NINOT Posted July 17, 2021 Share Posted July 17, 2021 Hallo everyone, I use Maas 15 submersible pump with cold water faucet. Works great until refilling of canister with water. After inserting pump back in the canister the pump works but the water is not coming out of the faucet. The pump is not able to get rid if the air bubbles in the hose. If I disconnect the hose from the faucet and suck the water and connect it, it works. The pump is brand new, I have tested it outside of my van it it works. Tested the faucet, it is ok. How do I solve this problem? Thanks Link to comment Share on other sites More sharing options...
fripp Posted July 17, 2021 Share Posted July 17, 2021 When you insert the pump into the water shake it up and down to displace the air pocket in the pump. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted July 18, 2021 Share Posted July 18, 2021 NINOT Unlike diaphragm pumps (eg. SHURflo ones) submersible water-pumps are ‘non-priming’. Although they will usually achieve a state of prime when covered with water, expelling the air in the submersible pump and along the water feed-line, this may not always happen. In his book “The Motorcaravan Manual” the late John Wickersham advised as follows: “Airlocks in submersibles. If a submersible pump doesn’t deliver water after it has been dropped into a water container, there are probably air bubbles caught in the casing. To expel air bubbles, disconnect the feed pipe from the motorcaravan. Keep the pump under the water and swing the feed pipe so that the unit bumps several times against the side of the wayer container. This dislodges air bubbles, some of which are sometimes seen rising in the water. Alternatively air is dispelled through the upper end of the hose. To reduce the likelihood of air bubbles getting caught in a pump casing, more recent products feature an air release hole in the top of the casing. The Whale 881 is an example.” JW’s advice is oriented towards usage of a submersible pump with an ‘Aquaroll-type’ water container, but (as fripp has advised) the thinking behind bumping/jiggling/shaking the pump (or tapping it against the water container) applies equally to when the pump is in a motorhome's onboard water tank - it’s to make the pump prime so that it will begin to deliver water. There’s similar advice here https://www.practicalcaravan.com/advice/guide-to-caravan-water-pipes-and-pumps (I have no practical experience of submersible water-pumps, but I was under the impression that nowadays this problem was rare with new good-quality submersible water pumps.) There are plenty of online ‘airlock’ comments. https://tinyurl.com/e4njrnbk but if your Maas 15 pump keeps doing this (I assume the pump needs to be vertical in the tank/canister) I suggest you replace it with a different make/model of pump (say a Reich or Comet pump) with a similar flow-rate and see if that improves matters. (If your Maas pump has a non-return valve, you’d need to make sure the replacement pump also had one.) Link to comment Share on other sites More sharing options...
NINOT Posted July 19, 2021 Author Share Posted July 19, 2021 Thanks, this will be of great help. Link to comment Share on other sites More sharing options...
Goodmorningblues Posted August 3, 2021 Share Posted August 3, 2021 I have a similar problem with air in a submersible pump - it happens every time I fill the tank. To remove the air by shaking the pump is not practical as the tank is under the seats and the pump is positioned away from the access hole.. Is there a pump that does not have this problem? Link to comment Share on other sites More sharing options...
747 Posted August 3, 2021 Share Posted August 3, 2021 Goodmorningblues - 2021-08-03 10:20 AM I have a similar problem with air in a submersible pump - it happens every time I fill the tank. To remove the air by shaking the pump is not practical as the tank is under the seats and the pump is positioned away from the access hole.. Is there a pump that does not have this problem? Have you tried opening the cold water drain tap? There should be a siphon effect when the water starts running out that could move the air out of the pump and into the water line. Your pump is then primed. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted August 4, 2021 Share Posted August 4, 2021 Goodmorningblues - 2021-08-03 10:20 AM Is there a pump that does not have this problem? I can't see 747's suggestion having any chance of being effective unless the pump's inlet were very close to the water-tank's drain outlet and there were a strong flow of water passing through the drain. Even then, I believe 'siphoning' of trapped air from the pump would be most unlikely to take place. You could try inspecting the current pump (that I assume is pretty old) to check that there is no muck/debris around its impeller. Otherwise replacing it with one of the better quality Reich or Comet pumps seems like the best approach (last paragraph of my posting above.) Alternatively, you could replace the submersible pump with a pressure-sensitive pump (eg. a SHURflo pump) that won't suffer from this issue. As your motorhome's water-tank is inboard under a seat, fitting a pressure-sensitive pump should not be too difficult - though this type of pump will be noisier in operation (and more expensive than a new submersible pump). Link to comment Share on other sites More sharing options...
