Water heater thermostatic mixing valve

[marchem]

Has anyone added a thermostatic mixing valve to their hot water heater? Because there's no adjustable thermostat on the HHW it comes out really hot at times. Seems like something like this would work well:

http://smile.amazon.com/LightInTheBox-Thermostatic-Mixing-Valve-PHW-02/dp/B00ATLZUCI

At the dock we are plugged into AC to keep the battery charger going and reefer cold. Our AC panel only has breakers, no switches (another upgrade project ahead of me), so I can't turn the HHW off, unfortunately.

 

[Stu Jackson]

Sure, Rob. Maine Sail has written about this many, many times. Search here on "Honeywell" for starters. Your choice is good, too.

But I find it hard to believe you don't have a water heater switch on you AC side. Our boat is much older than yours and we have one.

 

[Hello Below]

A bit steep but all the parts are included.

http://shop.sailboatowners.com/prod.php?5745

 

[marchem]

But I find it hard to believe you don't have a water heater switch on you AC side. Our boat is much older than yours and we have one.

The DC side of the panel has switches (and push button breakers), but the AC is only push button breakers. Not sure why Seaward/Catalina did that. I've got a new panel ready to go, just not a block of time to install it; plus it has larger studs for the battery cables so I've got to either drill out the old ones (not a good solution, I know), install new lugs (may not be enough length to do that), or run new cables (serious work!).

 

[marchem]

A bit steep but all the parts are included.

http://shop.sailboatowners.com/prod.php?5745

These days I appreciate not having to track down all the parts myself. Thanks for the tip. Seems like a real useful upgrade.

 

[peter_ms]

just received this Honeywell for installation this spring. $60CDN @ Home Depot, cheaper in the US. Lot more variety in the US as well.

Peter

 

[Allan12210]

Here is the link to my project last year. That valve looks familiar. I highly recommend the upgrade to your plumbing.

http://forums.sailboatowners.com/index.php?threads/thermal-mixing-valve.173481/

 

[Stu Jackson]

but the AC is only push button breakers

Still works as a shut off, no?

 

[marchem]

Still works as a shut off, no?

Unfortunately no. They have the same breakers on the AC and DC, but only the DC has switches. The only AC switch is all or nothing. Bad design.

 

[woodster]

Unfortunately no. They have the same breakers on the AC and DC, but only the DC has switches. The only AC switch is all or nothing. Bad design.

how do you disarm the device for servicing if there is no switch

 

[marchem]

how do you disarm the device for servicing if there is no switch

Turn off the main AC 30A breaker. But that means they all go down: charger, water heater, AC outlets. Kind of a pain. Thus my desire to install the new panel. Actually I've discnnected the wires from the breakers now and then to work on the devices and keep the other AC circuits alive. Just have to be very, very careful working with hot circuits.

 

[Ron20324]

I find it hard to believe there is not a thermostat under the cover where your 110 connects. Probably a thermal reset button, too.

 

[Stu Jackson]

water heater

Rob, maybe I'm not making myself clear. That IS the shutoff switch. I do not understand why you're doing this.

Here's a picture of our panel. AC main breaker (1986 single pole) and the water heater pushbutton switch below it.

http://c34.org/bbs/index.php/topic,2620.msg13781.html#msg13781

 

[RoyS]

With regard to your mixing valve photo: Honeywell has the same mixing valve available with threaded connections instead of the sweat fittings on the one shown. Try Pex Supply on the net. Some mixing valves require a fairly large flow rate to work, so I would avoid those.

 

[Blitz]

Turn off the main AC 30A breaker. But that means they all go down: charger, water heater, AC outlets. Kind of a pain. Thus my desire to install the new panel. Actually I've discnnected the wires from the breakers now and then to work on the devices and keep the other AC circuits alive. Just have to be very, very careful working with hot circuits.

Seems very odd with how it is wired. Hope you realize that if you don't have water in your hot water heater you can never turn on your main breaker.

Having a mixing valve is a safety item if you have kids or those not familiar with your boat - to prevent scalding. I personally just blend but my water heater thermostat is never high enough to scald anyone.

I think a bigger safety item would be to have your panel wired correctly. I think the first priority would be to adjust your thermostat on your hot water heater first, then replace the panel or correct the wiring system when you can. The mixing valve can always be done later.

 

[Cat 310 #1 in GA]

I only leave the HWH for about an hour and then shut it off. Water stays hot for a couple days so I also do not understand the need for a thermostat. My boat is also a 2000 C-310

 

[woodster]

I only leave the HWH for about an hour and then shut it off. Water stays hot for a couple days so I also do not understand the need for a thermostat. My boat is also a 2000 C-310

to keep the water temp lower than scalding ....if you have children or grand children you will understand

 

[marchem]

I find it hard to believe there is not a thermostat under the cover where your 110 connects. Probably a thermal reset button, too.

The water heater does have a thermostat and thermal reset under the cover. But the thermostat is fixed. The problem comes when engine cooling water is used to heat the hot water-there's no thermostat control for that, so the how water can get very hot.

 

[marchem]

Seems very odd with how it is wired. Hope you realize that if you don't have water in your hot water heater you can never turn on your main breaker.

Having a mixing valve is a safety item if you have kids or those not familiar with your boat - to prevent scalding. I personally just blend but my water heater thermostat is never high enough to scald anyone.

I think a bigger safety item would be to have your panel wired correctly. I think the first priority would be to adjust your thermostat on your hot water heater first, then replace the panel or correct the wiring system when you can. The mixing valve can always be done later.

There is a thermostat, but it is not adjustable, nor is there temperature control when the engine cooling water is used to heat the hot water. The mixing valve is the only way to control the temperature of the hot water in the boat.

The panel is wired correctly, it just doesn't have switches for the individual AC circuits, only breakers that's can't be turned off. I do plan to replace the panel, but more for convenience than safety, including having AC outlets when the water heater is empty.

 

[marchem]

Rob, maybe I'm not making myself clear. That IS the shutoff switch. I do not understand why you're doing this.

Here's a picture of our panel. AC main breaker (1986 single pole) and the water heater pushbutton switch below it.

http://c34.org/bbs/index.php/topic,2620.msg13781.html#msg13781

No picture. I've got a similar 30A master breaker, but the individual breakers can only be reset when they trip; no on/off function. On the DC side it uses the same breakers, but with switches on the side.