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Post by Bora on Jul 28, 2020 18:51:28 GMT
The parmax 4 can put out 40psi from what I can see, well below the pressure relief valve rating.
I assume the shore water connection puts out more pressure as when i’ve opened it up fully to fill tanks or rinse down it comes out at some rate but that could be more the 19mm hose that’s allowing it rather than pressure in the system.
I’ve tweaked the pressure switch on the parmax again and it seems to have helped a bit....although there is still enough water entering the bilge that if left on auto then the bilge pump will cycle every 20 min or so. I’ve taken to leaving the pump off and the deck plate off so I can monitor it.
Further to shantiskipper’s post above I wonder if the angle the calorifier is at has any relation? Maybe it could do with more elevation towards the stern and prevent any sediment from entering the valve?
As we all know getting into the FW tanks is nigh on impossible so come laying up time I might put some good chemical that’ll break down any minerals into the tanks and flush the entire system. I will of course then have to give the tanks numerous flushes with FW.
I’ve started filling the tanks and running shore connection with a filter, carbon I think although not sure on the microns....standard looking big water filter. So hopefully that’ll be the last of extra build up but I may well implement the 2 stage system as above.
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Post by rene460 on Jul 29, 2020 13:06:35 GMT
Hi shantiskipper, it’s great to have you come out of the dark. By now you will have noticed that this is a great place to contact like minded boating people.
Regarding the issue of having to run the pump with the taps open after emptying your water tank, it is quite normal.
When the tank empties, the pump draws air into the system. Due to the internal configuration of the pump, it cannot act as a compressor and pump air, so it never achieves the discharge pressure necessary for the pressure switch to stop the pump. It’s about clearance volume if you want more detail. The simple solution, as you have discovered, is to run the pump with the taps fully open, so that virtually no pressure is required to purge out the air and get the system full of water again. Then you can close the taps, the pump will reach the required pressure when operating on water, and the pressure switch will again operate.
You actually only need to purge the pump so it is operating on water, not the whole system, but you have probably also noticed that while discharging air, the taps splurt and splash and make a noise while discharging air. Consequently, for the sake of the taps and piping, and to prevent the splashing making a mess, I find it helpful to purge the air out at both the bathroom tap and the sink. However, I don’t worry about the transom shower, as it is used less often. When it is used, running it with the tap just a little open until any air is discharged, avoids the water hammer and the possibility of damaging the piping.
However, the pump continuing to run when you have plenty of water in the tanks is more puzzling. Two possible causes I can think of.
First, you could get some air into the piping of tanks are low on a rough trip. Then with some water use, that air reaches the pump, which cannot compress air enough to reach the pressure switch setting.
But more likely, several owners, including me, have had the filter on the pump inlet leaking around the cover. Because the inlet filter is at low pressure, especially when the tanks are a bit low, it leaks air in. Sometimes the clear cover is cracked, sometimes it is just leaking. It might be worth carefully removing the cover, lubricating the seal ring with Hydroseal, or Vaseline and refitting it. I say carefully because the cover seems easy to crack, possibly just old age of the plastic. I found lubrication seemed to be effective for a shorter time each time I did it, and I eventually had to replace the cover. It was not available as a separate item, so I had to buy the whole replacement filter. I think the manufacturer of the pump needs a flea in his ear, but I don’t have enough energy to fight that war. Which unfortunately means they get away with not improving the design, or at least supplying covers as available separate spare parts.
The discharge of the pump is always above atmospheric pressure when the pump is operating, so any leakage there will always involve water out, not air in.
rene460
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Post by Bora on Aug 7, 2020 9:04:43 GMT
So.....the hot water tank has been totally drained and there doesn't seem to be anything in there blocking the valve.
I've had the bike pump on the accumulator for a while now and when the valve goes into freeflow it is indeed over 6bar on the pump.
This is also when the pump is running but the green indicator isn't on, does anyone know what causes the green light to come on? If i short the two pressure switch wires then the pump goes on but I forgot to check if the light came on then as well.
So i'm wondering if there is possibly a problem with the pressure switch or perhaps the relay. Maybe if the relay is sticking "on" it could be that the pressusre switch is "off" (hence no green light) but the pump continues to run.
