Hot water pressure problem diagnosis & cures:

Hot water pressure & flow diagnosis & improvement - steps to correct bad hot water pressure or flow rate. When hot water pressure is noticeably weaker than cold water pressure that clue helps us diagnose the trouble.

Tthis article describes the steps in diagnosing & correcting bad hot water pressure. If cold water pressure is acceptable but hot water flow rate or pressure are weak you'll see what to do in this article.

4 Steps to Fix Bad Hot Water Pressure / Flow When Cold Water Pressure is OK

These questions and answers were posted originally

at HOT WATER PRESSURE IMPROVEMENT - please be sure to see the advice given there.

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On 2018-10-20 by (mod) - if building public water supply pressure is low how do I get better water pressure

Consider adding a pressure boosting pump to deliver both hot and cold water at higher pressure.

Your low pressure boiler might be used to heat an indirect fired hot water tank.

On 2018-10-20 by Samuel Bradley

Water supply for washing and bathing

On 2018-10-19 by (mod) -

Sam

I need a little clarification. What are we discussing here, building hot water supply for washing and bathing, or hot water hydronic heating system?

On 2018-10-19 by Samuel Bradley

I have a coal fired back boiler and also a oil central heating system which runs off a low pressure water system. Can I install a high pressure water system?

On 2018-09-24 by (mod) - why would hot water flow be weaker at night?

Thanks for an interesting question and not one I've run-into.

I don't know, Chuck, but let's start the diagnosis by thinking about what's different at night:

- other users

- low voltage to a pump

- drop in water supply pressure

- a timer somewhere in the system limiting a pump or valve's opening

- something else

On 2018-09-19 by chuckbrunsaz@gmail.com

My hot water flow is low at night. What is causing this situation. It happens periodically and not all the time.

On 2018-05-08 by (mod) - diagnosing no hot water

So start at the hot water heater:

is water flowing into the heater?

If you turn on hot water at any fixture do you get any water flow?

If not look for a blockage at the heater itself - e.g. a clog at the water heater outlet riser or valve at the heater top or a clog at the cold water inlet dip tube;

then look for a closed valve anywhere in the system;

then look fdor debris clogging at hot water piping or supply riser valves at fixtures.

For example a disintegrating dip tube or sacrificial anode sometimes breaks up into pieces that clog the outgoing hot water tank opening or pipe or a nearby valve.

On 2018-05-08 by Wally

Only hot water flow does work have no water coming out of hot water side. Only the cold has water flow.

On 2018-02-26 by (mod) - diagnose bad hot water pressure at just some fixtures

Rod

When there is good cold water (CW) pressure everywhere and good HW pressure at some fixtures and not others that's a clue to start looking for a blockage: a bad valve, a blob of glue, tape or solder at a joint, etc.

On 2018-02-26 by Rod Gonzalez Contractor lic.

Installed new 40 Gal. W/H, installed new 3/4" PEX to New 1/2" PEX some 10' run to new kitchen facet hot side pressure still sucks, connected New 3/4" PEX to existing 3/4" Galv. Hot side pressure fine at bathrm facet existing, what the hell

On 2018-01-07 by (mod) - frozen hot water pipe?

If the cold pressure is good and hot is poor, and IF you suspect a partly-frozen line, try leaving the hot water running for 5-10 minutes. If that makes no difference then the problem is elsewhere, such as a blockage at your water heater or a scale-clogged tankless coil.

On 2018-01-07 by Nan

Our hot water flow is almost non-existant. We have been below freezing for a few days. What do we need to do?

On 2017-12-14 by (mod) -

Siraj,

try going through the diagnostic suggestions in the article just above on this page

On 2017-12-14 by siraj

week hot water pressure but cold water pressure is acceptable no issue , how can we improve hot water pressure like cold water pressure

On 2017-07-01 by S

Cold water pressure no problem. Hot water pressure nothing

I relite the tank how long

On 2017-03-27 by (mod) - A new tankless water heater ought not cause a significant pressure drop

A new tankless water heater ought not cause a significant pressure drop - certainly I'd not expect it to already be scale-clogged.

Try removing your faucet strainers as often plumbing work sends clogging debris through the system.

Flush out all of the faucets. Do the same with shower heads.

On 2017-03-27 by Jeff

Just installed a tankless water heater and the water pressure drop significantly. What can be done?

On 2017-03-19 by (mod) - diagnosing no hot water flow at all

HOT WATER PRESSURE LOSS has some key diagnostics. Start there and let me know what you find.

On 2017-03-19 by Veronica

No hot water pressure in shower, tub or sinks

On 2016-10-29 by (mod) - no hot water coming out of bathtub fauset

Dan,

If you have hot water at other plumbing fixtures then we know the problem is not the water heater. What remains might be a closed valve or reversed or improperly connected hot and cold water piping.

Alternatively, if your bathtub uses an automatic anti scald valve right at the bathtub then it's possible that that device is incorrectly adjusted or defective.

On 2016-10-29 by Dan

There's no hot water coming out of bathtub fauset

On 2016-01-09 by (mod) - can I put a booster pump on the hot water line ?

Can, yes. Recommended, no. I think it'd be better to first diagnose the cause of bad hot water pressure, such as mineral clogging in a tankless coil or in the hot water piping, control valves, etc.

On 2016-01-07 by Ray M

I need help with this problem .. can I put a booster pump on the hot water line ??

I just replaced all the old water lines in my house ( old 1/2 to new 3/4 ). I looped the cold water line so all cold water lines come off the loop. I did not loop the hot water line. I have good pressure at basement sink and bathroom sink but poor pressure at kitchen sink and shower (the two places I need it most)

On 2015-05-18 by (mod) - can I get rid of water heater debris just by flushing at a bath tub?

No Lesa because the debris will enter the outlet of every fixture: shower heads, sink strainers, etc.

Also I found that in the heater that we disassembled the supply of debris particles was great ennough and the water velocity leaving the heater modest enough that you'd never remove the debris from the heater by trying to send it up to a bath tub.

On 2015-04-24 by Lesa

Can debris from old hot water dip tube, water heater has been replaced, be removed from hot water line by simply flushing through bath tub hot water spout? If so, is there a proper technique?

...

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