Water heater replacement - advice?

[Lou_tribal]

Hello fellow TFers.
Just got a new 11gal water heater to replace my old leaking 6gal one ( it is Xmas today! )
Both old and new have a heat exchanger that connect to engine cooling system.

Any advice to avoid getting a mess when disconnecting coolant hoses from the old one?
Also as I will certainly loose some of the coolant in the install, any advice on refilling? I mean is filling the coolant tank, running engine a bit, stop and refill until everything is back to normal the correct way?

Thank you!

L

 

[Capecodder]

When I changed my water heater the heat exchanger hoses were long and I had room to temporarily hang them higher the the engine and had minimal loss of coolant. But decided the long unattached hoses allowed neat way to drain and change the coolant.

When I refilled the system I did a few short runs at the dock and topped off a couple of times.

 

[bilge53]

Get you a small adapter to temporarily connect the two hoses from the engine clamp these closed before disconnecting and get you a short length of hose to use to drain heater into milk carton and then to connect inlet and outlet for the stuff that is waiting for you to move the heater so it will drain. Have a good supply of old rags around. Tape the breaker in "Off".

 

[Carolena]

When we replaced ours, which is a long run from and below the engine, I just used a couple vice-grips to crimp off the hoses near the heater. Maybe lost a quart or so of coolant. Then just refilled at the engine, ran it for a bit, and rechecked the level. If you go this route, just be careful not to put the grips on too tight. you want to just barely crimp the hoses not damage them.

 

[O C Diver]

A proper installation will have valves where the hoses connect to the engine. If not, they should be added. If the water heater loop develops a leak while underway, you want to be able to isolate (turn off) the loop.

Ted

 

[Lou_tribal]

A proper installation will have valves where the hoses connect to the engine. If not, they should be added. If the water heater loop develops a leak while underway, you want to be able to isolate (turn off) the loop.

Ted

Indeed this is a very good idea however I have no valve (yet)

L

 

[Ski in NC]

Once you get it hooked up and engine filled and started, make sure the lines warm up with the engine. This means coolant is circulating. It is possible for an air bubble to purge out of the heater loop and get your circ pump air loaded. Lines should get hot with the engine.

Keep a close eye on coolant level til engine has made a couple thermal cycles.

Valves are nice, but not necessary.

 

[BruceK]

Lou, we had to disconnect mine to access the stern gland under it,took quite a lot of bleeding afterwards.

 

[Lou_tribal]

Thank you all for advice, as usually I am so glad you are out there fellows
Was thinking (pretty sure over thinking) of something... what about filling the new heater coolant lines with coolant? I mean having a hose hooked up and pour coolant in the heater before reconnecting everything so only few bubbles stay in the lines.

L

 

[Pgitug]

Two friends of mine came within seconds of destroying their main engine due to a water heater failure. I have a generator that runs our AC as we travel. The use of engine cooling water to do other things on the boat has been removed. If one of those hoses to your cabin heater or water heater fails the main engine repair bill is north of $25,000.00.

 

[twistedtree]

This might be a good opportunity to drain all the engine coolant, install shut off valves, perhaps replace the hoses to the hot water heater, replace the HW heater, and fill the engine with new coolant.

 

[twistedtree]

Two friends of mine came within seconds of destroying their main engine due to a water heater failure. I have a generator that runs our AC as we travel. The use of engine cooling water to do other things on the boat has been removed. If one of those hoses to your cabin heater or water heater fails the main engine repair bill is north of $25,000.00.

I think catastrophic engine failure is very low risk if you are monitoring your engine temps, and with shutoff valves and a jug of coolant, you can be back in business is short order.

Generator powered electric HW heating is a great option if you otherwise have cause to run a generator all the time, as many in hot climates do. But in cooler climates one hardly ever runs a generator while underway, and having nice hot water during and after operation is really nice, and often all one needs. So under those circumstances engine heated water is very attractive, and has very manageable risk.

In Lou's case, I do think installing shutoff valves and replacing the hose (which is likely quite old) would be key to managing risk.

 

[C lectric]

Years ago I replaced the hot water tank hoses to the engine.
I installed ball valve shutoffs at the engine. Those valves are my last ditch if a hose blows or the HWT itself develops a problem. I can isolate the two.

EDIT:
I'll add to get GOOD quality hose which will reduce the chance of a hose failure to almost nil, not none , but close.

