Running out of hot water

[Tbone12]

Hi everyone,

I'm hoping someone here can offer some advice. I've seen so many helpful posts on this forum, so I thought I’d ask for your input.

We're relatively new to the caravan life and currently have a 2017 Compass Casita 840 with a Whale Intelligent Control panel. Our issue is that the hot water only lasts about four minutes. We’re on a serviced pitch with a mains connection, so the water supply itself isn’t the problem—it’s just keeping the water hot that seems to be an issue.

Previously, we had a 2004 Abbey caravan for a few months (our first van), which just had an Aqua Roll with a mains connector. With that setup, the hot water was constant and never ran out. I would have expected things to improve with a newer van, not the opposite!

Does anyone have experience with this or any suggestions on how to resolve it? Any help or advice would be greatly appreciated!

 

[Woodentop]

You need to increase the heating power - to 2kw or 3kw depending what your van has. Then (assuming you are talking about showers) you mix cold water with the hot to give you a warm shower, and you use it ONLY when you need it, most definitely NOT continuously!
It also seems to help if you have an air induction shower head - such as the Ecocamel unit - which draws in air to reduce water consumption.

 

[Mr Plodd]

What you are experiencing is 100% normal.
A caravans water heater only holds about 10 litres (roughly 2 gallons) and, if showering, that doesn't last very long at all.
You need to adopt the wet/soap/rinse regime!
VERY few caravans have a continuous water heater so just maybe your first one was so equipped. But that's a rarity

 

[otherclive]

Hi welcome to the Forum. I am puzzled wrt your comments on the 2004 Abbey with Aquaroll. I cannot understand why your hot water never ran out. Surely as you use hot water cold water from the aquaroll enters the water heater to replace the hot water used. But the rate of usage exceeds the rate of hot water replenishment, as the water heater cannot heat the water at a rate as fast as you are using it.

In your newer 2017 caravan what type of hot water system do you have and how are you using water?

 

[birdman101]

As said hot water flow will not last for ever as a domestic set up. You need the water heating set at the highest level and if only a still a small amount of hot water until running out,it possible one of the heating elements have blown.

 

[Mr Plodd]

As said hot water flow will not last for ever as a domestic set up. You need the water heating set at the highest level and if only a still a small amount of hot water until running out,it possible one of the heating elements have blown.

If one of the elements has "blown" the water will still get to the same temperature, but take longer to do so, and that amount of hot water within the heater will still last the same length of time.

 

[Andy Norfolk]

Does the hot water have a boost function? Our Aldi system has. I put the hot water on normal in the evening. Turn it off over night. When we get up I put it back on normal whilst we have breakfast. Once we've finished with the toaster and kettle I put it on boost. I shower first as I'm quicker leaving it on boost. Wife showers with it on boost. When she's done turn it off. Seems to work as a routine. I agree with all the other practical comments people have made.

 

[ProfJohnL]

Modern caravans are almost like living at home with all the mod cons, unfortunately that concept is shattered by the fact that in a caravan all normal supplies are limited, and you have to be more frugal and diligent in not wasting the resources you have, use things for the minimum amount of time, just be economic.

It doesn't really reduce the luxury, but it helps with the economy.

 

[Mr Plodd]

Does the hot water have a boost function? Our Aldi system has. I put the hot water on normal in the evening. Turn it off over night. When we get up I put it back on normal whilst we have breakfast. Once we've finished with the toaster and kettle I put it on boost. I shower first as I'm quicker leaving it on boost. Wife showers with it on boost. When she's done turn it off. Seems to work as a routine. I agree with all the other practical comments people have made.

Boost just increases the amount of heat (full power electric plus gas) that goes into the water in the heater. The water heats up quicker, but the volume of hot water remains the same, so it will still run out just as quickly.

 

[Andy Norfolk]

Boost just increases the amount of heat (full power electric plus gas) that goes into the water in the heater. The water heats up quicker, but the volume of hot water remains the same, so it will still run out just as quickly.

Yes but it reheats quicker. So whilst I shower it's reheating for OH quicker than if you don't use the boost function.

 

[Mr Plodd]

Yes but it reheats quicker. So whilst I shower it's reheating for OH quicker than if you don't use the boost function.

100% correct, but the original post was querying the fact that the available amount of hot water ran out after about four minutes.
Even on full boost the water heater cannot supply a constant stream of hot water, so, after about the four minutes mentioned by the OP there will still not be any more hot water until the boiler has heated up again will there? Hence my post.

