Draining water tank

[colmac]

If I drain my water tank down for winterising does this also empty the clarifier ? Thank you

[ditchcrawler]

If I drain my water tank down for winterising does this also empty the clarifier ? Thank you

No you need to do that separately

[Scholar Gypsy]

It is v unusual for water in the main tank to freeze, even though it is outside.

 

However the internal pipework is more vulnerable. I drain all of mine in the winter, some use greenhouse heaters...

[Chewbacka]

Most calorifiers have a non return valve so it is not possible to drain it from the cold water system.

[trackman]

Chewbacka is right. If there's a non return valve in the cold supply, as on Surecal calorifiers like we have, it's almost impossible to drain the calorifier.

 

When our first calorifer developed a split and leaked badly, I was still unable to empty it even after removing it! I left it overnight, on the bank outside, split side down. It was still partially full next morning & had to go in the skip about half full. I tried tipping it every which way to no avail.

 

So, the chances of emptying one in situ are minimal if it has an nrv.

 

What I do is to drain everything else after isolating the water tank & turning off the pump. It's probably not worth draining the main tank, but do that if you want to be sure. I leave all the taps and shower turned on to minimise the risk of pressure building up anywhere if ice forms.

[ditchcrawler]

 

What I do is to drain everything else after isolating the water tank & turning off the pump. It's probably not worth draining the main tank, but do that if you want to be sure. I leave all the taps and shower turned on to minimise the risk of pressure building up anywhere if ice forms.

Shower mixers are another high risk as water gets trapped inside the mix part, freezes, expands and splits the body open. Not always easy to drain as they are fitted with non return valves and the outlet is often the highest point. I pump my system up with a bit of air and then open taps to blast it out.

[Neil Smith]

My calorifier has a drain cock at the bottom,

 

Neil

[jonesthenuke]

Most calorifiers have a non return valve so it is not possible to drain it from the cold water system.

Are these valves built into the calorifier? Last time I tried to drain main I struggled to get water out of it, yet cannot see an external NRV.

I am going to have another try this weekend and am planning to modify the pipework to add a vent to the hot water outlet to facilitate draining.

[colmac]

Thank you all. I will drain the system then switch the pump off as the winter deepens.

[Joe the plumber]

I've been pondering how to drain ours as it has no drain valve. At the moment, I'm intending to remove the immersion heater from the top

and use a drill powered pump to empty it.

 

Incidentally, I can't believe anyone would take an old calorifier to the tip. If it's copper (actually I've no idea, are they usually, or stainless?), feel free to tip it in my

garden and I'll take it to the scrapyard!

[rubblequeen]

I fnd it hard to beleive that anyone would fit a calorifier without a drain off valve. Poor workmanship. So have a good look even round the back of the calorifier, it's generally in it's own boss or more usual on the cold feed just as it enters the unit.

 

If there really isn't one then consider fitting one once it's drained down. If your water is heated from a back boiler that water will be seperated from the water in the calorifier by a coil, this will not drain down from the main body.

 

Have fun

[ditchcrawler]

I fnd it hard to beleive that anyone would fit a calorifier without a drain off valve. Poor workmanship.

Lots are

If your water is heated from a back boiler that water will be seperated from the water in the calorifier by a coil, this will not drain down from the main body.

 

Have fun

You can use antifreeze in there just like central heating and the engine

[cuthound]

Lots are

You can use antifreeze in there just like central heating and the engine

The antifreeze would have to be drinkable, to avoid the potential for pollution your cold water. I know that these are available, but rather you than me.

[ditchcrawler]

The antifreeze would have to be drinkable, to avoid the potential for pollution your cold water. I know that these are available, but rather you than me.

assuming you heat your water from the engine do you have drinkable antifreeze in your engine.

[system 4-50]

Are these valves built into the calorifier? Last time I tried to drain main I struggled to get water out of it, yet cannot see an external NRV.

I am going to have another try this weekend and am planning to modify the pipework to add a vent to the hot water outlet to facilitate draining.

Do let us know how you get on. I want to do this too.

[blackrose]

Chewbacka is right. If there's a non return valve in the cold supply, as on Surecal calorifiers like we have, it's almost impossible to drain the calorifier.

