The flow diagram you attached is for a TCV equipped tank only and yours has no TCV installed so that diagram is not helpful in your case.
hot water from inverter
- Thread starter Hayden Watson
- Start date
Here is the schematic for water flange group on the M25XP. You are correct about the pin hole. That is why I cannot figure out why the engine will not heat up. I have contemplated temporarily replacing the thermostat with duct tape to stop all flow to see if it will heat up. the low coolant temp has me stumped.
As for Charles' suggestion of putting the WH in the primary circuit, that just might get rid of my low engine temp problem. The primary circuit is hose is 7/8" ID and only 7" long. if I cut that and add in the 5/8" ID WH line it would reduce the diameter of the hose to about 50% of spec and increase the length from 7" to probable 25 feet or more. That would certainly reduce my cooling capacity
Attachments
Here is the link to my owners manual http://www.suremarine.com/manuals/assorted-information/kuumawaterheaters.pdf
The schematic applies to WH's with and without the TCV and does not show the TCV at all. It has no bearing on the plumbing. Its purpose is to provide a temperature regulated self-contained bypass to limit the fresh water temperature to 120º.
In a Catalina 30, the engine is under the settee and the WH is under the quarter berth. The Tstat is about the highest thing on the engine to facilitate bleeding air from the system. This puts it at about 16" - 18" above the floor. the WH is under the Q-berth which is less that 10 above the floor and the HX ports are not more than an inch or two above floor level. as I have said, this is a direct replacement of the factory setup. The RedDot is in the toe kick under the oven so it is at the same elevation as the WH and significantly lower than the engine outlet. The connection to the engine is the high point of the entire circuit so this is not an issue.
The reason that Kumma suggests installing the WH lower than the engine is so that bubbles will not be trapped at the WH and will migrate back to the engine where they can be purged. The WH can be installed higher but it will need to have a T installed with a capped purge line extending upward from the highest point in the line to give a place to bleed air and trap small amount of air in the line to keep them out of the circuit flow. If this wasn't true all boilers in hot water heating systems would need to be mounted at the highest point of any building with all radiators below them.
It just aint so.
We have all of us ruled out some thermodynamic mystery long ago. Otherwise this group would not be trying so hard.
Instead of rejecting all suggestions thus inevitably leading to a diagnosis that it is all just unexplainable - how about we think through to plausible explanations for how this could possibly happen.
So far - you have ruled out every possible component failure, you have followed every factory detail to the letter including those from the folks here, and you say your dock mate's system is identical same motor, same hook up, same space heater .
And - the only thing different is his works yours does not. This cannot be so. His is different from yours in some important way. You are overlooking something.
Charles
Instead of rejecting all suggestions thus inevitably leading to a diagnosis that it is all just unexplainable - how about we think through to plausible explanations for how this could possibly happen.
So far - you have ruled out every possible component failure, you have followed every factory detail to the letter including those from the folks here, and you say your dock mate's system is identical same motor, same hook up, same space heater .
And - the only thing different is his works yours does not. This cannot be so. His is different from yours in some important way. You are overlooking something.
Charles
Still scratching my head over this one.., Hayden.. Couple of things that are musings and not conclusions.. First is that the temp control valve is something that I've not seen on other heaters..usually the domestic water is what is bypassed and not the engine coolant. This way, the water tank is at high temp and because the domestic water is tempered, the hot water behaves as if it had a larger tank.. have you removed the coolant side valve and are feeding coolant directly to the little stub instead of using the riser hose from the bypass? Couple of other musings.. ask Kumma if the space between the double wall exchanger tubes is supposed to be filled with a fluid to let the heat from the inside tube wall get to the outside tube wall..If they were using a heat exchange medium between the tube walls, and forgot to fill this one, that might act as a heat block and limit heat exchange between coolant and domestic water.. another heat exchange block: There may be a bubble trapped in the coolant tube which would very much limit the coolant contact with the walls of the exchanger tube yet allow a small flow through that would be enough to heat air in the Red Dot. If the coolant standpipe from the temp control valve remnants is still there, that could do that.. ?? dunno..
This is a strange one ..
This is a strange one ..
Darn it Hayden, no offense but I can't help myself after reading the 60+ posts of this thread. You were a diesel mechanic. Diesels are supposed to run hot ! 140 is way low. Universal 25MX specs call for operating temp from 165 to 195°
Why not go back to the basics i.e.:
1) Disconnect in and out coolant hoses to WH and Red Dot, and bypass with short hose from engine outlet to inlet. Run engine under load and make sure to get to "normal" operating temp for your engine. If not reaching 165 find out why and correct the problem.
