Heating Systems

[hopefulboaterlndn]

Hi everyone,

 

Me and my partner have just moved on to our 57 x 10 wide beam and are having a slight nightmare keeping the boat warm! Where we are moored we're not allowed to use the multi fuel stove so that leaves us with either the 5kw Webasto or electric fan/ convection heaters.

 

The Webasto heats the radiators and we've balanced them so that all get equally hot but there are only three and all are small so it does very little to actually keep the boat warm.

 

The electric heaters do warm the boat up but over the long run I'm assuming the cost will be more than other heating options? We are permanently moored with 240v

 

I think our options are 1) take the hit and use electric to keep it warm 2) buy a bigger webasto and presumably also bigger / more radiators or 3) install a diesel fuel stove? Although I'm not sure if this would be allowed either (I would need to check), the issue with the solid fuel stove is the smoke it creates, even smokeless coal

 

Any suggestions about which option to go for? Or anything else we could do?

Edited January 24, 2017 by hopefulboaterlndn

[The Bagdad Boatman (waits)]

go for a diesel fuel stove or a diesel Esse cooker.

[WotEver]

If you have a 5kW Webasto and only 3 small radiators then it sounds like the heater may be under-loaded. Do you find that it starts cycling once the rads are hot? If so then you could add more rads or increase the size of the ones you have. 5kW is probably twice the heat output of your fan heaters and should easily heat your boat.

[hopefulboaterlndn]

If you have a 5kW Webasto and only 3 small radiators then it sounds like the heater may be under-loaded. Do you find that it starts cycling once the rads are hot? If so then you could add more rads or increase the size of the ones you have. 5kW is probably twice the heat output of your fan heaters and should easily heat your boat.

 

 

I'm not sure - will turn on this evening and check it out. Thanks!

[ditchcrawler]

If you have a 5kW Webasto and only 3 small radiators then it sounds like the heater may be under-loaded. Do you find that it starts cycling once the rads are hot? If so then you could add more rads or increase the size of the ones you have. 5kW is probably twice the heat output of your fan heaters and should easily heat your boat.

 

 

 

I'm not sure - will turn on this evening and check it out. Thanks!

You should be able to run 3 double rads 1000 X 600 mm, are yours that big?

[OldGoat]

ditchcrawler, on 24 Jan 2017 - 1:00 PM, said:

 

You should be able to run 3 double rads 1000 X 600 mm, are yours that big?

Echo that. I have something similar on my 60ft. NB.

Heats the boat and a cold calorifier in about 1 1/2 hours and then it gets too hot. If the calorifier's hot (after day's cruising) It would take about 3/4 hour.

No point in going to a larger capacity heater as it's the size of the radiators' area that determines how quickly the boat warms up.

Shouldn't be too much of a challenge to fit more rads: - if of course there's wall room for them. Or you could consider a fan assisted matrix blower.

[hopefulboaterlndn]

I'm not at the boat right now but from memory the biggest is a single radiator approx. 1000 x 600 mm the other two are about two thirds of the size - all singles

 

Maybe all I need to do then is swap out the three small single radiators for three bigger doubles?

 

*Editing again* Is there any difference in running cost between a diesel stove and the Webasto?

 

editing again again* one radiator is cold in patches, colder at the bottom and warm at the top - am I right in thinking this means there is 'sludge' in the system? And if so can anyone tell me how to get rid of it?!

Edited January 24, 2017 by hopefulboaterlndn

[mross]

Long Johns or thermal underwear and warm boots etc can make it bearable when boat is cold. If you keep your core warm more blood flows to your hands and keeps them warm. Headgear is advisable too. Find a mooring without restrictions! Electric heating is very expensive!

[hopefulboaterlndn]

Long Johns or thermal underwear and warm boots etc can make it bearable when boat is cold. If you keep your core warm more blood flows to your hands and keeps them warm. Headgear is advisable too. Find a mooring without restrictions! Electric heating is very expensive!

 

Yes lots of jumps, hats and slippers! We would like to move to a mooring where we can use the stove but we're in London so although we'll keep an eye out, its unlikely to come up soon (or without a fight).

[chubby]

Surely a webasto is not much good for 24/7 heating . I wouldn t want to rely on one . If you cant burn coal beacause of the flats surrounding the moorings then i expect that a refleks or bubble stove is likely to be the next best option . Not cheap to buy nor run but it will go some way to feeling like a proper stove . You could perhaps remove & sell your existing solid fuel stove & use the same hearth .

I dont really see an alternative option to be honest .

