are no other fittings on this line.

I have taken some photos of the system that I would like you to see, but can't see how to download them to this reply. Could you advise the best way I could get them for you to see?

As I said before, I cannot find any NRV's in the syatem. Is there one in the Truma Ultraflow Compact Housing, or does the Whale Pressure Switch act as an NRV?

Cheers

Phil & Lesley

 

[ProfJohnL]

for details of how to post photos on the forum see

https://www.practicalcaravan.com/forum/our-website/48966-how-to-photos
It is essential that any storage water heater has a non return valve, otherwise the pressure inside the hot tank would push water back out of the heater into its feed line. This could allow the tank to empty which would be dangerous.

The Truma heaters usually combine the Non Return Valve into the the pressure relief and drain valve that you have identified.

 

[SirRogerFFS]

As you are now focusing on Non Return Valve this is a similar issue to mine. As already explained there will be non return valves in your system or NRV from now on . Now to make life easy I would start at where the water supply enters the caravan is where you should find an NRV if you havnt got one in then its a good idea to fit one its stops water running back to the aquaroll . Just be sure the NRV is like a joiner blue in colour with the supply going in and out they will be marked with an arrow.I suggest this as I have recently found problems with mine . If you find an NRV is fitted then carefully remove it and blow down each end if you can blow air each way replace it .But when you remove an NRV note which way the arrow on is pointing .I hope this will help in someway .
Regards Sir Roger Sir Roger

 

[adyt61]

Hi Prof

Sorry for not replying sooner.

I'm a bit busy with work at the minute but, as there is still a lot of hot water coming through the cold on both kitchen and basin taps, I'm suspicious whether the drain valve does include an NRV, or if it does may be faulty, so my next move will be to remove it for inspection.

Do you know if the Truma Ultraflow Compact Housing includes an NRV? If not, I feel the suggestion from Sir Roger to put one in is a good idea. Just wondering if it should be between the Housing and Whale Pressure Switch, or after the Pressure Switch?

Many thanks

Phil

 

[adyt61]

Hi Sir Roger

Sorry for not replying sooner, just been a bit busy.

Many thanks for your suggestion which, as per my reply to The Prof I think is worthwhile. Just wondering if it should be between the Truma Ultraflow Compact Housing and Whale Pressure Switch, or after the Pressure Switch?

Do you know if the Housing includes an NRV?

Cheers

Phil

 

[ProfJohnL]

Yes the housing does contain a NRV.

 

[adyt61]

Hi Prof
Many thanks.
Phil