Making A Calorifier with an NRV Able To Drain Down

[alan_fincher]

I'm about to start fitting a Surecal Horizontal Calorifier (55 litres).

 

We are not live-aboards, so it seems sensible to arrange ways in which it can be drained and left empty.

 

Obviously the drain needs top be from a low point, so the cold water feed, but the Surecal has a non return valve incorporated in the connection between inlet and tank, so water can't be drained or pumped back out through the feed, it seems.

 

There is a sideways stub, with the PRV on the end. The only way I can see to incorporate a drain point, is to lengthen this, to add it before the PRV, an untidy solution, in terms of space.

 

Am I missing something ? How else could you drain the Calorifier without a major battle, please ?

 

(I have PMed one member on this topic, but am obviously not expecting them to answer multiple times. )

 

Alan

[Guest]

Youmay have seen this Alan, but here is a link:

 

http://www.surejust.co.uk/PDF/connections.pdf

[Ray]

Can you remove the NRV, fit a "T" by the cylinder and then refit the NRV so you have the following order: (water) tank, pump, pipe, NRV, T, Calorifier. Fit a short stub on the open end of the "T" and then a gate valve. Keep the valve closed except when you want to drain the tank. You could even put the gate valve somewhere more convenient for draining.

 

I wonder if you could also use this configuration to drain the main tank as well.

[alan_fincher]

Youmay have seen this Alan, but here is a link:

 

http://www.surejust.co.uk/PDF/connections.pdf

Yes thanks, although I didn't have it at the boat today, when I thought I'd attach a cable to the immersion. (We don't have 240V, but it seemed sensible to add the cable whilst it can be accessed, in case we ever do).

 

Whatever language the terminals are in, they don't use 'L' 'N' & 'E' on my immersion, so I had to do it by thinking about it, not by labelling. (I did pass the test, it seems!).

 

Similarly the mixer valve labelling, (that's German, possibly ?).

[smileypete]

Does it look exactly like this?

 

 

cheers,

Pete.

[alan_fincher]

Does it look exactly like this?

 

cheers,

Pete.

No!

 

It didn't have the cable attached to the immersion, and the cover caps on the pipes on mine are red and blue.

 

Sorry, only joking!

 

Yes, that's the one, exactly.

 

There seems to be a non return valve incorporated into the point where the tail for the cold feed joins that 4 way connector at the bottom.

 

Otherwise I would introduce a drain point on the feed line just before it enters that tail.

 

 

 

Where the PRV is joined to the left of that 4 way connector, I suppose it's possible to break it, and introduce a drain point there.

 

However, if just in a line, that would then push the PRV well back beyond the line of the cylinder, and mess up my fitting options.

 

I hope that explanation is not too garbled.

 

Cheers,

 

Alan.

[OptedOut]

When you say "Drain" where will the water go?

[MtB]

Some thinking 'outside the box' is missing here. I suggest you don't NEED to drain it to for protection against frost.

 

Marks out of ten will be awarded for the best explanations of why not....!

 

 

Cheers, Mike

[LEO]

Some thinking 'outside the box' is missing here. I suggest you don't NEED to drain it to for protection against frost.

 

Marks out of ten will be awarded for the best explanations of why not....!

 

 

Cheers, Mike

 

Hi,

My hot tank was a vertical one but I did not have to drain it down due to superior construction materials used and the fact that water was taken from the top of the tank. I suspect that the tank being fitted may have an air gap at the top of it unless a means of venting it is provided.

 

The high degree of factory fitted insulation will protect it.

 

Leo

[alan_fincher]

When you say "Drain" where will the water go?

I'm tempted to say into the rear bilge, whilst using the pump to shift it overboard. I can't see why not.

[PeterF]

Alan,

 

Are you sure there is a non return valve, have you tried poking something in to check this, there does not appear to be that much room for an NRV to be installed there and the surecal info does not mention it. I have installed one of these calorifiers last winter and did not think there was an NRV, I put my own NRV in with a drain between the NRV and the calorifier inlet and use a drill pump to empty it out of the window into the canal.

 

Peter.

[alan_fincher]

Some thinking 'outside the box' is missing here. I suggest you don't NEED to drain it to for protection against frost.

 

Marks out of ten will be awarded for the best explanations of why not....!

Sorry, not sure ?

 

Possibly suggesting it should never get that cold inside the boat ?

 

I can't see that insulation helps over time, because whilst it will slow the cooling down, equally it will hold cold in as the outside gets warmer.

 

With enough persistent cold I'd have thought the contents could freeze eventually.

