How to plan for new master-shower?

Discussion in 'Shower & bathtub Forum & Blog' started by benze, Jul 23, 2012.

  1. benze

    benze New Member

    Messages:
    63
    Location:
    Montreal, Canada
    Hi,

    My wife wants a new master-bathroom with a kick ass shower. ie: multi-head body sprays, ceiling mounted rain-head, pulsating jets, etc. (She had even tossed in the term steam but I think I may have convinced her out of that). At this point, I realize I am outside of my comfort zone ensure that I have proper water pressure/flow to the bathroom.

    How can I calculate the necessary amount of pressure/flow I need, and if the city supply will even be sufficient? I presume the majority of homes run 3/4" to a bathroom like this, but is that enough? I believe I need to redo my city entrance to be a 2" to compensate for sprinklers in the new addition, so could potentially run larger pipe - I just don't know if I need to.

    Can anyone point me in the right direction and/or help me understand the subtleties of these kinds of installs?

    Thanks!

    Eric
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,949
    Location:
    New England
    First, what is your local static water pressure?

    The next thing to do is to determine how many outlets will likely ever be running at the same time, read their individual specs, and add up their flow. Then, look at the valve's specs to see how many GPM it can flow with the specified inlet. If everything aligns, it should work.

    Keep in mind that this car wash will need a very SIGNIFICANT water heater. A waste water heat recovery system should likely be considered in the plan to minimize the size requirement. Those require a decent vertical DVW section to operate efficiently (i.e., they don't work well on a horizontal section).

    You may need to upgrade your drain system, and consider multiple drains and larger diameter pipes. If you want to go with a steam shower, that is a whole other can of worms you need to add into the plans with its own requirements.

    I'd also look into surface applied waterproofing systems. Pretty much all of the thinset manufacturers and some other specialty houses have their own, and you'll get various opinions on which one is best. If properly installed with good workmanship, they all work, and, IMHO, are superior to the traditional methods.
  3. benze

    benze New Member

    Messages:
    63
    Location:
    Montreal, Canada
    I'm not sure of my exact static pressure, but I believe it to be around 80psi. I need to double check. I don't expect it to change if/when forced to change my main as it would still be drawing from the same city main.

    Thanks for pointing out the outlet vs the valve. I had never really considered that given that I always considered single head installs, and never had to worry about several outlets pulling from the same mixer/valve. I'll keep my eyes open on that one.

    Quite frankly, that is my biggest concern; I'm not sure how to account for how much hot water to plan for. I currently have a 60gal tank, and am under no illusions that it will suffice. My uninformed gut tells me I should opt for a tankless pre-heater for the hw tank. Concept being that if I preheat the water with the tankless to a lower-than-hot level I do not need a gargantuan unit to handle the required flow (since would only be warming from 10-35C) and then use the HW heater to heat the 35C-60C. By introducing warmer water into the tank, I suspect the temp drop in the tank will be much lower, and require less time/energy to keep heated to 60C (unlike pulling in 10C water).

    Using a hot water recovery would be a great idea too, just that my drain lines and supply lines do not meet up at all. And I would really much rather avoid tearing up my basement to get one installed - I just finished redoing my basement last year.

    I'm surprised to hear that they are more effective on vertical than horizontal. If I have a long horizontal run before the vertical, is there even any value left in using one at that point?

    Thanks!

    Eric
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,949
    Location:
    New England
    Gravity would tend to make the water only flow along the bottom of the pipe, severly limiting the surface area that gets hot by the waste water flowing through. On a vertical pipe, the water tends to flow along the inside surface of the pipe, allowing the heat to be collected fairly efficiently from all around the waste pipe.

    If you think you have problems now, with your likely wintertime incoming water temps in Montreal typically close to freezing, you'd need a MONSTER tankless unit, probably also have to upgrade your NG supply line and meter, and other supporting structures!

    A 1/2" copper pipe can safely flow about 5gpm - combine hot and cold and you might get more through a valve since most times, you're mixing the two. A 3/4" line at least double that, and maybe as much as triple that on average. But, if you take say 4 body sprays at 1gpm, a rainshower at 2, pulsating sprays, and who knows what all going at the same time, you can quickly exhaust a 1/2" valve or even a 3/4" one. Note that valves rarely can flow the full amount the pipe would indicate because of internal restrictions. As long as the supply can supply more than you're using, you should get adequate volume and pressure at the outlets...but, if you stress the supply (and valve's capability), you can be very dissapointed in the outlets.

