winterising

[rob 27]

Hi, just need some advise on winterising my bmc 1500 on my  seamaster 27 , only just bought it , thanks for any advise

[Tony Brooks]

Almost certainly heat exchanger cooled, so the raw water part of the system needs draining and at the very least the cover on the brass raw water pump loosening. Ensure you have enough antifreeze in the engine part of the system.

[Momac]

If you have shore power place a frost protection tube heater in the engine bay. This should be on a thermostatic control set to cut  in when the temperature falls below 5  degrees C or thereabouts.  

 

The domestic water system should be drained off as far as is possible. Food  safe antifreeze is available if required. Consider a frost protection heater near the calorifier as it is unlikely to be possible to remove all of the water.

 

Obviously if there is no shore power greater attention to draining  off water and use of antifreeze in the domestic system and in the engine raw  water side becomes more critical.

 

A boat in the water is better protected from frost than a boat ashore .

[rob 27]

Thanks for the advise , great help 

[Naughty Cal]

2 hours ago, Tony Brooks said:

Almost certainly heat exchanger cooled, so the raw water part of the system needs draining and at the very least the cover on the brass raw water pump loosening. Ensure you have enough antifreeze in the engine part of the system.

Not necessarily. We never drained down our raw water system but we did have access to reliable shore power so we kept the engine bay heated.

 

To the OP, don't forget to either drain down the boats fresh water tank and open the taps. Or again keep the boat heated.

[Onewheeler]

On 18/10/2023 at 10:27, Naughty Cal said:

To the OP, don't forget to either drain down the boats fresh water tank and open the taps. Or again keep the boat heated.

And drain the shower controller, waste pump and fresh water pump.

[Tracy D'arth]

If you have thermostatic valves on the shower and maybe the hot water system, drain then well then crack open the cold feeds as if there is water left in the valve and it freezes, the non return valves will allow pressure to crack even brass bodies. Plastic gubbings will stand no chance.

[Onewheeler]

6 hours ago, Tracy D'arth said:

If you have thermostatic valves on the shower and maybe the hot water system, drain then well then crack open the cold feeds as if there is water left in the valve and it freezes, the non return valves will allow pressure to crack even brass bodies. Plastic gubbings will stand no chance.

A good point. Most shower controllers of recent years have NRVs to comply with domestic water regs. You can't empty the feed pipes by blowing down them, but you can alternate between fully hot and fully cold settings and suck on each side.

[blackrose]

12 hours ago, Onewheeler said:

And drain the shower controller, waste pump and fresh water pump.

 

I thought as long as freezing water had somewhere to expand into (or out of) then no damage to pumps, etc would ensue? All I do is leave taps and shower controls open.

 

If there are NRVs on the infeed to a pump that will prevent water expanding on that side but if the other side has been depressurised (in the case of the freshwater pump) then the water can just expand into that side. 

 

I guess there's no harm in taking extra precautions. I can see the point in draining the freshwater pump I suppose, but I can't really see the point draining a whale gulper type shower drain pump as the waste pipe is open at both ends so the NRV won't stop freezing water expanding.

Edited October 20, 2023 by blackrose

[rob 27]

Thanks ,all advise is most helpful and welcome 

[Alan de Enfield]

7 hours ago, blackrose said:

I thought as long as freezing water had somewhere to expand into (or out of) then no damage to pumps, etc would ensue? All I do is leave taps and shower controls open.

 

I have found that water freezes from the 'outside inwards' (look at a bucket of water that is partly frozen). Once the 'plug of ice' has been made then continuing freezing of the remaining water expands the 'plug' in all directions, including, increasing the diameter if it is in a pipe, this is when the pipe splits.

It doent seem to matter a jot if both ends of the pipe are 'open' the pipe will burst if there is a 'puddle' in a low spot.

[blackrose]

1 hour ago, Alan de Enfield said:

 

I have found that water freezes from the 'outside inwards' (look at a bucket of water that is partly frozen). Once the 'plug of ice' has been made then continuing freezing of the remaining water expands the 'plug' in all directions, including, increasing the diameter if it is in a pipe, this is when the pipe splits.

It doent seem to matter a jot if both ends of the pipe are 'open' the pipe will burst if there is a 'puddle' in a low spot.

 

I think it does matter if the ends are open because the frozen plugs can move within the pipe and slide up the pipe with the expansion. Have you ever seen an offcut of pipe laying outside in the snow which the ice inside has split? Or to use your bucket analogy, the frozen surface of the water rises, it isn't static. After all, how many split frozen buckets have you ever seen?

Edited October 20, 2023 by blackrose

[Alan de Enfield]

12 minutes ago, blackrose said:

After all, how many split frozen buckets have you ever seen?

 

Many - when a plastic bucket full of water is left outside the stables, they are often split in the morning.

The Stable-Girl says she leaves the buckets full in case the taps are frozen the next morning - we got around it by using heat-trace cable on the taps.

[blackrose]

3 minutes ago, Alan de Enfield said:

 

Many - when a plastic bucket full of water is left outside the stables, they are often split in the morning.

The Stable-Girl says she leaves the buckets full in case the taps are frozen the next morning - we got around it by using heat-trace cable on the taps.

 

Well I've had 2 black plastic buckets on my bow deck for the last couple of decades which are often full or half full of rain water. Nether has ever split during a cold winter. I've never seen an open bucket split by ice.

Edited October 20, 2023 by blackrose

[David Mack]

A bucket is tapered so a plug of ice can rise up as it expands. The same could not happen with a cylindrical container.

[Onewheeler]

27 minutes ago, David Mack said:

A bucket is tapered so a plug of ice can rise up as it expands. The same could not happen with a cylindrical container.

There's a huge difference in the aspect ratio between a pipe and a bucket too.

[blackrose]

Ok let's stick to pipe rather than the bucket analogy.

 

For the people who say that ice will plug the open end of a pipe and cause it to rupture as the freezing water inside expands, I would propose the following test:

 

Take a single length of 15mm or 22mm plastic pipe and form it into a U bend. Use some duct tape, etc to maintain the U shape. Fill it with water and leave it outside in an upright position all winter. Assuming we have some freezing cold snaps you think that the pipe will split rather than any ice forming at the open ends of the pipe simply being forced out as the water/ice inside expands? 

 

I beg to differ. I think you could leave it full of water over 10 or 20 winters and it will never split. The UV light will get to it before the ice does.

Edited October 23, 2023 by blackrose