water heater

[Slow Dancin]

06 Hunter 38, hot water pressure is low and does not heat to hot. cold water is OK. I have been given several possible reasons; manifold, filters, and mixing valve.
Though I'd put it out here to see if any one had similar problem and what you found as the cause.

 

[SG]

Did this just start? Did it work before? When did it start?

You are saying the pressure is low -- or the flow is low?

The issue getting how water is different one from the hot water heater from the flow issues. Does it produce hot water with shorepower (i.e., AC) vs. with the heat exchanger off of the engine?

 

[Slow Dancin]

Just started with spring commissioning. All worked fine last year. Low heat is with AC power, don't know how it is with heat exchanger.

 

[SG]

If you only use hot water, i.e., no mixing of the unheated tank water , then the hot water flow from the tank is irrelevant to the temp of the water.

The flow through the tank is a different issue.

With regard to Heat with with the AC element, if you have some clear warming, but it’s not as hot then I’d thing about a bad AC connection or wire, a bad thermostat, or a heating element that going. If you have no heating of water. Then you could have no power, a bad heating element, or a bad thermostat. (Sounds similar. ). When you flip on the breaker for the hot water heater, with the tank clearly cold, do you show a 4 or 6 amp 110 v load? If not, then I’d check the AC at the hot water heater and see if you have juice there. My next guess would be that you heating element is shot.

If you have a conventional heater, I’d try the hardware store for a replacement. Assuming you have access to the heater, it’s a simple fix. Draining the tank will occur you need to make sure the AC is really OFF. Etc.

 

[CharlieSea]

Pressure from hot or cold should be the same as there is only one water pump. Could be crud in the hot water tank. Try draining the tank and see what comes out. There are two ways to drain. One is the over pressure valve and the other is the drain valve. Second or maybe first is look at the water manifold. On my H356 it is under the galley sink. The manifold has a hot and a cold side. The cold side comes directly from the water pump which has a tee to feed the water heater. The hot side comes from the water heater. It is set up so that the individual lines to the sink, head, etc can be turned off individually. Check to see all that are used are turned on (careful, there may be a spare not connected to anything, if it doesn't have a tube connected to it don't turn it on, they are usually well labeled). Last thing is that for lay up you would drain all the water lines and fill with antifreeze. When you recommission it's difficult sometimes to get all the air from the system. If the water heater is not full when you turn on the A/C it will fry the heater element. Google recommissioning the water system. Send some pictures of the manifold. Manifolds can be problematic.

 

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[quadrille38]

Have 2008 38.
I’d look at the mixing valve first. It’s the easiest first assessment. It’s on the outlet side of the water heater and blends cold into the hot as a way to extend the hot water capacity. If it’s blending too much that would cause cold water flow.

It’s an easy adjustment to increase / decrease the mix to see if anything changes.
From there it’s easy step to disconnect the fittings and check for clogs. I found mine had a fairly tight mesh screen that had clogged with debris. Mostly plastic shavings from the plumbing installation.
Clean the screens and put it back together and see what your temps are.

If that doesn’t do it more extensive assessment / fix may be required.
I ordered and replaced the mixing valve a few years ago.

 

[Boomer54]

Have 2008 38.
I’d look at the mixing valve first. It’s the easiest first assessment. It’s on the outlet side of the water heater and blends cold into the hot as a way to extend the hot water capacity. If it’s blending too much that would cause cold water flow.

It’s an easy adjustment to increase / decrease the mix to see if anything changes.
From there it’s easy step to disconnect the fittings and check for clogs. I found mine had a fairly tight mesh screen that had clogged with debris. Mostly plastic shavings from the plumbing installation.
Clean the screens and put it back together and see what your temps are.

If that doesn’t do it more extensive assessment / fix may be required.
I ordered and replaced the mixing valve a few years ago.

I agree. I had a very similar issue. Mine turned out to be screen on the outlet side of the water heater. It had clogged over time with crystals from the antifreeze. There is also a screen on the inlet side you may as well check. It also was a mixing valve issue. I winterize and commission our water system but apparently the marina turned the mixing valve off, don’t know why!

 

[MitchM]

" If the water heater is not full when you turn on the A/C it will fry the heater element:" on water heaters with an overheat thermostat , the overheat thermostat, if properly operating, will cut off AC power and save both your heating element and your tank. get the product deign and install specs on your HWH from the manufacturer. and note that on isotemp HWHs manufactured in the mid 2000's, when the overheat thermostat fails, the AC power is NOT shut off, and the tank overheats and deforms so as to become unusable.

 

[Slow Dancin]

thanks to all
i will be on the boat for a 3 day weekend so will have time to work down the list of possibilities.
sounds like filters is a good starting point.
will let you know the outcome

 

[Slow Dancin]

It was clogged in line screens that caused the low pressure.
Also bypassed the mixer and will adjust the water temp at the faucet.
All is well now
Thank you for all the great suggestions