On thursday just gone, I hooked up my caravan and drove the two hours to Wellingborough in Northamptonshire. I had decided to fit the Alde Flow continuous hot water system after experiencing a couple of cool showers recently whilst away in France.
The Alde boiler is made up of a central tube which works as a heat exchanger within which gas is burnt. This heats a chamber which contains Glycol for the wet heating system. If heat is being called for from the radiators (for want of a better word) this Glycol is then pumped around the caravan to warm the interior temperature to a preset value. The clever part is that there's an outer chamber which contains fresh water which is heated by the Glycol so you can run the system without any water without fear of damage and the water is effectively heated as a by product of the heating making the system pretty cheap to run in comparison. Another benefit is that the burner is shrouded by two fluid jackets making it also quiet. It seems the Americans are interested as their furnace systems are too loud to use at night. Within the Glycol jacket are also two elements (1kw and 2kw)) which allow the system to run on 1kw/2kw/3kw and gas if required and the hook up allows for it.
What the Flow system does is effectively increases the surface area of fresh water coming into contact with the heat from the Glycol. It's a chamber of heated Glycol from the main boiler which through a heat exchanger preheats the fresh water to about 20 degrees before it enters the main boiler. This then allows the water to run at 3.5 ltrs/min at 40 degrees limited only by your gas and water supply. I have a shower head which I bought at the Ideal Home show which uses very little water and slows the rate of water use but increases the pressure. This is done by way of a blade of razor thin stainless with holes that are only just visible the IZycare shower head reduces water use by 30-50% when showering.
My experience on Thursday was great. I'd wanted the unit fitted under the 3 drawer chest at the front of the van because it was wasted space. At first I spoke with Phil at Alde (Resident expert) who was doubtful it would fit but was happy to have a look. When I arrived he took a quick look and said he was sure he could do it. I arrived at 8:00am and the van was ready at 4:00pm so a good days work for them. It works a treat and gives me instant and continuous hot water without taking up any space at all. It also uses no more electric or gas to run it. I should also thank Leigh the MD for the guided tour of the premises and explaining the system to me. Everyone was extremely pleasant and helpful.

Interesting not suffered with a lack of hot water in our van with an Alde system but some friends have experienced it in their Elddis.

It only happened when we needed a shower immediately following the other without giving it time to boost. There’s a lot of me so I possibly use more water than most as well. This kit should allow me to run the water without switching off between shampoo on and rinse if I wish. I probably won’t but I can. The wife can then follow straight away with the same options.

OP, nice write up, thanks

Not cheap though. Around £700 isn’t it? 2010 MY Vogue SE TDV8 3.6 Stornoway Grey- fully loaded

Nothings cheap. I drive a Range Rover so who’s counting?
It does a job which I want so as I’m keeping the van for the foreseeable future I thought it gave value for me. It may not be suitable if you change your van regularly but I intend to keep mine for many years.

And its only 10 or less stays in a hotel so sounds like good value to me

I get your point and I’d choose my van over a hotel any day. I love it.
Value is always subjective. My mates think I’m crazy owning a FFRR but each to his own.