Sudden loss of pressure from hot/cold lines inside only???

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Bidet_Mate

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*Edit I am now convinced the blockage is on the hot water side only, and I'm wondering what the best way to go about back flushing the hot water side of the system is?


So about a week ago we suddenly lost pressure from both the hot and cold lines in our house. This is for every faucet and fixture in the house. The kicker is the outside faucets on the front, side, and rear of the house are at a full 12gpm. Aerators are fine, and we even replaced a bathtub faucet -full mixing valve and all- with the same result (broke it investigating). From the pipe in the wall, the master shower is now getting 4 gpm and the guest bath 3 gpm (a lot less than we were getting). The hot and cold water pressure from the kitchen sink is about 2 gpm each with the aerators off, but the bathtub hot flow looks to be a lot less than the cold. The water heater seems to be getting full pressure but I will be doing some further testing tomorrow. What else could it be? What should I look for?

I should also mention that we have very hard water around here and every couple of months or so they do a backwash sending a bunch of crap and rust colored water down the lines. They haven't done this for a while though.
 
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Jadnashua

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Do you have a prv? If so, it may be shot. It's not uncommon to plumb the outside hose bibs before a prv, and the rest of the house after it.
 

Bidet_Mate

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I was able to find the pressure regulator valve on the pipe coming out of the ground but there is a hose faucet directly after it with tons of pressure so the prv is good. After that it goes directly into the crawl space. I won't know until tomorrow what the pressure is like coming out of the water heater, but if it turns out to be low what could be the cause for the low cold water pressure as well?
thanks
 

Bidet_Mate

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Nope, no water softener. I now know that I 'm getting plenty of flow out of hot water heater and I'm convinced the problem is hot water side only. That pretty much only leaves one thing and that is a blockage in the pipe somewhere between the water heater and the faucets. Is there a way to back flush the whole system?
 

LLigetfa

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I now know that I 'm getting plenty of flow out of hot water heater and I'm convinced the problem is hot water side only.

First you say in the title "hot/cold lines", then you say the above. If there is "plenty of flow out of hot water heater" what problem is there on the "hot water side"? If there is a "blockage in the pipe somewhere between the water heater and the faucets" how did you determine there is "plenty of flow out of hot water heater"?
 

Jadnashua

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If it's only the hot water, if there's a heat trap, it may be lodged closed. But, you did say both hot/cold, which points to something common, not the WH.
 

Bidet_Mate

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Today I found that the output of the water heater is over 8 gpm, so the issue must be between the water heater output and the faucets. I was able to find some old readings I took of the water flow out of the front shower pipe, and compared to now I am down over 1 gpm at full mix. The confusion I had about it being both the hot and cold lines that were low was caused by a 'perfect storm' of variables that added up (kitchen sink had an aerator that we just replaced that seemed more restrictive, master sink had a bunch of black gunk in the aerator from crap in the lines stemmed from diagnosing the issue, guest sink has an automatic faucet and always seems low flow, guest bath tub is getting so much less hot water that to get warm water to flow the handle has to be turned very far to hot reducing the flow of cold as well, ect.. ) but I am now convinced it is just the hot water line.

I am going to bypass a couple of fittings and a right angle bend tomorrow with a shark fitting directly from the water heater flex hose to the the 3/4" copper pipe. If that fails to solve the problem I'm wondering what the best way to go about back flushing the hot water side of the system is.
 

MACPLUMB

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What I would do would be to a good leak proof garden water hose and run from front hose bibb into the guest
bath to the tub/shower arm use a 1/2" fip x swivel hose connector to connect to threaded shower arm found at most hardware stores
then using a second garden if needed run from the drain valve on the bottom of your water heater to outside
turn off cold water valve on top of wtr/htr open the drain valve and then with the tub valve turned to full
hot open your high pressure cold water hose bibb this will cause a water pressure back flow though the
shower valve back into the wtr/htr to the outside run this way as long as you feel needed
turn off cold water leaving the hose hookup alone for now,
turn off wtr/htr drain valve and open the cold water to your heater and check though out house for proper flow !
You may need to repeat or move hose from shower valve to other fixtures as needed to flush whole house !
 
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Cacher_Chick

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With the tiny ports and anti-scald features of todays tub and shower valves, I would not even open the valve if I thought there were any solids in the line- it's just asking for a problem.

The easiest way to backflush the output of the heater may be to close the heater supply valve, run a hose from an outside spigot into the hot laundry hose bib with the tank drain open let it rip.

If your water is hard and the heater older, the tank could be partially full of calcium/mineral. In that case you need a new heater and a softener to stop it from happening again.
 

Jimbo

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You've done a lot of work,,,checking flow rates etc. I would not hang too closely on the NUMBERS...since you have a "less than scientific" test method. HOWEVER...the numbers DO jibe with your PERCEPTIONS of a problem, and the is significant. I do think the problem is more basic than you think.... elbows and sharkbites are for all practical purposes in this discussion FULL FLOW fittings. The places that can constrict are the water heater nipples, stop valves, ports inside faucets and shower valves. If some dirt/sludge got into your water, you might have multiple problems. You might try to fix them one at a time, such as by trying the backflow blowout on one of the easily accessible items...maybe kitchen faucet.
 
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