Alde boiler gas consumption

[Gary Stacey]

I've mentioned the Alde gas consumption in another thread. I was just wondering what kind of gas consumption other Alde owners get. I can use a 13Kg bottle in three days in a cold spell on my barge. The boiler is used for heating and hot water, the cooker is gas run from the same bottle. Beginning to think that I may have picked the wrong type of boiler, any thoughts/ideas?

 

thanks in advance

 

Gary

[bottle]

I've mentioned the Alde gas consumption in another thread. I was just wondering what kind of gas consumption other Alde owners get. I can use a 13Kg bottle in three days in a cold spell on my barge. The boiler is used for heating and hot water, the cooker is gas run from the same bottle. Beginning to think that I may have picked the wrong type of boiler, any thoughts/ideas?

<{POST_SNAPBACK}>

 

Gary

This is a bit obvious and you probably know already, consumption would depend on, insulation, doors/hatches left open and windows open. The temperature difference inside to out, would have an effect also. How often you used the hot water, washing up, washing (could always share bath/shower )

[timboharticus]

The Gross Calorific Value of Propane is 50,000kJ per kg.

 

13kg therefore contains 650000kJ

 

If your boiler operates at 100% efficiency it will produce 1kW for

650,000seconds which is 180 hours.

 

To heat 50L of water through 40degrees would take 50x40x4.2=

 

8400kJ

 

Do Alde provide a figure for efficiency? I would expect it to be around 85%

 

Do you have a gas leak?

[Paul Evans]

We have an Alde in our 42' narrowboat. It heats 3 radiators in cold weather and is used as a back-up for the hot water as well. In October 2003 we had a week on the Oxford during a particularly cold spell so the heating was on 24 hours. We used 13kg of gas in that week. I wasn't surprised.

 

How much you use must depend on how long the heating is on, how much hot water you are using, the temperature setting, whether you leave doors and windows open or not, how well insulated the boat is and so on. Take a good hard look at the way you use the system. Are you making best use of it?

[Gary Stacey]

Hmm. alde quote about 480grammes per hour gas usage at maximum which gives approx 28 hours use out of a 13kg bottle. Reckoning on 6Kw usage using your figures and allowing for about 85-90 percent efficiency gives (180/6) * 85 = 25.5 hours which seems to tie in. I have checked for gas leaks, it must be the way i am using it! Or I have bought the wrong device for the size of boat i am expecting to heat (55 by 10ft 6 ") Gary

[bottle]

Gary

 

To keep any house /boat or room heated. The system has to put in more heat than that which escapes, as I said before and was confirmed later in another post.

 

If the "boiler" is not big enough you will never manage to maintain or raise temperature. It is this that causes high fuel usage.

 

If your boat loses e.g. 1 Kw of heat this has to be replaced by the heating system before a rise in temperature is obtained. The quicker you lose the more has to be replaced.

 

It is a balance so the best way is more insulation (less heat loss).

 

Go for less heat loss, more insulation, rather than a bigger heat source, more heat=

more fuel.

[Alan Saunders]

. . .

Do Alde provide a figure for efficiency? I would expect it to be around 85% . . .

<{POST_SNAPBACK}>

So would I but Alde say '420g/h for 19.2MJ/h'. So, at 50MJ/kg: 19.2 / 50 / .42 = 91.4% efficient!

I think 480g/h is for butane and gives 22.2MJ/h.

 

Designing central heating for a house I would calculate the requirements. The same should be done for a boat but I doubt it is. I am getting through 13kg of propane in 5 or 6 days, 16 hours heating per day, but my boat is much smaller than Gary's; 20' x6.5' cabin.

 

Assuming the same level of insulation; one inch of polystyrene, pine planking, some 6mm ply and and 50% of the length single glazed (18" high): I calculate that Gary might easily use twice as much gas as I do. Even in the summer I use 13kg in four weeks for cooking, one shower per day etc. In the winter it takes more fuel to heat the colder water supply and I have more hot meals.

 

I also loose a lot of heat by keeping the engine warm . The engine thermostat housing is just about bearable to touch. Starts easily though . I have finrads under the corridor side of the bunks. With radiators next to the hull, heat losses would be higher.

 

I find 20 C comfortable. If it is 3 C outside raising or lowering the cabin temperature by 2 degrees would increase or decrease fuel consumption by about 10%.

 

Propane is very expensive in such small quantities and the storage space used by the cylinders is large compared to that required by other fuels. The cylinders take up about 60 litres of space.

 

In the same space as one 13kg propane bottle I could store 66kg of anthracite, 48kg of diesel or, perhaps, 36kg of logs. Providing 164, 396, 490 and 80 useful kwh respectively.

