Keeping Out The Cold

[system 4-50]

It is simple isn't it? Use the formula to calculate how much ventilation you need at the time, considering the devices actually in use.

If you subsequently change any oxygen using process (turn on a Morco say) then recalculate and supply the necessary ventilation to match.

If you need to reduce the ventilation then reduce the oxygen consumers (stop cooking the roast dinner or eject a few crew members) to match.

But, always have some high ventilation

And, always have some low ventilation.

If you can't trust yourself to get it right, always supply the BSS figure.

I bet some forum members have got this automated using some complex acronym, you can do wonderful things with acronyms I'm told.

 

And why doesn't the formula include the number of dogs? They have a right to breathe as well.

[TaffyRon]

Is that Welsh? (I went to get my bicycle, and there it was, GONE!)

Awful racial far right kipper nf ss bile on this forum

[Loafer]

Awful racial far right kipper nf ss bile on this forum

I got my coat...

[jonesthenuke]

You can baffle the louvre door vents as long as the open area is not reduced.

 

But it is worth doing the ventilation calculation from the BSS Essential Guide to see if you have too little or too much.

 

Minimum effective area (mm2) = [2200xU]+[650xP]+[440xF]

U = total input rating (kW) for all appliances (including cookers) without flues

P = number of people for which the compartment is designed

F = input rating (kW) for all open or closed flue appliances

 

I have been thinking our boat is "over ventilated" for winter use, so I thought I would try the above guidance. I would welcome comments from anyone with experience of applying the BSS in this respect.

 

We have small wood burning stove, a Hurricane diesel heater and a Wallas diesel cooker. These are rated as follows:-

 

Wood stove 5 kW (an estimate, I cannot find the original handbook)

Hurricane 7.3 kW

Oven 2.5 kW (max)

Hob 1.9 kW (max)

 

The Hurricane is balanced flue so needs no ventilation, so can be ignored.The wood stove, oven and cooker all have sealed flues so only require combustion air. These thus contribute to "F" but not to "U". U is thus zero.

 

Its unclear to me how the number of people in the "compartment" should work. Our boat is 58 feet long and has three internal dividing doors, so could be four compartments, but we normally have all internal doors open, so could be just one. Its rare that there are more than 2 of us aboard, so I am going to use 2 for "P" as a first estimate of the overall requirements.

 

The total combustion air requirement is 440xF with F being 5+2.5+1.9 =9.4. 440F therefore is 4136 mm2

 

The ventilation required for people is 650xP with P being 2. 650P is thus 1300mm2.

 

Total ventilation area required is 4136+1300= 5436mm2.

 

We then have the installed ventilation. 6 off, 6" OD mushroom vents at high level. Assume the through bore of these is 80mm diameter (not measured so this is a guess) and another estimate that the outlet area under the mushroom is at least as big as the bore. The area is thus 3.14x40x40 = 5024mm2.

 

Given the BSS requires that:-

 

"The ventilation requirement needs to be split as equally as practicable between:

■ high level (ideally cabin roof), and,

■ low level."

 

Then one mushroom vent is more than enough to provide the high level roof vent requirements.

 

The low level vents consist of brass louvres, not measured but I think they are two off 6" by 6" in the front doors and two off 6" by 3" in the rear. A suppliers web site gives 6175mm2 for the large louvres and 2090 for the small. Seems to be more than enough.

 

The total boat ventilation is thus (based on the stated approximations):-

 

6 mushrooms at 5024 mm2 plus 2 large vents at 6175mm2 plus two small louvres at 2090.

Total is 30144+12350+4180 or 46674mm2 (almost ten times the BSS requirement.

 

There are some caveats to this.

 

• If we shut the internal doors then perhaps the calc should be repeated for the worst case compartments, however the internal doors are not tight fitting and there is probably enough free flow around them anyway. The BSS allows you to claim gaps around doors etc
• Using a larger number of people for "P" makes relatively difference in comparison to the currently installed ventilation area.
• We have a 3LW in engine room. Firing it up with all doors and windows shut and only the BSS minimum ventilation area would be daft thing to do (BSS does not allow for engines as far as I can see!). No doubt some would say this should be included.
• Ventilation keeps condensation under control.

