back bolier CH?

[Didger]

Hi All, be obliged if you could share thoughts on this...

 

I have a boatman stove with backboiler, running through 28mm copper convection pipes to produce hot water through calorifier in HW tank (have another engine fed calorifier that runs to same tank when cruising)

 

System runs well at the mo, gives me benefit of heat and HW without using any power.

 

I am considering fitting radiators to the back end of the boat, as the stove is at the front of the boat and heat doesnt make it to the back bedroom with space narrowed down by cupboards, bathroom etc, even with a fan sat on top of the stove.

 

In the past, someone has tried to extend the copper piping from the back of the stove to try and fit a convection ststem on it...there are Ts from the hot and cold return which run pipes for about a foot and are then blanked off, in effect the HW system runs from the back boiler down the port side,the exsisting system extention runs for a foot down the starboard side...

 

options are....

 

1) extend this system using 28mm copper convection by extending exsiting pipework down the S/board side into back bedroom

 

Issues with this... running 28mm through saloon and down entire cabin...I understand hot pipe needs a slight rise on it to work properly?...this would make radiator at bedroom end high on wall? also would want to run pipe under gunnel shelf so its out of sight and neat,so that would need to go up from the back boiler, run 30'feet then down 2' to the rad?

Would the system run two ways on gravity at once? and where can I source Rads with 28mm fitting for convection use?

 

2)Install 12 volt HW pump at back boiler end, reduce exsisitng 28mm down to 15mm, use speedfit palstic pipe to ordinary rads down starboard side, leave exsisitng HW convection in place, but connected up to this system.

 

Issues...

Running 12v pump on this sysem may cause it to back up on Cold return at back of stove(cold return still gravity fed)

 

System wouldnt heat up quickly enough with water circulating?

 

Might be bloody dangerous!

 

 

3) Make new loop/extension where 28mm convection return pipe runs out of cal...fit 12v pump and run 15mm speedfit from there down to rads in Bedroom and return to join cold return

 

Issues...

System wouldnt run normal convection as I am breaking into the pipe to fit pump, so would always require power to drive water round..even if I only want HW? Dont have access to shore power so concerned about power use...

 

Options...

 

option 1 low tech solution...but clumsy/messy

 

Option 2 dont think would work, may block up

 

Fit option 3 and always have concerns over power

 

Forget about it and wear a hat in bed...

 

 

all suggestions gratefully received..

El G

[KenK]

Our system is not the same but it might give you some clues. We don't live on the boat.

Hot water tank has two coils, one from the engine and one from the fire at the front of the boat.

The fire also feeds two radiators and a towel rail in the shower room.

 

We don't use the fire in the summer.

We cruise all day hot water tank full of nice hot water, next morning enough for two showers and washing up.

 

Cold evening after cruising we turn the fire on, it is a diesel Lockgate stove with a boiler and the system is pumped.

Boat nice and toasty warm including the bedroom which has one of the radiators other is at the front.

Next morning no hot water, the cold water circulates through the coil in the tank and that helps warm the radiators.

 

Cruising on a cold day, turn on the fire for a couple of hours before we stop, boat is like an oven, throw all windows

open to cool it down, reaches a reasonable temperature, toasty boat and hot water next morning.

 

We never run the fire during the night, pump is noisy when everything else is quiet and I don't like the idea of a fire

on when I'm sleeping.

 

Next morning boat is cold and I get kicked out of bed to make the dearly beloved tea and turn the fire back on.

 

If I lived on the boat especially through the winter I would invest in some kind of automatic system like my

central heating in the house. I'd have a tank filled with white diesel to avoid the red diesel problems. OK it is

an expensive solution and not eco friendly but you do stay warm.

 

Good luck

 

Ken

[Didger]

Thanks for the reply Ken, judging by the lack of other responses it looks a bit too difficult to be sorted on here!!

 

Im leaving it until the spring before I investigate further, then if i all goes wrong I have some time before the lack of heating is life threatening! It works fine at the mo, just dipping the toe in the liveaboard world this winter..hope I dont get too frostbitten!

Cheers

El G

[smileypete]

all suggestions gratefully received..

I'd go 15mm from back end rads then tee into pipes as close as backboiler as practicable. Speedfit/PEX is fine but change to copper 2 or 3 ft from the stove.

 

Put a pump in the 15mm return pipe from the rads 2 or 3 ft from the stove, cooler there so better for pump and furthest from bedroom.

