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JasonDS · 08-02-2017, 02:10

I've a small cat so space is limited but i need hot water for showers. I'm looking at the D4 but don't understand the setup.
Can the water flow through the d4 and straight out as hot water or does it need to circulate a few times?

Also, i was told i need a calorfier but if the water can go directly through the d4 and not a heat exchangerthen surely i just need a pump and a hot water tank?

I have outboards so no chance of using the engines to heat any water.

My current idea for the circuit is water pumped through the d4 to a hot water tank of 20 litres until 80 degrees as one circuit then another pump to a few bar to pressurise to the tap and shower head.

I was originally told to use the d4 to a calorfier as one circuit then a high pressure pump and expansion tank as the hot water circuit to shower and tap.

Thanks in advance for any help!

GILow · 08-02-2017, 03:15

Search for the thread posted by CF user Typhoon on his setup. It explains the issues. Mainly you want to avoid short run cycles on the heater.

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Typhoon · 08-02-2017, 06:57

First , you cant run your domestic water through this heater, these things don't work like that . They are filled with 50/50 antifreeze mix , the same you would put in your engine. You need to build yourself a circuit. With a buffer tank to add mass to prevent short cycling of the system . Short cycling causes a build up of soot in the combustion chamber and exhaust. You have to think of this heater like an engine , and remove heat from the circuit the same way you would with engine heat . You can put a copper coil inside the buffer tank and remove heat that way , or you can heat the water like you would with your engine heat running through your hot water engine loop circuit . The later is the simplest way but you will still need that buffer tank . If you don't use a buffer tank the heater circuit will reach its high temperature cut off point and then just short cycle . Also remember that the exhaust of these units get very very hot and will burn down your boat if it is not isolated from any thing combustible. These systems take a little bit of thought and design but if done right they are virtually trouble free .

Regards John.

Typhoon · 08-02-2017, 07:06

Also just a note, you could run the system with its on loop though the hot water tank. I have done this when testing units out of the boat. I don't recommend this , first of all you will have issues with priming the system and removing all the air from around the combustion chamber , if you run it dry you will be replacing the unit. Also there are different metals inside these units , the antifreeze protects these metals from reacting with each other and stops corrosion . Just like an engine with an aluminum head and an iron block. They are designed to pump coolant .

Regards John

JasonDS · 08-02-2017, 08:11

Quote:

Originally Posted by ColdEh Marine

Also just a note, you could run the system with its on loop though the hot water tank. I have done this when testing units out of the boat. I don't recommend this , first of all you will have issues with priming the system and removing all the air from around the combustion chamber , if you run it dry you will be replacing the unit. Also there are different metals inside these units , the antifreeze protects these metals from reacting with each other and stops corrosion . Just like an engine with an aluminum head and an iron block. They are designed to pump coolant .

Regards John

Thanks. So it looks like I'll need a expansion tank for the closed loop on the d4 and a calorfier to absorb the heat from the d4 heating circuit and another expansion tank on the hot water circuit to reduce pump wear and to keep it primed.

Typhoon · 08-02-2017, 08:21

Quote:

Originally Posted by JasonDS

Thanks. So it looks like I'll need a expansion tank for the closed loop on the d4 and a calorfier to absorb the heat from the d4 heating circuit and another expansion tank on the hot water circuit to reduce pump wear and to keep it primed.

If you build it right from the start , you will be very happy , and have many years of trouble free service.

Please , if you have any questions drop me an note , I will be glad to help , I have built a number of these systems . I was previously Typhoon .

Regards John.

Sputnik · 08-02-2017, 10:08

I used a second hand D4 to heat the water in my Hunter 356 so I did not have to run the engine to get hot water (we are on a fore/aft mooring with no shore power, just solar/wind). Initially I "T"d into the engine cooling system with one way valves to prevent the D4 outlet hot water heating the engine....this did result in not dumping the heat into the calorifier fast enough and short cycling the D4.
So I took the D4 circuit out of the cooling system and "T"d into the fresh water inlet and outlet of the calorifier (after having flushed any A'freeze out of the D4). Using an electronic controller (cheap off of ebay: 10A 12V Digital Temperature Controller Temp Sensor Thermostat Switch -40~120°C
to control the D4 (the sensor is tucked into the insulation blanket of the calorifier)
This works very well, from ambient (cold in the UK) to 130 deg F in about 15 minutes.
I did note some surface corrosion in the D4 on a later inspection, so have installed a zinc anode close to the D4 in a plastic T (anode connected thru the plastic and earthed on the D4.
You will need an expansion vessel to prevent hydraulic lock of the fresh water system when the water heats up....before I did that I kept blowing pipes out of jubilee clips.
It looks like you are aiming to do the same.....KISS.....Keep It Simple St*pid.
A coolant pump second had from a car will do the job of circulating the water around the D4. Another pump to pressurise the hot water tank to get it to the tap.
I used plastic "quick fit" pipe and couplings for the plumbing both hot and cold.
You will need a vent close to the D4 to clear any air from the system during commissioning. Again ebay search will find that.
If you do overheat the D4 it should shut itself down without damage.
A diagnostic device to plug into a laptop can be had from ebay cheap for sorting any problems with the D4.

Neil

JasonDS · 23-04-2017, 03:47

Thanks for the reply. Very interesting and glad it works. Not yet at the stage for installing but now i know what i need!

Sputnik · 23-04-2017, 23:55

Hi Jason,

Just re-read my post, not sure the vent was well explained....a picture is worth a thousand words:

Black Nylon 16mm Joiner With Bleed

Neil

JasonDS · 24-04-2017, 12:46

Quote:

Originally Posted by Sputnik

Hi Jason,

Just re-read my post, not sure the vent was well explained....a picture is worth a thousand words:

Black Nylon 16mm Joiner With Bleed

Neil

Out certainly does [emoji106]

JasonDS · 24-04-2017, 13:01

Quote:

Originally Posted by JasonDS

Out certainly does [emoji106]

***it*** certainly does :-)

cj88 · 03-06-2017, 16:37

Quote:

Originally Posted by ColdEh Marine

First , you cant run your domestic water through this heater, these things don't work like that . They are filled with 50/50 antifreeze mix , the same you would put in your engine. You need to build yourself a circuit. With a buffer tank to add mass to prevent short cycling of the system . Short cycling causes a build up of soot in the combustion chamber and exhaust. You have to think of this heater like an engine , and remove heat from the circuit the same way you would with engine heat . You can put a copper coil inside the buffer tank and remove heat that way , or you can heat the water like you would with your engine heat running through your hot water engine loop circuit . The later is the simplest way but you will still need that buffer tank . If you don't use a buffer tank the heater circuit will reach its high temperature cut off point and then just short cycle . Also remember that the exhaust of these units get very very hot and will burn down your boat if it is not isolated from any thing combustible. These systems take a little bit of thought and design but if done right they are virtually trouble free .

Regards John.

Are you able to post a sketch as I tend to learn visually and I'm trying to picture this? What size does the tank need to be?