Drain down water system

[Tom Richmond]

Hi there,

 

Have just left the boat for a week, opened all taps and turned off pump. Stuck my mouth around one of the basin taps (highest point) and blew like crazy, sent water bubbling out of bath taps (lowest outlet) until I heard air bubbling...

 

I have read that a drain down valve at the lowest point is generally a good idea.

 

In my system this would be under my bathroom basin, the aftmost point of the cold pipe run from the tank in the bow, before it rises up to the basin tap. It then goes through the gas water heater and returns alongside the cold pipe run feeding all of the hot taps.

 

Two questions:

 

1) The drain off valve would be about half an inch off of the floor, with no way of getting any kind of container beneath it. Would I be able to use a short length of hose and successfully siphon the water up over the edge of a washing up bowl or other collection vessel, as long as the outlet of the hose was lower than the level of the pipe? Would this still work if the water level in the washing up bowl rose higher than the level in the pipe?

 

2) Would I be able to pull the water from the low point of the hot side of the run, up to the height of the water heater (4' from the ground) and back down again to drain from a single low point? Or should I be looking at two drain off valves?

 

The only point on the boat that is lower than my proposed location for a drain off valve and easily accessible is the section in the engine room beneath the stern gland. This section is obviously already full of water and conveniently fitted with a pump. If I ran a pipe from the drain off point to the stern it could sit lower than any of the pipe work and allow me to easily dispose of all the water in my system without needing to worry about groping around on my bathroom floor with washing up bowls full of water. Is this a crazy idea? The layout of the bedroom (between bathroom and engine) was designed with a pipe run to connect to a calorifier in mind, so this would be a relatively easy install.

 

Thanks in advance

[Nickhlx]

A wet and dry vacuum and a tea tray would definitely help in this situation - I use a wet and dry vacuum to suck the water though all the pipes (leave taps open as appropriate) and also suck any water out of the basin etc U-Bends, and replace with a strong sugar solution also in the loo, I pour in the same and pump it through to the holding tank so the pump itself is not sitting in "fresh" water...

 

Nick

[springy]

I have a total of 6 drain points on various low point locations - in order to be able to drain everything (except the

actual pump which is under the floor some 2ft below the waterline and therefore relatively safe from freezing)

4 of which are connected via plastic tubing & T pieces to my shower sump, the 5th drains into the shower tray,

only the 6th which is at the front needs draining into a container.

 

Using your bilge pump to do the same job seems a perfectly sensible idea, ideally the drain should be all downhill,

although provided the drain pipe outlet is below the water system drain cock then you will successfully drain the

"closed" system, if you use plastic tubing for the drain pipe then even if some water remains in the drain pipe it

is unlikely to cause a problem - it will be below the waterline, and even if water in it does freeze the plastic should

cope.

 

One consideration - I presume you have a bulkhead between engine & cabin - you either will need a bulkhead

fitting where the drain passes through OR ensure that the tube is NOT the lowest penetration in the bulkhead.

 

springy

[Boredrider]

If you have a 12V supply in the area, then consider buying a cheap inline pump (about £20). I use one of these coupled to some hose to drain our calorifier. The pump outlet is Tee'd into the bilge pump outlet, via some one way valves. These pumps can also be very handy in any sort of wet emergency as well!!

[jonathanA]

Gosh think some people make it complex

 

I have one drain off point at the lowest point which happens to be next to the shower pump and simply have a shallow container to drain off the water in the pipes into

 

If there is bit of water left in the pipes so what ?

 

I don't drain the cauliflower down dont see the point it's insulated and under the bed so well protected from the cold

 

Winterising takes 10 minutes when leaving and a few minutes to turn off taps and open stop cock on water tank when arriving

[Guest]

Gosh think some people make it complex

I have one drain off point at the lowest point which happens to be next to the shower pump and simply have a shallow container to drain off the water in the pipes into

If there is bit of water left in the pipes so what ?

I don't drain the cauliflower down dont see the point it's insulated and under the bed so well protected from the cold

Winterising takes 10 minutes when leaving and a few minutes to turn off taps and open stop cock on water tank when arriving

I can see how some people might think draining a cauliflower might be complex....