I am tempted to block a number of the roof vents and half the door louvres. Currently the degree of ventilation (especially in the roof), must be a major cause of heat loss.

[rasputin]

It is gas (calor) that is dangerous because it is heavier than air and can sit in your bilges.

[Radiomariner]

 

I have been thinking our boat is "over ventilated" for winter use, so I thought I would try the above guidance. I would welcome comments from anyone with experience of applying the BSS in this respect.

 

We have small wood burning stove, a Hurricane diesel heater and a Wallas diesel cooker. These are rated as follows:-

 

Wood stove 5 kW (an estimate, I cannot find the original handbook)

Hurricane 7.3 kW

Oven 2.5 kW (max)

Hob 1.9 kW (max)

 

The Hurricane is balanced flue so needs no ventilation, so can be ignored.The wood stove, oven and cooker all have sealed flues so only require combustion air. These thus contribute to "F" but not to "U". U is thus zero.

 

Its unclear to me how the number of people in the "compartment" should work. Our boat is 58 feet long and has three internal dividing doors, so could be four compartments, but we normally have all internal doors open, so could be just one. Its rare that there are more than 2 of us aboard, so I am going to use 2 for "P" as a first estimate of the overall requirements.

 

The total combustion air requirement is 440xF with F being 5+2.5+1.9 =9.4. 440F therefore is 4136 mm2

 

The ventilation required for people is 650xP with P being 2. 650P is thus 1300mm2.

 

Total ventilation area required is 4136+1300= 5436mm2.

 

We then have the installed ventilation. 6 off, 6" OD mushroom vents at high level. Assume the through bore of these is 80mm diameter (not measured so this is a guess) and another estimate that the outlet area under the mushroom is at least as big as the bore. The area is thus 3.14x40x40 = 5024mm2.

 

Given the BSS requires that:-

 

"The ventilation requirement needs to be split as equally as practicable between:

■ high level (ideally cabin roof), and,

■ low level."

 

Then one mushroom vent is more than enough to provide the high level roof vent requirements.

 

The low level vents consist of brass louvres, not measured but I think they are two off 6" by 6" in the front doors and two off 6" by 3" in the rear. A suppliers web site gives 6175mm2 for the large louvres and 2090 for the small. Seems to be more than enough.

 

The total boat ventilation is thus (based on the stated approximations):-

 

6 mushrooms at 5024 mm2 plus 2 large vents at 6175mm2 plus two small louvres at 2090.

Total is 30144+12350+4180 or 46674mm2 (almost ten times the BSS requirement.

 

There are some caveats to this.

 

• If we shut the internal doors then perhaps the calc should be repeated for the worst case compartments, however the internal doors are not tight fitting and there is probably enough free flow around them anyway. The BSS allows you to claim gaps around doors etc
• Using a larger number of people for "P" makes relatively difference in comparison to the currently installed ventilation area.
• We have a 3LW in engine room. Firing it up with all doors and windows shut and only the BSS minimum ventilation area would be daft thing to do (BSS does not allow for engines as far as I can see!). No doubt some would say this should be included.
• Ventilation keeps condensation under control.

I am tempted to block a number of the roof vents and half the door louvres. Currently the degree of ventilation (especially in the roof), must be a major cause of heat loss.

 

A few misconceptions there.

First I should mention that the calculation for flue'd solid fuel stoves is H x 550 where H is the KW rating of the stove. This was introduced in 2013.

Gas Hobs & Ovens are unflued, as are some diesel ones therefor calculation becomes Kw rating x 2200

From your quoted power ratings I estimate the total ventilation requirement to be 13730 sq mm, (6855 high and 6855 low.) Considerably higher than your calculation

This is unusually low. I suspect you have either an extremely small cooker and hob or have just dreamed up their power ratings Hobs with more than two burners usually rate over 4 Kw. Example a Vanette 4000 hob is rated at 6.55Kw and Vanette GG7000 oven is rated at 3.3 Kw With those two appliances your total requirement would come to 25830 sq mm which is a much more "normal" figure.

