Finally -- Bus Heater Install!

[nmccubbin]

We installed a bus heater in 2011 and love it.
(We also have an Espar)
I would consider putting the heater well forward in the boat, since the main hatch will usually be open, losing heat. Wirh heater at the hatch, the rest of the boat will get little heat
This needs long hoses. We have 9 metres 5/8" hose each way, so a circulation pump is needed, but worth it
We Tee into the line from the engine to water heater. Pump sucks from it, through the bus heater then back to same line with another Tee
Shut off valve at each tee in case of leaks
Do not worry about heat control. In weather yuu want heat, if it it too hot, just open more hatches and dry out better
Mos useful improvement (which we could not make) is to have the bus heater draw air from outside, so that will dry the boat even better.

[kenbo]

As drawn, in parallel without the additional pump but I would substitute monoflow tees instaed of normal tees. That's how almost all hydronic heating systems are piped. See the attachment. Monoflows are available at any good plumbing/heating supply, in cast brass. Hose to tube adapters as necessary.

[kenbo]

No attachment the first try!

[seabreez]

Originally Posted by a64pilot

I would put it in series, the way you have it sketched there would be little or no water flow, water will take the path of least resistance and that most likely to keep going and bypass the heater completely.
So take one of your heater hoses and Plumb the heater into it, not both.
You have a separate pump? No need the engine pump will make the water flow.

You sure about 1/2” hose? Thats unusual 5/8” is standard heater hose, least for cars and I believe boats too.

On many automotive and trucks, the inlet pipe is 3/4" and the outlet is 5/8". Purposely done to retain coolant in the core and the 5/8" is a flow restrictor for the purpose of extracting as much heat out of the coolant and secondly it speeds up the coolant on the exit for the purpose of purging air out of the line. Also in a bus... the heaters are in series and since the heaters are a little higher than the radiator... many have a small purge valves to remove the air.

[sailingharry]

Originally Posted by Dockhead

Another question -- about the air. The current system flows unreliably, and I presume because I can't get the air out of the high point.


I think the circ pump should solve this, and just blast the air out of that, no? I know I could put bleed valves in those high spots, but I don't want to chop the hose more than necessary. The spot is difficult to reach, so not keen on it from that point of view, either.

Dockhead, You NEED a bleed at every high point. I just installed a hydronic heat system on my boat, and put in a bleed at (almost) every high point. My piping is clear PEX so I can see the water in it. Turns out, I have a 3' long run of pipe that has a slight bow to it, and is about 1" higher in the middle. Well, the heater on that branch was ice cold. The bubble wouldn't move. I even opened the circuit back at the heater, and attached a garden hose. STILL wouldn't move that bubble. I grumbled, bitched, and added a vent. Instant heat!


Bottom line, ANY high point MUST have a bleed vent.


Good luck,


Harry

[Brewgyver]

Originally Posted by wsmurdoch

I'm not sure that storing hot water for overnight boat heating is too practical.
(snippage) If the tank held 100 gal of water or 832 lb of water, it could store 25,000 BTU. If that heat were used over a 10 hr evening, that would supply 2,500 BTU/hr or about half the output of a 1500 W electric heater.

Bill

Off the top of my head I'd was the water sourced heat would be more practical than burning 15 kwh a night! You'd have to run a generator all night, hence the popularity of the Espar, et al diesel fueled heaters.

[Brewgyver]

Originally Posted by wsmurdoch

(snip) Your bus heater produces air 20F cooler than the water, so with 160F coolant the air is 140F, and the metal register on the bus heater will almost burn you if touched. (snip)

If you are using stored hot water, you want it as hot as you can get it. Hydronic systems for comfort heating are almost universally designed with 180 F supply water temp. The flow rate to the emitters (in this case, the bus heater) is restricted to achieve 110-120 outlet air temp. No safety concerns.

[dnight]

I have been looking at something along this route for our upcoming winter in the Med. But along with the engine heating the hot water through the calorifier, I would also like the heating system to work through the electric side of the calorifier when plugged into dock power. At the dock the calorifier heats the fresh water hot circuit, which I assume will also heat the coolant side of the calorifier. Then an electric circulation pump to pump the coolant around the vessel to the bus heaters/radiators. You would probably need to isolate this from the engine with valves so you're not heating the engine block as well, and obviously remember to open them again before start up. Has anyone had a go at something like this?

[a64pilot]

If your going to heat electrically, why not use oil filled electric radiators?
I doubt that the average water heater has enough heat to heat the whole boat. Most are 1500W or less, that of course if you ignore losses is what one little portable heater will output, but of course the losses won’t be insignificant, where the little portable heater has no losses.

[MartinR]

Originally Posted by dnight

I have been looking at something along this route for our upcoming winter in the Med. But along with the engine heating the hot water through the calorifier, I would also like the heating system to work through the electric side of the calorifier when plugged into dock power. At the dock the calorifier heats the fresh water hot circuit, which I assume will also heat the coolant side of the calorifier. Then an electric circulation pump to pump the coolant around the vessel to the bus heaters/radiators. You would probably need to isolate this from the engine with valves so you're not heating the engine block as well, and obviously remember to open them again before start up. Has anyone had a go at something like this?

Would work, but one or two cheap ceramic electric heater fans would do the same job, with less losses, no complexity, very little money and less to go wrong.

I mean you need the fan anyhow, and the heat is as easily proved by electric heating elements as by the calorifier.

[Dockhead]

Originally Posted by dnight

I have been looking at something along this route for our upcoming winter in the Med. But along with the engine heating the hot water through the calorifier, I would also like the heating system to work through the electric side of the calorifier when plugged into dock power. At the dock the calorifier heats the fresh water hot circuit, which I assume will also heat the coolant side of the calorifier. Then an electric circulation pump to pump the coolant around the vessel to the bus heaters/radiators. You would probably need to isolate this from the engine with valves so you're not heating the engine block as well, and obviously remember to open them again before start up. Has anyone had a go at something like this?

Nothing wrong with heating the engine block except possible heat loss, in case you have a cold engine room.



I'm sure this will work, at least to some extent, but you are limited by



(a) The heat capacity of the calorifier immersion heater. Mine is 1500 watts -- yours? Is that enough heat for your boat? I wouldn't get far on that amount of heat in my boat.



(b) Heat transfer ability of the coolant loop in the calorifier.




As Martin answered, if you're on shore power anyway, a couple of fan heaters is an easy, cheap solution. It's what I do.


You can buy a special electrical powered heater to put into your hydronic circuit. If you have radiators this might be sensible compared to fan heaters. You might even give it a separate shore power inlet. I wouldn't do this only because the fan coils in my hydronic system are kind of noisy. I prefer the fan heaters, although they don't distribute the heat quite as well as the hydronic system does.