Winterising

[Neil2]

As the Leeds Liverpool is about to freeze over (sorry Dean!)...

 

Seriously, something that's been on my mind for a while as I've not had a calorifier before is what to do about draining down. I tend to drain all water from the tanks pipes etc. but I will want to use the boat over the winter or at least run the engine from time to time. So, if I drain the calorifier tank what precautions are needed to avoid damage to the tank when the engine is run? There doesn't seem to be an isolater valve on my calorifier, well it would have to be a bypass valve anyway, so coolant will continue to flow through the heat exchanger which will heat the air, which will expand and...

 

I'm thinking could I just take off the drain plug or disconnect one or both of the fresh water pipes to allow the hot air out, or would just leaving the taps open do?

 

What do other folk do?

[alan_fincher]

I'm thinking could I just take off the drain plug or disconnect one or both of the fresh water pipes to allow the hot air out........

 

That may not be enough!

[mrsmelly]

As the Leeds Liverpool is about to freeze over (sorry Dean!)...

 

Seriously, something that's been on my mind for a while as I've not had a calorifier before is what to do about draining down. I tend to drain all water from the tanks pipes etc. but I will want to use the boat over the winter or at least run the engine from time to time. So, if I drain the calorifier tank what precautions are needed to avoid damage to the tank when the engine is run? There doesn't seem to be an isolater valve on my calorifier, well it would have to be a bypass valve anyway, so coolant will continue to flow through the heat exchanger which will heat the air, which will expand and...

 

I'm thinking could I just take off the drain plug or disconnect one or both of the fresh water pipes to allow the hot air out, or would just leaving the taps open do?

 

What do other folk do?

 

I do not have to winterise thank god because I live aboard but my brother in law has a marina mooring ( poor sod ) and weekends on his boat and for less than a pound a day he leaves two leccy heaters on all winter to stop anything freezing up, of course if you dont have leccy hookup that would be a problem. In the bad old days tho when I lived in my house and left my boat for the winter or some of it I found it had to be bloody cold for several days to do any real damage. I have had several beers tonite so take no notice of this post its even worse than normal...............

[Rod a mod from Tod]

That may not be enough!

Why not? Sound alright to me.

[n.b.Goldie]

At the beginning of last winter, which turned out be the hardest winter for some time, I turned off the isolator tap at the water tank, wrapped the water pump and accumulator units in an old blanket and wrapped the calorifier in two old sleeping bags. The calorifier already has its own 'spray foam' insulation, is under the fixed double bed and underneath the mattress so the insulation is quite good. Finally I ensured all taps including the shower unit was left open. Nothing was drained down.

 

And then I hoped..........

 

My internal min/max thermometer showed a minimum temperature of -9deg C and sub-zero temperatures were experienced for weeks and when everything was turned back on after winter there was no damage or leaks.

 

The water pipes run below water level and perhaps protected them from freezing except for the vertical run to the taps which were open to allow for any expansion resulting from freezing.

 

Bit of a risk but it worked, maybe just lucky.

 

Regards

Ditchdabbler

[alan_fincher]

Why not? Sound alright to me.

You are more likely to avoid freezing by letting water out, (not air, as suggested....).

[Capt Ahab]

At the beginning of last winter, which turned out be the hardest winter for some time, I turned off the isolator tap at the water tank, wrapped the water pump and accumulator units in an old blanket and wrapped the calorifier in two old sleeping bags. The calorifier already has its own 'spray foam' insulation, is under the fixed double bed and underneath the mattress so the insulation is quite good. Finally I ensured all taps including the shower unit was left open. Nothing was drained down.

 

And then I hoped..........

 

My internal min/max thermometer showed a minimum temperature of -9deg C and sub-zero temperatures were experienced for weeks and when everything was turned back on after winter there was no damage or leaks.

 

The water pipes run below water level and perhaps protected them from freezing except for the vertical run to the taps which were open to allow for any expansion resulting from freezing.

 

Bit of a risk but it worked, maybe just lucky.

 

Regards

Ditchdabbler

Last winter was as severe a test as we are ever likely to get. I merely turned off the stop cock and opened the taps and hoped for the best.