This (minimum requirement), should be "fixed" ventilation, that is to say, should not be closable without the aid of tools. Thus the boater must make a positive considered decision to take action to close any vents .

Edited December 10, 2014 by Radiomariner

[Gypsey_Kings]

Our CO alarm went off in the front bedroom (we have two CO alarms) - immediately sent the wife outside (for her to get help if anything happened to me) and opened the hatch and some windows, and then checked the alarm - reading 43 ppm (parts per million - alarm goes off at 50 ppm). I had been running the engine earlier with a tail wind blowing and the fire was just smouldering, so got the fire roaring, but could not get the reading to go below 20 ppm... so shutdown the fire altogether - opened all windows, hatches, doors and switched on the bathroom extractor fan...and eventually got the reading down to 0ppm. I did not know it was that difficult to get the CO out of the boat. Now I understand why it builds up to fatal levels - I then closed up the boat again with the diesel central heating going (wind no longer a tail wind) and the boat has stayed at 0 ppm. Next day thoroughly cleaned out the solid fuel stove and chimney and are still at 0 ppm with the fire going...

 

If we did'nt have a Carbon Monoxide alarm we would have been dead in the morning - If you do not have one, GET ONE NOW - please learn from our experience - they are invaluable . Could also have been the wind from the wrong angle, blowing it back down the chimney or a combination.

 

BTW ....

 

Carbon Monoxide (CO) is NOT heavier than air. This is a MYTH.
Not to be confused with Carbon Dioxide (CO2– what we breathe out), Butane and Propane Gas (what we cook with), which are heavier than air.

 

FACT: The density of Carbon Monoxide (CO not CO2) at 20 °C (room temperature) is 0.96716 compared to air (1.00). At lower temperatures its relative density does increase slightly relative to air.

 

CO has a molecular mass of 28.0, and air has an average molecular mass of 28.8 (78.084% nitrogen at 28, 20.948% oxygen at 32, 0.934% Argon at 39.9, 0.031% Carbon dioxide at 44 and 0.003% other gases). CO is therefore only slightly lighter than air at room temperature (3% lighter). The difference is so slight that CO at room temperature is found to evenly distribute itself indoors.

 

But CO is the product of combustion (with insufficient oxygen [O2] to product carbon dioxide [CO2]), so it's going to be hotter and thus more lighter than air most of the time. For this reason CO detectors are usually placed about or above head height. In the bedroom, the alarm should be in the breathing zone, just above your head.

• 35ppm - The maximum allowable concentration for continuous exposure for healthy adults in any 8 hour period, as recommended by the Occupational Safety and Health Administration (OSHA).
• 200ppm - Slight headache, fatigue, dizziness, nausea after 2-3 hours.
• 400ppm - Frontal headaches within 1-2 hours, life threatening after 3 hours.
• 800ppm - Dizziness, nausea and convulsions within 45 minutes. Unconsciousness within 2 hours. Death within 2 - 3 hours.

 

CO poisoning is actually the result of the head and heart not receiving sufficient oxygen… ie asphyxiation.

 

If a person is removed from a high-CO environment after acute CO poisoning they may still suffer difficulty with some mental functioning such as short-term memory, dementia, amnesia, irritability, an unusual walking gait, speech impairments, and depression. Some people have said it’s taken them months to fully recover their mental functioning after an acute exposure event to carbon monoxide.

 

Heavier than air ......

• Carbon Dioxide (CO2 – what we breathe out) has a molecular density of 44 (Air is 28.8) so heavier than air. No Alarm needed.
• Butane (for the stove) has a molecular density of 58 (Air is 28.8) so heavier than air. So LP- Gas alarm mounted near the floor.
• Propane gas (for the stove) has a molecular density of 44 (Air is 28.8) so heavier than air. So LP- Gas alarm mounted near the floor.

 

PLEASE MAKE SURE YOU HAVE A WORKING CO ALARM WITH ADEQUATE VENTILATION !!!!