 

[Dustydog]

A few ?s for the OP.

Have you read the Whale manual ?
Yes I am sure you have , so are you using the boost control plus gas and electricity together?
According to Whale your hot tank holds a maximum of 8 litres and should reach a max temp,of 70 degs C.
Is this temperature adjustable?
70 would scold you. So you must be adding cold water ?

All the other comments explain “ splash and dash”. We find we have more than enough shower temperature water to be fully cleansed.

You also need to consider the flow rate you are using?
Woodentop’s suggestion #2 about the Ecocamel shower head will certainly help.

In essence I would like to understand exactly how you are using the system ?

 

[IanB1485]

Many forget that when on gas the heat input is a lot greater ie a truma combi 4E is 4kW on gas and only 1.8kW on electric (EL2) . The olde truma ultrastore 850W on electric ( 1.3kW wattage versions are available) and 1.5kW on gas. The whale water heaters are about as powerful on gas as electric - approx 1.5kW . the Alde 3020 is 5.5kW on gas and only 3.15kW on electric . Compare those figures with domestic electric showers - quick search about 8.5kW-10kW, My domestic 'gas' shower run from the Worcester condensing boiler has a potential of 20kW . as the members say , you have to be frugal and quick( or use the onsite facilities)

 

[Buckman]

100% correct, but the original post was querying the fact that the available amount of hot water ran out after about four minutes.
Even on full boost the water heater cannot supply a constant stream of hot water, so, after about the four minutes mentioned by the OP there will still not be any more hot water until the boiler has heated up again will there? Hence my post.

On boost the water is heated up more than normal so more "cold" water is required to get it to a comfortable temperature therefore the hot water lasts a bit longer. Once we had the ALDE Continuous flow fitted we never ran out of hot water.

 

[Mr Plodd]

On boost the water is heated up more than normal so more "cold" water is required to get it to a comfortable temperature therefore the hot water lasts a bit longer. Once we had the ALDE Continuous flow fitted we never ran out of hot water.

I am struggling somewhat to follow your logic here.

On boost the water isnt heated up MORE than normal, its just heated up QUICKER.

The Combi boiler contains, for ease of explanation, 10 litres of cold water. That 10 litres takes a finite amount of energy to heat it to the pre-set temperature of either 40 or 70? degrees.

The more energy that is put into that water the quicker it heats up, but regardless of whether it's set on EL 1 EL 2, gas or any combination of the three it will STILL only get to one of the pre set temperature before the boiler thermostat shuts off the energy input. So how can it, as you have said, be "heated up more than normal"?

The more energy that's put in the QUICKER it heats up, but it doesnt/cannot get any hotter!

The Alde Continuous Flow YOU had is an entirely different system, that's like a domestic electric shower unit (7+kw) It provides "continuous" hot water with no storage facility. The clue Iies in part of the name "Continuous"
A Truma combi is more like a domestic hot water immersion tank, it heats a certain amount of water up and then stores it until needed. When using the shower, kr a hot tap, theTruma Combi will start heating the incoming water once it detects the temperature within it has dropped below a certain point, but it's simply not powerful enough to heat it quickly enough to provide a constant flow, that's why the hot water "runs out" if you leave the shower running rather than adopting the wet/soap/rinse routine.

 

[Mel]

The other thing the Boost function does is prioritise the hot water over the heating. Again, heating the hot water quicker but not hotter than its maximum. An easy way to check if the water is as hot as it’s going to get is to look at the Truma panel and see if the water heater icon has stopped flashing.
Mel

 

[Buckman]

I am struggling somewhat to follow your logic here.

On boost the water isnt heated up MORE than normal, its just heated up QUICKER.

The Combi boiler contains, for ease of explanation, 10 litres of cold water. That 10 litres takes a finite amount of energy to heat it to the pre-set temperature of either 40 or 70? degrees.

The more energy that is put into that water the quicker it heats up, but regardless of whether it's set on EL 1 EL 2, gas or any combination of the three it will STILL only get to one of the pre set temperature before the boiler thermostat shuts off the energy input. So how can it, as you have said, be "heated up more than normal"?

The more energy that's put in the QUICKER it heats up, but it doesnt/cannot get any hotter!

