Inline water heater

[Craigyoung]

Well I am yet to use my caravan shower as I have not had a problem with the on site facilities we use and I like at least a 2o minute plus shower so I can just chill out stand and relax ( no comment from Lc either ) !

You must tell me which sites you frequent so I and other don’t have to stand around waiting for shower cubicles to come free

Well Clive , what would be the use of that because if you's all turn up then I'll be waiting for a shower !! Usually club sites , you's must just go the wrong times when you want one !

 

[Dustydog]

Craig
I bet you’re so cosy in your 20 minute deluge you leave behind that expensive shower gel that I love acquiring

 

[Craigyoung]

Sorry Double D !
You've no chance to get my shower gel I never forget nothing !!!
The only thing I normally get the chance to acquire is someone's washing up liquid that they have left

Craig .

 

[Icaru5]

Sorry Double D !
You've no chance to get my shower gel I never forget nothing !!!
The only thing I normally get the chance to acquire is someone's washing up liquid that they have left

Craig .

You really should be careful there Craig ... I’ve never tried showering with second hand washing up liquid, but would imagine it may be a little too harsh for those more sensitive areas

We don’t want to see you walking back from the shower block with tears in your eyes and bubbles flowing out of the bottom of your trouser legs

 

[Raywood]

I appreciate you may have special reasons for wanting the extra capacity. I do wonder though if you might be better trying to use serviced pitches where you will get your own tap and can simply connect this to the caravan and have a constant supply of water. The tank may only be ten liters but if you have this at 60c you will need to mix it with cold and so you should get considerably more before the water runs cold.

I do wonder where the additional tank will fit. It is difficult to see how it could be fitted in our caravan but with others it might work. Not knowing what you have I cannot say what problems this might produce with space, you would have to take the weight into account though, and that might also be critical.

There are various problems here that it looks like no one here can answer, particularly the power needed and if you wish to go ahead I would be looking at getting advice from a caravan engineer who might just have the answer. I am not sure if you have experienced a problem or just foresee one, possibly if you have not tried the current system out it might be worth seeing if the current tank is sufficient for your purposes.

 

[Gafferbill]

.........according to Truma there should not be a problem here.
Truma has done calculations and testing to show how to get copious amounts of hot water from their unit.

They explain how to achieve this here.

Me........I'm still using a 23 year old Carver heater :cheer:

 

[Grey13]

Hi Gafferbill, Interesting read, although I have actually spoken to a truma engineer last week. I can say that often in warmer months I can get by with the system, but the problem comes in winter like this last one where we spent 2 weeks in Devon and the shower was inadequate. By way of clarification for a different poster, Truma no longer make a 14 litre unit. He the Truma engineer suggested fitting an extra 10 litre tank TYPICAL of this one http://www.rainbow-conversions.co.uk/heaters-motorhome-caravan/propex-10-litre-electric-water-storage-heater.html which is actually not that big. However I will not go that far right now, my electric heating element has blown and as soon as the ambient temp improves a little I will be replacing it. Being an electrical heating engineer involved with temperature control for most of my life, I will replace it with one that hass a little more power. The existing one is 850w so I am thinking of having one made by a mate who owns a heating element factory say about 1 kw ( about 4.16666 amps rather than the existing old one of 3.542 amps) That is a 17% extra heating power. I will also have it made with a built in sleeve to house a thermocouple and install a temperature controller near where the current Truma controls are sited. Typical controller would be https://www.vertex-qis.co.uk/F4_series.html which will serve 2 purposes. Make it impossible to accidently just switch on the c/b when there is no water, the probe will not allow heating without water ass it will sense the element overheating and allow me to control the water temp. The current “control” is a bimetal trip preset attached to the outside of the vessel. After all that I may well look at van hot water pipe insulation if next winter it is not spot on. Thanks anyway for a meaningful reply.

 

[otherclive]

Propex make a dual fuel water heater the Malaga that has 13 litres capacity. Don’t know whether this would be an option. I had Propex water and space heaters in a continental van that when imported had nothing. I found their kit to be good quality too. The 13 litre may be sufficient to obviate the need for a second 10 litre storage heater. Just a thought.

 

[ProfJohnL]

Looks like you have it all planned. Not a cheap solution, and others may suggest your proposed temperature controller may be over kill. Will you be using PID control? I do note the Propex 10 does have a digital temperature display, and it appears to be adjustable, so it might be a a more cost effective solution with only a few compromises.

When our home electric oven control failed, I replaced it with a digital PID controller and how much better it was.

As a bespoke project I wouldn't like to guess the cost, although being in the industry you will hopefully get items at cost price.

 

[otherclive]

Given the non linear variables in this system and a domestic cooker would it be better to use a standard PID controller or a fuzzy logic PID controller?

 

[Icaru5]

Looks like you have it all planned. Not a cheap solution, and others may suggest your proposed temperature controller may be over kill. Will you be using PID control? I do note the Propex 10 does have a digital temperature display, and it appears to be adjustable, so it might be a a more cost effective solution with only a few compromises.

When our home electric oven control failed, I replaced it with a digital PID controller and how much better it was.

As a bespoke project I wouldn't like to guess the cost, although being in the industry you will hopefully get items at cost price.

A PID Controller for a caravan water heater - Really Prof ?