 

The running cost for diesel is 50% and coal 40% that of propane. Wood is usually free. If you had a shore line and paid 9p or less per unit you would be better off using electric heating than bottled gas.

 

Gary has not chosen the wrong boiler but the wrong fuel. I reckon a 25kg bag of anthracite would keep Gary's boat snug day and night for 3 days. A friend's 50' trad narrowboat is unbearably hot with its morso squirrel stove ticking over. All those people with solid fuel stoves and a month's supply of coal on the roof, can't be wrong!

 

Alan

 

Broken anthracite 110%, fuel oil 80%, stacked logs ~60% of density of water.

1kg of: propane=14 kwh, fuel oil=12 kwh, anthracite=8 kwh, seasoned wood=4.4 kwh

I assumed a stove to be 50% efficient - better with a back boiler.

[John Orentas]

Alan.

 

Very impressive that lot but why would a back boiler give better efficiency to the stove.

[Paul Evans]

Alan certainly makes a strong case for solid fuel heating if you live on the boat but you need to have a convenient supply of the stuff and you have to put up with the occasional bit of mess. For those of us who don't live on board, I think that an Alde provides a quick and convenient form of heating.

[John Orentas]

Paul.

 

My thoughts went in the opposite direction, I visit my boat only perhaps once a fortnight in the winter, I have a wood burning stove which warms the boat very comfortably, I would reccomend the system to anyone with my kind of useage.

 

However the stove will burn a boot-full of wood in 3 days if the weather is very cold, a rate which I can easily keep up with but if I was to live on the boat I think I would soon run out of trees and pallets.

Edited March 5, 2005 by John Orentas

[Alan Saunders]

. . . why would a back boiler give better efficiency to the stove?

<{POST_SNAPBACK}>

John, this question was in my mind when I posted but I could not answer it - I just know, from reading I did 20 years ago, that was the general conclusion.

 

It depends on the design of the stove. We had a solid fuel cooker/boiler (Thermorossi Bosky) that ran the central heating for the whole house. The water jacket surrounded the fire box on four sides and the flue gasses passed from the top of the firebox back down past the water jacket before returning up again to the flue - triple pass. I think they claim more than 70% efficiency.

 

On a simplistic level I do have some ideas but don't quote me! No maths, I tried but I cannot manage it at 2am

 

The stove walls are inefficient at transferring heat to the surrounding air. Fins, possibly in copper or aluminium and/or forced air flow would improve the rate of heat transfer. A convective or forced flow in a water jacket adjacent to the fire is more efficient. The more heat removed the less goes up the flue.

 

Closer to the topic and as a practical example, the Alde has vertical, coaxial boiler about a metre tall with a further 50cm of flue above. They claim that less than 10% of the heat escapes from the flue. Imagine it was just 1.5m of 50mm id steel tube; no water. How efficient would that be? My guess is it would be similar to a solid fuel stove - about 50%.

 

Alan

Alde has blown out for the fourth time and I am going to bed!

[DHutch]

I agree, about stoves Vs Gas foir heating.

 

- As i sayed in another thread. We use a twin coilcalorifyer for water when where crusing, and a stove for hotwater and rads when its cold. And therefore only heat the hotwater with gas when its too warm for heating, but we have move that day (not often the case).

 

- This works well, and is very low cost as well, becuase we hardly run the paloma. A 13kg propaine cyclinder will last half the summer when where just using the cooker, although whe we use the waterheater it can emty one in a week.

 

Daniel

[gosser]

With my Alde heating a 59ft boat narrowboat (three big rads and skirting heating plus hot water) I reckon on getting 4 days from a 13k gas bottle, running 24 hours with the stat set to 22 deg. As the barge is wider, the usage seems about the same as mine.

[Gary Stacey]

Hmmm. it would appear that they are not a very economical way of heating a barge! Good job I have a stove as well (no back boiler)

 

Gary

[Mr Leigh]

Many good point raised about insulation and vents etc, but this is often overlooked and very Important.

 

When designing a system remember that the output of your radiators is as important as the output of the boiler. If the Boiler is 6kW and you only have 3kW of radiator you in effect have a 3kW boiler using fuel at a rate that should give off 6kW. You could turn the heating down by half and still get 3kW.

 

6kW is a large amount of Radiator. 15 meters of fin Rad. Output of Panel Rads can be got from the supplier but Eight 500mm x 1000mm Panel Rads = 6kW

 

Also consider location. A Radiator under a window will throw out just as much heat and insulate a very cold spot in the process.

 

Consider a programmable room thermostat to reduce consumption.

 

Boat Builders are not heating system engineers and your system design is critical. House builders spend a lot of money getting this right Design it right and the gas will go much further.

Edited March 18, 2005 by Mr Leigh