Hot water tank for liveaboard

[nwdiver]

Have a Hurricane hydronic heater with loop through a 20lt tank it gives demand hot water until the water tank is empty and heats my boat all done with diesel....the smaller tank is better with the demand heater and cheaper to buy........I also have a 4lt/min shower head.......

[Seafarer7]

Paul, you may be able to have your cake and it it too! I have probably the same Espar 5kw hydronic Heater that you do, but instead of a hot water tank (calorifier) I installed a compact but very high surface area heat exchanger, resulting in instant and unlimited hot water, from the diesel-fed Espar.
This is what I used:
Brazed Plate Heat Exchanger, 5x12- 30 Plate Water to Water Heat Exchanger 60,000 BTU 1" MPT B3-32-30 https://www.amazon.com/dp/B01DOC0O4C..._MDGsAbAEJQCY7

[Seafarer7]

* My earlier post isn’t showing *
Paul: if you haven’t made a commitment yet consider buying a high surface area heat exchanger instead of a tank (calorifier). I have the same Espar 5kw hydronic Heater coupled to one of those compact heat exchangers and have instant unlimited hot water from diesel

[GRIT]

Seafarer, that sounds very interesting. Could you tell me the name of the product you're using?

I notice you just joined cruisers' forum. Welcome.
Thanks. Paul.

[GRIT]

Nwdiver.

I looked at those units, and if someone wants to use propane, I'd say it's the best I've seen. It's also the only one I've seen, made for boats.

Thanks.
Paul.

[Seafarer7]

Originally Posted by svquintana

Seafarer, that sounds very interesting. Could you tell me the name of the product you're using?

I notice you just joined cruisers' forum. Welcome.
Thanks. Paul.

Paul

Yes I just joined the forum. I actually posted the link to the unit I bought (from Amazon) but that post is being held (perhaps because I’m a newbie on this forum - long time reader but new poster). Here is the name of the unit I use, purchased on Amazon:

Brazed Plate Heat Exchanger, 5x12- 30 Plate Water to Water Heat Exchanger 60,000 BTU 1" MPT B3-32-30

It is compact, and much much smaller than any water tank. It was also very easy to hookup.

Works great! The trick is to fire up the Espar at least 10 mins or so to let the coolant in your Espar heater loop get up to temperature. You’ll know when you are up to temp because the Espar throttles back a little.Then you’ll have instant unlimited hot water without a bulky tank.

[Seafarer7]

Attached is a photo of the heat exchanger, installed. It’s actually attached to the side of a 6-gallon calorifier (hot water tank) that is coupled to the Diesel engine coolant loop (which is totally separate from the Espar hydronic heater coolant loop).

The diesel engine coolant loop goes through the 6-gallon tank and also a red dot heater.

Espar’s (independent) coolant loop goes through the heat exchanger as well as separate cabin heat exchanger fans.

This was I have both hot water and cabin heat, from either the engine or Espar. The Espar loop does a far better job of providing hot water compared to the Diesel engine loop.

[GRIT]

Nice unit, I like the idea. For our purposes, perhaps that unit feeding a 25l tank would work well. I'd rather not have to start the espar just to do the dishes. but I would only need the very smallest of tanks this way.

Thanks very much for your input.

Paul.

[GRIT]

I didn't see the photos before my last post. I'll have a similar system to yours, but I'll link the two heaters, as the engines won't be heating water.

Cheers.
Paul.

[GordMay]

Greetings amnd welcome aboard the CF, Seafarer.
Yes, I believe you need 10 posts to attach a link.

[Seafarer7]

Thanks Gordmay. I’ll refrain from posting any links for now.

Paul:

Great idea to link the two.

In my case my 6-gallon tank was already plumbed into the Diesel engine loop.
I toyed with the idea of one combined coolant loop, ie linking the coolant loop of the diesel engine and Espar through the common hot water tank (see initial design diagram):



However I didn’t want to risk issues with the engine (failure of the loop could result in engine overheating).

I ended up using the separate loop for the Espar with this simpler design (minus the engine heater):

[GRIT]

Seafarer:

Yes, it's fairly common to have the two plumbed together, and often the espar heats the engine too. Piped in series, rather than in parallel.

I'm thinking, now, that I could run the espar through the tank, then through the exchanger. The exchanger would pre-heat the water going into the tank, and suck up as much heat out of the espar flow as possible.

Nice diagrams, I see you're far and away more computer savvy than I am.

As an aside, in which general area of the world are you located?

Cheers.
Paul.

[Seafarer7]

Paul:

Your design should work very well - a big advantage would be the long lasting “heat reservoir” effect you’ll get from all the heated coolant stored in the calorifier tank, much like a battery bank for solar.

I’m in the San Francisco Bay Area.

Cheers

[GRIT]

Ah, San Francisco. You were up early this morning.

Yes, I'd prefer to only have to run the Espar once a day. I'll have it start up about 30 minutes before we wake up, then shut down a few minutes after we finish our showers. That way there's hot water available for the day.

I'm on the East Coast of Canada, which is +4 to California, or +3 if you don't do daylight savings time, like Arizona.

Cheers, and thanks again for the clever idea.
Paul.

[Seafarer7]

Originally Posted by svquintana

Nwdiver.



I looked at those units, and if someone wants to use propane, I'd say it's the best I've seen. It's also the only one I've seen, made for boats.



Thanks.

Paul.

Paul

Just wanted to mention this: the Hurricane system Nwdiver is talking about is also a diesel unit, not propane. It combines pretty much ALL pieces (calorifier, heater, heat exchanger, pump, and even a mixing valve temperature regulator ) into a single unit. I installed this unit on a previous boat I had and it was excellent. Google “Hurricane Combo II Heater from ITR”. (ITR Heat is the Canadian company that makes them - I ordered mine direct from them, they ship international).

The big advantage of the Hurricane II Combi is you’ve got everything integrated into one single block: simply hook up your diesel lines, fresh water line and exhaust and you are good to go. You don’t even need a exterior coolant loop if you aren’t interested in cabin heat. It is also a powerful heater, much more powerful than the Espar 5kw unit, and can handle much bigger water & space heating loads. 40k btu vs 17k for Espar.

The disadvantages include:
- it is HEAVY!!! Difficult to install solo due to its weight
- very expensive (3 to 4 times the Espar cost, perhaps not as bad when you consider it includes the calorifier tank & heat exchanger, mixing valve, etc)
- it is somewhat a bit more complicated to work on if a problem develops.

In my previous boats I’ve purchased and installed heaters (both hydronic and non hydronic) from most of the major manufacturers (Espar, Webasto, ITR, Wallas): the ITR Hurricane Combi remains one of my favorite. If you have the space, funds and need, that’s the unit I would recommend (I had mine on a 43-foot ketch)