Poppin

I'm thinking the aerator in the tap is also reducing flow. Removing it however leaves me with a narrow jet (it's a pull out tap with Flexi hose inside). Is there such a thing as a high flow aerator that would basically allow the pumps capacity through? Like 11 litres/min. Can't find this anywhere, highest seems to be 7 litres/min.

I changed down to a Jabsco parmax 2.9, solved the issue. Flow rate was too great for my pipes. Now onto the next issue, the prefilter before the kitchen sink is reducing water pressure a bit too much, what would happen if I put a small accumilator between the filter and the tap, would that not improve pressure?

All of these things causing cycling when the taps are closed and the pump is supposed to be not in use. My problem is specific to the flow of the kitchen sink only. When the cold tap is open, the pump cycles on and off causing a pulsating flow. I naturally thought this was a blockage, until i changed the tap and got the same problem as of the second try.

can confirm its not the aerator, I removed it and still pump is cycling.

But if it is an aerator or small feed pipes, why would it work without issue for the first few minutes? The aerator clearly isn't blocked, its a new tap and behaves like the old one.

Ok so this is now a real mystery. I got to a point where everything is running well in all outlets except the kitchen sink (closest to the pump). Since BOTH hot and cold taps would cause the pump to cycle on and off every second, I reached the conclusion that the tap itself must be blocked with limescale or similar. Sure enough, I removed the top part of the tap (unscrews from the mixer), opened the taps and the pump engaged properly! I wanted to replace the tap anyway, with one of those large, pull out hose taps as we have a large Belfast sink. Just replaced the tap and pump engaged properly on first use. Now, however, it is cycling again!! What on earth could be causing this? And only in the kitchen outlet!? Could it be a symptom of the new pump with higher flow rate having undersized 15mm pipes? I do have a cold prefilter fitted just before the sink, but this prefilter also supplies the bathroom basin, and that flows fine, so can't be that messing with the pressure.

So you're saying that reducing the pressure to the pump cut in will make it BOTH an expansion vessel and an accumulator? Though with less expansion capacity... No the pre-existing outlet and inlet pipes are copper. I can quite easily replace with flexile hose if this will reduce the noise. I think we may have found the problem here. The last pump was something like 10 litres/min. The 45ft run (one way) is only 15mm speedfit pipe (and some copper). Since this pump is more litres/min could this be causing my pressure and noise problems?

So could this be my problem... The old shurflo I took out was a 30 psi pump, the Jabsco 3.9 I put in (whilst being 13 litres/min and horribly loud) is only 25psi. The pressure problems I've had since getting this boat could be due to the fact that 30psi wasn't enough to begin with. The water has to travel a good 45 feet to the calorifier. But at least it was enough to charge the calorifier. 25psi now just doesn't cut it, so I'm left with a very poor flow, both because the new pump isn't charging the calorifier AND because it's cut in pressure is too low causing it to cut in and out. Perhaps if I went for a 45psi pump (and pumped up the expansion vessel to match this), and perhaps also got an accumulator to go next to It to smooth things out?

Presuming the cold input to the calorifier is at the bottom and the hot output is at the top (am I right?), What I have is an isolation valve, followed by what looks like a non-return valve, followed by a T that leads to the expansion vessel, and then the calorifier. Does this mean I have an accumulator rather than an expansion vessel? Expansion vessels provide somewhere for expanding water pressure to go as it heats up, so if it were an expansion vessel it would be pushing the lower down water into the vessel, is this right? Is this tank being used as an expansion vessel? I'm wondering if fitting a separate accumulator closer to the pump would help my problems too.

Do you mean switch off the pump and then drain the pressure from the calorifier?

From what I gather, the new pump.is supposed to cut in at 15psi. How do I check the expansion tanks pressure? Do simply put a gauge on the Schrader valve on top? Or do I need to disconnect from calorifier first? Can it be pressurised with a simple bicycle pump!? I thought perhaps it takes its pressure from the calorifier. Is there any reason why the expansion vessel is fitted to a pipe that enters the calorifier at the bottom? Since hot water rises I would have thought higher up would make more sense? Can someone explain this to me? Here are some pics:

Right... So for a while I have been suffering with poor water pressure and various other problems. My shurflo started leaking so I decided to try a quick pump swap to see if it solved everything. I changed it for a Jabsco par max 3.5 (seriously LOUD pump!), and while everything was disconnected I also opened the sediment prefilter under the sink. The filter element was so clogged up that I decided to order a new one and, meanwhile, just put the filter housing back together without the element. I have a strange situation now. The pressure in most of the taps is fine. However the kitchen sink taps (closest to the pump), have terrible pressure and the pump basically goes on and off pushing out a poor, pulsating flow. This doesn't happen with the other taps. I have tried sucking on the mixtap in case of air lock. I have noticed a slow drip from the mixtap which I'm not sure is related. I will turn off the pump and inspect the washers. Furthermore, the old pump would pre-fill the calorifier until pressurised when the hot taps have been open. This pump does not, and simply pushes hot water through in a similar on/off fashion as the kitchen taps. I don't particularly miss the pressurising into the expansion tank that used to happen, because it would always be like stored cold water that I would need to get out of the tap before the hot came through. I could never figure out this problem either. Anyway, I have found the screw under the cover on the new pump that I imagine is a pressure or cut in adjuster. Can someone confirm this and how it works or if it's even part of the solution!? Any advice is much appreciated!

Smart bank advance is installed with smart gauge

Thanks for all the replies in such a short timeframe! I have been on the phone with Adverc and they've sent me over some documentation. Seems they do a reasonable discount if you purchase both a 90A alternator and Adverc controller. Just trying to absorb all the info in what they've sent. To quickly answer some of your questions: I base the SOC on the Smart bank advance system I have installed. Hopefully this picture will give you an idea of pulley ratio (I KNOW THE POWDER RESIDUE IS FROM THE BELT, this is an old pic)

We have had our Honda EU20i generator nicked and rather than replace it I'd like to get the engine charging up to scratch... We have a 550AH leisure bank, typically we would charge this with the generator via a 60A sterling pro charge ultra. Current engine charging setup has a BMC 1.8 and a single 75A alternator, which is currently putting out max 29A at the start of charge (with the bank at about 65%). This soon drops to 5-15A, long before the bank is at even 80%. As you can imagine, this all makes for slow charging. 1. Does it sound like my belt is loose? I would expect to get higher output from the alternator. 2. What are my options in terms of alternator upgrade? I'm sick of messing about with split charing so maybe I can take the opportunity to fit a second, higher output alternator exclusively for the leisures? I'm not hugely bothered about the engine's propulsion power being a bit affected. What is the highest output alternator one could fit to a BMC 1.8? 3. I know there are alternator to battery chargers that can increase the amps being put out, any experience with these? 3. Or maybe I should be looking at reducing my battery bank? We don't really consume much these days and charing is perhaps too much of a burden. Any advice you can offer is hugely appreciated!