The boat froze and no matter how much lagging there is no way the calrofier could avoid freezing. When it all thawed out the calorifier was fine.

[Neil2]

You are more likely to avoid freezing by letting water out, (not air, as suggested....).

 

Just to clarify or maybe calorify.. (sorry) my plumbing associates tell me that if you removes the water from a calorifier tank and allow hot water to run throught the heat exchanger coil, the effect of heating up air instead of water could result in damage to the tank. You are like creating a hot air balloon and if there's nowhere for the air to expand, well, think of the consequences.

 

But it seems like people don't bother draining their calorifiers?

 

I have heard several accounts now of boat owners just leaving all the taps open and in all cases no damage has resulted. Maybe I'm being over cautious.

[Rod a mod from Tod]

You are more likely to avoid freezing by letting water out, (not air, as suggested....).

But he had already stated in his second paragraph about draining the calorifier and i think he meant what the effect would be of the hot engine water going round the coil on the air now in the calorifier. I dont know whether the air would pressurize enough to cause any damage but i would have thought the PRV would cope with this. Just for belt and braces i suppose a union or push fit fitting could be split to leave the system open vented.

[Tony Brooks]

Just to clarify or maybe calorify.. (sorry) my plumbing associates tell me that if you removes the water from a calorifier tank and allow hot water to run throught the heat exchanger coil, the effect of heating up air instead of water could result in damage to the tank. You are like creating a hot air balloon and if there's nowhere for the air to expand, well, think of the consequences.

 

But it seems like people don't bother draining their calorifiers?

 

I have heard several accounts now of boat owners just leaving all the taps open and in all cases no damage has resulted. Maybe I'm being over cautious.

 

 

Consequences = zero

 

Air is compressible so any pressure rise due to heating will be far less that with water. If by some chance the air pressure did reach the PRV pressure then the prv would just vent. If the hot taps were left open it is very doubtful if the pressure would rise at all.

[Matthew Dowson]

Make sure you leave your shower head hanging down to drain, I left mine up one year and the mixer valve split, which can be difficult to notice behind the panelling. My boat LION was frozen solid and unused and unheated for a few months, and I'd just done the usual of draining down taps. The pump froze and split however, so some people drain it as well, I will this year. I leave my calorifier full and it sits in the engine room on a semi-trad.

[Neil2]

Consequences = zero

 

Air is compressible so any pressure rise due to heating will be far less that with water. If by some chance the air pressure did reach the PRV pressure then the prv would just vent. If the hot taps were left open it is very doubtful if the pressure would rise at all.

 

To be honest it was only a conversation with a plumber friend that got me started on this. He was adamant that running hot water through a HW cylinder with no water in it could end in disaster, even splitting the tank. I checked this with another guy and he said the same.

 

I'd still like to know if anyone has actually drained their calorifier and run the engine.

[Nickhlx]

To be honest it was only a conversation with a plumber friend that got me started on this. He was adamant that running hot water through a HW cylinder with no water in it could end in disaster, even splitting the tank. I checked this with another guy and he said the same.

 

I'd still like to know if anyone has actually drained their calorifier and run the engine.

 

I cant see how hot water running through the calorifier heating element (pipe) which is effectively sat in free air ( empty hot water tank) can split the tank...

 

Likewise I can't see how lagging e.g. a pump full of fresh water and then being subjected to -10 deg C for days on end will not stop it freezing. All insulation does is retard the rate of cooling (or heating), so it WILL freeze sooner or later. Of course lagging is useful if the cold lasts only a short time (hours) and the mass of the item does not drop in temperature to below freezing point.

 

I drain as much water out of the boat, including the main tank, pipes, shower fittings, U-Bends, and then suck them all out with a wet and dry Vacuum cleaner. I leave all taps open, and then pour in a solution of anti-freeze where water could collect. I also ensure all plugs are out of the basin / sink etc - the cost is trivial and saves pipes / porcelain cracking which would be heaps more hassle and expense. I also check the anti-freeze strength in the engine / heating system and top up if needed.

