wingcommander
Well-Known Member
My temporary ( now three years) installation to see if it produces sufficient volumes of hot water.
I will eventually get a round tuit.
Hot water options
- Thread starter Brooksie89
- Start date
I will eventually get a round tuit.
Moodysailor
Well-Known Member
My opinion, I would advise against tapping into the sea water coling loop for hot water for a few reasons:
1. It's the primary cooling circuit on the engine, if anything goes wrong you have lost all cooling.
2. On indirect cooled engines, the calorifier is tapped into the existing circuit with isolator valves - if there is a failure in the calorifier loop, this can be isolated and the engine continues to run. If you tap into the SW circuit, it would need to flow directly through the calorifier, this will load up the pump and adds extra points of failure
3. Eventually the calorifier will scale up and fail or restrict the SW pump flow
There are a few optiuons depending on budget, hassle factor and your appetite for installtion, on our boat we are going with a diesel hydronic heater (diesel water heater). Works the same way as you diesel air heater, just heats water instead or air. The HW can be piped anywhere around the boat - we will use ours to run a HW loop in the heads wet locker and heat the calorifier. Very efficient. Downsides are the installation which is failry easy but not always straightforward. They can be bought as little as £300 now.
I'm not a fan of the gas water heaters as there needs to be a good vent/flue, and i've never found a solution I fully like.
1. It's the primary cooling circuit on the engine, if anything goes wrong you have lost all cooling.
2. On indirect cooled engines, the calorifier is tapped into the existing circuit with isolator valves - if there is a failure in the calorifier loop, this can be isolated and the engine continues to run. If you tap into the SW circuit, it would need to flow directly through the calorifier, this will load up the pump and adds extra points of failure
3. Eventually the calorifier will scale up and fail or restrict the SW pump flow
There are a few optiuons depending on budget, hassle factor and your appetite for installtion, on our boat we are going with a diesel hydronic heater (diesel water heater). Works the same way as you diesel air heater, just heats water instead or air. The HW can be piped anywhere around the boat - we will use ours to run a HW loop in the heads wet locker and heat the calorifier. Very efficient. Downsides are the installation which is failry easy but not always straightforward. They can be bought as little as £300 now.
I'm not a fan of the gas water heaters as there needs to be a good vent/flue, and i've never found a solution I fully like.
vyv_cox
Well-Known Member
My boat came with a calorifier and seawater cooled engine. When about 15 years old I replaced the calorifier for one with an electric immersion heater. The copper tubes in the old one were perfectly OK when I cut them open.
The replacement calorifier did 5 years on seawater cooling until I replaced the engine. It is still working fine.
vyv_cox
Well-Known Member
There are thousands of seawater heated calorifiers out there. The 'weak link' is the electric pump with a life of 10 - 15 years. Otherwise they last well.
Moodysailor
Well-Known Member
"Thousands" sounds like a dramatisation, I doubt that very much since the vast majority of engines in operation now are fresh water (indirect) cooled.
Either way, it's a poor solution.
Fr J Hackett
Well-Known Member
There are many many thousands of old pre 90s & 80s boats with direct cooling you only have to look at the PBO section to see just how many post on here and they are not even a small fraction of the thousands of Moodies, Westerlies, Sadlers and a myriad of long since forgotten makes.
Moodysailor
Well-Known Member
I don't disagree that some exist, I do disagree the claim that there are "thousands". They simply weren't made in those numbers, and a decent proportion of boats still being used today woud have been repowered by now, most likely to indirect cooling.
I have seen multiple failures and issues with calorifiers from sea water cooled installations during my time as an engineer, and it was always a contentious issue when a repower came up due to the contamination and risk of corrosion in the existing calorifer.
It was offered by builders as an option at the time due to the prevalence of sea water cooled engines, and the desire for greater comfort onboard, but the relatively high number of gas water heaters fitted to boats of that age also show it was not universally selected by builders.
With a number of better options available, good advice is to look for an alternative - I have no idea why there is such passion to hang on to old concepts when better ones exist, are viable and proven.
