Non calorific water heating.

[Signed Out]

OK, so this is probably an old topic, but I am new, and cannot find an answer using search, so please be patient.

My boat has got a gas water heater that the surveyor has given me a big no-no about, so it must go, but I want hot water. But... my engine has only raw water cooling, so a calorifier is of little use to me, unless I splash out on converting to a heat-exchange.

Can anyone make a suggestion as to what I can get to provide me with hot water on tap? I have an Eberspacher 3DL cabin heater, but guess this can't be added to or altered to help. On eBay I have seen some Eberspacher waterheaters, but don't recall ever reading about these in the press- any use?

Cheers, Jem.

 

[fireball]

We have a calorifier on our raw water cooled Yanmar 2GM20 - may not get as hot as the freshwater jobbies, but (when I've sorted the thermostat!) still gives warm-hot water. + it has an immersion heater in for when we're connected to shorepower.

 

[boatbuilder]

This a common missinterpetration of the gas rules. There is noyhing unsafe with the standard gas water heater. if it is original equipment , it can be replaced with the same.
What you cant do is put them on new boats as new equipment.
Properly installed they are perfectly safe, if the pilot light goes out the gas is turned off automatically.

 

[jerryat]

Well we have a calorifier on our raw-water cooled Bukh and it produces water far hotter than you could keep your hand in!! We do have a Johnson ceramic impellered pump to force-circulate the seawater through the calorifier, since prior to this, the fresh water temperature only got fairly warm.

The pump (not cheap!) transformed the performance. We've had this set-up for 15 years now and, except for having to change the 22 year old pressure relief valve in the calorifier this lay-up, have had no problems at all.

PM me if you'd like details.

HTH's

 

[fireball]

Hmm - thats interesting - we think we've been lacking hot water because the thermostat isn't opening sufficently - how does the johnson pump get round this or does it just pump round all the time?

 

[charles_reed]

Surveyors

Well my boat, fitted with a LPG geyser hasn't been condemned by any surveyors.

If fitted as original equipment, with a flame failure device and adequate flue it's totally OK - until you want to take the boat into British Waterways, at which point their requirements come into effect and there's no appeal against their verdict.

 

[Signed Out]

Thanks, I think I need to track down a marine heating/gas system engineer and get the lowdown as keeping the original would be a bonus for me.

Otherwise, if I can use a calorifier, then that would make life easy. Jem

 

[cliff]

Ditto, Ditto and Ditto......

The circulation pump makes all the difference and the water in the calorifier is as hot as that in the HW tank at home - can't hold ones hand under the hot water coming from the tap.

The water is drawn off from just below the stat, pumped through the calorifier and returned to the bottom of the block. Handy on a really cold winter's morning as one can switch the pump on and draw heat from the calorifier to warm the engine a bit before trying to start it - handy when ones does not have preheaters. I fitted an extra cylinder blanket around my calorifier and insulated the hot pipes as far as possible to conserve heat.
--------------------

"Artificial intelligence is no match for natural stupidity"

 

[reeac]

What's this about a ceramic-impellored pump? Is the impellor more durable than the usual rubber one? Is such a pump useable for raw water cooling?

 

[Alastairdent]

Re: Surveyors

[ QUOTE ]
Well my boat, fitted with a LPG geyser hasn't been condemned by any surveyors.

If fitted as original equipment, with a flame failure device and adequate flue it's totally OK - until you want to take the boat into British Waterways, at which point their requirements come into effect and there's no appeal against their verdict.

[/ QUOTE ]

Not quite true.
If the water heater is fitted already, they will pass it as ok.
They were originally ruling them out, but as there was a lack of suitable replacements . . .

I have 2 boats with instant lpg water heaters, both with BW licences.

 

[scuby]

Re: Surveyors

The Ebespacher water heaters are often offered on Ebay as complete systems. They have usually been removed from BT vans. They can be good value but as for everything on Ebay - beware!

 

[pvb]

Ceramic impeller shaft pumps...

It's the shaft which is ceramic, not the impeller. This is a fairly common type of centrifugal pump for circulating water. The motor drives a cage of magnets which rotate outside the pump casing. Inside the casing, there's a plastic impellor with magnet moulded inside it. The impeller runs on a ceramic shaft for corrosion resistance. The motor-driven rotating magnets cause the impeller to spin inside the casing. The beauty of the design is that there's no need to have a seal on a rotating shaft, so no leakage, and there's nothing to corrode inside the pump casing. As it's a centrifugal pump, the impeller doesn't actually touch the casing so shouldn't wear out, although the ceramic shaft will gradually wear.

 

[jerryat]

Re: Ceramic impeller shaft pumps...

Yep, on checking, you are correct, ceramic shaft it is. Brilliant bits of kit and totally maintenance free!

 

[jerryat]

Hi Fireball and reeac,

I had a PM from another Forumite re this, so reproduce my reply here to save my typing finger! Hope it helps/explains.

"" Subject: Re: Hot Water

Hi,

Ok, Ill do my best to explain the installation for you.

First you need to identify the two points on your engine that will be used for the input to, and output from, the calorifer. In the case of my raw water cooled Bukh for example, there is a drain-down plug on the (starboard) side of the block, and another on the underside of the exhaust manifold, also on the starboard side.

Their equivalents on your engine may be slightly different, but should be broadly in the same place on one side or other of the engine.

Remove the plugs and insert a fitting in each with a hose tail connection for the hose size you intend using - the reinforced rubber, car type hose we use actually has a 15mm bore.