 

Insulate the 15mm pipes and box in with thin ply if you want. Since it's pumped they can both be run at skirting level.

 

Avoid any high spots in the pipework where air can collect if you can, if not fit a bleed screw or 'bottle' air vent (automatic).

 

cheers,

Pete.

Edited December 4, 2011 by smileypete

[Nev]

we have a solid fuel stove with back boiler running two rads one in the bed room and one in the bathroom (50 foot boat) the main pipes are 28mm dropping via T's to 15mm to the rads.

 

The system is open with a header tank in the wardrobe. I think it was designed to be convection as there is a rise of the 28mm copper on the out feed but at some point a pump has been fitted that is switched. I added a pipe thermostat switching the pump that works well - especially at night so I don't have to have the pump running but it sparks up if needed.

 

This system is simple basic and works. Only problem is no timer so when away from the boat the boat stays cold. if I were liveaboard it would be an ideal system.

 

I should also add that the feed can go into the hot water tank if we have not run the engine to heat up our water. It is valved so I can allow this or not. When cruising there is some heating up of the rads and pipe work which is good as on the days when the fire is not really needed the boat gets a bit warm via the engine and I can turn down the pipe stat to pump the water which helps heat the boat further.

 

KISS is my angle for all things boaty...

 

Good luck

 

Nev

 

NB Waterlily

[Pretty Funked Up]

and always have concerns over power.

 

all suggestions gratefully received..

El G

 

If you chose to go with a pump and select your pump carefully you needn't be worried about power really.

Some pumps have a draw of just 0.15amps which is the same as a computer fan OR 2 Ikea dioder LED bars.

[Smelly]

Hi All, be obliged if you could share thoughts on this...

 

I have a boatman stove with backboiler, running through 28mm copper convection pipes to produce hot water through calorifier in HW tank (have another engine fed calorifier that runs to same tank when cruising)

 

System runs well at the mo, gives me benefit of heat and HW without using any power.

 

I am considering fitting radiators to the back end of the boat, as the stove is at the front of the boat and heat doesnt make it to the back bedroom with space narrowed down by cupboards, bathroom etc, even with a fan sat on top of the stove.

 

In the past, someone has tried to extend the copper piping from the back of the stove to try and fit a convection ststem on it...there are Ts from the hot and cold return which run pipes for about a foot and are then blanked off, in effect the HW system runs from the back boiler down the port side,the exsisting system extention runs for a foot down the starboard side...

 

options are....

 

1) extend this system using 28mm copper convection by extending exsiting pipework down the S/board side into back bedroom

 

Issues with this... running 28mm through saloon and down entire cabin...I understand hot pipe needs a slight rise on it to work properly?...this would make radiator at bedroom end high on wall? also would want to run pipe under gunnel shelf so its out of sight and neat,so that would need to go up from the back boiler, run 30'feet then down 2' to the rad?

Would the system run two ways on gravity at once? and where can I source Rads with 28mm fitting for convection use?

 

2)Install 12 volt HW pump at back boiler end, reduce exsisitng 28mm down to 15mm, use speedfit palstic pipe to ordinary rads down starboard side, leave exsisitng HW convection in place, but connected up to this system.

 

Issues...

Running 12v pump on this sysem may cause it to back up on Cold return at back of stove(cold return still gravity fed)

 

System wouldnt heat up quickly enough with water circulating?

 

Might be bloody dangerous!

 

 

3) Make new loop/extension where 28mm convection return pipe runs out of cal...fit 12v pump and run 15mm speedfit from there down to rads in Bedroom and return to join cold return

 

Issues...

System wouldnt run normal convection as I am breaking into the pipe to fit pump, so would always require power to drive water round..even if I only want HW? Dont have access to shore power so concerned about power use...

 

Options...

 

option 1 low tech solution...but clumsy/messy

 

Option 2 dont think would work, may block up

 

Fit option 3 and always have concerns over power

 

Forget about it and wear a hat in bed...

 

 

all suggestions gratefully received..

El G

 

Well, if you've a pumped circuit at the end of the convecting circuit the convecting bit will stop it getting to dangerous. You could time or switch the pump so it only warms the bedroom up when you need the bedroom warm. Keeps power useage to a mimimum and ensures the fire's usueable in an electrical emergency. you could throttle the pump or indeed balance the radiators to maximise the spread of the heat.

 

I don't think it would back up on the cold end; it'd be more likely to distribute the heat evenly through the rads as the existing convecting rads would still be cooling and syphoning water down.