Forums » Ask a Question

Use this forum to post your questions to our experts – you need to be logged on to do it (you can register here ), then scroll down to the bottom of this page and click the blue Post Thread words

If you can help answer the question, feel free to post a reply – you need to be logged on to do it (you can register here ), then hit the reply button on the thread.

 

To go back to the experts page click here>>

AuthorMessage
BrendaW...
BrendaW...

Posted: Fri Apr 21, 2017 6:55pm

Post Subject: Calorifier not heating water

Hi, Our Viking 32 foot narrow beam is powered by a Volvo Penta 2002 series freshwater cooled engine and hot water is supposedly provided by calorifier fed from the engine. The pipe that takes water from the thermostat housing to the exhaust elbow is cut into and the water is run through the calorifier heating coil then to the exhaust elbow. The pipes are connected the correct way round and water flows freely through the coil, there are no blockages and no air locks. The thermostat is the correct rating and opens properly, I’ve tested it in a saucepan with a thermometer. My problem is that if I spend the day pottering at 1500 rpm, about 3mph on my log, the hot water tap gives tepid water only, not stone cold but not hot enough for a shower. If we need to make a bit more distance and run at 1700 rpm, about 3.5 mph, so the engine is working harder, the water is just warm enough for a fairly cool shower. Other than throwing a drag line out the back to load up the engine, what can I do to make the water hotter?

Tony-B...
Tony-B...

Posted: Sat Apr 22, 2017 7:52am

Post Subject: Calorifier not heating water

I need to know more about the cooling system in use. There are basically three possibilities. Direct raw water cooling where you never put any water or antifreeze into the engine, keel cooling or heat exchanger cooling. Both the latter have a separate water filler for the engine into which you put a water - antifreeze mixture. If you do not know which you have please send some photos to Tony@tb-training.co.uk so I can try to identify it. If this is one of the latter two systems then the connections are in the wrong place. If it is direct raw water cooled then it will be very difficult to get a calorifier to work because you will be feeding it with tepid water. In this case if you can send a scan or photo of the manual pages related to the thermostat housing plus a photo of the actual part so I can see if I can find a way of re-piping the engine to get hot water into the calorifier

Tony-B...
Tony-B...

Posted: Mon Apr 24, 2017 8:07am

Post Subject: Calorifier not heating water

I am home now on land line internet so have found an MD2002 manual on line and from what I can see the news is not good. To explain things a little further. A wet exhaust boat must always have sufficient water injected into the exhaust to prevent the exhaust hose burning. This means that whenever the engine is running the water flow must be maintained irrespective of the position of the engine thermostat. ON direct raw water cooled engines this is usually achieved by having a fancy thermostat arrangement so that when the engine thermostat is closed the raw water bypasses the engine and is fed into the exhaust. As the engine warms up less water bypasses the engine and more passes through the engine to cool it. However there is always far more cold water than hot being directed to the exhaust so the flow is never much more than tepid. Hence the problem. On some engines it is possible to either fit a distance piece to the thermostat housing mounting with a hot take off from the engine side of the thermostat or modify the pipe work but as far as I can see from the manual a pipe work mod is not possible and there is insufficient info to be sure a distance piece with take off will work. In any case a distance piece would need machining and may be expensive. If this is not a direct raw water cooled engine things look more hopeful. The manual shows at least one hot water outlet on the engine of the heat exchanger cooled version so it will only be a case of finding the return.This will often be on the input side of the ENGINE (not raw water) pump. In the case of a tank/keel cooled system it will probably be easiest to re-pipe the feed to the keel cooler/skin tank so it passes through the calorifier. This will give a slightly slower calorifier warm up time but it will eventually be fed hot water. If the calorifier only has 1/2" coil connections then doing it this easy way just might cause overheating but it is so easy to reverse I would try this first. There should be no problem with a 3/4" coil unless the calorifier is a very long way from the engine.

Tony-B...
Tony-B...

Posted: Mon Apr 24, 2017 9:25am

Post Subject: Calorifier not heating water

Having studied the manual some more I think I MIGHT have found a suitable calorifier take off point but as it is not possible to post decent images here I need the questioners email address. If they just email me Tony@tb-training.co.uk I will be able to send them the image and further explanation. Otherwise I will submit my whole reply for possible publication in the magazine, possibly the September edition (published August).

BrendaW...
BrendaW...

Posted: Wed Apr 26, 2017 7:37pm

Post Subject: Calorifier not heating water

Hi Tony, thanks for the prompt reply and apologies for my own slow response, I've had no internet for a few days. The engine is raw water cooled, the water cooling pump draws straight from the canal. I've sent my conact details to your email. Regards Keith

Tony-B...
Tony-B...

Posted: Thu Apr 27, 2017 8:47am

Post Subject: Calorifier not heating water

I have replied to the questioner in some detail and now the type of cooling system has been clarified I will edit my replies and submit them to the editor for potential publication in the magazine where images can be reproduced..

Like us on Facebook



Follow us on Twitter

Cache: Disabled for this object  Total Queries: 43.  Total Objects: 162.  Total Unserialized: 3. Total Runtime: 0.25 seconds.