Heating water

[Blackie]

Hi folks

 

Having read the forum as a guest for a while I thought that I would ask a question that has been bugging me for a while:

 

Why do some calorifiers have two coils?

 

B

[PeterF]

Hi Blackie,

 

One coil is heated by hot water from the engine, so is essentially free heat which would otherwise be transferred into the canal and the other coil is connected to your central heating boiler (such as an Alde, Erbespacher or Webasto) for when you are not running the engine.

 

Hope this helps.

 

Peter.

[Blackie]

Hi Blackie,

 

One coil is heated by hot water from the engine, so is essentially free heat which would otherwise be transferred into the canal and the other coil is connected to your central heating boiler (such as an Alde, Erbespacher or Webasto) for when you are not running the engine.

 

Hope this helps.

 

Peter.

 

 

Thaks peter but why not connect the boiler and the engine in prallel to the same coil?

 

B

[ChrisPy]

Thaks peter but why not connect the boiler and the engine in prallel to the same coil?

 

B

because

- when you're moored up on a cold winter night you don't want to waste heat warming up the engine.

- it is simpler to maintain, repair or modify the systems if they are kept apart.

- the two systems may require different head of water and protection, for example the stove sytem may boil so it should be vented to the atmosphere without a pressure cap.

[chris w]

Also heating the calorifier and all the radiators might not allow the engine to run at its correct temperature (ie: it might run too cool which may lead to bore glazing).

 

Chris

[bottle]

Also heating the calorifier and all the radiators might not allow the engine to run at its correct temperature (ie: it might run too cool which may lead to bore glazing).

 

Chris

 

Thought engines had a thermostat so that they always ran at the correct temperature.

 

Or are marine engines plumbed differently?

[chris w]

Yes of course, but if the heat sink is too large, the engine may never get to the correct temperature. It might be forever cycling around the thermostat temperature.

 

Chris

[Theo]

Thought engines had a thermostat so that they always ran at the correct temperature.

 

Or are marine engines plumbed differently?

 

I my innocence I have paralleled the calorifier, radiators, engine and Mikuni. The system works well and the engine seems to warm up quickly reaching 70deg C very little slower with all the circuits open than with them all shut off. I have fitted valves so that each circuit can be isolated and worked on leaving the others unaffected. In cold weather the Mikuni can be used to preheat the engine.

 

In answer to the above: the heater circuit is taken straight from the cylinder block so it bypasses the thermostat.

 

All I can say is that I seem to be lucky with the BMC 1.5. The system works and is helped by the fact that it has an unusually powerful water pump. I modified the system since last winter so I will have to see how it goes as the weather gets colder. If necessary I can turn off one of the circuits. I don't expect to be using the saloon radiators much as we have a stove in there.

 

Nick

 

Edited to add:

 

I can feel some more plumbing coming on. I could fit a branched hose and take the heating from the branch. This would be controlled by the thermostat, so the engine would have a bit more protection. I wonder...

Edited September 3, 2007 by Theo

[Blackie]

I my innocence I have paralleled the calorifier, radiators, engine and Mikuni. The system works well and the engine seems to warm up quickly reaching 70deg C very little slower with all the circuits open than with them all shut off. I have fitted valves so that each circuit can be isolated and worked on leaving the others unaffected. In cold weather the Mikuni can be used to preheat the engine.

 

In answer to the above: the heater circuit is taken straight from the cylinder block so it bypasses the thermostat.

 

All I can say is that I seem to be lucky with the BMC 1.5. The system works and is helped by the fact that it has an unusually powerful water pump. I modified the system since last winter so I will have to see how it goes as the weather gets colder. If necessary I can turn off one of the circuits. I don't expect to be using the saloon radiators much as we have a stove in there.

 

Nick

 

Edited to add:

 

I can feel some more plumbing coming on. I could fit a branched hose and take the heating from the branch. This would be controlled by the thermostat, so the engine would have a bit more protection. I wonder...

 

thanks everyone.

 

It looks as if most people don't follow Nick's plan then. Perhaps I will do what most do.