2) Once satisfied, connect WH but not Red Dot. Run engine under load again long enough to bring engine temp to normal and heat water (my Yanmar takes +/- 30 mn with same Force 10 as yours). Check water temp. If still cold, problem with tank. TCV ? I was advised by Force 10 to bypass it 5 years ago and WH has performed perfectly since. Seem to recall you adressed this issue earlier on this thread. If problem with tank, you might need to replace.
3) If satisfied, reconnect Red Dot and check again. If water temp drops, then suspect Red Dot. Getting air to comfort zone from 140° coolant is much easier than get water to 120 or 130° from same 140° coolant. Hoses may be too long ! Does your neighbor have the same length ?
If all else fails, replicate exactly your neighbor system (if same boat) or make an offer on Stu's boat ! Good luck and keep us posted please.
Why not go back to the basics i.e.:
1) Disconnect in and out coolant hoses to WH and Red Dot, and bypass with short hose from engine outlet to inlet. Run engine under load and make sure to get to "normal" operating temp for your engine. If not reaching 165 find out why and correct the problem.
2) Once satisfied, connect WH but not Red Dot. Run engine under load again long enough to bring engine temp to normal and heat water (my Yanmar takes +/- 30 mn with same Force 10 as yours). Check water temp. If still cold, problem with tank. TCV ? I was advised by Force 10 to bypass it 5 years ago and WH has performed perfectly since. Seem to recall you adressed this issue earlier on this thread. If problem with tank, you might need to replace.
3) If satisfied, reconnect Red Dot and check again. If water temp drops, then suspect Red Dot. Getting air to comfort zone from 140° coolant is much easier than get water to 120 or 130° from same 140° coolant. Hoses may be too long ! Does your neighbor have the same length ?
If all else fails, replicate exactly your neighbor system (if same boat) or make an offer on Stu's boat ! Good luck and keep us posted please.
Watson -
Attached is a link to the manual from your engine manufacturer. It addresses water heater installation at page 25. This is a better explanation than the water heater manufacturer has so far offered. The point is that if any part of the heat circuit - not just the heater itself - is above the reservoir then a secondary expansion tank is mandatory. The purpose is pretty obvious.
I hope no part of your system is above the coolant source, but if so we cannot conclude siphon theory will save the day. All things considered trapped air explains all the symptoms you describe.
Charles
http://www.westerbeke.com/operator's manual/200494_m320a_thru_m35b_operator_man.pdf
Attached is a link to the manual from your engine manufacturer. It addresses water heater installation at page 25. This is a better explanation than the water heater manufacturer has so far offered. The point is that if any part of the heat circuit - not just the heater itself - is above the reservoir then a secondary expansion tank is mandatory. The purpose is pretty obvious.
I hope no part of your system is above the coolant source, but if so we cannot conclude siphon theory will save the day. All things considered trapped air explains all the symptoms you describe.
Charles
http://www.westerbeke.com/operator's manual/200494_m320a_thru_m35b_operator_man.pdf
I do not see a way of avoiding getting the hands dirty. The chances of coming up with a solution by thinking through the problem seem to be nil. Time to start moving things around and isolating components to see how they behave by themselves. Somewhere an assumption is being made that is incorrect. The main ones are a) that the heater is of sound fabrication, that there is adequate water flow, that water temperatures are accurate, that there is no air trapped in the heater exchanger. Reconfigure, reposition and test and by process of elimination you should find the problem.
I didn't go back and read all replies, but could it be the water is moving too quickly through the water heater, and not allowing heat ransfer? I don't ecall anyone mentioning fins on the heat transfer tube, so guess it's just smooth-walled?
Last edited:
I agree with Claude, Charles & Benny, the OP will hopefully get back to us.
Only one thing: if there is an air bubble in the line from the engine, the engine would overheat, not run cool.
That's why we keep having to explain "How to Burp Your Engine" to so many new skippers.
Otherwsie, step-by-step is the only way to find out.
Only one thing: if there is an air bubble in the line from the engine, the engine would overheat, not run cool.
That's why we keep having to explain "How to Burp Your Engine" to so many new skippers.
Otherwsie, step-by-step is the only way to find out.
Hot Water
Hayden,
This may sound simplistic , but you might have the inlet & outlet hoses reversed at the heater. The labeling might have been incorrectly applied at the factory. Doug Ward
Hayden,
This may sound simplistic , but you might have the inlet & outlet hoses reversed at the heater. The labeling might have been incorrectly applied at the factory. Doug Ward
It is just a loop through the water heater. As long as hot coolant is flowing through the heater I don't think this would make any difference.
That's right, it does NOT make any difference.
I KNOW this because I went through it last year when I replaced our water heater and the year before that when I replaced the hoses from the engine.
