Any inline 48v water heaters?

[Swing]

Hmm, I don't know what shape of elements AC inline water heaters use, but it is a good idea to use that as a base. Eventhough you have to change some controls/relays as well.

Having an inline 48v water heater has multiple purposes, also depending on the power.
- real time hot water heating (lots of power!), I could use this in the campervan, but also at my house where I have a 48v system and an AC electric boiler right now. You may need something like 10kW or even 20kW depending on your needs, and my batteries can deliver that.
- heating a system through water or glycol. This means you could, in a campervan, reuse the exisiting infrastructure. Meaning you choose to heat the car via the existing interior heating (on coolant) and you can also choose to preheat the engine.
That last bit means you get to reuse earlier recovered energy to get your engine quicker up to working temperature, saving you fuel.
And heating the battery is sometimes also done through water/coolant.

However, if I would make and productize an all-in-one campervan/RV system, a lot of these steps would make it more complicated. And especially integration into the drive train. Even though I think it makes a lot of sense, to make a campervan into a (mild) hybrid that you can later cook and heat on.
And I am talking about having 10 or even 20kWh on board. so you can do a lot of stuff electrically, and also can deliver lots of power (preferably in DC).

But it is way more practical to just add some electric air heater with a fan, the install time and points of failure will be greatly reduced.

It is the consideration of getting to the best results with a fully integrated system that increases the price and complexity, versus a system that you can install in any van or RV.
However, I do think there is a lot to be achieved when integrating and recovering energy from driving.

And personally I don't like gas heaters in RVs/campervans. To be honest also not cooking with gas bottle.
Yes it works, and I live in the Netherlands were we use mostly gas to heat our houses.
However, the gas appliances (with the bottles) in the RV world are not of the quality you find in households.
Sometimes build up of gas itself, or carbon monoxide, happens.

 

[jameshowison]

Any advance here? In the building science world (non RVs) there is a lot of effort around hot water heating. Yes, heat pumps are used (including split systems with the compressor outside), but a few people use electric tankless. Generally the problem here is that the electric demands are quote high, meaning larger electric service from the grid and large wires long distances) e.g.,

and https://www.chronomite.com/product....ss+Water+Heater&productcategoryid=65&spr=true

The under sink ones run up to 2 gpm (which is enough for most showers) and that's like 9.6kW ... at 48v (nominal) that would be something like 200 amps. That is a lot, but not impossible for BMS as I understand it. For a sink, significantly less.

So could we have a tankless water heater that is slow-charging (regular household circuit) but able to dump lots of power quickly.

Perhaps a case for higher voltage batteries with lower amp hours of capacity?

 

[pvgirl]

So could we have a tankless water heater that is slow-charging (regular household circuit) but able to dump lots of power quickly.

This is basically a tanked water heater, unless there's some other form of energy storage that's efficient enough to make more cost effective then a tank of water. There's not really any way around the large amount of energy it takes to heat water.

 

[jameshowison]

Hah, good point, water tank is a type of battery I suppose there are differences in terms of space and energy loss over time, perhaps an electric battery would be smaller and lose less power when not being used, but definitely more expensive!

 

[Vigo]

Yeah, i think the critical mental leap to make is that an insulated water tank IS a battery and its a MUCH cheaper (and less environmentally impactful to produce) form of battery, so why avoid it?

There are under-sink water heaters with a small storage tank internally. It's possible some of those might heat the water well past what's comfortable and simply use a thermostatic mixing valve to 'release' water at a safe temp. The point of that would be to 'extend' the capacity of a smaller storage tank. I haven't looked to see if that's actually done but in theory one COULD build such a device and then have NO hot feed to the sink, simply a cold line feeding an inline heater which then feeds both the hot taps (through heater/tank and mixing valve) and cold taps (internally bypassing the whole rig).

It's also possible to set your main water heater tank to a lower temp to lower its power demand, and then use a small inline heater at the shower head to raise the water the rest of the way to desired temp.

I have a couple of inline heaters to experiment with (both old freebies) but haven't personally experimented with it yet.

I did just do the math that my 4500w 240v water heater elements would be 900w elements when driven with 48v.