New Isotemp Water Heater

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Back to Home ... s/v Stella Blue home ... Plumbing Page ... Projects

February 2007 --

It's been a year and a half since I pulled the old, leaking, rusted Raritan water heater out, while preparing for the repower. Oddly enough, I haven't really missed hot water on demand. Just like with a small boat, when I *really* needed hot water I tossed a pot on the stove.

I wasn't too happy about drilling holes in the bulkhead, because the bolt heads are exposed inside the head. I made small washers out of fiberglass, and painted them. They're sealed against the bulkheads with brown LifeCaulk, so that water won't get into the bulkhead when the shower is used.

It's not the most attractive thing.
I may look around
for some kind of
prettier bolt head.

The spot where the old water heater used to live is now occupied by the second house bank. This was the best place for the weight,
but creates a real challenge
for the new water heater.

If moisture gets trapped against the plywood bulkhead,
it'll rot in short order.

So the heater is set 3/8" away from the plywood
using some scraps of pre-fab FRP from McMaster-Carr.

This is the little locker next to the head.
It's amidships on the starboard side,
which is good as the hot water runs will be short,
and the weight is in a good spot for balance.

However, the hose runs from the engine will be long.
I'm just going to have to live with that, and
make sure that they're well protected from chafe.

The heater fits perfectly, and to my surprise didn't take up much space at all. I had thought I would lose this storage space, but a lot of stuff can still fit in here.
I'll just need to be careful to protect the hoses.

The back edge sits on the liner, against the hull,
so the weight is well supported on the bottom at two points. The heater is designed to be bolted to the bulkhead,
and the weight will be shared between
the bottom braces and the bulkhead.

I don't want the water heater flush against the plywood bulkhead. There might be condensation on the heater's shell, and I don't know how hot the heater will get.


The Isotemp slim square heater only holds four gallons, but is nice and compact.
I had to seriously think about only having four gallons of hot water. It's a great way to make sure no one takes a long shower!

All the Isotemp heaters have a reputation for quality construction and longevity, with all stainless construction and
good insulation.

The square design was new in 2006.
I hope they sell lots of them, so that if this one ever breaks I'll be able to replace it easily. Nothing else will fit.

There wasn't a good place in the engine area for it, unless I was willing to sacrifice good storage space. I need all the cockpit storage space, so the heater needed to be moved inside.
It almost fit under the quarterberth,
but almost doesn't count.

The fresh water hoses will run back under the heater, and through the bulkhead to the right.
This is a nice spot that will feed them under the liner, directly under the head. They'll reappear right under the sink/shower fixture.

The holes are painted with West Systems epoxy,
to seal the edges in case something leaks.

Now the hoses need to be hooked up.

I pulled the AC power to this space in April 2004, so that's ready to go.

April 2004? It's hard to believe I've been planning this for three years.
Where does the time go?

It was good to finally verify that the engine input and output fittings are well below the top of the engine, so I won't have to worry about air locks in the engine coolant hoses.

The fresh water input has a ball valve, in case there's something wrong with the heater and I need to cut the water supply.

All the new plumbing is FlexPex, a cross-linked HDPE pipe that is the current replacement for the old grey polybutylene pipe that was common twenty years ago. The white "Flair-it" fittings make assembly simple and easy.

Note that as the Pex pipe goes through the bulkhead and turns the corner, it is run through some good Shields sanitation hose.
That hose is very stiff, and helps the Pex turn the tight corner without exceeding the minimum bending radius for the Pex pipe. It also protects from chafe on the other bulkhead, which has
a rough fiberglass edge.

The output side was a lot easier to fit.

Note, the PEX can handle heat up to 180F degrees, and I don't believe the water heater can exceed that.
However, the product literature says that it shouldn't be connected directly to a water heater. That literature was written for domestic household water heaters,
but it's still prudent to pay attention.
I used a little but of Schedule 80 PVC as an insulator.
Hopefully, that will work well, but I'll keep an eye on it, and might replace it with a longer piece of brass.

Note: a week later. This didn't work. Stand by.

The water heater came with a standard 120V plug. I didn't see any reason to install a junction box and socket, so cut the plug off and spliced the wire directly to the Ancor three conductor wire.

I had pulled 12 gauge wire from the dedicated breaker to the heater, but the heater itself had 16 gauge wire. This required a "step down" butt connector. The blue strip identifies
the side for the smaller wire.



The yellow connectors were huge, and I didn't have a single piece of 3/4" heat shrink handy.
So I pulled 1/2" heat shrink right up to the connectors. The connectors themselves were sealed down with some thick 3/4"
adhesive lined heat shrink.

That'll keep it sealed up and dry.

I'm going to leave it with just AC inputs for now. Pulling hoses from the engine is going to involve pulling the cabin sole,
and I want to wait until I have
more than one job to do under there.