Water Heater Replacement

[Mike459]

Hello all, Working my way thru probs on my new to me Maxum 4100 SCB dual helm. My water heater is leaking. It's the original 1998 so I'm replacing it. Is there a trick to access the back screws holding down the water heater? Access is thru a side panel in the mid cabin. Waste tank is along side it. Macerator is in front of it. The screws appear to be under the reefer or shower??? No hatch there that I can see. Current plans are to lift the front of the heater and break the back screws with a long pry bar but thought I'd ask.
THX in advance!

[SteveP]

There’s no trick. I had the same issue when replacing the water heater in my 4600 SCB. Used some leverage to pull the screws out then repaired the damage before installing the same OEM heater. Only thing I would have done different is use a heater without the engine coolant option. Just reducing another possible failure point.

[Mike459]

SteveP, Thanks for the reply... I'm sitting here and laughing at myself for thinking that I could have it out and replaced in one day. The coolant part of the job was a mess. I had plugs handy but it still sprayed and leaked all over. I'm impressed the original heater lasted since '98. I also broke the screws last night after buying a long crowbar. Looking for seals now to use the original plumbing. Otherwise its out for replacement. I'm getting a good workout crawling around down there.

[Mike459]

My original heater (Attwood) had a painted steel cover. It lasted 20+ years but leaked. I figured a stainless version (Kuumu) would be best and I wouldn't have to think about it again. The best part of the repair was I can now hold water pressure for days and the pump doesn't need to be turned on for every quick hand wash or flush.

[yahoo82]

Hey Mike, glad you are happy with the results. I thought it was interesting that you said the pump didn’t run as much but then remembered an interesting blurb from my old Atwood manual … “The Atwood water heater tank is designed with an internal air gap at the top of the tank to reduce the possibility of dripping. In time, the expanding water will absorb this air and it must be restored.”

This is typical with any horizontal style HW tank because the outlet is below the top of the tank. When it’s filled, it doesn’t fill 100% but over time that air cushion will dissolve or agitation will flush it out.

If you find the pump running more often, just drain the tank a bit and refill to reestablish the air cushion. I ended up installing a small air bladder expansion tank in my system to accomplish the same thing. Works great.

Jabsco 30573-0000 Marine Pressurized Water Accumulator Tank with Bladder (1-Liter) , Black https://www.amazon.com/dp/B000O8D5XM..._kK6eXpZJLHevX


MPD 93757 PS 11.19.07.pdf


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[Mike459]

Thanks for the info/idea... My new Kuuma has the same info about the air gap as the original attwood. I didn't fully understand it but figured I'd deal with it if anything changed. My pump now pressurizes the system which lasts for days and is good for a flush or a hand washing or 2 when off which suits me fine. I typically leave my pump switched off, especially when I'm away. The old heater had a very slow leak into the bilge and the pump would come on every 20 minutes or so. As an added benefit, I had to disconnect the macerator to get the heater out and I used the same hoses but now that I resealed everything the slight odors I had are basically gone.