Pressure problem in new addition

[scott francis]

Hello all, great forum. Came here from John Bridge with a specific plumbing problem. Currently about done with a big addition and have a potential water pressure problem. I'll see if I can explain it well enough and maybe you guys have some ideas.

Currently have a small 20 gal welltrol pressure tank and a 50 gal water heater (electric). My well pump is running at 7.5 gpm. I have one bathroom 18 ft away and 8 ft above this system. Pressure is decent but not fabulous.

With the new addition I need to accommodate 2 new full bathrooms side by side about 50 linear feet away and 12 feet vertically. I have two new water heaters (rinnai 53i LP direct vent) one for old section of house immediately after pressure tank and one immediately under new baths 50feet away. The first one will feed old section of house (bath, washer, dishwasher, kitchen...) and 2nd will strictly feed two new baths. There will be a pex manablock (sp?) with the new heater to feed all fixtures in new section. We'll be running 1 inch pex from origin to manablock then 3/8" feeds for the two new baths to try to keep pressure but not sure thats sufficient.

I believe I need to add some kind of pressurizer to my lines to accommodate the new shower (moen head with 4 body sprays). We (GC, me and plumbing supplier) are afraid pressure will be insufficient.

I have looked at Davey BT20-40 and Aquaboost II systems but really don't understand it all. According to the plumbing supplier: add a new welltrol 84 gal pressure tank, a new 200 gal holding tank, aquaboost II pressure pump. This will cost about $1600. Problem is I don't have the room to add a new 45 gal and 200 gal tank plus rinnai water heater and pressure booster in the space available. I'm trying to find a way to get sufficient pressure by adding only one tank or just replacing old welltrol with new bigger one and some sort of pump.

Any ideas how I can get enough pressure to my master bath without all this????? Thanks in advance, I really appreciate it.

Scott

 

[Bob NH]

You need to get your whole water system planned before you add more pieces that may not work together. You are on your way to spending a lot of money on something that won't work because you don't have enough water supply. Then someone will have you adding bits and pieces that they tell you will fix the problem, and before long you will have the plumbing equivalent of a crippled elephant.

First, decide how much water you need (gallons per minute for how many minutes) for your peak demands. Will a 7.5 GPM well meet those demands? Is the 7.5 GPM based on capacity of the well, or the capacity of the pump in the well? If the well will deliver the peak demand you would be much better off with a larger pump in the well than with tanks and booster pumps.

Even if the well will not deliver continuous demand, it may have the capacity to deliver the intermittent damand that you need for the new bathrooms with multi-showers.

Will the water heaters, apparently on separate circuits, meet the demands of their respective circuits?

A 1" PEX line will carry a lot more water than you can pump.

People have reported problems with the Davey booster pumps and they use metric parts that are hard to get. I would find something else.

The 3/8" feeds to the baths are probably too small for multiple shower heads, unless you will have one line to each head.

Do you have or need a water softener? The instant water heaters are intolerant of hard water.

There are so many questions that you need to answer for yourself before anyone can give you really good advice, but the first thing you need to do is decide how much water you need and the best way to get it.

 

[Sponsor]

 

[Wet_Boots]

I would be thinking of more pressure-tank storage before I would ever consider anything like a booster pump. The existing pressure switch can always be readjusted for a higher cutoff, for more pressure in the house. The well/pump creates the supply, and the tank(s) help feed peak demands.

 

[scott francis]

Ok, decided to go with a new wellxtrol 86 gal tank. My feeds into and out of the tank will be 1". I will have 1" going to the manablock. To feed the shower head (2.5 gpm max at 80psi) i should use 1/2" pex?? Seperate feed for the 4 body sprays they are also 2.5 gpm max at 80psi each, should be 1/2" pex also correct??? I'll eliminate anything else for now.

I have plenty of draw for my well according to my well driller, my water level is at 80' and my pump is down 250'. My pump draws 7.5 gpm but if need be down the road I could go bigger.

My water needs are simply to get usable volume and pressure in the new master bath shower. I don't imagine I can hit max of 2.5gpm at the head and 4 body sprays but I just want to get sufficient pressure and volume. Thanks

 

[Wet_Boots]

so, it's 12.5 gpm for the shower? (2.5 gpm times four body sprays, plus shower head) - how long will the showering endure, and will your water heater be able to supply this bacchanalia?