 

Not had a problem yet and we saw -17 deg C last winter....

 

Nick

[IanM]

To be honest it was only a conversation with a plumber friend that got me started on this. He was adamant that running hot water through a HW cylinder with no water in it could end in disaster, even splitting the tank. I checked this with another guy and he said the same.

 

That is probably due to the fittings and the tank getting much much hotter than designed to as there is no water to dissipate the heat. A bit like leaving an empty saucepan on a hob.

[bizzard]

To be honest it was only a conversation with a plumber friend that got me started on this. He was adamant that running hot water through a HW cylinder with no water in it could end in disaster, even splitting the tank. I checked this with another guy and he said the same.

 

I'd still like to know if anyone has actually drained their calorifier and run the engine.

Anyone with instantaneous gas hot water heaters like myself.ALWAYS!drain them and leave hot taps open if boats unattended during the winter as the heat exchanger in them is thin copper and so will probably be the first thing to freeze on the boat. Have had to repair,solder,or replace lots of em. bizzard.

[alan_fincher]

Consequences = zero

 

Air is compressible so any pressure rise due to heating will be far less that with water. If by some chance the air pressure did reach the PRV pressure then the prv would just vent. If the hot taps were left open it is very doubtful if the pressure would rise at all.

I agree totally,

 

I really don't see how there can be an issue.

 

To be honest it was only a conversation with a plumber friend that got me started on this. He was adamant that running hot water through a HW cylinder with no water in it could end in disaster, even splitting the tank. I checked this with another guy and he said the same.

 

I'd still like to know if anyone has actually drained their calorifier and run the engine.

I think both these guys don't have a very good appreciation of science.

 

And yes, we sometimes have our calorifier drained down, and still run the engine.

 

That is probably due to the fittings and the tank getting much much hotter than designed to as there is no water to dissipate the heat. A bit like leaving an empty saucepan on a hob.

A very poor comparison, surely.

 

An empty saucepan left on a hob can rise in temperature to what the gas flame is capable of heating it to, ultimately even glowing red, I suspect.

 

The water in the heating coil of a calorifier shouldn't ever be much higher than the thermostat you have fitted to your engine, (typically somewhere between 75 and 90 degrees centigrade, depending on type). The copper construction of a calorifier will not be troubled by this, and anyway the domestic water in a calorifier can end up heated to virtually engine coolant temperature if you haven't drained it....

 

(Which is why people can get scalded from hot taps on boats, if there is no thermostatic mixer valve that limits the temperature actually delivered to the taps).

 

To some extent the decision whether or not to drain a calorifier must depend on its placement surely ? For example one under the stern of a "cruiser style" Liverpool boat with big air holes cut in the hull side may almost get a chill wind blowing across it, and it's feed pipework. One tucked down deep in the heart of a boat, say under a double bed, will in my view stand a much better chance of not freezing up if the boat is at the same location.

 

Anyone with instantaneous gas hot water heaters like myself.ALWAYS!drain them and leave hot taps open if boats unattended during the winter as the heat exchanger in them is thin copper and so will probably be the first thing to freeze on the boat. Have had to repair,solder,or replace lots of em. bizzard.

Again I agree totally.

 

These are not helped by the fact that they are connected by a great big open flue to the outside world, so the freezing North wind probably blows straight down inside on to some of the most easily frost damaged things aboard.

 

On mine the drain plug is not particularly effective, and often disconnecting plumbing will then still result in water running out that the drain plug failed to let escape.

 

And a new heat exchanger for a Morco is (very) well over half the cost of a new Morco...............

[Guest]

I did not drain our calorifier down last year, the first year I'd ever winterised a boat (though had winterised caravans before which are a lot eeaier TBH)

 

Ours sits under a bunk in the rear cabin. Given the depth and extent of the winter last year I still plan to do the same - though given we are further North this year I may treat it to being wrapped in an old duvet or something similar..it is lagged but I think this may help.

 

I also wrapped the pumps in cushions/pillows and left all the taps open, the exception was one of the 'filter' taps which was inadvertently left closed and the water froze in the very narrow pipe supplying it and 'blew' the connection.

