marmaduke Posted October 1, 2014 Report Share Posted October 1, 2014 (edited) Hi all, I'm about to change a faulty water pump and am looking at my current setup wondering if all of it is needed. See the picture below. I've been looking at trusted diagrams, and they all seem to say strainer > pump > accumulator > heater. I seem have some strange grey box attached between the pump and accumulator which has the electrical connections going through it. I'm guessing it is some kind of sensor for water pressure? The pump in use is not the original one. The original pump did not have a pressure switch, so perhaps this had something to do with it? I don't recall it doing anything noticeable though, before I changed it for the pressure switch water pump (that I am about to replace). Can I take it out do you think? I'm also wondering if I should change the accumulator for a new one, as this is from 1979. Any recommendations on what to get? The new pump will be a shurflo 30psi pressure switch pump. Any comments are greatly received. M Edited October 1, 2014 by marmaduke Link to comment Share on other sites More sharing options...
Eeyore Posted October 1, 2014 Report Share Posted October 1, 2014 (edited) Hi M The grey box is a pressure switch. These have been found by many to be more reliable than the pumps inbuilt pressure switch. It could be part of the original installation, or it could have been added to replace a failed inbuilt switch. Wire the new pump directly to the supply (black cable?) to preserve its warranty, and leave the grey pressure switch in situ just in case you need it later. NB The pressure settings are usually somewhere on the grey cover, maybe inside. This will be the pressure your system has been operating at in the past, and if you were happy with it, should be the pressure setting on the new pump. Steve (Eeyore) Edited October 1, 2014 by Eeyore Link to comment Share on other sites More sharing options...
marmaduke Posted October 1, 2014 Author Report Share Posted October 1, 2014 Great, thanks Steve, I'll do as you suggest. M 1 Link to comment Share on other sites More sharing options...
Oakie Posted October 2, 2014 Report Share Posted October 2, 2014 How strange that this query came up yesterday, when I have exactly the same problem now! Eeyore is quite right about it being a pressure switch. It is a Pumptrol Square D and is said to be very reliable; inside is printed ON 8, OFF 16, which are obviously the factory setting pressures. Mine does not work from the water pressure at all. I suspect that the inlet water pipe is clogged up, so I shorted mine out with a short length of copper wire screwed beneath the two terminals that would normally switch the pump on. This has worked fine for a long time until I found a water leak at the pressure switch end of the old Flojet pump, which caused air to leak into the system through the pressure diaphragm. I changed the pump for a Shurflo with a pressure setting of 35psi, but this appears to be too high and causes the pressure release valve on the top of the hot water tank to blow off, thus emptying the contents into the engine bilge - not good. I now have three alternatives:- 1. See if the centre screw on the pressure switch end of the new pump will lower the cut out point and leave the Pumptrol shorted out. (which is how I found this post). 2. Remove the Square D unit from the pipe and inspect the inlet pipe for crud. 3. Leave it until I get back to my home mooring and order a new Pumptrol Square D. You will find a lot of info about this unit in forums on the net; mostly American, as it is used extensively for controlling water pressure from well pumps. I will keep you up to date. Link to comment Share on other sites More sharing options...
davey b Posted October 2, 2014 Report Share Posted October 2, 2014 If your expansion chamber is from 1979, I'd definitely change it! Mine was only 10 years old when I took it out and I was horrified by the appearance of the water that came out. Link to comment Share on other sites More sharing options...
Oakie Posted October 2, 2014 Report Share Posted October 2, 2014 Bingo! I reduced the pump pressure by unscrewing the centre screw on the pressure switch end of the pump one complete turn. There is still good pressure at the taps and the PRV does not activate. Why don't they tell you this in the pump literature? I believe that some of the said pumps do not have this adjustment, so beware if you buy a new one. There needs to be five screws in the pressure switch housing; the centre one for adjustment. I found the answer from a post by Smileypete in Boating>Equipment>Freshwater pressure sensing nightmare. He seems to have all the answers to water problems! I am now a very Happy Bunny, having sorted out the final problem on this long cruise, which started at the beginning of May. You can read all about it in my blog if you want some good bedtime reading............it will send you to sleep immediately http://nbstronghold.blogspot.co.uk Link to comment Share on other sites More sharing options...
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