The flow (input) hose runs from the underside of the exhaust manifold as this is the hottest part of the cooling circuit (as it's just before the thermostat) and is connected to the TOP connection (input) on the calorifier. The 'return' hose is connected from the LOWER connection (output) on the calorifier and then to the other hose connector on the engine block.

Now this is where most people leave it, and indeed, given enough time, it will sometimes produce modestly warm water, but it can be dramatically improved!

Into this crcuit, I introduced a Johnson ceramic impellered pump. These are available from, amongst others, ASAP Supplies (Tel: 0845 1300 870) and are rated for different volatages and outputs. The one we currently use (we carry a spare) is Ref: ASAP 209602 Johnson Ref: 10-24501-03 which is 12v with 15mm connectors and has an output of 12.5 litres/min, more than enough to whizz the water throught this circuit! Current cost is circa £102.90 so NOT cheap, but then you never need to change the impeller!!

All these pumps are designed to run 24/7 as they are often used for fresh-water engine cooling retro-fits similar to Martec's and others. A bit more detail later.

Whether you insert the pump on the input or output side is a matter of personal choice and convenience of fitting. There are different points of view, but I changed ours from input side to output side early this season to give me better access to another item, and it's worked perfectly.

The pump is supplied with a two bolt bracket to allow it to be fixed in most places as long as the orientation complies with the requirements shown in the installation details. This avoids airlocks and ensures it's always primed - a particular requirement.

However, you must ensure that whichever position you choose, the flow goes FROM the exhaust manifold, down through the calorifier, and back to the connection on the block. It thus uses the hottest water to heat the tank before returning it to be heated again. Hope this is clear.

Finally, wiring the pump in. This is a matter of personal taste, but FWIW, this is mine. The (rather short) pump cable is connected to another (properly sized) cable with bullet connectors for easy removal. The positive of the cable is then taken to a circuit breaker on the switchboard and on to the ignition switch. Here it is connected to the 'running' connector, so that the pump starts running every time the ignition is on and the engine running. The circuit breaker protects the pump and allows us to turn it off if we are motoring for a long time and the calorfier is at maximum temperature. No point in wasting power.

The negative connection is obviously made to the negative bus-bar.

The pumps need no maintenance, and ours has been in place for about 12-13 years, including 7 spent full time cruisng. It's still perfect and we've never taken the spare out of it's box.

From cold, our 6-7 gall calorifier gives us piping hot water in about 15-20 minutes, certainly the water is far too hot to use without adding cold water, so be careful. For Marina use (rare for us!) we have a 2 KW immersion heater, that is switchable down to approx 1KW if the connection won't carry 2KW.

That's it. A very easy DIY installation that will hugely increase SWMBO's happiness as well as yours, so MASSIVE brownie points!! /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif Sorry it's so long, but you did ask!

If you need any further help/info, PM me and we'll sort it out. ""


Hope this helps others who are hankering after a hot shower or even plain old washing up water!! PM help apllies to all. /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif

Cheers Jerry

PS. Following pvb's post, I've just checked my brand new spare, and the impeller is 'glass reinforced plastic' not ceramic as above. Provided you do not run the pump unprimed for more than 30 mins (best not at all!) the impeller should virtually never need changing in normal us.

 

[jerryat]

Re: Ceramic impeller shaft pumps...

Ooops!! Not my day! /forums/images/graemlins/frown.gif The shaft is stainless steel and the impeller is glass reinforced plastic. Just checked my new spare and got the details, which were confirmed by ASAP.

Oh well, back to the Complan!! /forums/images/graemlins/wink.gif /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif

 

[KRG]

This forum's great, I've been considering doing this and was going to post a question when up pops this thread.

Has anyone done this with a Volvo 2002 who could tell me where the take off points are?

Thanks

 

[Phoenix of Hamble]

Interesting stuff Jerry.....

Do you find it has any impact upon exhaust temperature?.... and how does it affect the water flow out of the exhaust maifold?... and has it had any impact on engine running temperature given that the input (back through the drain plug) will be luke warm, rather than cold..... wondered whether it would be worth fitting a thermostatic switch rather than a breaker in order to switch the circuit out when water reaches desired temperature?

 

[pvb]

Volvo 2002...

If you download the workshop manual from here, there's a diagram in it of how to install freshwater cooling and this shows the various takeoff points.

 

[jerryat]

Hi NAS,

The installation does not affect exhaust water flow/temperature in any way that I've been able to spot. Certainly my temperature alarms have never once complained.

All it does is effectively increase the volume of the engine cooling water and the thermostat opens a bit later than it would otherwise do. Once the water in the calorifier has heated up to the engine's normal operating temperature, the engine thermostat opens, and the control process resumes as normal.

Assuming therefore, that you don't already have an over-heating problem, you will not be able to notice a difference.

The return doesn't actually go back to the engine lukewarm. The circulation is very fast, so the temperature drop across the inlet/outlet is very small. When you think about it, the total volume of water we're talking about in the HW circuit is very small so it heats up very quickly. The calorifier coil therefore gets hot and pretty well stays that way, despite obviously giving off heat to the surrounding water.

You could certainly install a thermostatic switch (indeed we considered this initially) but we reckoned it was another thing to go wrong, and we like 'mechanical' solutions if possible. A CB switch is simple and we control it!

Bukh Diesel UK approved the installation 'design' for the Bukh and I can see no reason at all for it not working on other raw water cooled engines since the principles are identical.

HTH's

 

[KRG]

Re: Volvo 2002...

Great, thanks.