Water Heater - Replacement Gotchas ??

[PKFK]

So - here goes -

My 1985 Ticon 30 with a Kuang hot water heater connected to a Volvo Penta 2002 diesel has decided to start leaking from inside the tank (not at the fittings).

So - time to replace it.

Question - what to look out for in this job ?

There are only 4 hoses (cold In, hot, OUT, and 2 lines running to the engine for the heat exchanger.

That should be easy - however - it's a boat, and nothing ever seems to be easy.

My big question is around the 2 hoses from the Volvo 2002 Penta engine - what "special" stuff do I need to do when installing the new heater ?

Common sense would indicate that I disconnect them, plug to stop leakage, and reconnect to the new heater.

HOWEVER - I *think* these hoses contain prestone (?) coolant - so - when I change the tank, what other stuff is required on the engine ? (for example - do I need to do anything to the engine heat exchanger ? vacuum pump the cooling system ? add coolant ? re-pressurize the engine cooling system ? etc. etc...?) You get the drift - basically - other than removing the hoses from the old tank and clamping them to the new tank, what wierd and wonderful things do I need to do to make sure both my engine and the new tank work in harmony ??

Advice please !!

Thanks,

Paul

 

[BroadReach]

new hot water tank.

What you may have is an insulated round tank in a square box.
The round tank has the input and output hoses mounted in the upper half of the tank.

You need to insure that all the air is out of the round tank before use as it lies on its side in the square box.. Hook one set of hoses, stand the tank on its end and fill it up to the top to insure all the air is out of the tank.

If not you will have problems.

Broad Reach

 

[Ken Palmer]

I just replaced the water heater on my Hunter 33.5. I replaced it with the same model bought on-line at Defender for a great price. When I disconnected the two hoses from the engine, I plugged them quickly with wooden plugs so that I wouldn't lose too much anti-freeze. After hooking up the new tank, I topped off the antifreeze at the engine. I then started the engine and let it run for a while, checking how hot the two hoses were getting by touch. They both got warm to the touch, so my guess is that there was no air-block in the lines. I used the engine for an hour this weekend, and nothing over-heated and the over-flow tank looks good. Oh yes, the water gets nice and hot and there are no more leaks.

 

[Dan Johnson]

Replaced mine in 2007...

and did the same things Ken Palmer did and have had no problems. Key to it is minimizing the coolant loss when the engine loop hoses are removed and reconnected. One unexpected outcome was that I had to add extensions to the original hoses due to the different location of the hose connections on the new heater. Be sure to put down a "diaper" beneath these connections to catch any coolant loss to minimize bilge contamination as well. Picture attached.

 

[PKFK]

Thanks folks for your postings - it sounds like the job should be straightforward.

I have 2 more questions thougth -

1 - for the Volvo Penta 2002, there are 2 hoses running from the engine to the old hot water heater - but they are not marked on either end !! Do any Volvo experts know which one is the "output" from the engine, and which one is the "return" from the hot water tank ? My new tank is labelled "In" and "Out" for the heat exchanger, but the old one has no markings - so I am not sure which is which.

2 - once I replace the water heater, I think i need to top up the coolant reservoir on the engine with a 50/50 prestone/water mix. (that is easy - just like a car). However - is there anything "special" I need to do to let air out of the cooling system ? On a car I just would let it run with the radiator cap off to let air out - but there is no radiator cap on my diesel that I can see......any ideas on how to bleed of any air in the cooling system after hooking up the new hot water tank ?

Thanks,

Paul

 

[Ron20324]

Use distilled water, not tap water.

 

[Dan Johnson]

Paul...

though I'm not familiar with your particular engine set-up, the "In" connection on the water heater is generally the hose that's connected near the thermostat housing on the engine. The "Out" hose generally is connected to the engine near the water pump housing.

Maybe someone with a Volvo motor can confirm this set-up.

 

[Chuckbear]

There is no in or out as far as the engine coolant system is concerned for most hot water heaters. This is simply a loop and it does not matter which direction the water flows. Are you sure the in and out on the hot water heater is for the engine coolant connections? Chuck

 

[PKFK]

Hi - just wanted to post a closure note - the tank is now replaced.

I am black and blue from working in behind the quarter-berth below the steering stuff - like working inside a coffin wiithout padding !

After removing the old tank I am convinced that the builder instlalled it FIRST, and then put the deck/cockpit on the boat - there is no way they could have fastened the aft part of the tank otherwise.

Unfortunately I was not about to hack a hole in the cockpit so I could do the work, so I spent quite a bit of time doing a poor imitation of a groundhog, headfirst into the back of my boat (I am 6'3" and 200 lbs - which is *not* an asset when trying to work in small spaces.

The engine cooling hookup that I expected to cause untold grief with airlocks, coolant loss, and heavens knows what else was actually straightforward - no problems at all - hooked up hoses to new tank and it worked - much to my surprise.

A couple TIPS to those who may be going down this road:

- the new tanks come with various mounting options (side-side or front-back) for the mounting tabs. Had I known this before I got started I would have selected a tank that had the fastening tabs more conveniently located.

- I pre-wired pigtails to the electrical part of the tank in the comfort of the cockpit, before installing it - that made final connections to the 110V much easier, due to poor access once the tank was fastened down

- I pre-assembled the fittings for the hot/cold hose barbs and only had to screw them into the tank after fastening the tank down - again much more comfortable to do in the cockpit rather than when hanging upside down. I had to do the final attachment of these to the tank after it was in place because the clearance was too tight to put the tank in with the fittings attached.

Summary - connecting 4 hoses, 3 wires, and installing 4 hold-down screws should have taken 20 minutes (max) if this was done with decent access. It actually took closer to 8 hours on the boat (over several days) due to access issues (had to remove and reinstall ALL batteries for access, plus cockpit drain plumbing), and the requirement to modify a bulkhead and one mounting bracket on the tank to address fit issues.

But we DO have hot water again - and with the cold summer this year in Ottawa, that is a PLUS.

Thanks again to all for your helpful suggestions.

 

[Dan Johnson]

Hey Chuck...

what you said was certainly true about the older marine engine-coupled water heaters of the past.

Take a look at the picture I posted earlier in the thread. You'll see a black hose that connects to an aluminum tubular device. This is a new design Force 10 water heater and the tubular device helps regulate the amount of heat absorbed by the water heater from the engine cooling circulation. This is where "In" and "Out" are most important as the flow from the engine must be the one regulated, not the flow back to the engine.

 

[PKFK]

Thanks Dan

I just followed your suggestion about the "in" and "out" heat exchanger hoses at the tank, based on the hose from the thermostat and the one near the pump and everything is fine.

However .....I have the same tank as you do (from the picture) - but I did not spring the extra $$ for the "regulated" heat - we don't have kids on the boat so therefore do not worry about having the water too hot. So I guess my new tank (without the heat limiter) is likely OK either way for the hookup - but if you have the heat limiter, then yes, you MUST have the In and Outs correctly hooked to the engine.....good point !!

Paul