How to replace water heater in 2016 R29

[Kenaithab]

I am looking for some guidance on how to replace our water heater. We have purchased the new Isotherm 8 gal water heater that Ranger now puts into their current R29. The difficult part of the switch looks to be swapping the hoses that bring the Volvo green coolant to the heater and then back to the engine. Any recommendations on how to do this with minimum loss of coolant? Even with the valve turned off it would seem that there is quite a bit of fluid in the heat exchanger and hoses. Does the system have to be purged after the swap? if so, how?

Thanks

 

[BB marine]

I believe you will lose some coolant from the lines and exchanger. It should be minimal but will still require adding to the coolant reservoir after a few runs. In theory it should bleed out the air after a long run of the engine. It may take a couple of runs to completely disperse all the air and maintain a level coolant level because of the length of the hose from the ball valves and the highs and lows of the hose run. I am interested in this question too. I'm replacing all the coolant in the engine based on the Volvo manual stating every second year.( Replace coolant D3) I have gone 3 seasons. My plan is to drain all coolant, flush with filtered water and then fill at the reservoir. I have a few months until spring commissioning so I will leave the reservoir cap off with the hopes that this will help vent some of the air out of the system while in storage. I'm interested in how others have successively replaced coolant and purged all air from the bus heater and water heater after a coolant change.

 

[Brian B]

I recently replaced the Seaward hot water heater on my 25SC which has a Yanmar. The engine coolant loss was minimal. When I disconnected the engine hoses to the heater I plugged the hoses with 5/8 wooden plugs I made up ahead of time.

 

[snydzy]

I'm replacing all the coolant in the engine based on the Volvo manual stating every second year.( Replace coolant D3) .

Brian, I checked my operator’s manual D3......It showed service of VCS (yellow) @8000 hrs or 4yrs. Not sure why the difference?

 

[S. Todd]

Because of the difficulty of draining all the fluid for a complete change I have opted to do what others on the forum suggested. I drain the heat exchanger on the engine every year and replace that amount of fluid, or about 6 quarts each year. Some gets refreshed each year that way. I add the amount drained out through the fill cap on the reservoir and never have had an issue with purging air from the system. We have a R25SC with a Volvo D-3. Replacing the water heater would give you a chance to change that additional amount of antifreeze. Running the engine should purge the system and just add fluid as needed.

 

[BB marine]

I'm replacing all the coolant in the engine based on the Volvo manual stating every second year.( Replace coolant D3) .

Brian, I checked my operator’s manual D3......It showed service of VCS (yellow) @8000 hrs or 4yrs. Not sure why the difference?

Thank you for posting this. I have a downloaded Volvo D3 owners manual on my computer that I use to reference maintenance schedules. After you posted this I looked at it again:
Every second year
Impeller, Seawater Pump. R
Coolant R
I looked at the hard copy manual and it shows exactly what you posted. Looks like I have another year of running before changing coolant.

 

[Scottfree]

If your going to the trouble of replacing your hot water tank I would suggest you take the time to install a corrosion rod. They are a universal pipe thread and can be bought at any place that has RV supplies. Also on my Hot Water tank I installed a set of RV Hot Water Tank bypass valves. I can now bypass the heater and drain it when winterising the fresh water system saving 6 gallons of RV antifreeze.

As for changing the engine antifreeze I found a convenient spot in the heater/hot water coolant loop and cut the hose. By inserting two pieces of the clear (half inch I think) hose about 4 feet long and taping the connection with electrical tape I was able to vacuum out the old antifreeze while drawing in clear demineralized water. Once I had clear running water I continued to draw out the water while drawing in Concentrate Anti Freeze (Not pre mix). When you start to see the anti freeze color coming through you can draw off some and test it for concentration with a cheap automotive anti freeze tester. Continue drawing in pure anti freeze until you reach the concentration/freeze protection you need for your area. I try to reach a 50/50 or -40 concentration to ensure I have enough corrosion protection as well. I joined the hoses with a brass barbed fitting and SS hose clamps. I then top up the overflow tank with an anti freeze and run the engine to operating Temperature. Keep checking the overflow tank and topping up accordingly. When the engine cools down it draws through the Radiator cap from the overflow tank. It does not matter the brand of engine.

When I get around to it I will install two three way valve in the heater loop for future antifreeze changes. You can use Long Life (10 years) antifreeze like they use in Semi tractors and maybe never do this again. Service manuals are designed to cheap manufacturers in cash flow.

This method is how mechanics do vehicles, it is also how they change automatic transmission oil. No mess!

Good luck, Leon