Is a stove in the middle of your boat classified as central heating??

[phishphace]

Does any one know / have experience of what is the max distance from the water tank, that a radiator can be placed and for it still to heat up?

 

Our central heating system has no pump, 22mm copper piping and a radiator right at the other end of a 25 ft run [and it does not get hot, warm or even loses that ice cold feeling ]

 

 

We are thinking of removing this one [and only] radiator, but are a little worried that a small boatman stove [in the middle cabin] would not be sufficient to heat the whole of the boat. [small boatman stove currently in garage so can not be tested in boat.... ]

 

any comments on boat heating welcomed

 

 

s

[DaveR]

The Bensham is 40 feet long, 4 feet for the bow and six for the engine room = 30 foot cabin.

 

Our stove is is the middle of that and works wonders. No problems about heating the whole boat, the bedroom at the fore end is a nice temperature for sleeping and the living area is toasty warm.

[bottle]

Does any one know / have experience of what is the max distance from the water tank, that a radiator can be placed and for it still to heat up?

 

Our central heating system has no pump, 22mm copper piping and a radiator right at the other end of a 25 ft run [and it does not get hot, warm or even loses that ice cold feeling ]

<<<<<<Snip

s

 

Hi

 

I think we need to know a little more about what you have got.

 

For instance:

 

What heats the water now?

 

'Central heating' is usually separated between hot water (the tank) and the radiators

 

You may have an air lock how far does the heat travel along the pipe from the heat source (boiler/heater)

 

Has it ever worked

 

I think a 50' run (there and back) maybe a little to far for convection to work.

 

Do the pipes run continuously 'uphill' to the radiator

[phishphace]

Hi Bottle

 

The boiler is an Ellis Heater - this heats the water up nicely.

the boiler heats up the water tank via a coil and the central heating runs off the same circuit as the coil

 

We have pretty level pipework - and don't think we have any air locks - only the first 2 ft of the pipe heated up [conduction>??] - the radiator valves were both open.

 

We don't know if the system has ever worked as we bought the boat in the summer from a marina [who was middle man] and they did not know if the radiator worked.

 

the 50ft run is what is concerning us too

 

 

s

[bottle]

This seems as if the radiator is 't'd off of the coil circuit otherwise the water would not get hot,

 

The flow is taking the least resistive path.

 

You will have a flow and return to the coil and a flow and return to the radiator, where does the flow and return from the radiator connect.

 

There may be valves to direct the flow to either the coil or the radiator.

[NB Alnwick]

Does any one know / have experience of what is the max distance from the water tank, that a radiator can be placed and for it still to heat up?

 

Our central heating system has no pump, 22mm copper piping and a radiator right at the other end of a 25 ft run [and it does not get hot, warm or even loses that ice cold feeling ]

We are thinking of removing this one [and only] radiator, but are a little worried that a small boatman stove [in the middle cabin] would not be sufficient to heat the whole of the boat. [small boatman stove currently in garage so can not be tested in boat.... ]

 

We have a Squirrel stove in the galley (centre of the boat) and it heats three radiators via 7/8 inch copper pipes (22mm) very effectively with no pump. We usually have the radiator in the bed'ole turned off unless it sis very cold but it can get extremely warm when on. Years ago we had a similar central heating system in a bungalow powered from a sold fuel Rayburn - the plumber who installed it seemed to have an excellent grasp of thermo-dynamics and explained the importance of connecting up the radiators correctly - the feed to each radator must be at the top so that as the water cools it flows down and out at the bottom.

[twoputtyrats]

Does any one know / have experience of what is the max distance from the water tank, that a radiator can be placed and for it still to heat up?

 

Our central heating system has no pump, 22mm copper piping and a radiator right at the other end of a 25 ft run [and it does not get hot, warm or even loses that ice cold feeling ]

We are thinking of removing this one [and only] radiator, but are a little worried that a small boatman stove [in the middle cabin] would not be sufficient to heat the whole of the boat. [small boatman stove currently in garage so can not be tested in boat.... ]

 

any comments on boat heating welcomed

s

 

Another way has a mikuni mounted in the engine-ole and a radiator in he tbedroom at the bow - must be a 45ft run each way - I'm sure we have a heating pump that runs up before the boiler fires sounds like it at least- but she works just fine...

 

small stove alone I don't think would be sufficient - we're looking to get an ecofan for spring cruising as the heat from the small stove we have spreads about 10ft either side, with quite a gradient as you head fromt he lounge, to the dining area, bathrrom anf bedroom...

 

Simes.

 

Simes

[blackrose]

Designing an efficient central heating system run on thermocycling from a backboiler is a bit of a black art with many factors to consider, length of main pipe run being only one of these.

 

Does the combined kw or btu output of the rads (+ pipe) approximate that of the backboiler for example?

 

Use as large dia pipe for the main run as possible. 22mm is good, 28mm is better, but this size will be limited by the outlets from your backboiler.

 

Keep bends in the main pipe run to a minimum and if possible use 2 x 135 deg bends rather than a single 90 deg bend.

 

Some people will tell you that the main upper run should rise all the way to the last rad because heat rises, but common sense tells me that the water from the stove will be cooling as soon as it leaves the backboiler and is only pushed upwards by the hot water in the boiler behind it. For this reason I think it's better to have a steep rise from the backboiler for a short distance, perhaps to the first rad and from then on the run should slope very slightly downhill all the way to the end of the top run and continue downhill on the return. This may be difficult to achieve on a long run.