 

 

[jonesthenuke]

 

A few misconceptions there.

First I should mention that the calculation for flue'd solid fuel stoves is H x 550 where H is the KW rating of the stove. This was introduced in 2013.

Gas Hobs & Ovens are unflued, as are some diesel ones therefor calculation becomes Kw rating x 2200

From your quoted power ratings I estimate the total ventilation requirement to be 13730 sq mm, (6855 high and 6855 low.) Considerably higher than your calculation

This is unusually low. I suspect you have either an extremely small cooker and hob or have just dreamed up their power ratings Hobs with more than two burners usually rate over 4 Kw. Example a Vanette 4000 hob is rated at 6.55Kw and Vanette GG7000 oven is rated at 3.3 Kw With those two appliances your total requirement would come to 25830 sq mm which is a much more "normal" figure.

This (minimum requirement), should be "fixed" ventilation, that is to say, should not be closable without the aid of tools. Thus the boater must make a positive considered decision to take action to close any vents .

Thanks for the comments Radiomariner they are helpful. I will update with the 550 figure, but I am of the view that my numbers are really not as far out as you suggest.

 

The oven and hob ratings are direct from Wallas, so I will take these as valid (and by the way Wallas cookers are slow to heat up so I am not surprised at the relatively low power rating). Also the Wallas cookers have exhaust vents piped directly outside via hull fittings, so they should be treated as having sealed flues and do not require treating in the way you suggest. It is perhaps for these reasons that the boat is "over ventilated" as the hull design would have assumed a more standard complement of equipment, in particular gas cooking and heating equipment.

 

Thanks

[Emerald Fox]

"Is that Welsh? (I went to get my bicycle, and there it was, GONE!)"

 

"Awful racial far right kipper nf ss bile on this forum"

 

Google 'Welsh jokes sickipedia" - I don't quite know why but most seem to involve sheep in one position or another.

[ditchcrawler]

 

A few misconceptions there.

First I should mention that the calculation for flue'd solid fuel stoves is H x 550 where H is the KW rating of the stove. This was introduced in 2013.

Gas Hobs & Ovens are unflued, as are some diesel ones therefor calculation becomes Kw rating x 2200

From your quoted power ratings I estimate the total ventilation requirement to be 13730 sq mm, (6855 high and 6855 low.) Considerably higher than your calculation

This is unusually low. I suspect you have either an extremely small cooker and hob or have just dreamed up their power ratings Hobs with more than two burners usually rate over 4 Kw. Example a Vanette 4000 hob is rated at 6.55Kw and Vanette GG7000 oven is rated at 3.3 Kw With those two appliances your total requirement would come to 25830 sq mm which is a much more "normal" figure.

This (minimum requirement), should be "fixed" ventilation, that is to say, should not be closable without the aid of tools. Thus the boater must make a positive considered decision to take action to close any vents .

A few more misconceptions No gas, No Hob The oven is flued. I am in a similar position with a Dickinson oven, fully flued and no flames on the top.

[Phil Ambrose]

It is gas (calor) that is dangerous because it is heavier than air and can sit in your bilges.

In fact any of the bottled gases used on boats is heavier than air, Calor is just a proprietry name the gases are usually Propane or Butane (less common) the name on the bottle is irrelevant.

Because these gases are heavier than I air I have a bilge blower which I run from time to time just in case.

 

Phil

[Radiomariner]

Thanks for the comments Radiomariner they are helpful. I will update with the 550 figure, but I am of the view that my numbers are really not as far out as you suggest.

 

The oven and hob ratings are direct from Wallas, so I will take these as valid (and by the way Wallas cookers are slow to heat up so I am not surprised at the relatively low power rating). Also the Wallas cookers have exhaust vents piped directly outside via hull fittings, so they should be treated as having sealed flues and do not require treating in the way you suggest. It is perhaps for these reasons that the boat is "over ventilated" as the hull design would have assumed a more standard complement of equipment, in particular gas cooking and heating equipment.

 

Thanks

 

 

A few more misconceptions No gas, No Hob The oven is flued. I am in a similar position with a Dickinson oven, fully flued and no flames on the top.

