Hydronic heater removal - hot water options

[evm1024]

I'm planning on removing our Hydronic heater this spring. I'm thinking that as we move closer to the equator we will not need it for heating the boat.

Removing it will free up a lot of "wasted" space both in the engine room and in the various lockers where the heat exchangers were mounted. If we were to0 keep it I would want to move those heat exchangers in at least 3 places to recover the space and to put them in a more protected place - they were more or less just bolted to the bottom shelf of the lockers.

With the removal of the diesel hydronic heater we will also lose our only source of hot water. We do have an Everhot on demand water heater that could be plumed into the engine or replaced with a hot water heater that runs off 120 VAC or the engine. I'll have to do some research on that.

The parts to the system are:

Webasto DBW2010 (or was it an 2020?)
5 gal coolant tank
AC coolant pump
Summer loop Y valves
Everhot hot water tank
2 dual vent heat exchangers
large heat exchanger
3 single vent heat exchangers
Shur Marine Services LCD control "box"

So, onto a few questions...

- We are planning n about a KW of solar. For those who have done it, how successful is heating water via your inverter off the batteries with solar assisting as it can? (we have greater than 5 KWH of LiFePO4)

- Is there much of a market for used Hydronic heater setups like this? What is it worth? (let's not get hung up on the worth question)

- Given that we would want solar/battery to power the heater when we do not run the engine is there a better hot water tank for that use? What tank in general is better than the others for full time cruising applications in the tropics?

I've been looking over the various hot water tank questions so no need to get too hung up in this thread.

Thanks

[Lepke]

How close to the equator? It gets cold in San Diego at times. Even Mexico. I think you'll miss the heat.

[evm1024]

Across it (the equator that is). Mexico with the Ha Ha this November. On to the South Pacific as inclination dictates.

I had thought to put in a small (13,000 BTU) forced air unit to take the nip off the boat when needed. Ducting only to the main salon. Not really needed till we are back out of the tropics.

The exhaust and fuel systems are in the boat for the hydronic boiler. Air ducting to the main salon is easy.

We do expect to hit the temperate zones every now and again.

We only use the hydronic heater in the fall/winter here in the PNW.

[CassidyNZ]

We haven’t ever owned a boat with a heater for cabin heat. Never felt the need for one even in New Zealand where winters, although not cold by North American standards, are a lot cooler than the areas you plan on cruising.

For hot water, we have a Force Ten unit that works off engine coolant as well as an electric element. It works OK but when the engine hasn’t been run the water heater is pretty power hungry (draws 120A from the batteries), not to mention the space it takes in the engine room.

Three friends have recently switched to a small LPG califont that provides instant hot water with quite frugal gas consumption. Whilst not exactly a renewable source of hot water, it is an affordable solution, one that I too am about to adopt.

[sv_pelagia]

You just might find yourselves back cruising in the PNW (and/or other "temperate" climates). Why downgrade your boat's capabilities? Something to keep in mind....

[evm1024]

I have thought about keeping the everhot hot water tank and using something like one of the instant hot water heaters to heat the everhot. That or keep the everhot and run it through the engine loop.

In 40 years of cruising the PNW this boat is the only boat that had a "whole" boat heater. I did live on a Cal 2-29 with a Force 10 Kerosene heater for winter heat but that was an exception.

When we are done with the cruise we are expecting to relocate to Florida. Actually we are likely to buy land and a house in Florida in the next 3 months which our daughter will live in for the next 5 years. Will we relocate back to the PNW? Who knows? We will likely downsize the boat if we do.

Mostly we are trying to reclaim space in the lockers where the heat exchangers we mounted. The engine room is huge so the current install is not too bad there. It is of course possible to remove the heat exchangers and just heat the main salon with the current system.

[Davidhoy]

Following this, as I have a similar system on my boat, installed by one of the previous owners. It does not currently work, so my choice is to repair it or remove it. Haven't decided yet.

-David

[rphdiego]

I would replace the Everhot with a more efficient Isotherm 6 gallon with 750 watt 120v element plus engine heat exchanger. Also I may be interested in your Webasto system. I have a yacht service business in the PNW. Ryan.

[mvmojo]

We've used a 6 gal GE home type hot water heater on MOJO for 20 years. We run it off the generator. 10-15 minutes gives enough hot water for 2 showers plus dishes. In the Caribbean, we found we didn't need hot water... the water in the tanks was at 80+ degrees and given the typical ambient temperatures, that was refreshing!

[evm1024]

Originally Posted by rphdiego

I would replace the Everhot with a more efficient Isotherm 6 gallon with 750 watt 120v element plus engine heat exchanger. Also I may be interested in your Webasto system. I have a yacht service business in the PNW. Ryan.

That is what I was thinking pretty much. 750 watts is a good number in terms of powering off the inverter/solar/battery. Better than 1kw.

[ALBACHIARA]

Heating water with electricity means consuming 1.16 Wh to heat 1lt up 1°C, so to heat 10Lt from 20° up to 40 °, 232Wh are consumed
I am using a 10lt domestic boiler and I put a diode in series in order to reduce the power to half

[evm1024]

One of the tradeoffs that I am looking is where the "waste" heat goes. Being that we expect to be in the tropics waste heat is something to keep out of the boat as much as possible.

Heating water with the Engine - Way too much "waste" heat. But if you have to run the engine then it is a "free" source of hot water (with the right hot water tank)

Heating water with the hydronic system - Unlimited hot water but the boiler and "coolant" lines even when only in a summer loop present quite a bit of heat in the engine room.

On demand heat - More unlimited hot water with some "waste" heat. Heat from the unit and heat from the exhaust fittings inthe engine room.

Hot water tank - limited hot water (tank size, heating rate) but a minimal amount of waste heat in the engine room. The tank is insulated and there are no exhaust fittings to transfer heat to the boat.

So many choices...

[drcot3]

Keep the system unless you need the room, its always available. otherwise wish you was in the UK/Spain and I would buy your system. whatever you do will end up being wrong sods law. so many choices so many thoughts toss a coin is as good as way to decide. always get it wrong David

[purplesunrise]

We are full time cruisers with 1.2 KW of solar and 1100 Amp/hrs of Battle Born lithium batteries. In Florida we are doing better keeping the batteries filled up but during our voyages to places north of here, it wasn't enough. If we tried to use an electric water heater, it would not work for long. We still need the generator for charging as well as making and heating water. If you are not full time, then I suspect you will be just fine without the hydronic heat. By the way, we are planning to add a Hurricane hydronic system. There is no way I will make the trek to Maine without diesel heat.

[evm1024]

Brief update - I have pulled the unit out along with most of the heat exchangers. The best part was chopping up the PEX that was run in the most annoying places. This is freeing up space in the lockers where the heat exchangers were mounted (in the way I might add) and in the engin room where I can install the isotherm hot water tank along with a washing machine.

I have 1 more heat exchanger to remove and the thermostats and associated wring.

I did buy a 6 gal Isotherm and one of the low cost (form China) forced air heaters.

The biggest hassle was draining the coolant and disposing of it properly.