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Hot Water Boiler Dropping

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RalphK View Drop Down
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    Posted: 28 May 2020 at 18:13
I also put a hose on the overpressure valve and drilled a whole into the aft compartment of the life raft and let it drain there. So no need to remember anything, I never had any water below the boiler..




Edited by RalphK - 28 May 2020 at 18:14
SY Wind Pearl, Hanse 385#358
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sflier View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sflier Quote  Post ReplyReply Direct Link To This Post Posted: 19 May 2020 at 15:34
Originally posted by Martin&Rene Martin&Rene wrote:

Isotemp stress that the calorifiers must be mounted horizontally and not vertically and so I wondering where that means there will actually be an air-space at the top of the tank which could absorb some of the expansion.  

  

I believe they want it mounted horizontally to provide a means of draining the tank.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Martin&Rene Quote  Post ReplyReply Direct Link To This Post Posted: 19 May 2020 at 12:44
I fitted one of the standard non-return valves from the chandlers into the cold water system and it leaked at an enormous rate.  I think that they are designed just for maintaining the fluid in the suction pipework of a pump or to prevent back-flow in a discharge pipe and not for use in a pressurised water system. 

Isotemp stress that the calorifiers must be mounted horizontally and not vertically and so I wondering where that means there will actually be an air-space at the top of the tank which could absorb some of the expansion.  

  
Martin&Rene Hanse 341 Dipper Wheel steering, 3 cabin layout, normally based in Scotland
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sflier View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sflier Quote  Post ReplyReply Direct Link To This Post Posted: 18 May 2020 at 18:17
Like others, I ran a hose from the pressure value to the engine bilge so it would be easier to monitor and mop up.  We also turn the water pump off when running the engine and relieve some pressure from the system via the sink water tap. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Wild Quote  Post ReplyReply Direct Link To This Post Posted: 18 May 2020 at 13:28
hello
to determinate the amount of water dripping from the pressure valve is not easy.
it depends on the capacity of the boiler and the temp inside at the moment you start heating and finaly at which temp the heating stops at max temp.
water increase 0.021% in volume each 1°C you heat it up .this is only correct at 20°C it change a bit at other temp but this is negligible.
example 1) boiler 40 liter startup temp 15°C end temp 80°C Delta T =65°C
                 0.0002x65x40=0.52 lit.
              2) the same boiler 40 lit startup temp 45°C end temp 80°C Delta T=35°C
                 0.0002x35x40=0.28 lit.
a other thing you have to keep in mind : the difference between the pressure in the watersystem( depends waterpump?)  and the pressure valve(normaly 6Bar, warranty tank?) at startup heating.
 dont't leed the draintube from the valve upwards (calcification can block the valve, warranty tank) it has to go free and open( no fix connection to avoid return in to watersystem by syphon) and always downwards in to the bilge, container our petbottle.
if this is not possible you can fix a non return valve and  a small expansion tank (Jabsco) downstream  the coldwater intake (pressure valve) of the heater tank to avoid dripping.
This is my idea as an ex plumber.


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Martin&Rene View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Martin&Rene Quote  Post ReplyReply Direct Link To This Post Posted: 18 May 2020 at 10:18
I have made a number of comments on this topic in the past, so I have pulled together some of the here.

You may have an adjustable water freshwater pump and you will find there is a knob on the top of the pump that you can adjust so that you can turn it down as low as gives you a satisfactory flow rate at the tap and at the shower.  If the pump setting is too high then when the water is heated in the calorifier, either because the heater is on or the engine is running, then the pressure in the hot water system may be too high for the over-pressure valve. 

A test is to dry the area by the calorifier valve.  Then whenever you switch the engine on or the water heater on, turn off the water pump and run the hot water tap until no water comes out.  Once the water is hot, you can switch the pump back on.  If this seems to eliminate the water leakage, then it is the PRV.

On the calorifier I have put a section of small diameter plastic tubing onto the overpressure valve outlet, secured with a jubilee clip, and then taken this up to the plastimo shower outlet in the transom in which I had drilled a small hole and just secured the tube with sikaflex.    So any leakage goes over the side.  When I drain the system in winter, there is normally just a bit of water in this pipe and this suggests the valve is still leaking slightly, but at least it is not back into the bilges.

I still appear to have a very small leak from where I installed a water filter for the galley cold tap.  So our practice is that when we start the engine or switch on the water heater, we switch off the water pump, run a small quantity of water from the hot water tap to slightly depressurise the water system and then switch the water pump back on again.  You do not want the pump to cut in again, so you may have to work out how much water to run off by trial and error.  This stops the pressure in the system climbing too high as the water in the calorifier goes through the initial stages of heating, which is when there is a probkem.

I drain the system with the cold water tap on in the galley and with the shower head switched on with the hot tap and placed on the floor in the shower tray.  When the water pump has ceased to pump water, I switch it off and then on my yacht (a 341 with the calorifier in the stern locker) I get a syphon effect as the calorifier is above the shower floor level and the calorifier basically drains into the shower tray.    Having drained the calorifier as above, I remove the tubing from the PRV and and drain the final small amount of water into a tray from the calorifier. 

 

 

Martin&Rene Hanse 341 Dipper Wheel steering, 3 cabin layout, normally based in Scotland
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is46664 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote is46664 Quote  Post ReplyReply Direct Link To This Post Posted: 17 May 2020 at 01:14
I
I use this set up - a length of clear hose into a container 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jens82 Quote  Post ReplyReply Direct Link To This Post Posted: 14 May 2020 at 21:21
Thank you all for your tips and experiences. I will connect a hose and see if it's getting better. Thank you all! 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MasterKeil Quote  Post ReplyReply Direct Link To This Post Posted: 14 May 2020 at 15:26
When we use the engine, then we switch off the water pump and open the hot water tap. So the expanding water in excess drops into the sink.
If your water boiler also drops when the water is heated electrically, then you should adjust the thermostat (lower the temperature a bit) to a value that prevents the overpressure valve to open.
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samuel View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote samuel Quote  Post ReplyReply Direct Link To This Post Posted: 14 May 2020 at 13:15
After the first 2 years I took the safety valve off altogether. I do not overtighten the heads tap. It drips for a while after I start the engine because the water gets very hot. I also make sure that the sink tap is not too tight if on shore power. Never had any problems since, apart from the odd dripping tap.

Daydream Believer- Hanse 311- No GBR9917T- Bradwell Essex
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