    80psi is the max (in the USA) allowed before pressure reduction is required, so if you have that, you should be fine as most valves are spec'ed at around 50-60psi. Deciding how big a supply you need to the house...same idea - add up the max expected useage at any one time, and make sure the pipe and meter are adequate. With a sprinkler system (is this irrigation or fire protection?), that may dictate your max usage.
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,537
    Location:
    Cave Creek, Arizona
    quote; I believe I need to redo my city entrance to be a 2" to compensate for sprinklers in the new addition

    If you NEED a 2" water line for your sprinklers, you either have a small factory, or a poor design.
  6. benze

    benze New Member

    Messages:
    63
    Location:
    Montreal, Canada
    Actually - not my call. From the feedback I've gotten from the city, it's a requirement for all new homes and/or extensions to homes to have fire suppression sprinklers added to any new construction. What sense that makes when just adding an extension or a floor is beyond me. So its great - my top floor (1000sq ft) will have sprinklers. The rest of the house (2500sqft) won't. Go figure the bureaucrats. Consequently, for sprinklers, they want a 2" main, and that's what they run for all new home construction.

    I may be able to get around that with a variance - I need to dig a little more at city hall to find out if I can avoid the extra 10K cost of plumbing a 2" main for a sprinkler system that really won't do squat for protecting the house.

    Thanks,

    Eric
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,949
    Location:
    New England
    Well, you could retrofit sprinklers to the rest of the house while you've got things torn out!

    Where I live, the water company charges a demand charge based on the size of the water main run to the dwelling. Even if you don't use much water, having a 2" main means you COULD, and they charge people for it in their base rate. Hopefully, that isn't an issue where you live. As the codes get more strict, I'm not sure how the utility company can really justify that rate difference on typical homes...it makes sense for say a factory that might actually NEED that capacity all of the time, but for the once in a blue moon if you have a fire...maintaining that demand and forcing people to pay for it, is kind of nasty...

    Your homeowners insurance will likely go down if you were to protect the whole house. How much, don't know, and it probably would take a very long time to recoup. Done right, though, they can be very unobtrusive.
  8. johnfrwhipple

    johnfrwhipple I love these ACO Shower Drains - Best in Class

    Messages:
    4,061
    Location:
    North Vancouver, BC
    Have your wife spend some time on Houzz.com and put a wish list together. Then work on the budget. Then price out your fixtures and tile.

    Any funds left over can be budgeted for the fancier items. Building a steam shower is a load more complicated than a regular shower.

    JW
  9. benze

    benze New Member

    Messages:
    63
    Location:
    Montreal, Canada
    I'm trying to plan out my renos with the least amount of destructive force to the rest of the house, although how feasible that will be, I'm not quite sure. I'll have to see about sprinkling the remaining part of the house because it is not an insignificant job, although I do agree that if it is to be done, this would be the ideal time. Quite frankly, I'm not crazy about installing sprinklers in the first place, mostly b/c I don't have any experience or knowledge about how they have to be plumbed. Obviously not a job I would do myself, but still to understand the needs of a system will help me map out the install process in my head, and figure out how/where I would run pipes.

    Intuitively, I suspect that the pipes all have to be in inside walls and outside of attic cavities (or the standing water would freeze), unless they fill the pipes with antifreeze when they pressurize the system. In which case I could run some in the attic. Do they check for leaks using compressed air? I can't imagine them actually running the system to see if everything works properly... If so, how do they bleed the air once the tests are done? Is there a bleed valve at the end of the line?

    Like I said, sprinklers scare me simply b/c I know so little about them. I guess I'll add that to my list of things to read up on....

    Thanks!

    Eric
  10. benze

    benze New Member

    Messages:
    63
    Location:
    Montreal, Canada
    Very cool site. Thanks! Had not seen/heard of it before.

    Eric
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,949
    Location:
    New England
    Some sprinkler systems are wet, some are dry and only become wet when triggered (at least from what I read). This opens up options as to how to run them and the potential for rusty stagnet water. Not sure what your options are.
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