The purpose of a PID controller is to determine and apply an appropriate and continuously variable output response in real-time, which is determined by a calculated error value within systems where digital logic is unsuitable. The use of PID control normally results in the magnitude of the output response reducing as the error value decreases. This would normally be employed in cases where maintaining a particular condition is process critical and over-compensation would result in erratic operating conditions of the system, whatever it may be.

When we are heating water for a purpose such as a shower, we have a measured temperature and a set point. Surely employing simple digital logic would be more than sufficient here ?

 

[Grey13]

Gent's the concept of a controller is probably an over-kill. However a slightly over sized heating element will bring down heating times when used with the gas heater. It will not however give me a longer shower, at best if longer, a longer one with warm water, not necessarily hot!. Bearing in mind the vessel is just 10 liters simple on off control similar to what they use now is probably good enough. I would however like a probe/sensor of sorts that will both regulate the temp and provide over temp/burnout of the element. I will need some time to figure that out. I am pretty sure using a sleeve of sorts attached or lying close to the element in the vessel will sense dry element overheating and switch it off. You may ask, why do I want that, well someone, probably my wife, accidentally turned the c/b on recently without water and burned the element out.That is why I am now having to change it! When I have had time to get the old one out and have a good inspection I will have to re-think. I have one of those controllers (in the link) on my domestic hot water tank but set and used as a simple on/off unit with a hysteresis of 1 deg C and it works very well. That is set at 57.5 deg C because the sensor is 2/3 of the way down the tank so the water at the outlet at the top exceeds 60 deg which is the recommended temp to kill Legionella contamination. I found that the simple bimetal switch most plumbers fitted were not reliable and you never really knew what the temp was and as a result mostly always over heated wasting energy.

 

[Grey13]

OK cold weather's back....I'm back on one of my favourite topics, shower hot water. In a few days i am off in the van having fully recovered from the woosie fest at Woodthrope a few weeks ago!

So for this trip am armed with 2 x 300 watt submersible heating elements. I will try different things but basically raise the water temp in my Aqua Roll to roughly 30 Deg C so that when I draw shower water the Truma heater is refilled with water almost at shower temp.

That's the theory anyway, even if the Aqua Roll gets to 20 deg C it will make an improvement to the situation. After having a good play around I will report back on my findings.

Cheerio !

 

[otherclive]

Grey
Await the results with interest. Happy showering

 

[Dustydog]

Grey,
I assume you are using an aquaroll insulating jacket and pipe work cladding tohelp B)
Let us know if it works

 

[Mel]

Good luck Grey. Let us know if it works. If it does, look forward to seeing you on Dragons Den.
Mel

 

[Anseo]

This thread reminds me that now that the colder weather is coming, I must get some insulation for my aquaroll, one of this type should do the job.

https://www.wickes.co.uk/Wickes-British-Standard-Hot-Water-Cylinder-Jacket---457-x-1066mm-PK4/p/210203
https://www.screwfix.com/p/hot-water-cylinder-jacket-18-x-80mm-x-1219mm/43483

 

[Hutch]

Anseo, I use the normal aqua roll winter cover, and if the weather is supposed to be really cold , below freezing then use an old anorak, zipped round the aqua roll and cover with the water hose coming out of a sleeve. Never had a fully frozen aqua roll "yet" maybe just the top 1 inch of water.

 

[Sproket]

Alde have been testing a extra water heater for some time & now it's available in two top of the range vans but it's also available to be retro fitted to the Alde 3020 system

But if your van has blown air heating rather than the Alde set up i would fit this item and pipe it inline with you water heater instead of trying to pre heat the water in your aquaroll..

Just my two penn'orth

 

[Craigyoung]

....This thread reminds me that now that the colder weather is coming, I must get some insulation for my aquaroll....

Just had loads of carpet fitted in the house and have a lot of spare decent underlay left , might just measure up and take enough to go around aquaroll this weekend and keep it in place with a bungee ?!? should do the trick

 

[Gafferbill]

......just fitted a 25ltr onboard water tank with plumbing and valves to use the internal or external supply as required.
Heat from the caravan keeps the water temperature of the inboard tank much higher. .......no danger of freezing.

 

[ProfJohnL]

The mass of the water in the internal tank will also act like a storage heater, helping to moderating the temperature variations inside the caravan.

 

[Dustydog]

....This thread reminds me that now that the colder weather is coming, I must get some insulation for my aquaroll....

Just had loads of carpet fitted in the house and have a lot of spare decent underlay left , might just measure up and take enough to go around aquaroll this weekend and keep it in place with a bungee ?!? should do the trick

Hope it’s waterproof and doesn’t freeze in situ. :evil:
Also worth placing the aquaroll off the ground, wood etc for further insulation

 

[ProfJohnL]

Also worth placing the aquaroll off the ground, wood etc for further insulation

The ground often retains more heat than the air above it, so if it's not frosty during the day, then leaving the water container on the ground may allow it to keep a little warmer by drawing heat from the ground.

If the ground is all ready frosty, then the water container should be insulated from the ground, but not exposed to the air

 

[Dustydog]

Also worth placing the aquaroll off the ground, wood etc for further insulation

The ground often retains more heat than the air above it, so if it's not frosty during the day, then leaving the water container on the ground may allow it to keep a little warmer by drawing heat from the ground.

If the ground is all ready frosty, then the water container should be insulated from the ground, but not exposed to the air

Mmmm. Hence the Christmas Carol, In The Bleak Mid Winter B)
Actually Prof, any insulation in the winter is as we agree essential