How to remove and replace my twin coil calorifier without flooding my boat

[Roy Batty]

Dear Canal World folk,

 

I have ordered a new twin coil calorifier to upgrade the inefficient original one in my 24 year old narrowboat.

 

I understand the principle of the thing so realise that there are three sources of water entering the old calorifier....from the water tank (via the pump and accumulator), from the gas central heating boiler, and from the engine cooling system.

 

My issue is that the calorifier is awkward to get to and is at the lowest point in the boat....

 

....so my question is:

 

How do I go about draining the different systems the best I can so that I don't spill gallons of water inside my boat?

 

If anyone has any experience in this matter I would be very grateful.

 

Obviously, in the absense of any advice I will muddle through but I would prefer to cause as little water damage to the lining of my boat as possible.

 

Thank you all in anticipation.

 

My best regards,

 

Roy

[Ray]

Is the calorifier vertical or horizontal?

 

I used a couple of piece of softwood clamped together with the hoses from the engine in between to minimise the escape of water from the engine cooling system.

 

I'd loosen the lower of the two connections from the boiler and let the water drip/drain into a pot below and suggest fitting a drain off point when you re-plumb into the new calorifier.

 

I believe that water should only escape from the inner part of the calorifier if there is a way for air to replace the water that is leaving it. Consequently, (I think that) provided that you remove the highest connection first and replace it with a blanking plate you should be able to do something similar with the lower connection afterwards. You can then drain the water from the calorifier off the boat but the calorifier and water will weigh a fair bit so this may not be an ideal solution.

 

Another option could be to turn off your water pump, open all your taps and let the pressure escape from the system, Close all taps again. if you haven't got a non return valve on the cold feed to the calorifier you should be able to cut into the supply pipe and fit a drain off point or valve to control the exodus of water from the cylinder. If you then remove the hot water (out) connection from the calorifier you should be able to drain the cylinder through the drain off.

 

Just a few ideas with no guarantee that any is better than the other or that they will work in your situation. Others may know better.

[larkshall]

I agree with Ray, plus I would turn off stop valave between water tank and pump. I would also try and empty some water out of the calorifier. I would undo the hot water out union which will be at the highest point , and pump as much water out of the tank as possible. I have used an old electric bilge pump with some odds and ends of plastic pipe to drain overboard. The weight is a killer as its in an awkward spot.

 

I am presuming from your description that the boiler is much higher than the hot water tank?. If so you are going to loose some water when you crack the fittings to the tank coil. Turn off water feed to boiler though first, and if (as the previous poster stated), you have flexible hoses between the boiler and tank, then clamp both with bits of wood and mole grips or 'G' clamps. Even so you will loose the water contents of the coil itself. Ditto on flexible hoses between engine and tank.

 

When fitting the new tank, incorporate bleed valves at both the coils return side..

 

Oh and don't forget to add something like fernox to the boiler ot water heating side. and top up the engine coolant with the correct anti-freeze. If per chance you have to drain down any radiators on the heating side of the boiler, I would also add fernox when refilling. It inhibits corrosion, and can quiten and 'knocking' in the system

[jelunga]

We had our horizontal one changed last year. They always seem to be fitted in the most inaccessible places. Depending on what sort of pipe work you gave fitted different approaches are necessary. We have drain valves all over the place but even so he only drained the water from the drains near the calorifier. Then the plastic pipes were capped or tied up above the level so nothing drains out. The water in the calorifier will be the most difficult to get out in situ. You could try pumping it out using a portable drill powered pump. But each litre of water will weigh 1kg so the more you can get out the lighter lift it will be. Lifting 20kg at arms length is not for wimps like me.

[Roy Batty]

Thank you Ray, Larkshall, and Jelunga,

 

I will try to incorporate all of that.

 

I have a horizontal tank....it is pretty useless as I think it was an old house one laid on its side. The new one is a purpose built horizontal calorifier made of stainless steel with a plastic casing.

 

The new one has arrived so when I have a couple of days in a row off I will start digging around to see if there are and stop cocks or drain points....and I will do as you say....try to get as much water out before I try to lift the old one out.

 

Good tip about replacing antifreeze or similar.

 

Nervous but excited.

 

Regards,

 

Roy

[Jigsawged]

Just a thought, has your new tank been pressure tested for the water supply on the boat? When I was fitting out, a plumber pal of mine took care of all that side of things but he fitted a domestic tank which is designed to operate at a lower pressure than the pump deliver. The end result was that after a while, the whole thing grew by about 4 inches in height, lifting all the pipe work with it. It had to be replaced with a suitable unit and as you know these things aren't cheap.