That would be true if the water coming out of the engine kept getting cooler but according to Hayden there is a steady inflow of water at 140 degrees so that would mean that the temperature inside the coil stays at a temperature between 140 and 134 degrees Fahrenheit which the manufacturer states should be adequate to heat water inside an hour. When I was a teenager I removed the thermostat from a car engine and as a result the car started overheating. A old mechanic told me that the water was flowing too fast through the radiator and not cooling enough so temperature built up. The radiator was working at capacity but was overwhelmed by the added volume of hot water. In this case the heat exchanger is not being overwhelmed it is working at minimum efficiency.
The coil temp can stay between 140 and 134 degrees without the water in the heater getting up to temp in a reasonable period of time, it all depends on how much heat conductance the exchanger provides. If it's a good insulator, very little heat will be transferred regardless of how hot the water is on either side of the exchanger.
Regarding the thermostat story, I think you've broken at least one law of thermodynamics. The radiator may transfer less heat per pass if the fluid is moving faster but by the same token, the engine will transfer less heat to faster fluid too. By design, the radiator can dump more heat than the engine can produce. If that weren't the case, the engine would overheat at a given throttle setting and above. My guess is that when you pulled the tstat, you introduced air into the system and prevented coolant flow through the radiator, causing the engine to overheat.
That is what I said the manufacturer's representative had indicated that 140F was adequate temperature to heat water within an hour. I agree that efficiency of the exchanger is a primary concern. Regarding the thermostat story it was true that the overheating took place when the engine was ran over a certain RPM. Until then the radiator was able to cope with the increased flow of heat arising from the increased volume of passing coolant. Above that RPM range the radiator was working at its maximum capacity and was overwhelmed and the circulating coolant was increasingly gaining in temperature in subsequent passes as the coolant entered and exited the engine. The net effect was as if we had installed a smaller radiator inadequate for the task at hand. I just wanted to illustrate the point that speed of the flow may affect the temperature of the coolant in the loop but if the inlet temperature to the exchanger remains constant then it is up to the efficiency of the exchanger to do the work. The radiator indeed was designed to work with a thermostat to cool the engine. By removing the thermostat I fouled up the design criteria. If we slow up the flow in Hyden's heater we could probably get an exit temperature of 120 but no more heat would be transferred into the tank as then the average temperature in the coil would be the around 130F instead of the current 137 F. You and I are basically saying the same thing but from opposite perspectives.
Curious why the op's engine coolant is 140 degrees. Any fresh water cooled engine I have come across runs at about 180 or 190. This is the most efficient temperature.
Raw water cooled engines run at 140 to prevent salt build-up in the engine cooling passages. This makes for a less efficient engine but is necessary. As many know it is very hard to heat a water tank with a 140 degree salt water cooled engine.
Raw water cooled engines run at 140 to prevent salt build-up in the engine cooling passages. This makes for a less efficient engine but is necessary. As many know it is very hard to heat a water tank with a 140 degree salt water cooled engine.
Space heater (downstream of water heater same circuit) returns coolant to motor 40F colder. Remove space heater from loop and motor coolant temperature will rise - probably.
Problem here is something else I think - no transfer hot coolant to cold water heater contents. There is only one thing that explanations this that I can see.
Charles
ps hand me the wrenches
Problem here is something else I think - no transfer hot coolant to cold water heater contents. There is only one thing that explanations this that I can see.
Charles
ps hand me the wrenches
Seems like Maine sail hit the nail on the head about 40 posts ago. If the thermostat is closed flow of coolant will be inadequate to heat water. I have not seen where you actually pulled the outlet hose off the liquid to air HX to check the flow. Hot before cold after tells nothing about the flow.
Even with 45 degree water your engine should get to operating temp no problem. I ran my M25 all the time in water that cold and it always warmed up to steady state. I doubt the liquid to air HX without a fan running to force air through it will transfer so much heat to stop the motor from reaching proper temp. Without air flow the air temp around the fins will increase reducing your delta T and minimizing further heat transfer. Yes you will have convection but it won't be like a fan or driving 30 miles an hour.
Your operating temp is more likely related to raw water HX capacity. What size HX is in the raw water circuit?
Even with 45 degree water your engine should get to operating temp no problem. I ran my M25 all the time in water that cold and it always warmed up to steady state. I doubt the liquid to air HX without a fan running to force air through it will transfer so much heat to stop the motor from reaching proper temp. Without air flow the air temp around the fins will increase reducing your delta T and minimizing further heat transfer. Yes you will have convection but it won't be like a fan or driving 30 miles an hour.
Your operating temp is more likely related to raw water HX capacity. What size HX is in the raw water circuit?
Like "mitiempo" indicates, experience has taught us that it is very hard to heat water with a raw water cooled engine. It is hard down here in Florida so it must be almost impossible further North. Hayden if your set up works well with shore power and you do not want to tinker with it then you may want to consider a propane powered tank less water heater.