 

B

[DHutch]

Or alternativly, while crusing with the stove lit, the water could be heated by the stove to approaching 100c, which would clearly not allow cooling of the enigine.

- Or if otherwise plumbed, running water at 80c odd into the stove, would almost certainly cause it to boil if a fire was present in the stove. Basically, far better and safer as two non interconected loops!!

 

Also, on a steam boat the second coil can have live steam blow though it to heat the water, with the other coil again being used with the stove.

- Ill get my hat...

 

 

 

Daniel

[bottle]

In answer to the above: the heater circuit is taken straight from the cylinder block so it bypasses the thermostat.

 

Thanks Theo

[David Schweizer]

My boat is fitted with a single coil calorifier, taking hot water from either the engine or the Ellis Heatmaster Gas boiler, heating both the domestic water and the radiators. The engine runs quite happily at 82 degrees (as it should), the Heatmaster does not heat up the engine because there is a non-return valve in the engine heat flow pipe, preventing back cycling, and the head of water issue is resolved by having a second header tank adjacent to the forward radiator (inside a neat little cupboard).

 

I have also designed a system of valves which allows any section of the system to function independantly without loosing heat to another section, and if anyone inadvertently closes off all the valves, the system does not allow pessure to build up.

 

Thie basic system was on my boat when I bought it, but I have modified it to eliminate heat loss, and like Nick the power source is a BMC 1.5 which has a powerfull pump which circulates the water around the system with ease, whether it would work with a modern Japanese unit I do not know.

[Richard T]

Just a thought on safety - please fit thermostatic mixer valves on taps which could be used by children or vulnerable adults. Hot water generated by an engine driven calorifier is much hotter than a normal domestic (house) hot water system and serious scalds could easily happen. My own boat gets hot water at around 85 to 90 deg C. We have TMVs on our shower and wash basin regulated to 43deg C which is the normal hospital setting. We do not regulate our sink tap as we like to wash up in very hot water. TMVs are not expensive and are easy to fit. You can fit one near to the calorifier to regulate the supply to all taps.

[Theo]

Just a thought on safety - please fit thermostatic mixer valves on taps which could be used by children or vulnerable adults. Hot water generated by an engine driven calorifier is much hotter than a normal domestic (house) hot water system and serious scalds could easily happen. My own boat gets hot water at around 85 to 90 deg C. We have TMVs on our shower and wash basin regulated to 43deg C which is the normal hospital setting. We do not regulate our sink tap as we like to wash up in very hot water. TMVs are not expensive and are easy to fit. You can fit one near to the calorifier to regulate the supply to all taps.

 

Now that is important. That has been on the "next plumbing job" list since we took our first week long cruise to Newark.

 

Nick

[DHutch]

We dont have mixers on any of our taps, and run the system of simply warning all partys unfamilur with the boat.

- We dont have many small children, but the few we do have are loosly supervised, and soon learn that red means hot!

- One day i might fit a mixer tap so luke warm water can be attacved from the tap, but that could still as easly be turn to hot anyway.

 

Its a balence thing, removing potential fatal or invisable hazards is a good thing, but try and prevent anything ever going wrong just means the children dont learn that i can go wrong.

- Plus, take darwinian action away completly, and you have a real problem on your hands that the whole human race will slowly begin to fall back to the leval its lowest common denominator!

 

 

Daniel

[ChrisPy]

Its a balence thing, removing potential fatal or invisable hazards is a good thing, but try and prevent anything ever going wrong just means the children dont learn that i can go wrong.

- Plus, take darwinian action away completly, and you have a real problem on your hands that the whole human race will slowly begin to fall back to the leval its lowest common denominator!

Daniel

[PeterF]

Just a thought on safety - please fit thermostatic mixer valves on taps which could be used by children or vulnerable adults. Hot water generated by an engine driven calorifier is much hotter than a normal domestic (house) hot water system and serious scalds could easily happen. My own boat gets hot water at around 85 to 90 deg C. We have TMVs on our shower and wash basin regulated to 43deg C which is the normal hospital setting. We do not regulate our sink tap as we like to wash up in very hot water. TMVs are not expensive and are easy to fit. You can fit one near to the calorifier to regulate the supply to all taps.

