Leaking calorfier

[tolhurstorganic]

I have a Vetus calorfier 3 years old and it has until recently been a very efficient way of heating 31 litres of water. A leak has developed which is probably somewhere on the exterior skin. I have had to turn off the taps from the flow and return pipes from the engine to retain the engine coolant. The leak is not obvious due to the insulation jacket, but the water is dripping out at the lowest point adjacent to the return pipe where it exits the tank. Removal of the tank will be a big job so I am wondering if a Radweld type product is worth trying. The leak is about 1 litre per hour. Anyone have experience of this?
The tank has always been kept filled with anti-freeze in winter and the fresh water drained. Does anybody have an idea as to what may have caused the leak?

 

[TradewindSailor]

You say water is dripping out .... do you mean coolant? If it is water then it will be on the service water side ..... which will be either a breach in the tank, seepage from the pressure relief valve, or leakage from the hose or connections.

It would be pretty unusual for the calorfier to develop a fault, especially in the coolant side. My guess is that the hose fitting is defective. Check the condition of the hose, the hose clamp, and perhaps any screwed connections into the tank.

If that doesn't fix it then you should get it silver soldered ... if you can find the source.

 

[vyv_cox]

From your description it would seem that the leak is in the coolant coil? I have come across corrosion of the coil before and wrote up a piece about it, printed in PBO last year. In that case the coil had corroded through both inside and outside the calorifier. The external leaks had been repaired but the internal ones had been missed. The symptoms were that coolant was overflowing from the engine into the bilge when the fresh water pump was switched on, pressure in the fresh water being far greater than in the coolant. If you do not have a pressurised water system the coolant would simply leak out when the engine was running. Be careful that antifreeze is not leaking into drinking water.

I doubt that Radweld would fix such a big leak but it has to be worth a try. I believe that it works when the active ingredient hardens on contact with air, so you would need to empty the fresh water from the calorifier first, in case there are internal leaks.

 

[tolhurstorganic]

The leak is definately from the coolant side of the tank. I have put dye into the system to confirm that. No trace in the fresh water side. I have eliminated any possibility of fresh water getting into the coolant by monitoring the pressure pump.
The coolant is dripping from the hole around the plastic insulation cover where the return pipe goes into the tank. At first I suspected the fitting and took it off and re-bedded it but have since managed to get a small mirror underneath where the coolant drips from and can confirm that it is not the fitting. Appears the coolant is soaking into the insulation and running to the lowest point. The drip starts very slowly for a while(1 drip per minute) until the insulation is saturated then speeeds up to a drip every 10 seconds, yes I know its almost as bad as watching paint dry!
As you point out a rad sealer needs some air to work, so does that mean that the wet polyurethane insulation on the cylinder would probably prevent the stuff working properly? And if it did work can it be considered as permanent? I treated the rad on an old tractor of mine decades ago that had a similar speed leak and that is still good.
Much appreciate your help so far.

 

[vyv_cox]

I suspect the best you can do is allow the insulation to dry out for a day or two, then try the Radweld-type sealant. My son in law is in the automotive repair business, he buys stuff that is a lot better than what they sell in car parts shops, so I would go to a factor. I repaired my radiator with stuff that he bought for me, was effective for the next couple of years I owned the car.