CLAN1 Posted March 18, 2021 Report Share Posted March 18, 2021 Hi, just fitted a new jabsco fresh water pump replaced like for like.turn on cold tap water flows ok pump works ok consistent flow, then pump starts to pulsate water still flows. Amy ideas why???? Link to comment Share on other sites More sharing options...
BEngo Posted March 18, 2021 Report Share Posted March 18, 2021 Is the pump pulsing on and off? If so, have you checked the accumulator pressure settings? Pump off taps open to check the pressure, which should be the same as the pump cut in pressure. Is the pump pulsing but running steadily? If so, it is probably air in the pipes. Check the water tank is full, turn fully on all the taps ( including the hot ones) with the pump switched on and wait till pulsing stops. Then turn the taps off, starting at those furthest from the pump and working toward the pump. N 1 Link to comment Share on other sites More sharing options...
CLAN1 Posted March 18, 2021 Author Report Share Posted March 18, 2021 Removed the accumulator as apparently pump doesn't need it been having lots of problems lately think accumulator us so not replaced it, water starts to run even flow then pulses, all air out of system, Link to comment Share on other sites More sharing options...
ditchcrawler Posted March 18, 2021 Report Share Posted March 18, 2021 18 minutes ago, CLAN1 said: Removed the accumulator as apparently pump doesn't need it been having lots of problems lately think accumulator us so not replaced it, water starts to run even flow then pulses, all air out of system, Not a good move in my opinion. Does the pump stop as soon as you turn the tap off? Link to comment Share on other sites More sharing options...
Ex Brummie Posted March 18, 2021 Report Share Posted March 18, 2021 6 hours ago, CLAN1 said: Removed the accumulator as apparently pump doesn't need it been having lots of problems lately think accumulator us so not replaced it, water starts to run even flow then pulses, all air out of system, If the pipework volume is relatively small, you may find that with a tap open, the cut off pressure will be reached and almost immediately switch back, and repeat. Your pressure switch will not last long this way. Replace your accumulator. Link to comment Share on other sites More sharing options...
Tony Brooks Posted March 18, 2021 Report Share Posted March 18, 2021 If this is not a variable seed pump the only other ones that I know of where Jabsco say they don't need an accumulator are the bypass pumps with a bypass valve set a little below pump cut out pressure. This allows the pump to keep running with excess volume returning to the tank/inlet. In theory if the ports are large enough the pump should never reach cut out pressure so keep running. I think most have assumed the "pulsating" is typical on - off cycling but I wonder if the bypass valve is "bouncing" so the pump keeps running but the water flow pulsates a bit. Just a thought. Link to comment Share on other sites More sharing options...
Sea Dog Posted March 18, 2021 Report Share Posted March 18, 2021 7 hours ago, CLAN1 said: Removed the accumulator as apparently pump doesn't need it been having lots of problems lately think accumulator us so not replaced it, water starts to run even flow then pulses, all air out of system, I replaced my Par Max 2.9 a bit back due to a small weep. The instructions with that new pump said it didn't need an accumulator. I read that... then still fitted a new accumulator at the same time. Both old pump and accumulator are now carried as 'get out of jail' spares. My advice to you is don't believe the marketing department - stick with what the engineers tell you! Link to comment Share on other sites More sharing options...
Momac Posted March 18, 2021 Report Share Posted March 18, 2021 Try it with the water tank filler cap removed Link to comment Share on other sites More sharing options...
MartinW Posted March 21, 2021 Report Share Posted March 21, 2021 I am gradually recommissioning ( a posh word for replacing everything) my long-neglected boat and got around to filling up the water-tank and opening the main stop tap. The Jabsco 2.9 operated as advertised but was very noisy. After two days of congratulating myself on my hose-pipe and tap-turning abilities the pump stated to run on after taps were closed. I have no accumulator fitted, just a calorifier, so I assumed I had a tired pressure switch. I fitted a square D from RS on a Tee in the pump output pipe and wired it in. As I did that, I realised that the pump and pipes were touching the tank at one side and the bulkhead at the other which explained the noise. The pump runs much quieter but still doesn't shut off when the taps are closed. I adjusted the screws on the switch but cannot stop the pump. I will have a look at the calorifier today and see if I can see the Schrader-valve to check what's happening there. I did notice that warm water was coming out of the cold tap in the galley but thought that that might simply be because the two pipes run next to each other. I guess that you are now about to tell me that my cauliflower is cooked.... Link to comment Share on other sites More sharing options...
Jen-in-Wellies Posted March 21, 2021 Report Share Posted March 21, 2021 15 minutes ago, MartinW said: I will have a look at the calorifier today and see if I can see the Schrader-valve to check what's happening there. Not a Schrader valve, a pressure relief valve (PRV). If it gets a bit of scale under the valve seat it will leak and prevent the water system from staying pressurised and could lead to what you are seeing. A leak anywhere on the system could also do that. The accumulator and expansion tanks, if fitted, have Schrader type valves to allow them to be repressurised from a car/bike pump. 18 minutes ago, MartinW said: did notice that warm water was coming out of the cold tap in the galley but thought that that might simply be because the two pipes run next to each other. I guess that you are now about to tell me that my cauliflower is cooked.... Do you have a non return valve in the cold water input pipe for the cauliflower? If not, then you can get a situation where opening a cold tap can draw hot water back out of the cauliflower, giving what you are seeing. Link to comment Share on other sites More sharing options...
Tony Brooks Posted March 21, 2021 Report Share Posted March 21, 2021 37 minutes ago, Jen-in-Wellies said: Do you have a non return valve in the cold water input pipe for the cauliflower? If not, then you can get a situation where opening a cold tap can draw hot water back out of the cauliflower, giving what you are seeing. Especially if you have air in the top of the calorifier or hot pipes acting as an accumulator. It might be the pump valves have got hard with lack of use and are not sealing so pressure can escape back to the tank/pump inlet. Have you checked the pump inlet strainer is clean. Link to comment Share on other sites More sharing options...
MartinW Posted March 21, 2021 Report Share Posted March 21, 2021 Thanks Jen. Yes I cleaned the inlet filter. I'll investigate the rest after I investigate a leaking sink waste. Cheers Link to comment Share on other sites More sharing options...
MartinW Posted March 22, 2021 Report Share Posted March 22, 2021 I'm guilty of kidnapping this post so I'm sorry but just to let everyone who was kind enough to help know, I have 55litre twin-loop Surecal but it has neither accumulator on the cold feed or expansion bottle. It does have a PRV as standard. The system was obviously put in at a bare minimum specification so I will probably have to set-to and do it right. Thank you for your forbearance and apologies to Clan1 for the rudeness. Link to comment Share on other sites More sharing options...
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