I used Aeroquip hydraulic hose ~ 20 yrs ago and it is still flexible. Don't remember the specific grade now. The original hose was so stiff I had a tough time extracting it and it was not as old then is this stuff is now. What I used was overkill , I think now, yet I suspect it will still be going when I'm not. Good stuff and not the typical auto parts store stuff. GO to a hose specialist if you have one available.

 

[sunchaser]

Two friends of mine came within seconds of destroying their main engine due to a water heater failure. I have a generator that runs our AC as we travel. The use of engine cooling water to do other things on the boat has been removed. If one of those hoses to your cabin heater or water heater fails the main engine repair bill is north of $25,000.00.

There are many different hoses, fittings, valves etc to check and maintain to insure coolant, fuel, raw water, fresh water, hydronic heating, AC and washers don't sink or damage the boat. Water heater hoses are pretty long lived if installed properly.

Possibly your friend was not as diligent as he could have been. ER checks both at the dock and while underway can pinpoint most trouble spots.

 

[psneeld]

People destroy boats every day because of all kinds of reasons.

Run new cheap lines and replace the hose clamps every 6 months...or splurge and use the best for another $20.

Cheap and easy, all but guarantees a tiny chance of failure and the reward is great.

If I based my boating decisions onbwhat the masses encounter, I would sell and RV full time....

No wait, highway accident statistics...egads!

 

[Lou_tribal]

Speaking of shutoff valves I guess I would need to setup a bypass as the coolant is leaving the engine to go in the water heater and go back afterward. In my understanding if I want to had a valve to bypass the WH I need the valve to allow coolant to return directly to the engine.
Like TwistedTree mentioned I will change the hose as I don't know how old they are and I want to run them properly attached and not the way they are now.

L

 

[Xsbank]

I bought a cheaper water heater this time, Torrid has just become silly with their prices, especially in Canada. I installed my 1-year warranty tank with Sharkbite connectors and used valves inline so the entire thing is easily isolated and tossed. I can get 4 of these Kumho heaters for the same price as the same size Torrid. I figured there was no point in buying a really good heater for the next owner.

 

[Lou_tribal]

I bought a cheaper water heater this time, Torrid has just become silly with their prices, especially in Canada. I installed my 1-year warranty tank with Sharkbite connectors and used valves inline so the entire thing is easily isolated and tossed. I can get 4 of these Kumho heaters for the same price as the same size Torrid. I figured there was no point in buying a really good heater for the next owner.

My old one was a seaward 6gal. I went to a Khufu mon 11gal for my replacement. I got it at special price for 300$CA, hard to beat. Like you said, cheap and for what I am expecting to do with it it will be far enough.
One thing I am not sure though is if I need to put an anode in it in place of the valve or not.

L

 

[twistedtree]

Speaking of shutoff valves I guess I would need to setup a bypass as the coolant is leaving the engine to go in the water heater and go back afterward. In my understanding if I want to had a valve to bypass the WH I need the valve to allow coolant to return directly to the engine.

That's not necessary. The coolant bypasses internal to the engine. When the external loop isn't used, those ports are just plugged. There is no problem just using shut off valves, one on each port.

 

[alormaria]

I replaced my water tank with a Force 10 6 gallon a few years ago. I remember stuffing wooden plugs into the coolant lines for the few minutes it took to install the new unit. I don't believe I have any shutoff valves. My lines are mostly copper with short hoses at each end.

 

[Lou_tribal]

In 2 weeks I expect to be able to start working on the boat and install the new water heater. Speaking about heater anode, what kind of anode are you using. I saw that 2 model are available, one with a drain plug in it and one without. If using the one without drain plug, how do you drain the heater before winter (for the one who winterize), just remove the anode and let the water flow?

L

 

[FF]

Some folks want to use the engine heat for FW heating as well as cabin heating with a "bus" box heater.

This is best done with 2 circuits with shut off valves.

The problem with a series (both in line) is many FW heaters make an attempt at keeping the FW from being scalding.

They do this cheaply by slowing/ stopping the flow thu the heater, it doesn't work overtime as eventually the FW in the heater becomes engine coolant temperature.

However when throttled the cabin heater gets very little hot water to heat the cabin.

 

[Maerin]

Strongly recommend installing valves on the engine side of the coolant circuit, close to the block. These mini-ball valves make an in-line install easy with a minimum of fittings. The valves have a small profile that makes them easier to swing when making up the joints. Servicing the hose, or taking the heater out of service is simply a matter of closing the valve. In the event of a coolant problem, you'll really be glad you added the valves when you had the opportunity.

