Seeing
http://www.pentairaqua.com/en-US/product/standard/valve-in-head/ I see that there is a product with a built-in bypass. However those, such as Pentek 150164, do not seem to use 4.5 inch diameter elements. Maybe I have missed it. If I did, I would find the model number you are looking for, and include that in your searches. I see a lot of hits when I search for
Pentek 150164.
Instead you might consider making your own bypass. It could be implemented with 3 valves.There is just a red button on the top of the regular BB filters that allows water to dribble out for the purpose of relieving pressure after you have isolated the filters with your bypass.
While plumbing, you might consider having a water pressure gauge before and after the filters to gauge when the backpressure is getting higher to help decide when to change the filters. In my case, getting a boiler drain valve (faucet) plumbed in is useful for handy water access. But that will not be something you will need.
I suggest that you have a spare O-ring, but since you are wisely planning a bypass, that is not so critical. You also want some plumbing silicone grease to lube the O-rings each time. Wear nitrile gloves when handling that grease. It is not poison, but it can be messy. I got MolyKote 111. That is thicker than some. The purpose is to lube the O-ring so that it spreads out evenly, so a less viscous silicone will work too. Never use petroleum product on the O-rings.
I went for the 4.5x20 inch housings. They are heavier when full, but they have more capacity, less backpressure. So depending on the room etc, that might be an option. However the 10 inch Big Blues have much more capacity than your average sediment filter. Do not use a wrench to tighten, but you want a wrench to loosen. I have used discountfilter store. They have a nice finder for filter elements. But there are other good sources. The housings are intended to mount to the bracket with 5/16 x 1 lag bolts. I used a tap and machine bolts because it was handy. They are offered pre-mounted and interconnected. Do not use a galvanized nipple to connect. I used both teflon and pipe dope, but that is overkill if you are using a good nipple.
If your water is not chlorinated, use polypropylene filter elements; stuff can grow on cellulose. I opted for DGD-5005-20 polypropylene spun 50-5 dual gradient 20 gpm and PENTEK-WP1BB20P polypropylene wound WP1BB20P 1 micron. I also have the first of 3 housings empty. It's more than I needed, but I took a more pessimistic approach that I did not know, so better overkill than underkill.