[hopefulboaterlndn]

Surely a webasto is not much good for 24/7 heating . I wouldn t want to rely on one . If you cant burn coal beacause of the flats surrounding the moorings then i expect that a refleks or bubble stove is likely to be the next best option . Not cheap to buy nor run but it will go some way to feeling like a proper stove . You could perhaps remove & sell your existing solid fuel stove & use the same hearth .

I dont really see an alternative option to be honest .

 

I would love to be able to use the stove - the installation cost puts me off though unless I can 'justify' it by lower running costs. Especially if we do ever move the boat and we would have got rid of our lovely multi-fuel for no reason.

[cuthound]

Heat generated from landline electricity at say 15p per kWh-hour will be cheaper then the Webasto, particularly when servicing costs are taken into consideration.

[hopefulboaterlndn]

Heat generated from landline electricity at say 15p per kWh-hour will be cheaper then the Webasto, particularly when servicing costs are taken into consideration.

 

 

Just did some quick calculations and it seems we are paying approx. 22p per kWh-hour, hmmm

[mross]

A litre of diesel has about 37,000kJ of energy and costs about 60p. A kWh of electricity equals 3,600KJ and costs 15p. That's 620kJ/p for diesel and 240kJ/p for electricity. The diesel heater won't be 100% efficient.

 

The Webasto Air Top 2000 STC has a 2kW output for a fuel consumption of 0.24l/hr. That's an energy input of 8.8kw. So, the efficiency is only 23%. This does not include the energy to run the fan and pump.

 

So the conclusion is that the electric heater is cheaper!

[mross]

But, according to this website, electricity is much more expensive than gas oil for heating your home!

 

https://www.ovoenergy.com/guides/energy-guides/heating-costs-gas-vs-oil-vs-electric-storage-heaters.html

[Robbo]

A litre of diesel has about 37,000kJ of energy and costs about 60p. A kWh of electricity equals 3,600KJ and costs 15p. That's 620kJ/p for diesel and 240kJ/p for electricity. The diesel heater won't be 100% efficient.

 

The Webasto Air Top 2000 STC has a 2kW output for a fuel consumption of 0.24l/hr. That's an energy input of 8.8kw. So, the efficiency is only 23%. This does not include the energy to run the fan and pump.

 

So the conclusion is that the electric heater is cheaper!

I think you need to revisit your calculations. A litre of diesel is around 10kwh therefore 0.24l/hr is around 2.4kwh, making it around 80% efficient.

[ditchcrawler]

Heat generated from landline electricity at say 15p per kWh-hour will be cheaper then the Webasto, particularly when servicing costs are taken into consideration.

But the op probably only has a 16 amp supply so 4Kw tops.

I'm not at the boat right now but from memory the biggest is a single radiator approx. 1000 x 600 mm the other two are about two thirds of the size - all singles

 

Maybe all I need to do then is swap out the three small single radiators for three bigger doubles?

 

*Editing again* Is there any difference in running cost between a diesel stove and the Webasto?

 

editing again again* one radiator is cold in patches, colder at the bottom and warm at the top - am I right in thinking this means there is 'sludge' in the system? And if so can anyone tell me how to get rid of it?!

I would swap all the rads for doubles, that is an easy upgrade to your system. Convector doubles have about 30% more output.

[mross]

Diesel has a lower calorific value of about 43,400kJ/kg. Its density is about 0.85. That gives 36,890kJ/litre. So 0.24 litres per hour is 0.24 /3,600 litres per second. (this is a step I missed). That gives an energy input of 2.46kW. Corrected efficiency is 81%.

 

So we now get 620 x 0.81 = 502kJ/p for diesel and 240kJ/p for electricity.

 

Electricity is over twice the cost - avoid!

[chubby]

 

I would love to be able to use the stove - the installation cost puts me off though unless I can 'justify' it by lower running costs. Especially if we do ever move the boat and we would have got rid of our lovely multi-fuel for no reason.

Which is all fine & good .

 

However you bought a boat with a stove that you knew you cannot use . So its a totally redundant bit of kit of no use to you just now . Whereas that same space could have a Refleks / bubble / Kabola diesel stove instead .

 

It also depends on your attitude to a stove i think . To me the stove is a " feature " of living aboard a boat - ie a positive aspect which i really love about winters onboard . If you just want heat then just use oil filled radiators etc & put on some M&S thermal underwear , but if you want a toasty saloon / living room with the stove as its " heart " then you ll be having to put your hands in your pockets to replace the useless lump of cast iron thats currently there . You can sell what you have to part fund its replacement or store it & keep it for a possible use later on . You can change your current rads and thats very worthwhile but i d suggest that a webasto is still not a suitable bit of kit to rely on for 24/7 heating . To me theyre a " back up " or theyre for Spring & Autumn when its not cold enough for a blazing stove but you want some heat .