 

If so, is it not then just like a very large bore copper pipe ?

 

Copper pipes burst when frozen with water in ?

 

Go on, what have I missed!

[Big COL]

Sorry, not sure ?

 

Possibly suggesting it should never get that cold inside the boat ?

 

I can't see that insulation helps over time, because whilst it will slow the cooling down, equally it will hold cold in as the outside gets warmer.

 

With enough persistent cold I'd have thought the contents could freeze eventually.

 

If so, is it not then just like a very large bore copper pipe ?

 

Copper pipes burst when frozen with water in ?

 

Go on, what have I missed!

 

 

Alan

 

The insulation should be enough to protect the tank, If you do feel the need to drain down the calorifier then you could do so by holding the red knob on the prv so its just on its cam, at this point water will drain out through the prv.

As for water left in the pipes through the boat all you can do is to leave open all taps to allow for ice expansion.

Edited November 23, 2008 by Big COL

[smileypete]

There seems to be a non return valve incorporated into the point where the tail for the cold feed joins that 4 way connector at the bottom.

 

I'd give Surecal a call tomorrow to double check and get their advice on NRV removal, draining, frost protection.

 

I'd also go along with PeterF's comments in post #11.

 

cheers,

Pete.

Edited November 23, 2008 by smileypete

[MtB]

Go on, what have I missed!

 

It doesn't matter if the tank freezes. You're worried about the tank suffering frost damage, yes? Damage from burst by ice, yes?

 

Well ice forms as a crystalline structure at first, suspended in the liquid water, and the during the time the water is crystallising and expanding in volume (the effect that does the damage), the water/ice mix is still fluid. This means the pressure relief valve will still work and pass enough water/ice mix to keep the pressure inside the tank below the 3.0 Bar for which it is tested and safe. The tank can freeze solid and suffer no ill effect. Pipes burst when there is NO provision for expansion on freezing of the water inside them.

 

There may be other reasons for needing a drain point but I suggest frost protection isn't one of them.

 

Cheers, Mike

[Gibbo]

It doesn't matter if the tank freezes. You're worried about the tank suffering frost damage, yes? Damage from burst by ice, yes?

 

Well ice forms as a crystalline structure at first, suspended in the liquid water, and the during the time the water is crystallising and expanding in volume (the effect that does the damage), the water/ice mix is still fluid. This means the pressure relief valve will still work .............

 

Until it freezes. And as it's not insulated it will actually be one of the first things to freeze.

 

No?

 

Gibbo

[alan_fincher]

Are you sure there is a non return valve, have you tried poking something in to check this, there does not appear to be that much room for an NRV to be installed there and the surecal info does not mention it

 

Yes, for definite - you can see it down the connector, and it's not possible to push something down.

 

I've not dismantled, but it seems to be a small part sandwiched in between the connector and the 4-way fitting.

 

 

I'd also go along with PeterF's comments in post #11.

 

As above.

 

The Surecal install instructions don't mention it's presence, but one of their brochure's does.

 

The insulation should be enough to protect the tank, If you do feel the need to drain down the calorifier then you could do so by holding the red knob on the prv so its just on its cam, at this point water will drain out through the prv.

 

Ah, that may suffice.

 

I wasn't sure if you could force them to be open - thank's for that!

[rjs]

Regarding draining the tank - the water pipes/valves on my boat are so organised that the normal water pump can be used to discharge the water - there is a valve to which a length of hose pipe can be connected to run into the sink.

 

When I pump the water out during winterisation its just a matter of setting the valves appropriately and then opening the drain valve and waiting half an hour for the calorifier to be drained. I then disconnect the pump and take it home to keep it out of any severe cold.

 

Richard

[steelaway]

Alan

 

The insulation should be enough to protect the tank, If you do feel the need to drain down the calorifier then you could do so by holding the red knob on the prv so its just on its cam, at this point water will drain out through the prv.

As for water left in the pipes through the boat all you can do is to leave open all taps to allow for ice expansion.

 

 

Dont forget the shower mixer valve if you have one.

Take off the head and lower the flex into the base ond open the the mixer, run the shower drain pump dry

A friend had his mixer completly destoyed by freezing water.

My calorifier is vertical by the side of engine in the bilge.

The only way to drain this is to remove the bottom connection and pump it out by the bilge pump - if I ever thought it nessessary.

 

Alex

[Big COL]

Yes, for definite - you can see it down the connector, and it's not possible to push something down.

 

I've not dismantled, but it seems to be a small part sandwiched in between the connector and the 4-way fitting.