 

The top pipe run should continue right around the last rad becoming the return run, rather than using just the rad itself to transfer water from top to bottom run as you would if using a pump. This will enhance circulation and hopefully the hot water will then fill the last rad anyway. Connect all four fittings on the final rad. Intermediate rads may only require 2 diagonally opposite fittings connected.

 

A header tank at the highest point off the main run will mean the system is self-bleeding, but might have the disadvantage of producing steam in the boat because the highest point might also be pretty hot. For this reason some people have the header tank coming off the return run with the tank raised up higher than the rest of the system. If you do this you have to put a bleed nipple at the highest point on the top run. It's an idea to put a couple of blanked off T compression fittings in different places on the main pipe, so the location of the header tank can be changed easily if it doesn't work the first time.

 

I know you're not designing a system from scratch but it's difficult to comment on a particular system unless one can actually see it. Each boat's system is a one-off, not usually designed and built by a heating engineer, so they'll all work at different efficiencies.

Edited December 4, 2006 by blackrose

[Tony Brooks]

Does any one know / have experience of what is the max distance from the water tank, that a radiator can be placed and for it still to heat up?

 

Our central heating system has no pump, 22mm copper piping and a radiator right at the other end of a 25 ft run [and it does not get hot, warm or even loses that ice cold feeling ]

We are thinking of removing this one [and only] radiator, but are a little worried that a small boatman stove [in the middle cabin] would not be sufficient to heat the whole of the boat. [small boatman stove currently in garage so can not be tested in boat.... ]

 

any comments on boat heating welcomed

s

 

 

My Ellsi di a 54ft boat just fine, but itw a sin 28mmpipe.

 

As this is a gravity system I assume the "hot" pipe is at gunnel level or higher - if not, hard luck.

 

 

At the far end of the "hot" pipe run replace the elbow with a reducing T so you can ruin a small bore vent tube up to ceiling level and the out through the front bulkhead. I suusepct you can not get the air out of the top pipe, this will do it as long as the boat trims down by the stern a bit.

 

The other thing is how was the antifreeze put in? On central haeting systems ALWAYS mix the antifreeze and water BEFORE it is put into the system. Hot pure antifreeze is denser than cold water so gravity will not get it circulating properly - come to that on pumped systems the pipes get hot but the rads stay cold!

 

Tony Brooks

[blackrose]

My Ellsi di a 54ft boat just fine, but itw a sin 28mmpipe.

 

As this is a gravity system I assume the "hot" pipe is at gunnel level or higher - if not, hard luck.

At the far end of the "hot" pipe run replace the elbow with a reducing T so you can ruin a small bore vent tube up to ceiling level and the out through the front bulkhead. I suusepct you can not get the air out of the top pipe, this will do it as long as the boat trims down by the stern a bit.

 

The other thing is how was the antifreeze put in? On central haeting systems ALWAYS mix the antifreeze and water BEFORE it is put into the system. Hot pure antifreeze is denser than cold water so gravity will not get it circulating properly - come to that on pumped systems the pipes get hot but the rads stay cold!

 

Tony Brooks

 

I only put inhibitor into mine, not antifreeze. Is ordinary car antifreeze ok? Will it mix with the inhibitor that's already in there or does antifreeze already contain inhibitor? Do they put anti-freeze into domestic central heating systems in houses? I live onboard so when it's cold the stove is on anyway. I wonder if it's worth me putting some in and at what %? Perhaps next winter I'll do it - I suppose there'a always the chance of me having to go somewhere when we get a cold snap.

Edited December 4, 2006 by blackrose

[phishphace]

Thanks for all the comments so far -

 

The set up seems to be correct with the hot pipe uppermost. We have not added any antifreeze to it ourselves, so do not know whether that is the problem.

[Tony Brooks]

I only put inhibitor into mine, not antifreeze. Is ordinary car antifreeze ok? Will it mix with the inhibitor that's already in there or does antifreeze already contain inhibitor? Do they put anti-freeze into domestic central heating systems in houses? I live onboard so when it's cold the stove is on anyway. I wonder if it's worth me putting some in and at what %? Perhaps next winter I'll do it - I suppose there'a always the chance of me having to go somewhere when we get a cold snap.

 

 

Not having antifreeze in i snot a problem appart from corrosion and freezing, your inhibitor shoudl have sorted out the corrosion.

 

I have no idea if antifeeze and your particular inhibitor will mix, but as I said, always mix before putting into system.

 

I did not notice if you said you had a way of venting the "front" of the upper pipe.

 

Tony Brooks

[blackrose]

Not having antifreeze in i snot a problem appart from corrosion and freezing, your inhibitor shoudl have sorted out the corrosion.

 

I have no idea if antifeeze and your particular inhibitor will mix, but as I said, always mix before putting into system.

 

I did not notice if you said you had a way of venting the "front" of the upper pipe.

 

Tony Brooks

 

My header tank is Td off at the highest point of the system so it's self-bleeding. I can empty the whole system easily enough through a tap at the bottom before it goes back into the backboiler, so I could always mix up some antifreeze next summer and change the fluid.

[blackrose]

Phishphace, I think at least part of your problem might be that you have a calorifier in the system. You said it heats up the hot water nicely and this is probably where most of the heat is going. The other problem is that without a pump it's very difficult to get the hot water moving through the thin lines of a calorifier and thermocycling is reduced.