No water pressure on the "hot" side

H

hd12121

Member
May 13, 2009
61
GULF OF MEXICO
Boat Info
2002 310DA
Engines
TWIN 350 MAG MPI
I have an unusual problem (I think). Its a 2002 310DA but the same ShurFlo set up as ususal. I have very little water pressure on the hot side. When I turn on the faucet I get a burst of pressure which then turns into very light flow and then a trickle. I thought it was an air pocket in the hot water heater and tried to bleed it with no success. Its the same with the on board ShurFlo pump or connected to shore water. Even connected to shore water there is light flow from the drain on the water heater. Anyone have a problem like this before. It seems that there must be an obstruction inside the water heater, but what could be in there? Any suggestions?
 
How did you bleed the heater?

Just like a home hot water heater, you can get mineral build up. It's possible that you have enough mineral build (original heater?) up that it's either clogging the output connection or, if you're lucky, maybe just the aerators at the faucets. You didn't mention if you have the same issue at ALL hot water faucets? Either way, the fix is to remove fittings and clean. If there's a large enough build up inside the heater, the problem will likely come back. There are ways that you can 'attempt' to clean it out, but it's often all for not and, if it's original, it's probably time to replace.
 
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Another thought. I had a similar issue. With the water COLD because it will spray everywhere. Pressurize the system and disconnect the closest hot water hose connected to the hot water putlet. I will be hard to do cuz there's pressure. This will force any air out of the hot water tank. Reconnect and try your faucets. You will need to bleed the faucets again so give it a minute. I did that by accident thinking there was no pressure in the lines but it worked. Please make sure the water is cold you will get covered in water
 
Xplicitlnck said:
Another thought. I had a similar issue. With the water COLD because it will spray everywhere. Pressurize the system and disconnect the closest hot water hose connected to the hot water putlet. I will be hard to do cuz there's pressure. This will force any air out of the hot water tank. Reconnect and try your faucets. You will need to bleed the faucets again so give it a minute. I did that by accident thinking there was no pressure in the lines but it worked. Please make sure the water is cold you will get covered in water
Click to expand...

Good thought and that's along the lines of why I wondering how he bled the system. However, even easier... just open the pressure relief valve.
 
Lazy Daze said:
Good thought and that's along the lines of why I wondering how he bled the system. However, even easier... just open the pressure relief valve.
Click to expand...

I bled the hw heater per the mfg instructions: open the nearest faucet and open the pressure relief valve at the same time. Also, yes, all 3 hot water faucets are weak. the swim platform shower, the bathroom and the kitchen faucets. Yes, I did remove the strainers and they were clean. Also the strainer at the pump was clean. I would think that if sediment in the hw heater was the root cause, some sediment would have made its way to the strainers/ filter screen.
 
I would bypass the hot water heater at this point just to make sure there's not something else going on in the water system. Just get a connector that allows you to connect the hot and cold lines into each other. If you get strong pressure when bypassed, I think I would then try to remove the water tank if feasible, clean it all out, and check to see if there is any blockage. Maybe even consider buy a new one if yours is original (13+ years?).
 
gerryb said:
I would bypass the hot water heater at this point just to make sure there's not something else going on in the water system. Just get a connector that allows you to connect the hot and cold lines into each other. If you get strong pressure when bypassed, I think I would then try to remove the water tank if feasible, clean it all out, and check to see if there is any blockage. Maybe even consider buy a new one if yours is original (13+ years?).
Click to expand...

Good idea.

If the lines "slip"/"push" together, a piece of garden hose and a couple clamps will work. If the lines screw onto the heater, you can get 2, inexpensive, plastic fittings from Home Depot (1/2" pipe to barb, 90*, if memory serves) and a short length of hose to connect the two fittings together.
 
Lazy Daze said:
Good idea.

If the lines "slip"/"push" together, a piece of garden hose and a couple clamps will work. If the lines screw onto the heater, you can get 2, inexpensive, plastic fittings from Home Depot (1/2" pipe to barb, 90*, if memory serves) and a short length of hose to connect the two fittings together.
Click to expand...

Also, if I recall correctly, some water lines in that size/year boat were metric (15mm). You should be able to use one of the black elbows near the water tank and slip both ends carefully into each side of the 15mm seatech elbow.
 
gerryb said:
Also, if I recall correctly, some water lines in that size/year boat were metric (15mm). You should be able to use one of the black elbows near the water tank and slip both ends carefully into each side of the 15mm seatech elbow.
Click to expand...

In this case, though, it won't matter. A piece of regular water hose will fit over the 15mm lines just as well as 1/2" lines. If he has the screw-on connections, the "screw-on" part will still be 1/2" pipe, regardless of the hose size. But, yes, removing both lines and one fitting and then joining the two together with the fitting is a viable option - depending on the style of fitting and amount of "slack" in the lines, of course.
 
gerryb said:
I would bypass the hot water heater at this point just to make sure there's not something else going on in the water system. Just get a connector that allows you to connect the hot and cold lines into each other. If you get strong pressure when bypassed, I think I would then try to remove the water tank if feasible, clean it all out, and check to see if there is any blockage. Maybe even consider buy a new one if yours is original (13+ years?).
Click to expand...

I did replace the water heater once after the salt water connection ate it away. That still would have been about 6 or 7 years ago. I did not reconnect the engine hoses to the water heater. We just "rough it" while cruising. The gulf water temp is upper 80's lower 90's so even the "cold" water is toasty warm enough. I'm having a hard time believing that sediment is plugging it up. A home water heater turns tens of thousands of gallons of water a year and I use maybe 50 gallons of warm water a year. But I have no other ideas so I'll check it out.
 
The initial burst of pressure tells me you have a restriction somewhere - pressure slowly builds up until hot and cold are equal, but the flow exceeds the restriction so it can't keep up. First place I'd look is the hot water heater. Bypass it and see if flow improves. The hot water heaters aren't expensive - just re did mine for under $300.
 
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