 

When our first calorifer developed a split and leaked badly, I was still unable to empty it even after removing it! I left it overnight, on the bank outside, split side down. It was still partially full next morning & had to go in the skip about half full. I tried tipping it every which way to no avail.

 

So, the chances of emptying one in situ are minimal if it has an nrv.

 

Mine has an NRV and I've emptied it without too much of a problem in order to fit an immersion heater. I just took the joint apart at the NRV. The vacuum in the tank prevented all the water pouring out until I twisted open the pressure relief valve at the top of the tank and filled a washing up bowl several times. It wasn't really that difficult at all.

Edited November 18, 2015 by blackrose

[Scholar Gypsy]

I hope this extract from SG's manual may be helpful - it took me several iterations to get to this position. The pump also doubles as the cabin bilge pump (rarely needed),

 

Boat_instructions_v3.11.pdf

 

I can now drain the hot water tank in 5 mins, and refill it in the same time. I do not have a NRV on the cold feed, but could obviously add one. I do have a mixer valve to produce warm water for the bathroom, and one needs to think how to drain the "warm" pipework.

 

A couple of other points:

• you have to drain the water via the cold inlet, as that is (or should be) at the bottom and the hot outlet is at the top,
• remember to open the hot taps (not the cold) to let the air in when you pump the water out.

Edited November 19, 2015 by Scholar Gypsy

[cuthound]

assuming you heat your water from the engine do you have drinkable antifreeze in your engine.

No I don't, but I consider the possibility of the engine coil (or the diesel boiler coil for that matter) leaking to be quite small. I hope I would notice the need for more frequent topping up of the engine or boiler.

 

 

ETA leaking after a gentle nudge from another forumite - thanks Simon.

Edited November 19, 2015 by cuthound

[Sea Dog]

Well my leaning towards draining my Surecal calorifier went out of the window when I realised that the previous owner didn't for 5 winters. Now I open all the h&c taps and drain the shower mixer and let the highly insulated calorifier fend for itself. I was going to say perhaps I've just been lucky, but she's been through some harsh winters with temperatures about as low as we get so luck hasn't played a part really. Too much risk? I'm not sure.

[jonesthenuke]

Do let us know how you get on. I want to do this too.

I spent all Saturday afternoon and some of the evening investigating. The installation included a 15mm cross (4 way fitting) at the cold feed to the tank connected as follows:-

1. Cold feed inlet, with isolation valve on the feed and a drain valve between the isolation valve and the cross fitting.

2 Cold feed supply to temperature control mixing valve on tank outlet

3. Connection to Calorifier

4 connection to Safety valve.

 

All of these connections looked much the same, i.e. standard compression joints. What I found was the cold feed supply point on the Cross includes a non return valve function within the fitting. This cannot be seen externally. This was non return valve was preventing any drainage from the calorifier when opening the drain valve (essentially it was draining the foot or so of pipe to the feed isolation valve). THis may be standard but I have not worked on boat plumbing before.

 

I have now changed this by adding a T between the cross and the Safety Valve. This then leads to an isolation ball valve, a 12V pump, then a non return valve which tees into the discharge line of the safety valve (which has its own non return valve).

 

Draining the Calorifier is now simple:-

 

A. Run hot water until it becomes cool (to save the pump from hot water)

B Isolate the cold feed supply

C Open the valve to the drain pump, water immediately passes to outside the hull via the pump, under residual pressure in the calorifier.

D Open hot taps to allow air to enter calorifer when running the pump (to avoid sucking it down)

E Run drain pump until water stops.

 

On completion shut valves etc ready for next refil (or leave open if sure of doing it next time). The process takes about 15 minutes.

[Scholar Gypsy]

Well done - that sounds rather neat (photos please?). I don't bother with step A. It prompted three thoughts:

 

• I guess the discharge line goes uphill (assuming the calorifier is under a bed somewhere), so you might want to add a drain cock to drain that bit of pipe.
  
• Do you want to drain the hot water pipes, the section between the calorifier and the mixer, and then from the mixer to the taps?
  
