Multiple Showerhead Question from Newbie

Discussion in 'Shower & Bathtub Forum & Blog' started by thediyer, Feb 22, 2010.

  1. thediyer

    thediyer New Member

    Feb 22, 2010
    Oakland, NJ
    What do I need to take into consideration when putting in multiple showerheads? For example a shower with a fixed showerhead and then a handspray or a “rainfall†overhead showerhead. I would imagine I would need a pipe bigger than the ½ I have in there now. Would ¾ be sufficient? What about the demand for hot water? Currently I have a rather new set up with a Amtrol Boilermate 40 gallon indirect hot water heater attached to my 90% AFUE Lennox Boiler. Would that be able to keep up with demand (assuming the shower is the only call for heat at the time)? Do you think I would need to put in a tankless water heater just for the shower to play it safe? If so, what type of BTUs am I talking and how many gallons per minute should it be able to pump out? Also, I heard some people say to hook it up in series with your existing hot water to sort of provide a backup so when the hot water from your hot water heater falls below a certain temp, the tankless pops on to keep the hot water at the desired temp. Is that possible? Or should these always be connected to a cold water intake?

    Sorry for all of the questions.

  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    Look at the ratings of the things you want to run simultaneously. Only then can you make a logical assessment. 1/2" supply shouldn't be asked to source more than about 5gpm. if you want more than that, then you probably want a 3/4" valve with associated supply pipes. It also depends on the temperature you keep the indirect. The hotter it is, the less hot you use since it is mixed with more cold. Then, decide how long you would run all of those things at once. How big is the boiler? Is the indirect set up as a priority zone?

    I think you'd find it cheaper to replace the indirect with a larger one, if you end up needing it than a tankless.
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  4. johnfrwhipple

    johnfrwhipple BATHROOM DESIGN & BUILD for both Canada & the US

    Jul 20, 2009
    Design Work World Wide: Bathrooms Vancouver Area
    North Vancouver, BC
    Also consider your drain pipe size and vent pipe size. An inch and half pipe might not be able to handle the extra water flow.

    I still haven't found a good resource that lays out max drain rates for the different sized common home pipe sizes. Jim, Terry do you know of any?
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