weak hot water pressure

B

bbarquilla@gmail.com

New Member
Feb 16, 2007
51
water pump seems to be fine as i get great water pressure. However, hot water pressure is just a trickle. Can't even take a hot shower anymore. It didn't used to be this way. Where do I start in troubleshooting?
2000 290 AJ
 
First question would be is this from every faucet or just the shower?

You might try bypassing the water heater to eliminate that as a source of the restricted flow. Other than that, look for a pinched hose or closed water manifold valve.
 
Agree that we need to know if it is everywhere or just the shower. If it is just the shower, can you tell us what the faucet is or looks like in the shower?
 
OK, so the restriction is somewhere after the feed to the heater is split off from the cold water and prior to where the hot water branches out to all the fixtures. Again, I would start by by-passing the water heater to eliminate it as the source of restriction.
 
papertrail290AJ said:
water pump seems to be fine as i get great water pressure. However, hot water pressure is just a trickle. Can't even take a hot shower anymore. It didn't used to be this way. Where do I start in troubleshooting?
2000 290 AJ
Click to expand...

check valve on hot water heater possibly installed wrong way
 
papertrail290AJ said:
the problem is throughout the boat. Not just at the shower head. Thanks for the help guys.
Click to expand...

How is your cold water flow at all the boat faucets and transom shower?
How is the cold water flow from the spigot in the transom locker?
After leaving a hot water faucet on to a trickle, how long does it take for the pump to build pressure and shut off? Longer than normal?
 
First and foremost you should start with cleaning the screens in all faucets. The hot water lines are longer runs and require more pressure than the cold, so with a retriction the cold takes over. By cleaning the screens you'll most likely find that your hot water has returned.
 
Stray Cat said:
How is your cold water flow at all the boat faucets and transom shower?
How is the cold water flow from the spigot in the transom locker?
After leaving a hot water faucet on to a trickle, how long does it take for the pump to build pressure and shut off? Longer than normal?
Click to expand...

cold water pressure throughout the boat is fine. The pump doesn't act any differently when hot water is on.
 
I'm a little confused by the symptom descriptions but I'll give a few suggestions.

I would first pull out the manual for your boat and look at the routing of the water lines.

My guess is that you have a transom shower on the stern and that is going to be first in line with the water system and so I would use that to test the system. On the transom shower, if you ONLY turn on the hot water, do you get a trickle or do you get good water flow and just no hot water? Either way, if you are getting no hot water on your transom shower, you can narrow it down to three possibilities.

1. Hot water tank problem - If you are getting good water flow when only the hot water is turned on and it's just not hot, it may be the heating element has gone bad. I don't know what brand of heater you have and some of them are replaceable and some are not. You could also have sediment that has built up in the tank causing an issue... but your boat is not that old.

2. Tempering Valve problem - There is probably a Tempering Valve (or mixing valve) on the outlet of the hot water heater that mixes cold water with the very hot water from the heater. The concept is to make the hot water very hot to kill bacteria and also make the hot water last longer and then deliver it a little cooled down to the faucets to prevent scalding. It is possible a restriction (i.e. crude/scale) is clogging up the hot water side of this valve and you are only getting cold water delivered to the hot water circuit (but probably at a lower volume than the cold water side of the circuit).

3. Hose restriction - It's possible the hot water hose has been pinched or restricted in some way... I think that's generally hard to do, but it's a possibility and if you are getting really low pressure on the transom shower with only HOT water turned on, it's more probable (although that could be item 2 above as well). Since I'm assuming the transom shower is first inline, the restriction would be between the hot water tank and the transom shower which you should be able to see in the bilge without pulling stuff apart.

Anyway... get the manual out and see what the routing is and good luck.
 
Last edited:
boater4life said:
First and foremost you should start with cleaning the screens in all faucets. The hot water lines are longer runs and require more pressure than the cold, so with a retriction the cold takes over. By cleaning the screens you'll most likely find that your hot water has returned.
Click to expand...


:grin::smt038
I remember from school that pressure is staying the same no matter how long is the hose (hard hose or pipe)
you need more water pressure for hot side on your water system because you need additional pressure to force water inside heater trough spring loaded check valve, installed inside "IN" "nipple" on water heater (to prevent hot water from returning to cold line)
most possible reasons are:failed check valve on water heater(is very hard to open, because spring is corroded) or clogged water heater (try to bypass it and verify that is not a problem), also there maybe water temperature limiter installed on water heater and it failed
if overall water pressure is weak (even on cold side) - clean screen inside clear strainer right before water pump
 
Yeah... I think Mr. Boatmailster has got it down from what he learned in school... It's all about the pressure on long hoses that has caused this.

I doubt from reading his posts he even owns a boat. He/she just keeps putting crap up here on this board.

Geez....
 
Last edited:
Four Suns said:
Yeah... I think Mr. Boatmailster has got it down from what he learned in school... It's all about the pressure on long hoses that has caused this.

I doubt from reading his posts he even owns a boat. He/she just keeps putting crap up here on this board.

Geez....
Click to expand...
Sorry to hear that:smt009
but is not possible to loose water pressure inside hose because of it length
water can not be compressed with use of domestic water pump and hard blue and red hoses are not flexible enough to change diameter so there is not pressure lose while water is inside hose (length translates to water volume not water pressure) (that is also why you can have few hundreds of garden hose and still not loose any pressure on hose nozzle) and I hope that that hoses on Mr. Papertrail290aj boat suddenly didn't stretched out because problem just appeared (maybe cold water hoses shrunk?)

ps: sorry for my crap
i hoped that i gave some good info for other users, but looks like i shoud discontiune further posts to keep your and my blood pressure on lower level
 
never argue with a NASA engineer about plumbing.
 
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