Any issues with bypassing water heater?

[leecea]

As part of bypassing my water heater for eventual replacement, I'd like to disconnect the two coolant lines that run from the engine to the water heater.

I would disconnect them at the water heater end, then simply connect them together to make a loop.

My assumption is that the coolant will flow from the engine, around the loop, and back to the engine with no issues.

Is there any concern with doing this?

Thanks,
Andy

[Bowdrie]

Originally Posted by leecea

Is there any concern with doing this?
Thanks,
Andy

Not at all, it's a quite common procedure, not unlike the heater in your vehicle where a valve just shuts off the flow or bypasses the heater.

[chrisr]

alternatively you could blank off both ends where the heater water comes out & returns to the engine

possibly a neater option with less chance of going wrong eg split hose...but depends on when you plan to reconnect the heater

cheers,

[wsmurdoch]

What engine do you have? What water heater do you have?

Where in the engine's cooling loop does the supply to the water heater leave the engine?

Where does the return from the water heater enter the engine's cooling loop?

What is the diameter and length of the hoses to and from the water heater? Are there any elbows or other restrictions in that circuit?

If for instance, the supply to the water heater leaves the engine's cooling loop immediately after the circulating pump where the pressure is high and returns to the engine's cooling loop immediately before the circulating pump's suction where the pressure is low, you will create a low pressure drop - high flow bypass by removing the resistance of the coil in the hot water heater; more coolant will flow through your bypass and less coolant will flow through your engine.

[leecea]

wsmurdoch,

I see what you are saying.

I have a 3GM30F and a Force10 water heater that currently has a Kuuma temperature compensation valve that limits coolant flow based on the heater water temperature. That valve is no longer made.

Based on what you saying, maybe I am better off plugging the two coolant lines so there is no flow through them?

Andy

[wsmurdoch]

To me knowing little of your actual installation, it seems like the better plan. In addition as chrisr suggested, plugging off at the engine would also eliminate the risk of a hose failure.

[Bowdrie]

When viewed against the restrictions of the fittings at the engine and water heater plus the length of the hoses, (not to mention the convoluted passages in the engine itself,) the pressure drop across the large radius of a metal pipe loop/partial loop in the water heater is but a "grain of sand on the beach" so to speak.
The same with dire warnings of split hoses.
It's all "Majoring in minors"
Typical hose is, (or should be,) "Dayco" premium heater hose, (widely available at any reputable auto parts, (NAPA,) it's designed to carry ~240-degree coolant and has a rating of ~125psi.
If that's not enough, there are silicone hoses available that will exceed that at much greater cost.
Connect the hoses together or cap them off, take your choice, it isn't rocket science.

[john.mackenzie]

Should be a straight forward DYI project. Did this on a previous boat. Much to the chagrin of my spouse, we enjoyed daysailing with cold water for a few years before getting around to installing the new water heater. The solution in my situation was about a 8-12" bypass tubing (rated for application as recommended in another post) connected between the output and input sides of the coolant circuit at the engine (arrows in attached pic). This loop was visible and could be monitored for leaks. The bypass hose was shorter (and new) compared to the actual heater loop, so I assumed less prone to failure. The bypass loop was easier in my situation as it would have taken me some effort to find caps. Be sure to have a plan to recapture the coolant in the lines when decommissioning. Recommissioning presented other considerations (mainly in the proper hose connections to the heater) since I went with different brand of water heater (switched from a rusted out Raritan to Isotemp).

Good luck,

John

[Rackman]

This used to be part of my winterization process. Once a realized I didn't really need the water heater I never hooked it back up and ran it like that for years.

[leecea]

Thanks for the advice everyone. I think I'm good now.

[SV Confianza]

We had some issues on a new beta marine engine install. Beta USA suggested that the hot water hoses should NOT be just connected together. The engine is not designed to have a longer run unless it's transferring some heat to a water heater.

They had me put in shut off valves at the engine instead, and apparently this is "best practice."

It sounded like a crock of crap to me, but I complied anyway. Didn't solve the issue either...

[stormalong]

Originally Posted by BistroMath

We had some issues on a new beta marine engine install. Beta USA suggested that the hot water hoses should NOT be just connected together. The engine is not designed to have a longer run unless it's transferring some heat to a water heater.

They had me put in shut off valves at the engine instead, and apparently this is "best practice."

It sounded like a crock of crap to me, but I complied anyway. Didn't solve the issue either...

What was your issue?

[SV Confianza]

Originally Posted by stormalong

What was your issue?

I'm going to do my best not to derail this thread...

We have an abnormal amount of what appears to be steam coming from the exhaust. I did not get the more advanced gauge package, so we don't have a proper engine temp sensor (wish I realized this when purchasing). Beta has had dealers look at it and haven't found a resolution (yet). I'm going to post a much more detailed write up as this progresses.

[goboatingnow]

Originally Posted by BistroMath

I'm going to do my best not to derail this thread...



We have an abnormal amount of what appears to be steam coming from the exhaust. I did not get the more advanced gauge package, so we don't have a proper engine temp sensor (wish I realized this when purchasing). Beta has had dealers look at it and haven't found a resolution (yet). I'm going to post a much more detailed write up as this progresses.

That’s not being caused by the heater pipe run

[Rumrace]

If the heater is helping cool the engine you are in trouble. If the cooling system were failing it might help you may have a simple pressure leak causing boiling. I know Mercruisers drive lines really well. No problem disconnecting the heater. Can’t see a reason why you can’t either. Could be where you are pulling in air???