Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Cold Shower

Options
boulderz
boulderz Member Posts: 31
in THE MAIN WALL
Hi, I have a shower that gets cold when you turn on the hot water in the kitchen sink (kitchen and bath right next to each other). It seems like it shouldn't happen as there is 3/4" supply pipe with 1/2" tees off for the shower and kitchen sink. I am wondering if the way the 1/2" comes off the main line is causing the problem (see attached photo - 1/2" comes off the elbow end). Wondering if I change the 3/4 elbow to a regular tee will it fix the problem? I am just guessing here - maybe there's some other problem. As you can see I have to change out the leaking shutoff valve so would do it at the same time!

Comments

  • boulderz
    boulderz Member Posts: 31
    Options
    To clarify, the 1/2" line in the pic goes up to the shower. The 3/4" continues and then supplies the kitchen and another bath located in the basement..
  • Jamie Hall
    Jamie Hall Member Posts: 23,427
    Options
    Unfortunately, while rearranging the piping might make a small difference, it won't make that much -- this is a very common problem. What will make a difference is an automatic shower (or bath!) temperature control valve. They aren't cheap. They work...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • boulderz
    boulderz Member Posts: 31
    Options
    Shower is a clawfoot tub with hot/cold valves and shower riser..
  • Jamie Hall
    Jamie Hall Member Posts: 23,427
    Options
    Oh dear. That does make it considerably more complicated; all the temperature control or pressure balance contorls I've seen are the "modern" single handle variety. They almost have to be, as they are mixing the hot and cold...

    I don't suppose you have enough space to run a completely separate line for the tub/shower feeds?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Hilly
    Hilly Member Posts: 427
    Options
    You'd need a proper point of use anti scald device to take care of a two handle faucet.
  • boulderz
    boulderz Member Posts: 31
    Options
    OK, but what causes this? I thought a 3/4" line is sufficient for (2) 1/2" feeds. Not every shower goes cold when 2 hot faucets are running..
  • Leon82
    Leon82 Member Posts: 684
    edited December 2016
    Options
    The shower valve compensates fore pressure too. There's a spool thingy inside and its trying to adjust
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
    Options
    Do you notice any pressure drop, or just a temperature drop? What do you have for a water heater? You may have a flow issues with your water heater, not able to supply enough flow for simultaneous hot draws. May be from scale.

    More info

    Taylor
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • Jamie Hall
    Jamie Hall Member Posts: 23,427
    Options
    Leon82 said:

    The shower valve compensates fore pressure too. There's a spool thingy inside and its trying to adjust

    This works -- if it is a single mixing faucet. There are a whole bunch of different valves out there -- pressure balance, temperature controlled, etc. -- for that application. If you have two separate valves -- such as the OP has in the application -- they don't work.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Hilly
    Hilly Member Posts: 427
    Options
    Having 3/4 main trunk with 1/2 branches to the fixtures will mostly help ensure that you can run multiple fixtures at the same time will little change in intended performance. Having the larger trunk will only lessen the pressure drop and accompanied temperature swing, it won't eliminate it. If you were to run the DW or Laundry on a hot water cycle you'll get the opposite where freezing water would be the complaint. You need a pressure balancing thermostatic balancing device to protect the shower, it's your only proper protection. There are shower head anti-scald devices available. I've never tried one, but I have seen them in literature somewhere along the way.
  • Jamie Hall
    Jamie Hall Member Posts: 23,427
    edited December 2016
    Options
    I'll note it again -- the OP has two completely separate valves for his shower and tub. One hot, one cold. Mixing occurs downstream from the valves at the shower head or tub spout. I've seen many designs for anti-scald and temperature control -- in mixing faucets only. I've never seen one for two separate controls...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • boulderz
    boulderz Member Posts: 31
    Options
    Solid_Fuel_Man said:

    Do you notice any pressure drop, or just a temperature drop? What do you have for a water heater? You may have a flow issues with your water heater, not able to supply enough flow for simultaneous hot draws. May be from scale.



    More info



    Taylor

    Could be right - it's a Laars Endurance EB110 which handles domestic. I had an issue before with scaling due to hard water when the water softener wasn't working right.
  • Leon82
    Leon82 Member Posts: 684
    edited December 2016
    Options
    Ah, I see.

    Now that I think about it, my shower has 2 single handle mixing valves it it and if you adjust one on one wall the other wall needs to be adjusted too because it either cools or gets warmer. They each have dedicated hot water runs from the recirc loop and a cold line in 3/4 reduced to half at the tee for the first valve

    What if you made a pressure balancing loop in the basement and then run lines to fixtures from there?. I made them for my body sprays so they are equal flow.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    Options
    Does the kitchen sink have a restrictive orifice aerator on it? If not, it needs one. It's robbing flow.

    ME

    There was an error rendering this rich post.

  • Larry Weingarten
    Larry Weingarten Member Posts: 3,328
    Options
    Hello: You might want to check for a cross connection. If cold were getting into the hot side, it could cause trouble. Do the test by shutting off the supply to your water heater and then open a hot tap. It should stop running in seconds. If it keeps running, you know there is a prollem! ;)

    Yours, Larry
    rick in Alaska
  • psb75
    psb75 Member Posts: 844
    Options
    The Laars Endurance EB 110 is not a good DHW maker. It has a flow restrictor before the plate x-changer. It can't supply two fixtures at the same time with DHW. I just worked on one. Terrible machine...made in Russia. Really. It looks like it too. Wiring inside is all over the place, like spaghetti, and it is "fried" in places, after 13 yrs. I'm replacing boiler in a week.
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
    Options
    I think it's a flow from water heater. Laars explains it. There are other possibilities as mentioned a cross connection as well. But my money is on restrictive water heater.

    1/2 copper can flow a substantial amount of water, and 3/4 almost doubly so. That's not the problem, it's the water heater restricting flow and causing the hot water pressure to drop.

    A typical 2.5 gpm shower head is going to consume about 2-2.25 gpm of hot water, the balance being cold for tempering. I have no qualms of a single 1/2 pipe of reasonable length supplying 2 fixtures. Heck I have 3/8 soft copper supplying my kitchen sink and a vanity in a bathroom no flow issues. Gets hot and cold water to the remote sink faster. I run the well at 40/60 psi.

    Taylor
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • boulderz
    boulderz Member Posts: 31
    Options
    Thinking as we go here, I'd also like to say when washing dishes while the shower is on the water at the kitchen sink is hotter than normal.

    Thanks all for your help, I thought there'd be an easy fix.

Categories