singleprop

There is a timer on the valve - I will need to find out how many seconds it has to stay open before hot water comes out, this will reduce the "hot water waste". Returning the hot water to the calorifier tank might be problematic due to the water pressure from the accumulator tank - the calorifier tank has the same pressure as the accumulator so opening a valve with the same pressure on both sides of the valve will not create a flow. I'm using the differential pressure between the accumulator and the unpressurised water tank to create this flow.

Yes, its a ring of hot water, but the return to tank is closed by a solenoid controlled valve which opens temporarily by a switch at each shower and sink.

What's the problem with returning the water to the fresh water tank - I could re-route the return water to a sump box or an overboard drain, but that would defeat one of the purposes of it (to save water) Do you have a link for the Dometic shower pump switch, just in case...

I ended up ordering a 24V water valve, I'm placing it on the hot water return pipe to the fresh water tank (not on the calorifier tank). There is a switch at each location, which opens this valve. The water pressure is supplied by an accumulator tank, so when the switch is activated the valve opens for 30 seconds, allowing the hot water to flow - which flushes the cold water in the pipes into the fresh water tank.

So, I guess that a couple of years have gone by now, enough time to figure out if the Drayton Tapstat works? Any update availabel on the installation? Thanks

Already taken care of. Any advise on a 24V pump as discussed above?

Already thought of that but 3 separate calorifier tanks makes plumbing impossible (3 locations) .The current plan is to heat the calorifier by the genset, the engine + electrical and then have one continuous hot water pipe running from the calorifer and back to it again.

This system is describing what you and Smiley are suggesting. Actually, it describes two different systems, one which guides the whater from the hat water line into the cold water line, and one where the hot water is recirculated back to the calorifier tank. http://www.hvacquick.com/catalog_files/Met...AND_Catalog.pdf http://www.freshwatersystems.com/specifica...L-UP-TL-043.pdf Now I just need to find it with a 24V pump..

Yes, this will work as well to cut out the pump, but what about starting the pump... Any recommendations on the 24V circulation pump (I have looked intensively, but not the right places because I cannot find one).

Thanks guys, All your replies are valid considerations and as usual a compromise will have to be made.... In this case the water usage has to be reduced as much as possible (4-5 persons on board at most times). The 75 liter calorifer has a mixing valve so it will not be affected much if 5 liters of cold water returns to it. How about a flow switch that activates a timer and pump?

Hi all, I am planning a hot water system (for shower, and galley) with a pump that circulates the hot water (from the calorifer and back to the calorifier) once the pressure in the line drops. The idea is that if I need to use hot water, I then open the fixture for say 2 seconds. This will result in a pressure drop in the line and this activates the circulation pump. Then a timer on the pump would turn off the pump after say 20 seconds. The advantage is that all the cold water which is stored in the pipes will be routed back to the tank, which will save valuable fresh water for other usage. So I am looking for a pressure drop activated (or flow activated )24V DC pump with a timer. Any recommendations?