homemade water heater

[broke4now]

Hi,i have been thinking of making a water heater for my boat.its a regal 242 cabin cruiser and does not have hot water plumbing to the fixtures but has the inline electric water heater.it does not work very well at all.my idea is to put the copper wound tubing in the can ,weld it back and pipe the transom shower hose with it.i dont want hot water throughout the boat just at the back for a warmer showeroff before bed.i plan on going between the tstat housing and manifold.to avoid air trapping i would put the inlet of the water in the bottom and let it fill up and then push water to the manifold.the shower is about a 1 gallon a minute rate so it should be slow enough to make somewhat of a heat exchange.my question is about the plumbing,do you see a problem with going between the manifold?is there a better way of doing this,aside from a normal water heater which i dont have room for anywhere as its all taken up with batteries,generator,a/c,and holding tanks.its tight allready.like i said i dont need gallons of hot water ,just enough heat to make a more comfortable spray down.any suggestions are appreciated.

 

[ENSIGN]

Re: homemade water heater

I think you're going to need more copper coils in there.Built a fuel cooler and the more coils it had the better it worked

 

[Tahorover]

Re: homemade water heater

Use a heater core out of a car

 

[broke4now]

Re: homemade water heater

yes sir,i do hvac so i have plenty of it,i just through this together to get my thought across.thanks though

 

[Bondo]

Re: homemade water heater

i plan on going between the tstat housing and manifold.to avoid air trapping i would put the inlet of the water in the bottom and let it fill up and then push water to the manifold.

Ayuh,.... What motor,..?? by Whom,..?? What Vintage,..??

Generally speakin', Hot water is drawn from the intake manifold, 'n returned to the circulating water pump housing....
Higher pressure feed, vs: lower pressure returns...

 

[broke4now]

Re: homemade water heater

Hi, the engine is 1998 volvo 5.7,i have a 1 1/2 foot hose that goes from tstat housing to exhaust manifold.i plan on going between those.so my hose will go from tstat to bottom of my tank,fill up then the top hose will connect back to exhaust manifold cool it and exit boat.i know regular water heaters use the engine to heat them, i just am not sure how they hook up.thanks for looking!

 

[Bondo]

Re: homemade water heater

Hi, the engine is 1998 volvo 5.7,i have a 1 1/2 foot hose that goes from tstat housing to exhaust manifold.i plan on going between those.so my hose will go from tstat to bottom of my tank,fill up then the top hose will connect back to exhaust manifold cool it and exit boat.i know regular water heaters use the engine to heat them, i just am not sure how they hook up.thanks for looking!

Ayuh,... Forget about cuttin' the line to the manifold, 'n LOOK at yer circulating waterpump...

I'm Bettin' the 1/2" pipe plug is there to do it Right...

Also, the odds are there's a 1/2" pipe plug in yer intake manifold for the hot water take away...

You say ya do Hvac, so you know ya can't just pick a spot, 'n tap in, just because it's Easier...

 

[broke4now]

Re: homemade water heater

Bond-o ,thanks thats exactly what i was looking for.i was up late looking at the internet with no clear directions.the volvo penta water heater pdf had a very generic diagram of the flow but nothing that made sense,it said to pick up the inlet to the water heater from the hotest point which is after the block and heads and to hook up the outlet side of the heater
on its return to the engine or, if the engine is
seawater cooled, before it is discharged overboard.so you can see why i thought i could get between the two.i assure you i was not trying to take the easy way out.i went out and looked and i can do it right (which is why i was asking) with the plugs.once again i thank you

 

[smokeonthewater]

Re: homemade water heater

unless I read it wrong you are planning your your heater inside out.... the water from the engine runs through the coils and the water you use for the shower fills the tank

engine water goes in at top and out at bottom. shower water goes in at bottom and out at top

 

[Bondo]

Re: homemade water heater

unless I read it wrong you are planning your your heater inside out.... the water from the engine runs through the coils and the water you use for the shower fills the tank

engine water goes in at top and out at bottom. shower water goes in at bottom and out at top

Ayuh,.... I agree with ya, as to what Normally happens,....

I'm guessin' he's turnin' things around, so his shower water ain't all Rusty...
'n he's lookin' for Warm water, more so than Hot water....

 

[broke4now]

Re: homemade water heater

smokeonthewater-you didnt read wrong,i know thats the usual way ,i was intending to warm the water up by passing it through the hot water as i dont need bulk hot water,(my brother in laws will take the hide off of you even with mixing cool water)its like the electric on demand should work only better (hopefully).the hose routing was because i didnt want to create a air gap between my exhaust manifold and heater causing it to get hot,i thought if i pushed the water and air up it would fill and then go to the manifold.however bond-o straightened me out on that so it is not necessary for me to hook it that way now.if this does not work ill go back to your suggestion.thanks

 

[smokeonthewater]

Re: homemade water heater

the water in the tank will never get over about 140 degrees as the temp is controlled by the t-stat in your engine.... do not fill the tank with engine water or your bellows and flappers will be dry for to long at startup and get melted by uncooled exhaust.

Also the way you have it planned, you will get a slug of hot water followed by lukewarm every time you turn the water off and on. The slower the water flows, the hotter it will be and the faster, the cooler.

Also, after you have it done, insulate the tank to keep the engine room cooler and more importantly, to keep hot water for hours while at anchor. that way you have a warm shower ready when you are.