As far as using the valves for throttling- my keel-cooled 6BT has a 193F thermostat. The diesel likes the higher temps, but the water heater consistently goes over temp to where it trips the high limit in the element thermostat. It needs to be reset to allow water heating on shore/gen power. A PITA. Not to mention the very real scald potential.

The recommended solution is to throttle the flow, but it only works on a short engine run; eventually the temps equalize even with a tiny bit of flow and the water heater overshoots. My solution was to pipe in a 12VDC normally closed solenoid (about $30), and control it with a W1209 digital thermostat (less than $10) with the sensor stuffed between the tank and the insulation by the hot water connection. The electronic thermostat is only powered when the ignition is switched on, and it opens the solenoid when the engine starts, closes the valve when the water temp in the tank reaches the setpoint (about 71C). It's working great, it takes all of about 20 minutes of run to heat the 20 gallon tank and it shuts off the remainder of the run and the water temp is easily adjusted. No more opening the case of the water heater to reset the snap switch limit.

Yes, less is more, but I just couldn't find a simple hydraulic thermostat or tempering fitting that would accomplish the objective without more complicated piping than the simple bang-bang solenoid function. Tempering the domestic side wouldn't correct the limit problem.

BTW, it's a WATER HEATER, not a HOT WATER HEATER. If the water was hot, there'd be no need to heat it. plumber humor

 

[timb]

Maerin,
that's a great idea .I think I would also like to have another thermostat on the engine so that it will not start heating the water until the engine is somewhat warmed up.
my boat had a diesel furnace that I have removed .the radiators are still there. this would also be a good set up for them . my engine is very slow to warm up .

 

[FF]

" my engine is very slow to warm up ."

The difference in having i0 G more of fresh water to heat compared to a 2500lb engine is minor.

How much load do you have while warming underway.?

 

[timb]

I usually wait for the temp gauge to move before I leave the dock . it starts at 100 so 105 110 I leave. what is the recommendation on a leman ? what rpm is it best to warm up at?

sorry for the hijack . we may be off topic

 

[Maerin]

Maerin,

that's a great idea .I think I would also like to have another thermostat on the engine so that it will not start heating the water until the engine is somewhat warmed up.

Not worth the trouble, what would be the benefit? It's gonna get to temp regardless, so why add a delay? The W1209 module does have a programmable delay if you'd like. They are very versatile for the all of 10 bucks cost.

FWIW, one got flakey right out of the box, they sell them in pairs- telling? I wouldn't use for real critical applications, that's one reason I used a N/C valve to fail safe. But they are a great device for lots of different temp control apps.

 

[Lou_tribal]

sorry for the hijack . we may be off topic

Just a bit but that is fine if I can get some hint about water anode

L

 

[FF]

Draining a FW heater works IF the entire FW system is drained and air blown thru for an hour or two.

Many folks prefer to fill the FW system with pink goo antifreez , but to do this the heater must be taken out of the circuit, or will require filling with goo.

The easiest method is a by pass so the piping can be filled with pink goo, but the FW heater left empty.

At your local RV store for a few RV , not boat bucks.

https://www.google.com/search?q=rv+hot+water+heating+winterize&ie=utf-8&oe=utf-8&client=firefox-b-1

*****************
"I usually wait for the temp gauge to move before I leave the dock . it starts at 100 so 105 110 I leave. what is the recommendation on a leman ? what rpm is it best to warm up at?"

Diesels are very efficient at idle and create little extra heat with no load.

After engine start about 1 or 2 min of ideling the engine will run smooth , so its time to get underway.

800-1000 RPM underway until the water temp is 120F or so then slowly go to cruise , where the temp should stabilize .

Prolonged idle is never good for an engine ( just like a weekly run it for 10 min) so the oil may need to be changed more often.

 

[Maerin]

Just a bit but that is fine if I can get some hint about water anode

L

If winterizing is an annual task, then go with a configuration that allows draining the tank with a valve rather than wrenches. If it means doing some repiping to get the valve in place while retaining the benefit of the anode, probably worth the effort. If you annually fill the system with pink, then pipe in a bypass on the water heater with a pair of 3 way valves, that way you can prep the water heater for winterizing by swinging two valve handles and leave the wrenches in the tool box. Bypass it, drain the water, leave it empty, then treat the system with pink, saving the amount that would be wasted in the water heater. If there's concern about the amount of water remaining in the tank after it's drained, simply release a bit of pink into the tank for insurance.

Hope that's the answer you were seeking.