New boat questions. Plumbing.

[mross]

I might risk one point!

[WotEver]

Just now, mross said:

I might risk one point!

Too late now, the moment has been lost. 

[DHutch]

On 27/02/2017 at 18:55, nicknorman said:

.... my suggestion would be to not depart too far from normal boat practice. If you tailor you boat specifically to your present circumstances, you may regret it later. I doubt you have any security of tenure on this  mooring and even if the landlord isn't going to change their attitude, your needs might change and you might want to move or sell the boat.

So normally you will have a water tank and pump. Then you just have a choice between an instant water heater, which has to be gas not electric for the reasons mentioned earlier. Or a hot water storage tank aka a calorifier, which can typically be heated by up to 3 sources, ie electric immersion element (1kw is adequate), the engine's cooling system and the system that heats the radiators (gas, diesel or solid fuel back boiler). Calor gas is fairly expensive, diesel heaters not that reliable or very expensive to install, so the cheapest solution is likely to be shore power electricity via the immersion heater. These are always thermostatically controlled so can just be left permanent switched on and you will always have a tank full of hot water (if you are on shore power).

 

I cant fault this.

Fill the tank as normal, have a pump running, as normal, and then pick either a instant gas water heater or a hot water tank with an electric immersion heater. However temping a permanent feed might be, there are some significant drawbacks as side, and a good pump and accumulator will work well.

Gas gives you flexibility when away from a mooring but not running the engine and we would not be without ours. However they do use a stack load of gas, a lot more than a few rings on a stove or even normal oven use and its not the cheapest way to buy energy. Therefore if I where you I would go down the stored hotwater route, this will give a finite amount of hot water which will run out (as you will pull the hot out, faster than you can heat the incoming cold) however on a widebeam you should be able to have a reasonably larger hot water tank. If you are on a really good hook up (32amp, or 16 and large inverter to smooth supply and demand) you might even be able to use a larger domestic spec 3kW element which would obviously greatly reduce the time to reheat. 3kW is almost all of a 16amp feed, so this would very much limit what else you could run at the same time.

Daniel

[cereal tiller]

18 minutes ago, DHutch said:

I cant fault this.

Fill the tank as normal, have a pump running, as normal, and then pick either a instant gas water heater or a hot water tank with an electric immersion heater. However temping a permanent feed might be, there are some significant drawbacks as side, and a good pump and accumulator will work well.

Gas gives you flexibility when away from a mooring but not running the engine and we would not be without ours. However they do use a stack load of gas, a lot more than a few rings on a stove or even normal oven use and its not the cheapest way to buy energy. Therefore if I where you I would go down the stored hotwater route, this will give a finite amount of hot water which will run out (as you will pull the hot out, faster than you can heat the incoming cold) however on a widebeam you should be able to have a reasonably larger hot water tank. If you are on a really good hook up (32amp, or 16 and large inverter to smooth supply and demand) you might even be able to use a larger domestic spec 3kW element which would obviously greatly reduce the time to reheat. 3kW is almost all of a 16amp feed, so this would very much limit what else you could run at the same time.

Daniel

My Paloma is 11.6 KiloWatts,WHICH is similar to 5/6 Boat size Gas rings on at the same time

Roughly 14 hours running time on a 13 KG Cylinder so lots of hot water at reasonable cost

CT 

[rusty69]

4 minutes ago, cereal tiller said:

My Paloma is 11.6 KiloWatts,WHICH is similar to 5/6 Boat size Gas rings on at the same time

Roughly 14 hours running time on a 13 KG Cylinder so lots of hot water at reasonable cost

CT 

How would you go about calculating whether it is more economic to heat water via calor gas or electric? 

We have always heated water with the Paloma, but having recently installed a calorifier now have an alternative. 

Edited March 2, 2017 by rusty69

[cereal tiller]

1 minute ago, rusty69 said:

How would you go about calculating whether it is more economic to heat water via calor gas or electric? 

We have always heated water with the Paloma, but having recently installed a calorific now have an alternative. 

Have both,so Engine heated water,Immersion heated water or Paloma

Can't recall shore KWH  cost but lets says 15 Pence a time

1 KWH generated is around £1.50

Paloma around  70 pence per KWH

All rough figures but shows the differences

[rusty69]

9 minutes ago, cereal tiller said:

Have both,so Engine heated water,Immersion heated water or Paloma

Can't recall shore KWH  cost but lets says 15 Pence a time

1 KWH generated is around £1.50

Paloma around  70 pence per KWH

All rough figures but shows the differences

Thankyou. 

