Gas Hot Water

[tdw]

In the diesel engine forum I've been bemoaning the fact that our engine stubbornly refuses to produce enough heat to make an heat exchanger do its thing. Ergo I've been looking at options.

Bosch (for one) manufacture an instant gas hot water heater which has AGL approval for installation in boats but to my mind is problematic. For one they suck up oxygen at an alarming rate meaning that ventilation is crucial and installing one in a head compartment is fiddly to say the least. They also of course have to be mounted on a bulkhead taking up space in an already crowded compartment. Also, in the case of the Womboat, there is no suitable place to install in the galley.

I did look at a 12v electrical heater a year or so back but the thing simply sucks up too much juice to make it acceptable on a sailing boat. I like it because it took up little space and didn't require heat exchanger (optional) or mains voltage which we do not have access to.

Enter the Truma B14.


Truma - Boat boiler for hot water while offshore

LPG powered (a mains voltage booster is an option), fully approved and at 14 litres is small enough to fit into the limited cockpit locker space we have available. Takes about half an hour to heat up from cold using 120g/h whatever that means though my gas fitter reckons that is pretty good.
We are not concerned by the relatively small capacity. All we are after is hot water for a couple of navy showers a day and any left over will be used for washing up. Gas will not be left turned on permanently, we'll turn it on at bottle, heat water, turn off, just as we do with our stove. We also have a pressure gauge on our gas line that detects any gas leaks. No need to run engine even if that was doing its job temperature wise.

Thoughts anyone ?

[sailingdog]

14 liters is four gallons or so... and more than enough for two navy-style showers. Does it have a tempering valve??? If not, how do you set the thermostat on it?

Also, what ignition source does the water heater use??

[Faster]

Good questions SD... The capacity is plenty for two... and the only real knock on these (in general) so far is possible lack of approval for insurance reasons. If this one's managed to get around that then it's worth a try, esp since you've already got propane on board anyhow..

If you're going to look at these, does this company make an on-demand heater? That would make the most sense...

[tdw]

Originally Posted by sailingdog

14 liters is four gallons or so... and more than enough for two navy-style showers. Does it have a tempering valve??? If not, how do you set the thermostat on it?

Also, what ignition source does the water heater use??

You dial in max temp on the control panel. I'm not sure what a 'tempering valve' is but it does have a pressure release valve. I was reading a review on an RV forum and one of the members suggested that you need to install something to catch any water dripping from that valve. OTOH, they also said that only happened if the unit is left turned on permanently.

It has one of those Piezo (sp?) electronic ignition systems, ergo needs a 12v power source.

btw there is also a ten litre version but they have not been imported into Australia. If they were I would probably downsize.

[tdw]

Originally Posted by Faster

Good questions SD... The capacity is plenty for two... and the only real knock on these (in general) so far is possible lack of approval for insurance reasons. If this one's managed to get around that then it's worth a try, esp since you've already got propane on board anyhow..

If you're going to look at these, does this company make an on-demand heater? That would make the most sense...

Fast,
I've checked and this thing has full AGL (Australian Gas Light ) approval ergo no problems with insurance provided it is installed by a licensed gas fitter with marine accreditation.

See OP re on demand gas heater. Only one approved down here is by Bosch (Model W125). Physical size is the problem. There is simply nowhere in the head or galley where we could mount the thing. Beyond that venting the thing is a nightmare. By regulation we would have to install a permanently on solar powered exhaust fan with an alarm should it stop working or be disconnected.

Bosch w125

[Gene T]

I would think it woudn't cost much more to just put in a small diesel Hydronic water heater by Webasto or Espar.

I have looked at hot water solutions for a while now and there are a lot of ways to get it. To me Hydronic is the best and you get cabin heat too.

Gene

[tdw]

Originally Posted by Gene T

I would think it woudn't cost much more to just put in a small diesel Hydronic water heater by Webasto or Espar.

I have looked at hot water solutions for a while now and there are a lot of ways to get it. To me Hydronic is the best and you get cabin heat too.

Gene

I do like the look of the Webasto Thermo Top and it has the added advantage of cabin heat as well.

Size would be a problem but not a huge one. Storage tank can be as small as 20 litres though this is some 50% larger than the 14litre Truma to which has to be added the admittedly small size of the TT itself.

I'd need to get this quoted by Webasto Aust. but if I go by UK prices then the TT alone will cost roughly twice the price of the Truma to which must be added the tank. All up, at a guess three times the Truma price.

Were this for our ultimate live aboard long term cruiser that might not be a problem but for our current weekend warrior status plus a couple of longer cruises per year it is probably excessive, particularly when you consider that down here the heater would be idle for all but a few weeks each year.

Thanks for the suggestion but I'm thinking overkill. (Nonetheless I'll speak with Webasto Oz next week and let you know how I go).

ps - am I wrong in thinking you need a storage tank or can this be used purely as an on demand system after it has warmed up ?

[Gene T]

Most people have an electric hot water tank that is also heated by the engine. The Hydronic systems just tie into that.

Gene

[MacGyverRI]

I use one of these, I have almost endless hot water. I'm making a stand to put it in the cockpit along w/ quick connect fittings so I can stow it inside in the winter months when it's not being used. Very similar to the Bosch unit but this one is only $135 delivered

The EZ101 Tankless Water Heater by EZtankless.com

[tdw]

GeneT...right now we have nowt but cold water unless we put on a kettle or leave the solar bag out in the sun. The Truma kills two birds with one stone and is supposedly saf enough not to take two Wombats with it.

MacGyver.....I've seen a couple of cheaper alternatives to the Bosch but unfortunately they are not licenced/approved for use in Australia so there are insurance implications.