I thank you both for your remarks. I am aware that such appliances as yours exist. But they are not the norm for IW. Beside considering that Jonesthenuke may have underestimated the Kw ratings of his appliances I was concerned that other readers may consider his figures to be around normal.

BSS Examiners can give you an "Appliance Record" which shows how the ventilation requirement and how the actual ventilation is calculated. I always do, but I am aware some do not. You should ask for a copy (The examiner has to do the calculations for himself anyway) You could then see if the examiner has it wrong, or work out how much ventilation you can block off.

[Rob@BSSOffice]

 

BSS Examiners can give you an "Appliance Record" which shows how the ventilation requirement and how the actual ventilation is calculated. I always do, but I am aware some do not. You should ask for a copy (The examiner has to do the calculations for himself anyway) You could then see if the examiner has it wrong, or work out how much ventilation you can block off.

 

 

I'd like to back Alan up. I highly recommend asking the examiner for the appliance record.

 

If appliances need changing or adding to, then it is possible to re-assess the ventilation provision.

 

Only yesterday I spoke to a new owner of a refurbished boat. The BSS certification was carried out with only a diesel and 12v system aboard.

 

If gas and solid fuel appliances had been added post-examination, the ventilation need would have changed significantly.

[ditchcrawler]

.

 

Only yesterday I spoke to a new owner of a refurbished boat. The BSS certification was carried out with only a diesel and 12v system aboard.

 

If gas and solid fuel appliances had been added post-examination, the ventilation need would have changed significantly.

We had one like that on our moorings, BSC issued when fit out just started and sold before the next BSC. No high level ventilation at all. Luckily the new buyer was aware of the situation,

[pquinn]

 

 

I'd like to back Alan up. I highly recommend asking the examiner for the appliance record.

 

If appliances need changing or adding to, then it is possible to re-assess the ventilation provision.

 

Only yesterday I spoke to a new owner of a refurbished boat. The BSS certification was carried out with only a diesel and 12v system aboard.

 

If gas and solid fuel appliances had been added post-examination, the ventilation need would have changed significantly.

Hard to believe that the bss certification still stands if ''gas and solid fuel appliances are added post-examination''.We got our boat built in England so it came with all the relevant safety standards of the time and have not altered anything but here in Ireland there are no such certs or examinations,not even down to basic things like gas,presumably because not enough people have died yet.You would not believe the things i have seen and heard lately regarding carbon monoxide,ventilation etc.I am surrounded by exposed gas bottles,buskets of oil and diesel.

One of my neighbours cracked the glass on his squirrel stove ,it fell out,he has the fire lighting and has not replaced the glass.A couple of weeks ago i went round and he was heating the place with his gas hob.I gave him a carbon monoxide alarm .not that it will do any good.I shudder with some of the madness i see.Blocked vents,no vents many boats that should be condemned before they condemn their owners.

I for one would welcome some basic safety standards over here.

[b0atman]

Mot for vehicles are the same only valid for I believe 24 hours.

Remember that the owner can change out equipment at any time .

This is what defeats the object of BSS as witnessed by people blocking air vents in the winter.

It is why I believe that the system is wrong and should be done from new maybe also a staged BSS for sail aways.

[Loafer]

Mind you, some BSC criticisms seem to be a bit OTT. Not being allowed to have anything other than gas bottles in the bow locker, for example (If that's where your gas bottles live). Every 4 years I have to remove my anchor, chain, water hose, and any other rarely-used bits and pieces, then put them all back again when he's gone!

 

Oh - and to remove the generator petrol to the roof! (Although I don't consider THAT one to be OTT)

Edited December 11, 2014 by Loafer

[bizzard]

Eat winter mixtures dissolved in hot Mulligatawny soup.

[Loafer]

Incidentally, petrol vapour sinks in air.

[b0atman]

Have a low level naked flame it will burn off any petrol fumes

[Loafer]

Have a low level naked flame it will burn off any petrol fumes

 

Ah! Good idea! (rushes off to find lighter...)