This is now my third parmax4 and the issue has been with all 3 so i'm starting to lean towards the relay now.
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Post by Bora on Sept 2, 2020 16:52:22 GMT
So it appears the saga has come to an end!!!! I took the relay for the water pump apart and found that there was scorching on the contacts, not sure if that was as a result of sticking or perhaps was causing the sticking. A new relay and much time checking the pressures are correct for the accumulator and pump and we're back in action. To get the pressures right I checked what they were supposed to be on the Jabsco website then connected a bike pump to the accumulator and then let all the air out, then with the pump on and the tap open that allowed me to check the CUT IN pressure was ok. I then pumped the accumulator up to the pressure stuck on the pump/valve/accumulator backboard (was all supplied as one unit from Jabsco by the looks of it) 1.2 bar if i remember right, which is just BELOW the CUT IN pressure of the Parmax4. NOT the pressure that is stuck on the side of the accumulator which was 3.5 bar and is what the tank is initally supplied with. I then sat with the bike pump where i could see it and a small screwdriver on the pressure adjust screw. Then with the expert help of the girlfriend taps were opened and closed as needed until i had the pump cut out set correctly as per the Jabsco site (2.8 bar i think.) All is now running well and cycling as it should be with no over pressures and no leaking calorifier!!!! It's had me chasing for 18 months but happy it's now fixed
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Post by moonshadow on Sept 3, 2020 12:24:00 GMT
I had problems with hot water tank valve when a wrong pump was installed on my boat. The previous owner had installed a pump not designed for a system with an accumulator and the whole system went wacky. There was no Place for excess pressure to go as water was heated unless the accumulator was very carefully and precisely set. I don’t remember what worked. I changed the pump back to simple pump and it all worked again. As to noise, I use rubber feet on the mounting bolts and the noise is just enough that I know when it runs. Not bothersome. But perhaps my hearing isn’t what it used to be.
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Post by pipemma on Sept 7, 2020 14:24:59 GMT
This is an interesting thread... I just came on to post a new thread (and will still do so - feel free to redirect me back to this one) because of water in the bilges that we're 99% certain is coming from the FW expansion tank.
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rods
Full Member
Posts: 25
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Post by rods on Nov 30, 2020 14:30:55 GMT
Hi I have been facing the same problem on on my SO 35 2006 and tried everything but to no avail. I currently run the outlet into a plastic bottle in the bilge and empty when full. I now have floor up to see Ida route the outlet from the pressure release valve to the outside of boat. The closest sea Cock outlet is he swine valve for the lift keel which is lower than the outlet of the pressure relive valve. Has any one done this or can this cause a problem
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Post by zaphod on Nov 30, 2020 20:45:55 GMT
I know this is an old thread, but it seems to be a recurring problem.
There are only a few things that will cause a pressure relieve to open, (aside from a faulty valve). If the accumulator has failed and lost it's air cushion, then pressure will build up as cold water heats because there is no room for the water to expand as it heats. If the pressurized water pump cut-out setpoint is higher than the opening pressure of the relief. Sometimes pressure relief valves will not seat properly once they have opened.
Something else to keep in mind is that on all hot water tanks on land the valves are pressure AND TEMPERATURE reliefs. They have a temperature sensing element that will open the valve if the water gets too hot even if the pressure is ok. I don't know if all boat water heaters are T&P, but it wouldn't surprise me. Someone in this thread mentioned that their water was very hot; that could be what is going on.
The water could be getting too hot because of an incorrectly set or faulty thermostat.
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Post by Bora on Nov 30, 2020 23:40:03 GMT
if the accumulator is holding pressure and there is no sign of water in it (turn off the pump and let all the air out of the accumulator to check) then it'll likely be a faulty valve or pump pressure.
If you have a pre-made water board (with the pump, valves accumulator etc. all mounted) from the likes of Jabsco then there may be some numbers on there that will tell you what the accumulator pressure should be set at. My accumulator said 3 bar on the cylinder but according to the sticker from Jabsco it needed to be set much less.
In the end I ended up with a much lower pressure in the accumulator than I thought I needed and then adjusted the pressure on the Jabsco Parmax4 to the settings as described on their website.
This fixed everything and I could then use the whole system as normal again, no more free running water pump pushing it all into the bilge via the calorifier.
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