Water Pump Replacement

Based on the amount of racket coming from the water pump, it was clearly time for a change. I had replaced the pump head portion last spring, to solve a problem with the check valve, or at least that is what I think it was, although it may have been a diaphragm issue. It was fine after this repair, but then late last season, it started to make a fair amount of noise. This got worse as this season went along, to the point where it became very annoying, and clearly something was screwy with the motor.

I found a good deal online for the Shurflo 4008 Revolution pump, which is what goes into Altos now. This pump incorporates a bypass valve, which is supposed to reduce the rapid on/off cycling of the pump, providing a smooth steady flow of water. This will be an improvement, as the constant cycling of the pump can be quite noticeable. The installation instructions also make it very clear that they do not recommend the use of an accumulator tank, which suits me just fine, as the plan was to remove this when I changed the pump. The accumulator was of no real benefit, mostly because of its minimal water storage capacity.

The first step was to figure out how to rework the Pex tubing to make the connections. The inlet/outlet connections on the pump are at a different height, but this is not really an issue as I am also going to use flexible hoses. More on this later. As I have not invested in a Pex crimping tool, and investment is the correct word to use for that purchase, you then have to rely on another method to tie into the existing tubing. There are a number of fittings out there, such as the Flair-It compression used now in the alto, but they can be very difficult to install, pressing them onto the Pex requires almost super-human strength. My neighbour told me about the Sharkbite brand of Pex fittings, and the great success he had with them at his cottage. I looked into them and they seemed a good choice.

I wanted to reposition the new pump a bit, as well as move around the water filter to be more accessible for easier cleaning. now was the time to do all this planning. I also planned to use flexible hoses to connect to the pump. This is recommended by Shurflo, and is mentioned in all sorts of DIY forums. Currently, the Pex connects directly to the pump, which can allow any vibrations to travel along the Pex, these vibrations are then transmitted to the Alto body, increasing the potential for rattles and noise. Flexible hoses absorb the vibrations of the pump so they are not transmitted to the hard Pex tubing and beyond. You can use any sort of tubing, applicable to the pressure of course, but I prefer the braided stainless with integrated fittings.

Once I determined how I wanted to plumb it to the existing, it then just became an exercise of selecting the Sharkbite fittings needed, attaching the flexible hoses, and then pressing on the Sharkbites. I loosely put everything into place, then fastened the pump to the floor, with an additional bit of cushioning to help absorb the pump vibration. The Sharkbites are real easy to use, they slide onto the Pex with little effort, and have the ability to be removed if needed. Wired up the pump and then turned it on. Always quite satisfying when it comes up to pressure and all the joints are tight.
The pump is quiet. Real quiet. I believe the combination of the bypass valve and the flex hoses make a huge difference. Under constant demand, the pump simply does not cycle, but maintains a consistent pressure and flow. The cycling on and off, which our previous Shurflo (2088 model) did, added a lot of noise to the process. You can see the flex hoses absorbing the movements of the pump while it is running. Given the recommendations to use flexible pump attachments, I'm surprised SC has followed this. From a production perspective, I can't see it  making that much of a difference in the assembly process. The bypass seems to be a great addition to the function of the pump. Perhaps that's the revolution they are referring to when they named the pump. I would have to agree.


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