If the OP does go with a sea water loop to the calorifier, it should be plumbed so that the calorifier is an 'auxilliary loop' from the block or other take-off point, and not plumbed in series with the feed to the exhaust water (this is why electric pumps were used, to provide circulation in the secondary loop). Particularly in a sea water cooling system where a leak is not limited only to the volume of the fresh water cooling system and is potentially capable of sinking a boat, there must be a way to isolate the calorifier with valves as close to the engine as possible - if the calorifier is plumbed in series, a leak would mean that isolating the calorifer would block the cooling system. Being in series would also add pressure restriction to the sea water pump, and I expect this would result in the engine having some overheating issues in time.
Brooksie89
Well-Known Member
Do you have the controller?
Where do you divert the hot air, I'm thinking about the brief summer we sometimes get in the UK. Ideally I wouldn't want a cabin at 40 degrees.
wingcommander
Well-Known Member
The hot air is diverted via the y section see photo. When heating water its all blown through the matrix ( surprisingly cool exitiing the matrix into my locker) which meansthe efficiency of transfer must be quite high . I never fitted the hubble controller as its easier for me to open locker lid to set to water or heating, or you can even do both simultaneously. Though I would expect to wait a while doing this.
wonkywinch
Well-Known Member
Electric heating from batteries needs some power. Our calorifier holds 80 litres. To heat that amount of water from 15C to 65C would take c 17 million joules. That's 4.7kWhr or 390 A/Hr at 12v (excluding any inefficiencies).
For lead acid, max safe discharge is 50% so you'd need almost 800 A/Hr of batteries to heat the water once.
A more modern solar/lithium set up might be needed if you wanted electric heating.
Water Heating Calculator
For lead acid, max safe discharge is 50% so you'd need almost 800 A/Hr of batteries to heat the water once.
A more modern solar/lithium set up might be needed if you wanted electric heating.
Water Heating Calculator
PCUK
Well-Known Member
Not in the USA!
PCUK
Well-Known Member
You need an inlet and outlet on the block that won't affect engine flow. It's not a problem. As said, thousands running like this.
Brooksie89
Well-Known Member
I haven't found a way of doing this on the Yanmar 3gm so far, hence why the common theme for this engine seems to be to revert back to indirect cooling via a kit and connecting it that way.
The diesel heater option is appealing, as you can have hot water within half an hour of running, without depleting the batteries or having to run the engine. The cost for this would be nearly half than going to indirect cooling, as there's already one fitted.
LittleSister
Well-Known Member
I have a direct (seawater) cooled Bukh 36, with a calorifier connected (by a previous owner) as per Vyv's website advice - i.e. with a small electric pump taking water from, and returning it to, the engine block (using fittings in place of a pre-existing drain plug and another opening). It works perfectly, and appears to have been insitu for some years.
(The calorifier also has a mains immersion heater, but I've never yet used it.)
(The calorifier also has a mains immersion heater, but I've never yet used it.)
geem
Well-Known Member
Fitting hydronic heating would do the job. Feed the calorifier and radiators/fan coil units. 15 mins of 5kw heat output to the calorifier should give you enough water for a couple of showers. I have just switched over from air blown diesel heating to hydronic so we can heat how water
Brooksie89
Well-Known Member
Reviving this thread a bit, but I found an interesting picture online.
The two hoses in the middle of this of the exhaust manifold/mixing elbow are normally plugged. I believe the engine in the image had an anti siphon in place there, but I may have read that wrong. It's in line with the raw water cooling circuit.
Is there no chance of using this because it would compromise the cooling circuit, or it isn't hot enough, or both?
The two hoses in the middle of this of the exhaust manifold/mixing elbow are normally plugged. I believe the engine in the image had an anti siphon in place there, but I may have read that wrong. It's in line with the raw water cooling circuit.
Is there no chance of using this because it would compromise the cooling circuit, or it isn't hot enough, or both?
Dockhead
Well-Known Member
And if it's used with LPG (butane or propane), it's a very serious safety issue in a boat.
Dockhead
Well-Known Member
That's what I would do.