Its not just the engine, my Erby heat up to around 80°C aswell because that is the internal temperature control for the circulating water within the erby so the calorifier just gets up to that temperature. Had a look at the TMVs for direct on the output of the calorifier and that looks a good idea.

 

Peter.

[Maverick]

Whats the advice for calorifiers during winter months on boats not lived on. Should the hoses be reconncted so that the engine can be run but the calorifier is drained?

 

I also noted that on my keel cooled boat the total water capacity for the keel tank, engine and calorifier piping etc totalled abot 6-7 gallons on estimate. Thats an awful lot of antifreeze. Anyone else have this problem?

[David Schweizer]

Whats the advice for calorifiers during winter months on boats not lived on. Should the hoses be reconncted so that the engine can be run but the calorifier is drained?

 

I also noted that on my keel cooled boat the total water capacity for the keel tank, engine and calorifier piping etc totalled abot 6-7 gallons on estimate. Thats an awful lot of antifreeze. Anyone else have this problem?

I always drain down the calorifier over the winter, but leave the water in the heating coils, connected to the engine cooling system. The cooling system has a 40%v antifreeze mixture in it which is left in the system permanently, you just have to bite the bullet and buy enough atifreeze to protect the sytem, and do not forget the radiators, unless you drain them down, you will need antifreeze in them as well.

[DHutch]

Yeah its quite a lot, ours is somthing like 20% or some other fairly low leval, and its been in there nearly 10 years. No problems yet tho.

- Its deffonatly worth the money tho when you talking an bleading a largish, naterally cycaling (no pump) system, including the coil in the cal.

 

 

Daniel

[chris w]

Whats the advice for calorifiers during winter months on boats not lived on. Should the hoses be reconncted so that the engine can be run but the calorifier is drained?

 

Check your engine manual. On my Isuzu engine they say NOT to connect the two (calorifier) hoses together if the calorifier is not used, but to simply blank off the two pipes. (I have inserted gate valves for this purpose).

 

Chris

[blackrose]

Just a thought on safety - please fit thermostatic mixer valves on taps which could be used by children or vulnerable adults. Hot water generated by an engine driven calorifier is much hotter than a normal domestic (house) hot water system and serious scalds could easily happen. My own boat gets hot water at around 85 to 90 deg C. We have TMVs on our shower and wash basin regulated to 43deg C which is the normal hospital setting. We do not regulate our sink tap as we like to wash up in very hot water. TMVs are not expensive and are easy to fit. You can fit one near to the calorifier to regulate the supply to all taps.

 

Is it worth fitting TMVs if you have mixer taps?

Edited September 4, 2007 by blackrose

[chris w]

Is it worth fitting TMVs if you have mixer taps?

 

IMHO, only if the mixer taps are likely to be used by someone who doesn't appreciate just how hot the water can be, if not mixed properly.

 

I have put a TMV on the only non-mixer tap (in the boat's bathroom) because one couldn't get one's hand under the hot tap after the engine had heated the water - it's scalding; but not on the shower or galley which have mixers.

 

Ideally, if cost and effort are no issue, it must be safer obviously to fit them to all outlets.

 

Chris

[blackrose]

Ideally, if cost and effort are no issue, it must be safer obviously to fit them to all outlets.

 

Chris

 

I think I'll just have one TMV on the calorifier outlet - that will do everything. I can't see the point of putting a TMV on each outlet?

[Maverick]

I always drain down the calorifier over the winter, but leave the water in the heating coils, connected to the engine cooling system. The cooling system has a 40%v antifreeze mixture in it which is left in the system permanently, you just have to bite the bullet and buy enough atifreeze to protect the sytem, and do not forget the radiators, unless you drain them down, you will need antifreeze in them as well.

 

So having hot water going around the coils will not harm an empty calorifier?