 

 

 

 

As above.

 

The Surecal install instructions don't mention it's presence, but one of their brochure's does.

 

 

 

Ah, that may suffice.

 

I wasn't sure if you could force them to be open - thank's for that!

 

 

Alan

 

Its not a case of forcing them open, you should operate the the prv valve manually as routine maintenance to stop them from scaling up. When you turn the red knob the valve will open and close as it is spring loaded, if you hold the knob at the 1/2 turn stage this should hold the valve in its open position.

[OptedOut]

I'm tempted to say into the rear bilge, whilst using the pump to shift it overboard. I can't see why not.

 

Just a thought as the last two boat we've owned had a "Dry" bilge from the engine room forward.

The current set up is a 3 way valve on the bath/shower pump.

 

Edit: The three way valve also connects to the calorifier drain.

Edited November 23, 2008 by OptedOut

[Big COL]

I'm tempted to say into the rear bilge, whilst using the pump to shift it overboard. I can't see why not.

 

Alan

 

Dump it overboard through a skin fitting. It will be at 3bar pressure, why would you want to dump it first then pump it overboard?

[andywatson]

I'm about to start fitting a Surecal Horizontal Calorifier (55 litres).

 

We are not live-aboards, so it seems sensible to arrange ways in which it can be drained and left empty.

 

Obviously the drain needs top be from a low point, so the cold water feed, but the Surecal has a non return valve incorporated in the connection between inlet and tank, so water can't be drained or pumped back out through the feed, it seems.

 

There is a sideways stub, with the PRV on the end. The only way I can see to incorporate a drain point, is to lengthen this, to add it before the PRV, an untidy solution, in terms of space.

 

Am I missing something ? How else could you drain the Calorifier without a major battle, please ?

 

(I have PMed one member on this topic, but am obviously not expecting them to answer multiple times. )

 

Alan

 

My thoughts for comment:

 

So far (last couple of years) I have so far got away with the following when leaving my boat:

 

1 Close valve between water tank and pump. Switch off pump.

2 Open all taps to depressurise the accumulator and the hot and cold water supply (which is hep20)

 

I have therefore relied on having some air space in the pipes although I can't be sure if it's in the right place.

If it's been really cold I've been to the boat and run the c/h to heat up the calorifier although if the weather is well below freezing for long enough it could in theory freeze, even though insulated.

 

It strikes me that the most convenient way to comprehensively drain the entire system including the calorifier and pump would be to use air.

To that end, why not "T" in an air connection (eg car tyre valve) immediately after the valve on the water tank then use this to displace all water using air, from a small pump or compressor?

To empty each branch just open that tap untill all water is expelled and air comes out.

This would empty the calorifier if hot taps were run.

 

I think the above would be easy to plumb in and leaves the system quick and easy to refill when required.

Any comments....................?

 

 

 

To drain the bath/ shower pump a valve T'd in at the lowest point should suffice.

[Guest]

My thoughts for comment:

 

So far (last couple of years) I have so far got away with the following when leaving my boat:

 

1 Close valve between water tank and pump. Switch off pump.

2 Open all taps to depressurise the accumulator and the hot and cold water supply (which is hep20)

 

I have therefore relied on having some air space in the pipes although I can't be sure if it's in the right place.

If it's been really cold I've been to the boat and run the c/h to heat up the calorifier although if the weather is well below freezing for long enough it could in theory freeze, even though insulated.

 

It strikes me that the most convenient way to comprehensively drain the entire system including the calorifier and pump would be to use air.

To that end, why not "T" in an air connection (eg car tyre valve) immediately after the valve on the water tank then use this to displace all water using air, from a small pump or compressor?

To empty each branch just open that tap untill all water is expelled and air comes out.

This would empty the calorifier if hot taps were run.

 

I think the above would be easy to plumb in and leaves the system quick and easy to refill when required.

Any comments....................?

 

 

 

To drain the bath/ shower pump a valve T'd in at the lowest point should suffice.

Given the cheap portable compressors now available, I think your idea of blowing out the water is excellent. Certainly a method used in industry.

[alan_fincher]

Its not a case of forcing them open, you should operate the the prv valve manually as routine maintenance to stop them from scaling up. When you turn the red knob the valve will open and close as it is spring loaded, if you hold the knob at the 1/2 turn stage this should hold the valve in its open position.

Sorry Col,

 

Bad choice of words by me,

 

I didn't mean "force it", as in apply lots of excess pressure. I meant "make it open, other than because it's opening pressure had been reached" - if that makes sense ?