The Alde Continuous Flow YOU had is an entirely different system, that's like a domestic electric shower unit (7+kw) It provides "continuous" hot water with no storage facility. The clue Iies in part of the name "Continuous"
A Truma combi is more like a domestic hot water immersion tank, it heats a certain amount of water up and then stores it until needed. When using the shower, kr a hot tap, theTruma Combi will start heating the incoming water once it detects the temperature within it has dropped below a certain point, but it's simply not powerful enough to heat it quickly enough to provide a constant flow, that's why the hot water "runs out" if you leave the shower running rather than adopting the wet/soap/rinse routine.

Bad wording on my part ad you are correct about maximum temperature. On boost it uses 3kw of electric and does heat the water quicker, but the temperature of the hot water also increases as the boiler has a thermostat switching on and off. If you shower when the water is cooler i.e. before the thermostat kicks in you will have a shorter hot shower. On boost, it over rides the thermostat and keeps temperature at maximum heat giving you a slightly longer shower.

 

[ProfJohnL]

Bad wording on my part ad you are correct about maximum temperature. On boost it uses 3kw of electric and does heat the water quicker, but the temperature of the hot water also increases as the boiler has a thermostat switching on and off. If you shower when the water is cooler i.e. before the thermostat kicks in you will have a shorter hot shower. On boost, it over rides the thermostat and keeps temperature at maximum heat giving you a slightly longer shower.

I seriously doubt the Thermostat is over ridden, that is a primary safety device. Its more likely the fact that cool water is being pumped into the heater which mixes with the hotter water, and the combined water temperature is dragged below the thermostats cut off temperature, which results in the heater continually running until the water draw is stopped and the whole tank can reach the thermostats cut off temperature.

 

[Dustydog]

Mr Plodd,
Help me here please. I thought the OP had a Whale Expanse dual -fuel underslung water heater not a Truma system?
The Whale I believe is 8 litres compared to the Truma 10.

The boost system is supposed to heat the water a lot faster than normal so more hot water ,at I assume the fixed temperature , is available earlier giving the sensation of more hot water, but perhaps not continuous?

The Prof knows these things better than me😉

 

[Martin_E]

Truma have now brought out a continuous flow Cobi, I can’t remember if the Dometic new combi is continuous or not……just looked it’s not continuous https://www.dometic.com/en-gb/outdoor/motorhome-and-van/heating-solutions/combi-heaters

 

[IanB1485]

Most water heaters are designed to avoid mixing of cold water with hot water. Cold water goes in at the bottom and hot water out at the top. There will some inevitable mixing to due to turbulence, Thats not why older caravan systems can't maintain a hot shower its due to the following:- Given the maximum flow rate of a internal pump is about 19 litres/minute it would take 39kW to continuously heat it from 10 Deg C to 40 Deg C( 4200J/s (W) x 0.315kg/s. x 30 Deg C temp rise .) Fortunately a shower doesn't take that much water per minute, but still even at a tenth of that flow rate it would take 3.9kW to maintain an output temperature of 40 Deg C, which is what a truma combi 4E(gas or mix) can do , if it shuts down the air circulation motor to prioritise hot water production.

 

[Dustydog]

Most water heaters are designed to avoid mixing of cold water with hot water. Cold water goes in at the bottom and hot water out at the top. There will some inevitable mixing to due to turbulence, Thats not why older caravan systems can't maintain a hot shower its due to the following:- Given the maximum flow rate of a internal pump is about 19 litres/minute it would take 39kW to continuously heat it from 10 Deg C to 40 Deg C( 4200J/s (W) x 0.315kg/s. x 30 Deg C temp rise .) Fortunately a shower doesn't take that much water per minute, but still even at a tenth of that flow rate it would take 3.9kW to maintain an output temperature of 40 Deg C, which is what a truma combi 4E(gas or mix) can do , if it shuts down the air circulation motor to prioritise hot water production.

Thanks Ian
I thought the target temperature was 70 degs C? 40 degs is just above body temperature. Have I missed something?

 

[IanB1485]

Please don't try showering in +70 Deg C water anything above 50 Deg C is 'Scalding' temperature, The Truma Ultrastore on electric is indeed set at 70 Deg C ,on gas its adjustable . The Truma combi 4E has two settings on the old analogue dials of 40 and 60 Deg C and on the LCD control ECO is 40 Deg C and HOT is 60 Deg C. ( can't find the word BOOST in the combi 4 e operating instructions) .The ultrastore on electric uses the eight litres of stored water at 70 Deg as a buffer to mix with cold water to provide more water at about 40 Deg C at the shower head.

 

[Mr Plodd]

Still runs out pretty quickly though!