Hot water Pressure low

[rcswando]

Guys, I just took delivery of the boat('99 2800 SCR). I always think you find a lot more out once you have the boat...

The hot water pressure is low. Here is what happens, I turn on the hot water side in the sink. It flows normally(no hot water yet) and then warm water starts to come out after 30-40 seconds, then slowly the pressure starts to drop and then turns to a trickle. I turn it off, the cold water on and the pressure is normal. Turn the hot back on while the cold is on and then turn cold off, hot water comes out semi normal then very quickly back to a trickle. Almost as if the cold is crating a suction to bring the hot forward, but once the cold is removed it turns back to a trickle. This happens at all three points, the salon sink, head sink, and swim platform shower head.

I checked all the hoses, no kinks, pinches, or visible restriction.

I have searched the internet, I have heard some say check the filter.

Where is the filter??

Any help would be appreciated.

[Phillbo]

Has the heater been used a lot ? Maybe they are prone to clogging up from hard water..

[rcswando]

I am not sure. Just bought the boat. Works fine for 30 seconds once pressure has built up(i am guessing). Long enough to pass a sea trial and survey. I thought it was totally functional.

[mcoffey]

Any chance it has a water heater bypass installed on it? They are useful when winterizing so it is common for them to be used. There are many models of thse bypass kits but I have had 2 different on my RV.
Kit 1 simply had a 1 way valve on the hot side so water could exit only, not enter. Then there were shut off valves and 3 way T fittings that allowed you to shut off the cold intake which diverted water up to the hot side (which is supposed to block water coming in to the tank). Now this 1 way valve is just a spring loaded plug that can become stuck on you. Mine stuck but for me it just allowed 6 gallons of AF to fill the tank instead of bypassing it. I guess it could stick in a way to restrict flow though.

I have since replaced that system with a kit that has 2 3 way shut off valves at the cold and hot side and then a jumper hose between them. Set both valves to open and water flows into the tank on cold and out of the tank on hot. Set both to bypass and water is diverted from the cold up the jumper hose and then out the hot side hose outlet. In theory you could have a restriction here as well or maybe it is just not open all the way?

That is about all that I can think of on the hot side that could cause this that would not affect cold.

Good luck!

[seapuppy]

interesting that the hot water is the only one affected....otherwise I'd say you have to pull the screens at the faucet to clean them out....might wanna do that anyway just to see if there is any trash getting in the way....

the hot water system is really simple...pressure from the pump charges the cold water system which feeds the water heater...then pushes the water to the faucets...that's about all there is....does the water pump stop cycling when the water starts to trickle????......could be an air block...maybe....

I'll have to think about this one...definitely something is stopping the water flow...

SP

[shrew]

I tried to draft a reply, but timed out. Luckily for you, here is the short version. As SP said (above) the water tank goes into a pressure water pump that feeds both teh hot and cold side. You should hear the pump coming on the minute you open any valve (hot or cold). Confirm that you're hearing the pump cycle on and confirm that it sounds the same. Trace the water supply from the pump to the HW tank, then from teh tnak to the faucets. Does this occur on ALL faucets? does the sound of the pump decrease or the cycles decrease when the hot side is open?

If you do have a HW bypass, try bypassing the HW tank and see if you can reproduce. This will essentially run cold on both sides, however if it pumps strong by bypassing the HW heater, then it is something or somewhere on/at the HW heater.

[MCM]

Just a note;

I use an inline water filter on the inlet side of my hose when filling the water tank. This keeps bad stuff from getting into my hose and onboard water systems as well as keeping hard water spots from forming while cleaning the windows and fiberglass.

http://www.amazon.com/Camco-40043-Ta...=1ROOYQ2TR53MQ

[seapuppy]

it sounds like you are pulling a vacuum on the system at the water heater side and then it keeps the water from flowing once a vacuum has built up...



SP

[shrew]

Originally Posted by MCM

Just a note;

I use an inline water filter on the inlet side of my hose when filling the water tank. This keeps bad stuff from getting into my hose and onboard water systems as well as keeping hard water spots from forming while cleaning the windows and fiberglass.

http://www.amazon.com/Camco-40043-Ta...=1ROOYQ2TR53MQ

Good idea. I have an inline water filter as well. Mine is on the pump, either just before or just after the pump. (I haven't looked at it in months)

[shrew]

Just a thought. Is the release valve at the top of the hot water heater leaking at all? I recall that being a common problem. That could darw air in and create a vacuum situation.

[rcswando]

Thanks guys, I will check it out tomorrow, I feel like an idiot though. I get down there and look at it, and it looks fine, no kinks, no visible blockages. I guess it is because I real do not understand how it really works. Am I wrong, it is just an intermediate between the fresh water tank and the faucets, it has no pump, it is pressurized by the water pump, and just holds and heats 6 gallons of water....

I looked at all the connections, even the release valve and it ll seems sound.

[mcoffey]

Yep, pretty much a simple holding tank. Pressure is from cold water inlet. The inlet pumps cold water into the tank at the bottom. Hot water is forced out the top (heat rises). So since you have good pressure on cold side, seems like some sort of blockage somewhere. I would guess it is closer to the tank though since it will build up pressure after a short time. It probably is filling up the pipes and building pressure and once opened, the pipes drain and there is not enough flow to keep it going.

Generally if there is no bypass kit, there should be no valves or anything on inlet or outlet. I suspect you have a bypass kit and something has gone wrong there.

[rcswando]

Ok, I looked into it a little harder with all your suggestions. When I run the cold water side, the pump operates with a normal pump sound. When I operate the hot water side from the galley, I go back an listen to the pump and it seems like it is intermittent. it just clicks, like it is sputtering.

I must have a blockage somewhere and the water cannot be pumped clearly to the hot water tank.

Going to try and dig a little deeper. Thank you to all for your ideas on where to look.

[seapuppy]

definitely blocked on that water line someplace...
thanks for reporting out....
keep us informed....
SP

[rcswando]

I am going to try an back flush the hot water line back into the fresh holding tank. Seems like my only easy option. Should I just disconnect at the hot water pump and forcer water back to the holding tank or do it intermediately in one of the connections down the line first?

[Motala]

Hi rcswando

I know this was some time ago. Can you tell me what fixed your issue?
Thanks in advance