• I don't quite see how opening the hot taps will let water into the calorifier - unless (like my installation, see diagram above) you have hot taps (unmixed hot water) and warm taps (mixed hot and cold water). The thermostatic mixer should also have a one-way valve (or probably two) within it, which would stop air flowing backwards.

[jonesthenuke]

 

Well done - that sounds rather neat (photos please?). I don't bother with step A. It prompted three thoughts:

 

• I guess the discharge line goes uphill (assuming the calorifier is under a bed somewhere), so you might want to add a drain cock to drain that bit of pipe.

• Do you want to drain the hot water pipes, the section between the calorifier and the mixer, and then from the mixer to the taps?

• I don't quite see how opening the hot taps will let water into the calorifier - unless (like my installation, see diagram above) you have hot taps (unmixed hot water) and warm taps (mixed hot and cold water). The thermostatic mixer should also have a one-way valve (or probably two) within it, which would stop air flowing backwards.

 

I'l load some photos next time I go to the boat. Currently I only have pre-modification photos.

Taking your points above:-

 

I have added a drain on the discharge of the pump, I did not mention it as I was keeping the description to the minimum.

 

The air is drawn back through the hot taps. The mixing valve seems to have no non return function, and when cold (after flushing the calorifier with cold water at the start of the process) will be open to allow hot water flow out of the calorifier and so lets air back in. I have fitted a drain valve at this point but it is unnnecessary to get the drain process working.

[Scholar Gypsy]

Very good, all you need now is some freezing weather to give it all a good test.

 

A couple of years ago one of my sons forgot to close the drain valve between the main isolator (near the cold water tank in the bows) and the water pump. I think I have now forgiven him. He said my instructions were too complicated ...

[system 4-50]

I spent all Saturday afternoon and some of the evening investigating. The installation included a 15mm cross (4 way fitting) at the cold feed to the tank connected as follows:-

1. Cold feed inlet, with isolation valve on the feed and a drain valve between the isolation valve and the cross fitting.

2 Cold feed supply to temperature control mixing valve on tank outlet

3. Connection to Calorifier

4 connection to Safety valve.

 

All of these connections looked much the same, i.e. standard compression joints. What I found was the cold feed supply point on the Cross includes a non return valve function within the fitting. This cannot be seen externally. This was non return valve was preventing any drainage from the calorifier when opening the drain valve (essentially it was draining the foot or so of pipe to the feed isolation valve). THis may be standard but I have not worked on boat plumbing before.

 

I have now changed this by adding a T between the cross and the Safety Valve. This then leads to an isolation ball valve, a 12V pump, then a non return valve which tees into the discharge line of the safety valve (which has its own non return valve).

 

Draining the Calorifier is now simple:-

 

A. Run hot water until it becomes cool (to save the pump from hot water)

B Isolate the cold feed supply

C Open the valve to the drain pump, water immediately passes to outside the hull via the pump, under residual pressure in the calorifier.

D Open hot taps to allow air to enter calorifer when running the pump (to avoid sucking it down)

E Run drain pump until water stops.

 

On completion shut valves etc ready for next refil (or leave open if sure of doing it next time). The process takes about 15 minutes.

Thank you for publishing this. It helps me a lot!

Now all I have to do is get the water out in order to make the modifications that you have... !

[jonesthenuke]

I have tracked done some details of the calorifier and the embedded (stealth!) non-return valve.

 

Surcals web site says

The SureCal comes complete with:

Surecal comes complete with thermostatic mixer valve, 4 bar pressure release valve, 1kw immersion heater, non return valve, 15mm barbed connections for coil and ready for push fit plastic plumbing in 15mm. Also supplied st/steel mounting feet

But its not obvious that an NRV is fitted on their installation diagrams:-

http://www.surecal.co.uk/documents/Horizontal%20twin%20coil%20fitting%20instructions.pdf

This picture shows the cold feed connection but does not mention the embedded NRV, so I guess its easy to assume a drain on the cold feed pipe would drain the calorifier tank (as my boats original installer seems to have done). Surecal's description shows the PRV dumping to the bilge, so could then be usd as a drain (though it would be slow), this would not work on my installation as the PRV discharge is piped up and out through the hull, above calorifer level. As described in earlier post, I have added a new Tee before the PRV and can pump to waste from there.