[Yachts]

2 months ago the shower would not get hot only Luke warm and would not change temp. Everyone said it was the cartridge. Newell installed a new one. It got hot scalding hot and would not cool down. At newell now they removed reinstalled and now it’s back to Luke warm won’t change temp and the other faucets are not hot. Newell is stumped.. any ideas

Btw aquahot is working perfect for the bays and heater..

[Trainer]

Under the burner is the tempering valve. It is a brass valve with a black knob. Remove the burner. Use pliers to gently rock the black knob back and forth till it is broken loose. Move the knob all the way one way and all the way the other way three times. Return the knob to the starting point.

Install the burner and heat the coolant up. Turn the sink hot water facuet on and check temp. If cool reach under burner and turn top of knob toward the tank. If too hot, turn top of knob away from the tank.

If that does not work, replace the guts with the innards of a new valve. Loosen the nut that holds the valve in place and remove valve. Insert new valve and tighten nut. No need to solder a new valve body.

These are Watt valves and can be ordered from Grainger.

This solves temp not getting hot enough. Does not address water being to hot and then to cool. So check at sink that does not have a cartridge like the shower does.

[Yachts]

Is that the mixing valve Rudy?

[Yachts]

Rudy, I did as you suggested and found that when to turn the valve all the way towards the tank I get the hot water but not much change I’m thinking the valve is bad as you suggested?

[rheavn]

Here are the parts you need.

https://www.homedepot.com/p/Watts-1-2-in.../205492524

Newell has lost so much experience over the last few years, they are stumped on a repair that should have been simple.

[cknuth]

Here are the parts you need.

https://www.homedepot.com/p/Watts-1-2-in.../205492524

Newell has lost so much experience over the last few years, they are stumped on a repair that should have been simple.

[cknuth]

Sharing my experience and a question, relevant to this thread. I too have had good space and radiant heating running diesel or electric, but lukewarm DHW. Decided to pull the burner to get at the mixing valve. No problem with the burner. The valve was too tight initially to move by finger strength, but a little careful rocking with a pliers got it moving. I worked it both ways numerous times and was surprised to see that the eventual full range of motion was less than 360-degrees. The knob on the valve did not have any of the markings shown on photos I've seen; I set it to fully counterclockwise (hottest.) With everything reassembled, the boiler fired and heated up to 220F indicated (that's another story.) Temperature at the tap is now over 100F, a big improvement. Nonetheless, I would expect either 120F or 160F, depending on which cartridge is in the valve. So that's the lead-in to my questions: Should I still replace the valve guts? And should I use the lower (100-130) or higher (120-160) temp range?

[bestgenman]

There are a couple of things that come to mind here, and mind you, I am not an expert.  Rudy is the expert.  
1.  If the coolant level in the AH is not full, the DHW doesn’t provide the temperatures that the cabin heating systems see.  Your expansion tank (that’s the plastic tank next to the AH) should be lower when the system is cold as opposed to hot.  Several inches difference.  If your not seeing those level changes, fix that issue first. 

2.  The mixing valve has a plastic knob that has splines inside and the shaft (brass) has mating splines.  Turning the knob with pliers can strip the splines and even though it moves from stop to stop, the brass shaft isn’t turning.  I’m not sure, but I think there are replacement cores that come with a new knob.

[cknuth]

Thanks Gordon,
The coolant level was down maybe a pint, so I've topped that off. Expansion tank is functional.
The mixing valve was not injured in the loosening-up, but I've ordered a repair kit nonetheless.
I didn't have a fuel filter on hand when ambition struck this time so did not renew the burner orifice. Next pass gets it all done.
Cheers,
Chuck

[Trainer]

A properly full overflow tank does not confirm a full heater coolant tank. Only opening the radiator cap and making sure the tank is completely full confirms that. Missing overflow hose clamp(s) and/or cracked overflow hose will let overflow tank stay full and coolant tank slowly go down.

The Least important part of burner service is the fuel filter, especially the big one on Newels. The most important part is the nozzle and then cleaning the combustion chamber. Replacing the filter and not the nozzle accomplishes nothing.

Once the new nozzle and clean combustion chamber is in place, run the burner once per month or more to keep it operating properly for 1, 2, maybe 3 years. That is every month year round, occupied, stored or sitting at some repair facility.