Slow bathtub/shower

Reply

  #1  
Old 11-22-16, 12:29 PM
P
Member
Thread Starter
Join Date: Dec 2015
Posts: 99
Received 0 Votes on 0 Posts
Slow bathtub/shower

I have a very slow running bathtub and shower head. I will start by saying I know my pipes in the walls are older and likely need replacement. However, there is something else at work here. If the tub is running full hot, and I turn on the sink full hot, the tub slows way down. Obvious answer; clogged supply pipes elsewhere in the system. This I know. If the tub is running full hot, and I turn on the sink full cold, there is no change in pressure, so household pressure is OK. (most other rooms have new pipes and supply from street to house is new) Here's what I am curious about: If the tub is running full hot, and I turn on the tub full cold as well (two separate handles, not one), the water pressure/flow doesn't increase. I find that odd. Full hot/full cold/full both all have the same level of pressure for the tub/shower. If if water pressures were low, both valves being open should double pressure/flow, right? Does that indicate some clogging in the pipes at a point beyond where the hot/cold mixes?
 
Sponsored Links
  #2  
Old 11-22-16, 01:47 PM
T
Member
Join Date: Jan 2015
Location: USA
Posts: 708
Received 29 Votes on 27 Posts
If the tub is running full hot, and I turn on the sink full hot, the tub slows way down. Obvious answer; clogged supply pipes elsewhere in the system. This I know. Not necessarily. Unless your pipes are made of expandable plastic, your water is limited by the size of the pipes and (assuming all your bathroom faucets are on the same line) taking water from one faucet can impact another.If the tub is running full hot, and I turn on the sink full cold, there is no change in pressure, so household pressure is OK. Hot and cold pipes are on different lines so they don't directly impact each other.(most other rooms have new pipes and supply from street to house is new) Here's what I am curious about: If the tub is running full hot, and I turn on the tub full cold as well (two separate handles, not one), the water pressure/flow doesn't increase. I find that odd. Full hot/full cold/full both all have the same level of pressure for the tub/shower. If if water pressures were low, both valves being open should double pressure/flow, right? You may have a clog but your test doesn't confirm it. As I said, you can't double the pressure in that way. Did you ever pour into a funnel. You can pour from a quart bottle or a gallon bottle into the the funnel but the liquid comes out the funnel at the same rate. It would be like being able to sip soda twice as fast from a 16 oz glass as you can from an 8 oz or saying it's twice as sunny with both eyes open.Does that indicate some clogging in the pipes at a point beyond where the hot/cold mixes?Yes, your pipes may have a buildup of some kind.

If you can, go into your basement and follow the pipes to the bathroom. This may give you a visual of what's happening.
 

Last edited by Tony P.; 11-22-16 at 02:33 PM.
  #3  
Old 11-22-16, 02:34 PM
P
Member
Thread Starter
Join Date: Dec 2015
Posts: 99
Received 0 Votes on 0 Posts
Thanks for responding! I think we're on the same page. Your comments below in italics and my response below that.

Not necessarily. Unless your pipes are made of expandable plastic, your water is limited by the size of the pipes and (assuming all your bathroom faucets are on the same line) taking water from one faucet can impact another.


Right; we are in agreement. The pipes to this bathroom are original 90 year old galvanized. I am confident they have a build up, which is why turning on the faucet has such a large impact.

Hot and cold pipes are on different lines so they don't directly impact each other.

Yes, also in agreement. I just meant that my whole-house pressure is good; the pressure loss isn't at the main supply line from the street.

Yes, your pipes may have a buildup of some kind. If you can, go into your basement and follow the pipes to the bathroom. This may give you a visual of what's happening.

I can follow the pipes. The last section of supply pipes are all 90 year old galvanized in the walls. Other remodeled rooms have new copper lines and good flow/pressure, so I bet the galvanized pipes are restricted. I also know that the pipes from the bathtub valves to bathtub spigot are copper, so they likely aren't restricted, right? I guess I am confused. Let's assume the supply pipes from basement to the valves are restricted (smaller diameter), but the copper from the valves to spigot is not restricted (larger diameter). Shouldn't turning on both hot & cold increase flow (two smaller diameter pipes entering one larger diameter pipe)?

Is there a good way to inspect the valves and the section from the valves to spigot for clogging? I can access them from the back if needed through a wall access panel. I've never taken the faucet spigot off either; not sure if I can visually inspect that.
 
  #4  
Old 11-23-16, 02:04 AM
T
Member
Join Date: Jan 2015
Location: USA
Posts: 708
Received 29 Votes on 27 Posts
There's an inexpensive gauge you can get at HD (http//www.homedepot.com/p/3-4-in-Plastic-Water-Pressure-Test-Gauge-DP-IWTG/100175467) you can attach to the shower. Have the person at HD suggest adapters you may need. Then do the same at any faucet / spigot that can be fitted. Just make certain the pipes are the same diameter. Note that pipes will not have equal pressure but it can give you an indication of a problem.
 
  #5  
Old 11-23-16, 09:50 AM
P
Member
Thread Starter
Join Date: Dec 2015
Posts: 99
Received 0 Votes on 0 Posts
Would I just test pressure at the shower head vs. pressure at other locations in the house, to make a "map" of sorts?
 
Reply
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: