Accumulation Tank in cooling/hot water heater system

[mherrcat]

I have an "accumulation tank" in the fresh water/coolant system between the heat exchanger and the hot water heater. If the hot water heater is removed, is there any need to keep the accumulation tank plumbed into the cooling system? Can the coolant hose that currently goes to the accumulation tank just connect directly to the exhaust manifold, bypassing the whole water heater system?

 

[Prairie Schooner]

Hi Mark,
There was some helpful discussion on this subject in the thread below, starting with post #63:

Coolant Conundrum/Exhaust Riser Replacement [Master Thread]

How to Flush Cooling System Without Starting Engine? It's clear that salt water has been getting into the coolant circuit. A small leak could be the reason I could never keep fluid in the overflow tank. The overheat that precipitated this work might have enlarged a small preexisting leak...

ericsonyachts.org

They are discussed in other threads as well.

My takeaway is that their necessity depends on the arrangement of the different coolant system components, in particular their respective heights. I think some people have concluded they are more of a convenience than requirement. I'd be inclined to leave it in.

 

[mherrcat]

I found this explanation of the purpose of the accumulation tank:

Hot Stuff: Keeping Your Boat’s Water Heater Safe & Efficient

A reliable onboard water heater is key to comfort. Learn essential maintenance tips for air, temperature, pressure, and plumbing to keep it running.

www.cruisingworld.com

So it seems with no water heater installed at a height above the fill cap on the engine exhaust manifold there is no need for the accumulation tank. I will leave the tank installed however in case the water heater gets reinstalled at some point, then the accumulation tank can be plumbed back into the system. I see no need to maintain the excess coolant in the system that the accumulation tank holds.

The water heater has always been an issue when having to get into the area behind the engine to change the heat exchanger zinc, check/change the transmission fluid, or replace the filter element in the primary Racor fuel filter.

 

[Slick470]

I added one to the shopping list to re-do our freshwater system as it's also supposed to help smooth out the pressure and extend pump life in systems with single speed on/off pumps.

No personal experience. I bought all the stuff and it's in a box in my basement waiting for time to get to that part of the project, so YMMV.

 

[mherrcat]

I added one to the shopping list to re-do our freshwater system as it's also supposed to help smooth out the pressure and extend pump life in systems with single speed on/off pumps.

This is a different type of "accumulator" tank. The one I am referencing is part of the engine coolant system, between the engine/heat exchanger and the hot water heater. The Ericson documentation describes it as an "accumulation tank." So I guess there are two different kinds of "accumulation" tank.

 

[Captain Pete]

I had one of those tanks in the 35-3 I had that was high up in the starboard locker. I believe it was from the original build of the '85 boat that originally had the universal and who knows what for a water heater. It had since been repowered with a yanmar and a newer water heater. The hot water heater was not connected so this was tank not in use. When I tried to get the hot water system connected and functioning I tried several combinations of hose connections and routing, including using this thing. It was quite frustrating (swear swear swear). I wound up not using it since, as others have noted, the hot water heater was not higher than the top of the heater exchanger. At this point it is just scrap metal.

 

[Prairie Schooner]

I had one of those tanks in the 35-3 I had that was high up in the starboard locker. I believe it was from the original build of the '85 boat that originally had the universal and who knows what for a water heater. It had since been repowered with a yanmar and a newer water heater. The hot water heater was not connected so this was tank not in use. When I tried to get the hot water system connected and functioning I tried several combinations of hose connections and routing, including using this thing. It was quite frustrating (swear swear swear). I wound up not using it since, as others have noted, the hot water heater was not higher than the top of the heater exchanger. At this point it is just scrap metal.

What's weird is that our '86 didn't have one when we bought it from the original owner, with the original engine (tho with rebuilt top end) and a new WH.

 

[Captain Pete]

What's weird is that our '86 didn't have one when we bought it from the original owner, with the original engine (tho with rebuilt top end) and a new WH.

Maybe they got smarter by 86 and realized the tank was unnecessary. I wish old boats could tell us their history - where they've been, what's been done over the decades, who treated them with care and love and who didn't. But then again, like having a new girl friend, we may be better off not knowing

 

[Prairie Schooner]

Maybe they got smarter by 86 and realized the tank was unnecessary. I wish old boats could tell us their history - where they've been, what's been done over the decades, who treated them with care and love and who didn't. But then again, like having a new girl friend, we may be better off not knowing

There's a whole book in that paragraph, Peter. Though I'm not the guy to write it.