Temperature compensating valve for water heater

[YARGESOL]

I'm rebuilding a hot water system. Existing system uniting 2 Raritan 12 gallon has no TCV,neither expantion tank. I've got experiance of hot water overflowing the bilge - redirected overflow to the tank - had hot water runnig from the head and, finally one Raritan is gone. Planning to change it to 11 gall SS Isotemp.
It has a mixing elbow,good. The questions are:
- what type of Temperature compensating valve is reccomended to control the coolant flow from 3Gm30 ?
- what size of expantion tank reccomended for complete system ? Total volume of hot water will be 33 gal/125 liters+pipes
Appreciate advises

[aluijten]

Why would you introduce this complexity? To limit the volume of overflow water? I wonder if that would make a big difference. Yet another thing to fail. The other thing you may need to investigate is if limiting the flow through the water heaters is impacting the coolant flow through the engine. I personally would try to think of a good way to disperse of the overflow water (not back in the tanks by the way! That may introduce unwanted bacteria growth in some places of the fresh water supply.

Arno

[YARGESOL]

Originally Posted by aluijten

Why would you introduce this complexity? To limit the volume of overflow water? I wonder if that would make a big difference. Yet another thing to fail. The other thing you may need to investigate is if limiting the flow through the water heaters is impacting the coolant flow through the engine. I personally would try to think of a good way to disperse of the overflow water (not back in the tanks by the way! That may introduce unwanted bacteria growth in some places of the fresh water supply.

Arno

Arno,
Why the coolant should impact engines ? Same amount of coolant - either cooled by sea water , or partially by the fresh water inside the heater.
Redirecting the water - if not to the tanks, neither to the bilge - rest only overboard... Fresh water ??

Vlad

[steamgoat]

As a rough guide, 40gall of Water,heated from 4°C to 80°C expands to 40.6gall.So if you designed your system to allow for half a gallon expansion,you would be very safe.

[YARGESOL]

Originally Posted by steamgoat

As a rough guide, 40gall of Water,heated from 4°C to 80°C expands to 40.6gall.So if you designed your system to allow for half a gallon expansion,you would be very safe.

Thanks, I 've got advise from local plumber to got expantion 10% of total volume - so, almost 3 gallons!! Hard to locate. Half a gallon will fit quite easy

[Bill O]

Attached is the manual for the Raritan 12 gal. water heater. On page 7 they show a way to cut down/meter the coolant flow to keep the water from getting too hot.

We've had several of Raritan heaters in various boats, never put in any coolant metering valve and to date never blown the expansion valve. In our current set up off the Perkins 4.236, the take off for the coolant is in the "cooler" part of the engine and is approx. 165F.

Maybe your Yanmar runs much hotter than our motor or the expansion valve is bad/has sediment in it. Would think it would be much easier to change the valve than purchase a new tank.

Bill O.

[YARGESOL]

Originally Posted by Bill O

Attached is the manual for the Raritan 12 gal. water heater. On page 7 they show a way to cut down/meter the coolant flow to keep the water from getting too hot.

We've had several of Raritan heaters in various boats, never put in any coolant metering valve and to date never blown the expansion valve. In our current set up off the Perkins 4.236, the take off for the coolant is in the "cooler" part of the engine and is approx. 165F.

Maybe your Yanmar runs much hotter than our motor or the expansion valve is bad/has sediment in it. Would think it would be much easier to change the valve than purchase a new tank.

Bill O.

Well noted... I shall check it on his brother - port Raritan.But, my Starboard Raritan is bleeding (the wall,not valves). Suupose to be rusted. The boat is in Europe and Isotemp is more common here. It's in stainless on top, not glass lined.

[Bill O]

That makes more sense that the tank is not good and to replace it. We looked at the Isotherm units and they looked pretty good (the old bullet shaped ones). Thought it was odd that they didn't have/use sacrificial anodes in them.

We changed our anode rod recently and it was overdue. Without a good anode the glass lined steel tank (Raritan) will rust out quickly. Keeping my fingers crossed, but so far our old heater is still working well.

Bill O.