Yes pex will work with Sloan valves, its simply a matter of sizing the system correctly. Sounds like you may need a 1" trunk line, also at least a 3/4 hot water trunk line. Are you looking for material costs or labor costs also, because labor is completely dependant on you area.
I'm in Detroit. Let's see if we can do a rough estimate on both. I know I can get the materials, as far as the piping but I'm not sure about a manifold for the pex. Also, the main water line from the street and the water meter in the house has already been replaced with CPVC piping. Problem is it's tied into old galvanized riser piping for the hot and cold water.
Well you can do pex 2 ways. You can run it like you would copper. Meaning you run one main line and put in T's for all the fixtures as you go. You can also do what is called a "home run" system, where you run individual lines from a manifold as you were referring to. Since you have sloan valves, you would have to run individual larger lines from the water service to provide them with the needed water volume, if you ran a home run system.
Let's go with the home run system then. What you first described has already been attempted by a plumbing company that I hired. It not only looks terrible, 2 of the sloan toilets don't flush properly. The do have new Zurn valves on them now but it has galvanized risers. The other sloan toilet still has the original sloan valve and it flushes fine but it's tied into a copper riser. That's the only riser that is copper.
This house was built in 1926, the galvanized pipes need to go. All of them.
Copper from the boiler and the hot water heater is new so you can omit that. Also copper to the washing machine is also new. I forgot to mention that. That can also stay.
I completely understand, I dealt with alot of old galvanised. I believe you will need around 1500 feet of 1/2 pex and 1 roll of 3/4 pex. You will need a 10 tap cold manifold and an 8 tap hot manifold.. You will need 4 3/4 T's for the toilets. I would expect the materials to run around $900-$1200. This should take 2 men 2 to 2.5 days if everything is readily open and easy access so 32-40 man hours at $75/hr $2400-$3000 in labor at a service rate. A bid job would probably make it about 15-20% cheaper.
I would look into a "mana block" system for your 1/2 inch lines, its cheaper than the manifolds and you can expand it as you need to.
Well that's good news. Unfortunately I paid $6000 for the hack job that was done and I am not happy at all. The original contract states they were to install a Pex Distribution System and it was not done. The plumber that did the work was eventually fired but not because of me. So now the plumbing company keeps making band aid fixes. I've had at least 6 leaks and this has been dragging out since Sept 6th! I live in the house and I feel like I'm camping.
I've seen that before and I feel for you. That is deff the advantage of the home run system. No Joints!! One warning on it though, it takes a long time to get hot water to the farthest fixtures.
I would consider talking to the city about the companies surety bond. If the work is substandard they are required to fix it or the bond is forefiet. meaning they can't work in the city.
Don't worry. I made the owner of the company come over here today and I had a list a mile long. They are "working on" a resolution. I personally don't think I want them to touch another thing in this house so that's why I contacted you so I have a rough idea of the cost to have another company come in and do the job.
Now that's some great advice! I will get in contact with the city.
Good luck, have a good night!