 

Edited March 2, 2017 by rusty69

[DHutch]

9 minutes ago, rusty69 said:

How would you go about calculating whether it is more economic to heat water via calor gas or electric? 

We have always heated water with the Paloma, but having recently installed a calorifier now have an alternative. 

There are two ways as I see it.

 - One is to work out the cost per kWh of the gas you are buying (aka, the energy in a 13kg bottle) and compaire with the cost of a kWh of electric, including a reasonable factor of efficiency for the gas heater of choice. Electric is 100% efficient and point of use, so the losses are taken account of in the billing.

 - Two is to work out the rating of the water heater (be that in kWh output, or rate of gas consumption) when running and compare that to the amount of energy required to heat water that same amount to get a figure for the electric, which is then also able to assumed to lossless at point of us.

This makes the assumption that you use the same amount of water on both, where in practice the gas heater might limit the flow rate a little more, and also that the hot water tank insulation afford no lost heat.

However while closer when on mains gas, unless you are getting you 13kg bottle very cheaply I expect you pay more for the energy in that than coming down the wires even before efficiency losses.

 

Daniel

 

[cereal tiller]

1 minute ago, rusty69 said:

Thankyou. 

Sounds like it will be more economical to use the electric then. 

On Shorepower(National Grid) much cheaper although there will be some Heat loss from Calorifier and Pipe work.

Gas heating is handy if the Boat is Static and power coming in from solar only

 

 

[rusty69]

10 minutes ago, DHutch said:

There are two ways as I see it.

 - One is to work out the cost per kWh of the gas you are buying (aka, the energy in a 13kg bottle) and compaire with the cost of a kWh of electric, including a reasonable factor of efficiency for the gas heater of choice. Electric is 100% efficient and point of use, so the losses are taken account of in the billing.

 - Two is to work out the rating of the water heater (be that in kWh output, or rate of gas consumption) when running and compare that to the amount of energy required to heat water that same amount to get a figure for the electric, which is then also able to assumed to lossless at point of us.

This makes the assumption that you use the same amount of water on both, where in practice the gas heater might limit the flow rate a little more, and also that the hot water tank insulation afford no lost heat.

However while closer when on mains gas, unless you are getting you 13kg bottle very cheaply I expect you pay more for the energy in that than coming down the wires even before efficiency losses.

 

Daniel

 

Thanks for that. We actually use 19kg bottles as they are the same cost as 13kg from our local supplier. 

Looks like I will have to get my calculator out and dust off the old grey matter. 

 

Edited March 2, 2017 by rusty69

[cereal tiller]

14 minutes ago, rusty69 said:

Thanks for that. We actually use 19kg bottles as they are the same cost as 13kg from our local supplier. 

Looks like I will have to get my calculator out and dust off the old grey matter. 

 

From memory a 13 kg is approx 174 KWH

Edited March 2, 2017 by cereal tiller

[ditchcrawler]

30 minutes ago, cereal tiller said:

From memory a 13 kg is approx 174 KWH

How much would that cost ?

 

[cereal tiller]

Just now, ditchcrawler said:

How much would that cost ?

 

Last one I purchased was 24-25 pounds last October

[rusty69]

29 minutes ago, ditchcrawler said:

How much would that cost ?

 

We pay £ 25 for 13 or 19 kg

Propane =13.9kwh/kg

264kw/£25

9.5p/kwh for gas. 

17p/kwh for electric. 

Looks like the gas may be cheaper in our case. Although that only applies if the heater is turned off after use. Typically ours is left on pilot all day. 

Edited March 2, 2017 by rusty69

[ditchcrawler]

4 minutes ago, cereal tiller said:

Last one I purchased was 24-25 pounds last October

About the same price as buying electricity so its down to the efficiency of the heater 

[cereal tiller]

2 minutes ago, ditchcrawler said:

About the same price as buying electricity so its down to the efficiency of the heater 

My paloma is listed as 85% efficient

I got the gas cost wrong looked again and it comes to 12 pence per KW,thanks

Must get a new Mainspring for my Clockwork Calculator!