747 Posted August 4, 2021 Share Posted August 4, 2021 Au contraire Derek. My cold water drain starts siphoning as soon as I open it. Plus a lifetime as a mechanical engineer gives me practical experience of siphoning. The OP has not given specific details of his pump. Therefore I conclude that it is faulty. It is either a cheap and nasty (but expensive) Whale pump that does not have a NRV fitted as standard, or it is another make with a faulty NRV. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted August 4, 2021 Share Posted August 4, 2021 Based on Colin's comment in the penultimate posting here https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/New-sea-sloop-5-owner/57108/#M695171 it's reasonable to assume he owns a SEA/ADRIA Sloop 5 motorhome. This model was not produced after mid-2006 (when Ducato X250 vehicles began to be built) but I've no idea what make(s) of water equipment was used in Sloops. Given that Sloops were not manufactured in the UK, it seems unlikely that a Whale water-pump would have been installed, though there are online comments indicating that Adria has fitted a Whale pressure-sensitive switch in some of their caravans and motorhomes. I accept that, if there were no NRV in the water system (or the NRV were faulty) draining water from the tank could suck water back though a submersible pump, but if Colin's Sloop's water system has no NRV (or the NRV is duff) he'd experience much bigger problems than the pump's initial reluctance to self-prime. Using 'lung power' (ie. sucking on a tap) is sometimes suggested as a means to encourage submersible pumps to prime, but a good modern submersible pump should self-prime without needing work-arounds to get it to do so. Link to comment Share on other sites More sharing options...
747 Posted August 4, 2021 Share Posted August 4, 2021 Derek Uzzell - 2021-08-04 1:47 PM Based on Colin's comment in the penultimate posting here https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/New-sea-sloop-5-owner/57108/#M695171 it's reasonable to assume he owns a SEA/ADRIA Sloop 5 motorhome. This model was not produced after mid-2006 (when Ducato X250 vehicles began to be built) but I've no idea what make(s) of water equipment was used in Sloops. Given that Sloops were not manufactured in the UK, it seems unlikely that a Whale water-pump would have been installed, though there are online comments indicating that Adria has fitted a Whale pressure-sensitive switch in some of their caravans and motorhomes. I accept that, if there were no NRV in the water system (or the NRV were faulty) draining water from the tank could suck water back though a submersible pump, but if Colin's Sloop's water system has no NRV (or the NRV is duff) he'd experience much bigger problems than the pump's initial reluctance to self-prime. Using 'lung power' (ie. sucking on a tap) is sometimes suggested as a means to encourage submersible pumps to prime, but a good modern submersible pump should self-prime without needing work-arounds to get it to do so. No Derek, you have got that the wrong way round. The purpose of an NRV is to keep the delivery line full of water, even when the tank has run dry. It stops the water returning to tank. When the tank is refilled there is a ready made head of water and the tiny amount of air in the pump will be put under pressure by the head of water in the newly filled tank. That air will be pushed along the delivery line and may give a tiny splutter as it emerges at the tap. The only pumps that may not work after running dry are submersible pumps without an NRV. I had the misfortune to have a pump failure halfway through a trip and had no choice but to buy a Whale pump. I had similar problems and bought a ridiculously expensive but cheap and nasty Whale NRV which had to be bodged to fit inline with a Whale pump. *-) 8-) Fluid Dynamics is an interesting subject .... to some anyway. :D Try this for some light bedtime reading. ;-) Link (Edited to shorten link to correct page width error) Link to comment Share on other sites More sharing options...
Derek Uzzell Posted August 5, 2021 Share Posted August 5, 2021 The issue that has historically bedevilled the submersible water-pumps used in leisure vehicles is as stated in the quote from “The Motorcaravan Manual” that I included in my posting of 18 July 2021 9:07 AM above. When a water tank/container is filled, air bubbles will tend to collect around the impeller that’s housed in the submersible pump’s water-intake. If the bubbles remain there, when the pump begins to operate this air-entrainment prevents the pump’s impeller getting a ‘grip’ on the water and stops water moving through the pump’s outlet and on into the leisure-vehicle’s water pipework. The time-honoured ploy to encourage a reluctant submersible pump to release air from its intake is to bang the pump against the inside of the water tank/container - but (as Colin has highlighted) often this may not be practicable. It should not be necessary for a tank/container to be filled to a point where there might be sufficient ‘head’ of water to pressurise the pump’s impeller area and ‘push’ any air bubbles up through the pump. If there is enough water in the tank/container to fully cover the pump, the pump should begin to deliver water through its outlet when it starts to run, and this should be the case whether or not there’s a NRV and whether or not the rest of the water system is completely ‘dry' or has water in it. (Plainly, with a submersible pump system, there ought to be a NRV on the pump or separate - but that’s another matter.) That the potential for air entrainment in leisure-vehicle motorhome/cravan submersible pumps is well recognised should be clear from this Reich advert https://reich-web.com/en/products/water-pumps that says that some of their water pumps have A patented ventilation system which is integrated into many of our pumps provides immediate output after immersing into the tank. I’m not omniscient regarding submersible water-pumps (none of my motorhomes have had one) but this Comet advert https://www.scan-terieur.com/comet-submersible-water-pumps/ suggests that ‘basic’ pumps may be vulnerable to air-locking and that - for motorhomes where a submersible pump is in the fresh-water tank - a pump advertised as having a ventilation system or an air lock release capability should be chosen. Link to comment Share on other sites More sharing options...
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