[jonathanA]

Very nice with cheese sauce I find ?

[Scholar Gypsy]

My own arrangements are set out in this extract from the boat manual. Takes 5 mins to fill the calorifier on arrival, and under 10 to empty it.

 

Slightly OTT, I know - but it works ...

[nicknorman]

 

The only point on the boat that is lower than my proposed location for a drain off valve and easily accessible is the section in the engine room beneath the stern gland. This section is obviously already full of water and conveniently fitted with a pump. If I ran a pipe from the drain off point to the stern it could sit lower than any of the pipe work and allow me to easily dispose of all the water in my system without needing to worry about groping around on my bathroom floor with washing up bowls full of water. Is this a crazy idea? The layout of the bedroom (between bathroom and engine) was designed with a pipe run to connect to a calorifier in mind, so this would be a relatively easy install.

 

Thanks in advance

This is what we have - pipe with a tap exiting near the stern gland. The other thing worth bearing in mind is that most water pumps (presuming they are of the diaphragm type) don't mind running dry for a bit and are quite good at pumping air. We have a T connection between water tank and pump, the 3rd arm normally has the tank level sensors in it, but this can be unscrewed in 10 seconds (having turned the water tank stopcock off) leaving an open pipe. I then turn the water pump on, open all the taps and my drain at the stern, and the pump pushes air through the system and pushes most of the water out. I then close all the taps and use the pump to push air through those little things that one forgets - the dump-through water valve, the washing machine inlet valve. Finally I leave it with all the taps and drains open - been OK so far although I'm sure there will some water in the pump etc. in general however, things below the waterline tend not to freeze. This technique doesn't empty the calorifier but again, it is on the swim and very well insulated so unlikely to freeze. Edited February 14, 2015 by nicknorman

[Peter-Bullfinch]

We are fortunate in having an electric point adjacent to the boat all winter. We never drain down but use two small oil filled radiators plus a decent plug in thermostat switch set at 7 degrees. We leave doors and cupboards open. In very cold winters we use up to £40 of electricity which compared to the cost of a pump broken by freezing doesn't seem so bad.

One radiator is placed in the engine room and the other is in the living area. In milder winters the cost can halve.

[blackrose]

I don't drain the cauliflower down dont see the point it's insulated and under the bed so well protected from the cold

Your boat is insulated too, so why do you drain the pipes down?

 

Some people don't understand how insulation works. Without a small heat source on one side of the insulation the temperatures on both sides will eventually reach equilibrium. A thermal gradient cannot be maintained by insulation alone.

 

So your calorifer will freeze if it gets cold enough.

 

-------------------------------

 

In terms of draining down, it's difficult on most boats since pipes run along the floor which is usually the lowest point, so pumping or sucking the water out with a wet vac seems easier to me.

Edited February 15, 2015 by blackrose

[David Mack]

We are fortunate in having an electric point adjacent to the boat all winter. We never drain down but use two small oil filled radiators plus a decent plug in thermostat switch set at 7 degrees. We leave doors and cupboards open. In very cold winters we use up to £40 of electricity which compared to the cost of a pump broken by freezing doesn't seem so bad.

One radiator is placed in the engine room and the other is in the living area. In milder winters the cost can halve.

But you are then wholly reliant on the electricity supply to the boat not being interrupted for any reason.

[Tom Richmond]

Wet vac not really an option for me, as I need to get the genny out on the shore (see other post about fireballs) to power it. Knowing how lazy I am a system which required this would definitely result in me leaving the boat undrained sometimes...

 

I will run a pipe to the stern bilge, from where I can let the bilge pump do the hard work.

 

I propose to set this pipe outlet lower than the lowest point in the system; am I right in thinking that the rest of the pipe run (max 4' high where it goes into gas water heater) will siphon down to this point when I open a tap at the far and of the pipe run?

