Water Heater Discharge

[SV Bella]

this is what I read on the internet. Is it true? I don't know. We'll see when it gets here and installed.

"Moreover, to help ensure safe operation, the Kuuma’s has an automatic reset function that limits temperature from going too high. Another great feature of the Kuuma unit that we like is its patented temperature control. This feature keeps the potable water on your boat at a safe 140°F by controlling the coolant flow in its heat exchanger system"

 

[DeniseO30]

Well I found it it is a TCV model so you may want to check what you actually ordered. I didn't think I was crazy LOL

 

[SV Bella]

Denise030,
What is the source of that attachment?

Kuuma doesn't sell a heater with the external TCV that is pictured in the attachment. I've read those external TCV failed regularly. Many people just bypass the TCV. Mine was bypassed by a previous owner.

Kuuma's website gives no written description on the capabilities of the heaters.

I did find this on one seller's website:

• Patented temperature control keeps potable water at approximately 140 Deg. F. by controlling coolant flow through the 7/8" heat exchanger, reducing the risk of scalding

I'll call Kuuma and ask them what their heaters do.

 

[DeniseO30]

It appears it is no longer available!

that would be the one item that keeps the engine water from overheating the water heater I guess a mixing valve could also be used for that because it would temper the water going through the heat exchanger https://ca.binnacle.com/pdf/Kuuma Marine Water Heater Owners Manual 0313.pdf

 

[DeniseO30]

My lifetime has been in HVAC so it's second nature for me to search in those areas. Engine coolant loop is really no different than hydronic hot water from the boiler so it seems to me one of these would work on the engine coolant side of the heat exchanger. In automotive applications they're made of plastic!

https://www.amazon.com/dp/B082M73L38/ref=cm_sw_r_apan_i_AD7QHESPEQ2CNTQZ485B

 

[DeniseO30]

Heres a " marine" type.

Whale Seward https://www.amazon.com/dp/B07SF78N5V/ref=cm_sw_r_apan_i_4T4RCWSEN64CVMKFNR7X

 

[twalker H260]

There are 2 types of valves being discussed here. Just want to make sure people are clear.
1 Tcv -temperature control valve. -controls the flow of engine coolant through the heat exchanger of the water heater based on the the temperature of the water in the tank. Prevents water in heater getting to the same temperature as the engine coolant.
2 mixing valve which mixes the hot and cold potable water together to limit the water temp flowing into the hot water lines to a set temperature to avoid scalding when water in tank is at too high a temperature.

A mixing valve will not work to control the engine coolant flow as it relies on mixing cold and hot water together to adjust temperature. The tcv valve has a temperature sensor on one side that can be electric or wax and simply opens or closes the coolant water flow from the engine. You could do this manually on long trips by inserting a regular ball valve in the coolant line and closing the valve after the water in the tank is hot.

 

[DeniseO30]

There are 2 types of valves being discussed here. Just want to make sure people are clear.
1 Tcv -temperature control valve. -controls the flow of engine coolant through the heat exchanger of the water heater based on the the temperature of the water in the tank. Prevents water in heater getting to the same temperature as the engine coolant.
2 mixing valve which mixes the hot and cold potable water together to limit the water temp flowing into the hot water lines to a set temperature to avoid scalding when water in tank is at too high a temperature.

A mixing valve will not work to control the engine coolant flow as it relies on mixing cold and hot water together to adjust temperature. The tcv valve has a temperature sensor on one side that can be electric or wax and simply opens or closes the coolant water flow from the engine. You could do this manually on long trips by inserting a regular ball valve in the coolant line and closing the valve after the water in the tank is hot.

 

[DeniseO30]

Boat systems are low-tech. When DIYers and manufacturers try to "improve" things get more complicated and quite often more unreliable.

And really, there are more than two types of valves to control temperature, temperature, pressure, flow,

 

[twalker H260]

Denise030. - I agree there are many types of valves etc. which is why manufacturers have catalogs of them and many ways an effective, safe system can be designed. My comments are strictly in relation to the discussion that has occurred in the thread to this point, which revolves around modifications occurring at the hot water tank and utilizing primarily the current hose configurations.

My concern is that from the exterior many valves may appear similar, but internally function very differently. In my attempt to keep things basic I did a poor job of expressing my concern explicitly - that a person could accidentally interconnect the cooling system with the potable water system - which causes problems for both systems but could be toxic on the potable side.

Perhaps you would be willing to share a diagram or two for the members on how you would safely use/connect the mixing valve to control the temperature of the coolant being sent to the water heater?

Being about safety I would still want to have a thermostatic mixing valve of some sort on the potable water side of any water heater capable of being heated by the engine coolant.

 

[SV Bella]

The Kuuma does not control the coolant flow.