[rusty69]

31 minutes ago, rusty69 said:

We pay £ 25 for 13 or 19 kg

Propane =13.9kwh/kg

264kw/£25

9.5p/kwh for gas. 

17p/kwh for electric. 

Looks like the gas may be cheaper in our case. Although that only applies if the heater is turned off after use. Typically ours is left on pilot all day. 

How much does the pilot light typically consume? 

Answers on a postcard please. 

Think an accurate answer will only be obtained by empirical measurement! 

Edited March 2, 2017 by rusty69

[smileypete]

18 minutes ago, rusty69 said:

How much does the pilot light typically consume? 

Answers on a postcard please. 

As an outright guess, for a small morco I'd say 75W to 150W.

Anyway for working out the gas cost for a conventional boiler it's more accurage to use 'lower heating value':

https://en.wikipedia.org/wiki/Heat_of_combustion

So this would give 8% less heat for propane (that absorbed by water vapour formed when propane is burned)

Seems Calor pitch their bottled gas prices to come out about the same energy cost as domestic grid electric (ie not higher marina prices)

Edited March 2, 2017 by smileypete

[rusty69]

3 minutes ago, smileypete said:

As an outright guess, for a small morco I'd say 75W to 150W.

Anyway for working out the gas cost for a conventional boiler it's more accurage to use 'lower heating value':

https://en.wikipedia.org/wiki/Heat_of_combustion

So this would give 8% less heat for propane (that absorbed by water vapour formed when propane is burned)

Seems Calor pitch their bottled gas prices to come out about the same energy cost as domestic grid electric (ie not higher marina prices)

It's getting too complicated for me.

 

Think I will try the electric for a while and work it out from there. 

[smileypete]

28 minutes ago, rusty69 said:

It's getting too complicated for me.

 

Think I will try the electric for a while and work it out from there. 

Something that counts against eleccy is the standing losses when you need less than a tankful for immediate use.

So for the odd bowl of washing up water the paloma could work out cheaper, as the tank may largely cool down before it's needed again, eg for showers.

I get 18p/kWh for water heated by paloma, based on £25incl for a 13kg bottle.

25/(13.9 * 13 * 0.92 * 0.85) = 25/141 = £0.177

13kg at 13.9kWh/kg HHV, LHV is 92% of HHV, 85% efficiency

So kWh cost is 13kg bottle cost divided by 1.4. If you need to remember 1.4 it's very close to the square root of 2! (1.414)

 

Edited March 2, 2017 by smileypete

[rusty69]

8 hours ago, smileypete said:

Something that counts against eleccy is the standing losses when you need less than a tankful for immediate use.

So for the odd bowl of washing up water the paloma could work out cheaper, as the tank may largely cool down before it's needed again, eg for showers.

I get 18p/kWh for water heated by paloma, based on £25incl for a 13kg bottle.

25/(13.9 * 13 * 0.92 * 0.85) = 25/141 = £0.177

13kg at 13.9kWh/kg HHV, LHV is 92% of HHV, 85% efficiency

So kWh cost is 13kg bottle cost divided by 1.4. If you need to remember 1.4 it's very close to the square root of 2! (1.414)

 

Not too easy to compare the two then! 

Not forgetting the added condensation the gas may cause. 

Edited March 3, 2017 by rusty69

[nicknorman]

15 minutes ago, rusty69 said:

Not too easy to compare the two then! 

Not forgetting the added condensation the gas may cause. 

Well hopefully the condensation / water vapour goes up the flue.

But if we are looking at cost, there is the capital cost of the equipment to take into account. What is the installation cost vs lifespan, servicing and repair costs for a gas water heater vs a calorifier with immersion?

what about the burden of lugging cylinders to and from the boat vs a plug and lead left permanently connected?

[rusty69]

18 minutes ago, nicknorman said:

Well hopefully the condensation / water vapour goes up the flue.

But if we are looking at cost, there is the capital cost of the equipment to take into account. What is the installation cost vs lifespan, servicing and repair costs for a gas water heater vs a calorifier with immersion?

what about the burden of lugging cylinders to and from the boat vs a plug and lead left permanently connected?

Good points. 

In our case, both are already installed. The Paloma has had no major parts as yet, so minimal cost so far. 

Our electric is not permanently connected, so gas is required anyway, although will obviously use less if supplemented with electric . 

Edited March 3, 2017 by rusty69