PRESSURISING WATER SYSTEM - CALORIFIER LOCATION

[alisdair4]

The second big project I am embarking on is the fitting of a calorifier to give domestic HW. Again, I have had lots of good advice about how to harness the cooling water from my MD11c. Looking at the options for placing the calorifier, it would appear that it is going to have to be about 2 feet above the cold water tank (in my case, a flexible tank in the bilge). How does the cold water from the tank get to the calorifier? Do I have to pressurise the cold water system starting from the CW tank, in order to get the water to the calorifier?
Sorry if this is a gormless question - but I am probably in good company!

 

[Frontier]

Hi

My cold tank is amidships in the bilge. The outlet goes directly into a pump, which is right by the tank. I don’t have a pressurising cylinder. It then goes off to the calorifier, which is beside the engine and cold taps And back for the calorifier to the hot taps of course.

All seems to work OK. The top of the calorifier has a pressure relief valve which is tee’d into one of the cockpit train pipes.

Good luck with it.

D

 

[Richard10002]

I dont know how it works, but my system pressurises the cold water side of things which must force the water into the hot water tank. presumably the cold goes in at the bottom of the tank, the hot tank is pressurised by the cold going in and, when you open a hot water tap, the hot water comes off the top of the tank, then more cold goes in the bottom and so on.

Short answer is it's pressurised from the water pump.

 

[tillergirl]

Simple answer is yes. You could jsut pressurise the HW side but that would be a little odd. You need a pump with pressure switch (you get them combined) on the outlet from the water tank. Run the outlet from the pump to an accumulator (to even out pressure fluctuations which cause cycling of the pump). After the accumulator tee the outlet between the HW and CW side. One becomes the feed to the Calorifier and the other goes to you existing CW side. There is no issue about whether the feed to the calorifier for domestic water is above or below your main tank but there is an issue about the height of the calorifier in relation to the feed of hot water from your engine. On my system it is a requirement (of Mr Volvo not the calorifier manufacturer) to have the upper edge of the hot water heater placed a min of 50mm below the engine's heat exchanger. These instructions came with the tee kit from Volvo to take off the hot water from the engine. This is a 2030 so whether its the same with you engine, you best ask. This is presumably so that the engine can cope with the extra fluid it has to push round. Only difficulty I had was getting the air out of the circuit from the engine. Wasn't too difficult but needed priming.

 

[LittleShip]

A one way valve between the pump and the inlet to the cylinder (close to the cylinder) is a good idea, This will allow water to flow to the cylinder but not back into the cold water pipes.

Also a pressure release valve fitted to the cylinder....... just in case?

Tom

 

[alisdair4]

Thanks to all - I now need to review where the calorifier will fit. Given the age of the engine, I don't want to make it work any harder than it has to.