 

When I put it all back together the tap had been damaged infernally and wouldn't switch off completely so it needs replacing - haven't got around to it yet!!

[Tony Brooks]

To be honest it was only a conversation with a plumber friend that got me started on this. He was adamant that running hot water through a HW cylinder with no water in it could end in disaster, even splitting the tank. I checked this with another guy and he said the same.

 

I'd still like to know if anyone has actually drained their calorifier and run the engine.

 

 

The plumbing lecturers at TVU told me that the problem was that there is no water to support and damp vibrations in the heating coil(s) so they are more likely to split. To a degree I can agree with this because the only calorifiers that failed on the hire fleet were horizontal ones with a poorly supported "coil" and they usually did it over the winter. However I think their experiences were with domestic indirect cylinders that tend to be more lightly built than a decent calorifier. I also have reservations about how well "fast recovery" units with thin crimped coils will cope with running empty.

 

Having said all that I have no worries about running my vertical unit without water in it and so far, so good.

[Nickhlx]

That is probably due to the fittings and the tank getting much much hotter than designed to as there is no water to dissipate the heat. A bit like leaving an empty saucepan on a hob.

 

I don't see that at all - the heating water is at around 80 deg C, so it doesn't compare at all to leaving an empty saucepan on a hob, which could reach hundreds of degrees.... The tank or fittings can never get any hotter than the temp of the heat source, around 80 deg C if heating by the engine coolant, or "Webasto", and it would reach these temps every time on a long run ( couple of hours) with no water being drawn off....

 

Nick

 

ETA - Tony already had said what I repeated... I hadn't read the whole thread before replying...

Edited September 21, 2011 by Nickhlx

[IanM]

I don't see that at all - the heating water is at around 80 deg C, so it doesn't compare at all to leaving an empty saucepan on a hob, which could reach hundreds of degrees.... The tank or fittings can never get any hotter than the temp of the heat source, around 80 deg C if heating by the engine coolant, or "Webasto", and it would reach these temps every time on a long run ( couple of hours) with no water being drawn off....

 

Nick

 

ETA - Tony already had said what I repeated... I hadn't read the whole thread before replying...

 

I was trying to think of an example where water wasn't there to dissipate the heat... obviously I picked a bad one.

[Bloomsberry]

Surely there are isolation valves in the calorifier heating circuit that can be turned off so the engine coolant just circulates around the skin tank only and not the calorifier circuit ? Thus no heat in the calorifier heating coil and no problem !

 

If there's an expansion tank present then I assume you would have to make sure this was still connected to the engine coolant circuit also ?

[ditchcrawler]

Just to clarify or maybe calorify.. (sorry) my plumbing associates tell me that if you removes the water from a calorifier tank and allow hot water to run throught the heat exchanger coil, the effect of heating up air instead of water could result in damage to the tank. You are like creating a hot air balloon and if there's nowhere for the air to expand, well, think of the consequences.

 

But it seems like people don't bother draining their calorifiers?

 

I have heard several accounts now of boat owners just leaving all the taps open and in all cases no damage has resulted. Maybe I'm being over cautious.

And I know some who had them split/bulge and had to replace them.

[alan_fincher]

Surely there are isolation valves in the calorifier heating circuit that can be turned off so the engine coolant just circulates around the skin tank only and not the calorifier circuit ?

Do you mean"there are", or "there could be" ?

 

It's possible, of course, but by no means a normal arrangement, I would say.

 

You would need to be careful that any valve inserted was a full flow type that didn't restrict the flow, at least.

 

I still can't see it being a problem to have a heated coil inside the tank. How does that really differ from any other heated bit of pipe ?

[Nickhlx]

And I know some who had them split/bulge and had to replace them.

 

Presumably through leaving them full of water and they froze up ?

 

Someone I know fitted isolation valves on the input and output of his immersion heated DHW cylinders ( he had 3) and the immesion heater came on as usual.

I didn't think they could expand as much as they did without splitting - quite a sight with the concave end ending up convex !!

 

 

Nick