 

Also, where would be best to place the drain off cock/tap/valve? It could easily and sensible go either over the stern bilge, or immediately after the T point where the pipe begins it's run from the existing system to the stern, (or both, but I cannot see an advantage to this).

 

 

 

One consideration - I presume you have a bulkhead between engine & cabin - you either will need a bulkhead

fitting where the drain passes through OR ensure that the tube is NOT the lowest penetration in the bulkhead.

 

 

No, I do not have a steel bulkhead. I have a trad stern, with small (8"?) risers that create the stern gland collection section, and the base for the engine mounts, as well as the engine oil collection "pit", forming a low level barrier between engine and cabin. Having had a boat full of water (search my old thread "rotten bilges") I have a separate cabin bilge pump. It will not be an issue to route the pipe over these section dividers, and while they are marginally higher than the lower points of the pipe run, the level of the water in the stern section is significantly lower, so as long as the pipe outlet is securely held at a lower point I am confident that siphoning will work.

[jonathanA]

Your boat is insulated too, so why do you drain the pipes down?

Some people don't understand how insulation works. Without a small heat source on one side of the insulation the temperatures on both sides will eventually reach equilibrium. A thermal gradient cannot be maintained by insulation alone.

So your calorifer will freeze if it gets cold enough.
.[/quote


Not really sure what your point is ?
Yes the boat has insulation but the windows/ hatches don't.
the point of pipe lagging / insulation is that it slows down the transfer of heat energy delaying substantially the point at which freezing occurs

 

Edited to remove mobile induced double post !

Edited February 15, 2015 by jonathanA

[trackman]

I wouldn't fancy relying on the calorifiers insulation in weather like we had in 2010. Some nights went to -15 or so & many days never got above freezing where we were.

Our calorifier gets cold from engine coolant temperature in a couple of days which indicates how good the insulation is, it clearly isn't perfect!

Our water pump got damaged by ice one night in a heated boat!

[Keeping Up]

Our (upright) calorifier froze once, and it pushed the base of the calorifier out into a hemisphere so that the calorifier rocked around like one of those child's toy clowns - but at least it didn't leak!

[smileypete]

Our (upright) calorifier froze once, and it pushed the base of the calorifier out into a hemisphere so that the calorifier rocked around like one of those child's toy clowns - but at least it didn't leak!

 

A weeble

 

cheers, Pete.

~smpt~

[Nickhlx]

Our (upright) calorifier froze once, and it pushed the base of the calorifier out into a hemisphere so that the calorifier rocked around like one of those child's toy clowns - but at least it didn't leak!

 

 

A friend has a B and B and had one of his DHW cylinders' thermostats weld its contacts together, and it kept on heating until it boiled, blowing the bottom inside out, like the top. The only thing that stopped it exploding was a tap connector let go in an empty room, spraying boiling water / steam around - he forgot to fit a pressure release valve !!

 

Nick

[jonathanA]

 

 

A friend has a B and B and had one of his DHW cylinders' thermostats weld its contacts together, and it kept on heating until it boiled, blowing the bottom inside out, like the top. The only thing that stopped it exploding was a tap connector let go in an empty room, spraying boiling water / steam around - he forgot to fit a pressure release valve !!

 

Nick

 

bet the guests were a bit surprised - wonder what they wrote in the visitor book...

 

oh sorry missed it was an empty room... phew broiled guests could have ruined his reputation....

[Nickhlx]

 

It was in winter / shutdown, and he had turned the tanks on to guard against freezing - the rooms were empty

 

Nick

[smileypete]

 

It was in winter / shutdown, and he had turned the tanks on to guard against freezing - the rooms were empty

 

Nick

 

Sounds like it could have been a vented domestic cylinder with a frozen header tank, worth ensuring the thermostats are the modern type with secondary cutout (have an extra tiny button which pops out when tripped).

 

cheers, Pete.

~smpt~

Edited February 18, 2015 by smileypete

[Nickhlx]

It was in France ( ex-Pat doing up his own place) and was about 15 years ago around the turn of the century - Even if rules had applied, I doubt much heed would have been taken of them - the electrics generally were ( and probably still are) simply terrifying !!