 

It depends on what you want ultimately - a stove thats a focal point & the heart of your home or just warmth from argos oil filled rads etc .

 

cheers

Edited January 24, 2017 by chubby

[hopefulboaterlndn]

Which is all fine & good .

 

However you bought a boat with a stove that you knew you cannot use . So its a totally redundant bit of kit of no use to you just now . Whereas that same space could have a Refleks / bubble / Kabola diesel stove instead .

 

It also depends on your attitude to a stove i think . To me the stove is a " feature " of living aboard a boat - ie a positive aspect which i really love about winters onboard . If you just want heat then just use oil filled radiators etc & put on some M&S thermal underwear , but if you want a toasty saloon / living room with the stove as its " heart " then you ll be having to put your hands in your pockets to replace the useless lump of cast iron thats currently there . You can sell what you have to part fund its replacement or store it & keep it for a possible use later on . You can change your current rads and thats very worthwhile but i d suggest that a webasto is still not a suitable bit of kit to rely on for 24/7 heating . To me theyre a " back up " or theyre for Spring & Autumn when its not cold enough for a blazing stove but you want some heat .

 

It depends on what you want ultimately - a stove thats a focal point & the heart of your home or just warmth from argos oil filled rads etc .

 

cheers

 

 

yes I think you're right, for us really the benefits of having a stove outweigh everything else. Are there any major differences between the brands of diesel stoves that we should consider when shopping around?

 

Diesel has a lower calorific value of about 43,400kJ/kg. Its density is about 0.85. That gives 36,890kJ/litre. So 0.24 litres per hour is 0.24 /3,600 litres per second. (this is a step I missed). That gives an energy input of 2.46kW. Corrected efficiency is 81%.

 

So we now get 620 x 0.81 = 502kJ/p for diesel and 240kJ/p for electricity.

 

Electricity is over twice the cost - avoid!

 

Thanks! This makes sense - we are spending a lot on electric heating right now

[MtB]

Diesel has a lower calorific value of about 43,400kJ/kg. Its density is about 0.85. That gives 36,890kJ/litre. So 0.24 litres per hour is 0.24 /3,600 litres per second. (this is a step I missed). That gives an energy input of 2.46kW. Corrected efficiency is 81%.

 

So we now get 620 x 0.81 = 502kJ/p for diesel and 240kJ/p for electricity.

 

Electricity is over twice the cost - avoid!

 

 

The cost of the electricity to run the webasto motor may cease to be insignificant though once out CCing. My very elderly webby draws about 3A at full chat. Dunno what a new one uses.

 

Does anyone fancy a stab at the cost calculations to put that electricity back into the batteries after say, ten hours of running it? I've no idea of the fuel efficiency of a generator or diesel engine being run to charge a battery, but I'd imagine it is very low especially as the charge current reduces towards the end of a charge.

[mross]

If you guessed at about 35-40% efficiency you would not be far out. Assuming 12v this equates to 36 Watts or Joules per second. Over 10 hours this is 36 x 10 x 3,600 which equals 1296kJ. Diesel has an energy density of 37,000kJ per litre. Even with the low efficiency you can see that the cost will be pennies.

 

You could get 30Ah into your batteries in less than an hour and probably use less than a litre of fuel.

[MtB]

If you guessed at about 35-40% efficiency you would not be far out. Assuming 12v this equates to 36 Watts or Joules per second. Over 10 hours this is 36 x 10 x 3,600 which equals 1296kJ. Diesel has an energy density of 37,000kJ per litre. Even with the low efficiency you can see that the cost will be pennies.

 

You could get 30Ah into your batteries in less than an hour and probably use less than a litre of fuel.

 

 

Aha you fell into my trap!

 

Yes the first 30AH when charging batteries might an hour but the last 30AH (to get them up to 100% charged) takes about ten hours

(By 'fully charged' I mean achieving an electrolyte SG of 1.277.)

[mross]

Not really. I'm talking about the additional costs for running the Webasto. You would have to charge the batteries regardless. A handy figure to remember is 1kWh = 3,600kJ (kiloJoules) and this is about 1/10 litre of diesel (at 100% efficiency) or if you assume 40% efficiency for the engine, about 1/4 litre or 15p!

[cuthound]

Don't forget the servicing and repair costs for the Webasto, say £150 every couple of years. Electric heating doesn't usually need specialised servicing or repair.