Pumps!

[WJM]

http://www.tnorrismarine.co.uk/

 

 

This company sell 12v circulation pumps specifically for central heating systems on boats.

[lewisericeric]

Reviving this topic again guys. The heating is in, and we ended up going for a 12v pump..... do you have to have this on constantly though to keep the water moving? Or can you just have it on for say 15 mins every hour etc???

 

It is rather noisy which I was expecting but I just don't know if I'm to have it on constantly or what?!

 

Cheers!

[blackrose]

If it's not on then water won't circulate and your backboiler will eventually overheat.

 

We told you to go for a pumpless thermocycling system but you wouldn't listen!

 

Seriously though, if the pump is noisy it could be that there is still some air in the system (specifically in the pump).

[bottle]

The heating is in, and we ended up going for a 12v pump.

 

but which one?

 

You could fit a 'pipe stat', so that it turns itself on and off. Will not stop it being noisy though.

Edited October 19, 2011 by bottle

[lewisericeric]

I know fitting a stat wont stop it from being noisy but it would be great, for example, if it would run for 15 minutes or whatever for every hour to keep things ticking over but meaning that it doesn't haev to be on permanently!

It was the Jabsco heating pump

 

 

Thermosyphoning was off the cards when a boat fitter i mentioned it to slated it beyond belief, saying that the first rad is usually ok but any subsequent radiators are going to most likely be cold ??

[Theo]

I think that this would live more happily in another forum...

 

I will leave the link in this one, though.

 

Nick

[bottle]

I know fitting a stat wont stop it from being noisy but it would be great, for example, if it would run for 15 minutes or whatever for every hour to keep things ticking over but meaning that it doesn't haev to be on permanently!

It was the Jabsco heating pump

 

 

It will be on all the time the water is up to temperature, so could be on all the time.

 

 

Thermosyphoning was off the cards when a boat fitter i mentioned it to slated it beyond belief, saying that the first rad is usually ok but any subsequent radiators are going to most likely be cold ??

 

Even I know that is utter tosh and I do not have any qualifications in this area. (Balancing the rads, as you will still need to do, will solve that problem)

[ditchcrawler]

I know fitting a stat wont stop it from being noisy but it would be great, for example, if it would run for 15 minutes or whatever for every hour to keep things ticking over but meaning that it doesn't haev to be on permanently!

It was the Jabsco heating pump

 

 

Thermosyphoning was off the cards when a boat fitter i mentioned it to slated it beyond belief, saying that the first rad is usually ok but any subsequent radiators are going to most likely be cold ??

If it was plumbed correctly for thermosyphoning then it would have worked, but not if it was plumbed like a domestic central heating system with pipes along the floor and T up to each rad it wouldn't.

[Paul Coleman]

It will be on all the time the water is up to temperature, so could be on all the time.

 

 

 

Even I know that is utter tosh and I do not have any qualifications in this area. (Balancing the rads, as you will still need to do, will solve that problem)

 

 

Seconded - I fitted my boat with two thermosyphon radiators, and both get really hot!

 

Important things:

 

Pipe diameter - 28mm is best. Don't cheap out on this it will cost you in the end.

Radiator height - top of rads MUST be higher than the top of the back boiler, the higher the better.

Bends - get a pipe bender. Avoid 90 degree bends where you can. I only have four, two on each radiator.

Bleeding - Make your system self bleeding or at least easy to bleed. There is no pump to push air out of badly designed pipework!

Pipe layout - No U bends, or inverted U bends they will prevent thermosyphoning.

Pipe layout - Hot water likes to be high. Keep it high until it cools down. Likewise with the cool pipe.

 

Unimportant things:

 

Constant raise along the pipe: Once the water has left the boiler, it is cooling anyway. There MUST be a rise somewhere though.

Aesthetics: When it's -20 outside the warm glow of smugness as you feel the silent heat from the radiators beats an ikea-esq minimalist floating penthouse any day.

 

My mental model of the thermosyphon goes like this:

 

1/ Hot water will try to find the highest part of the system. Make sure it finds a radiator there.

2/ Cool water will try to find the lowest part of the system. Make sure it finds a boiler there.

3/ Any fool can be cold

Edited October 19, 2011 by Paul Coleman

[Alan Saunders]

To obtain a thermo-syphon the the heat sink, radiators etc, must be above the heat source, boiler. Ideally the supply (hot) pipes should rise and the return (cold) pipes should descend. There may be vertical sections of pipe in between. As Blackrose says, this will usually be a single pipe system, the radiators will have the feed connection at the top and return at the bottom of the opposite end.

 

A back boiler must have an adequate thermal circuit to dump heat and prevent local boiling which corrodes the boiler. In a domestic installation this is usually provided by the the hot water tank circuit and one or more radiators. As it is difficult to obtain a Calorifier for a boat with adequate diameter heating coils it may be best to use a circulating pump to feed the calorifier through smaller (e.g. 15mm) pipes. This is best achieved with an injector tee which can be assembled by soldering e.g. a 22/15mm reducer into a 22mm tee. The thermal circuit remains intact and the pump can (should) be used to initiate convection.

 

You should have a thermostat that activates the circulator before local boiling damages the interior, maybe 80C-90C. To avoid condensation damaging the exterior of the boiler a second thermostat should prevent the pump from running below perhaps 60-70C. Be assured, those boiling and burping noises mean your boiler is being destroyed.

 

The nicest installation I have seen had a pair of 50mm+ (2"), maybe larger, copper pipes rising through the length of the cabin.

 

Alan

[Alan Saunders]

. . . Balancing the rads, as you will still need to do, will solve that problem.

Yes, reducing the output of each radiator to optimum is essential for a two pipe, pumped system. A single pipe system allows no such adjustment.

 

Alan

[Smelly]

 

 

Thermosyphoning was off the cards when a boat fitter i mentioned it to slated it beyond belief, saying that the first rad is usually ok but any subsequent radiators are going to most likely be cold ??

 

Your boat fitter is wrong; I've got 5 rads, total 1750watts plus the calorifier teed off the back of the fire spreading 11 metres of the boats length; they're all toasty warm atm...

[blackrose]

 

A back boiler must have an adequate thermal circuit to dump heat and prevent local boiling which corrodes the boiler. In a domestic installation this is usually provided by the the hot water tank circuit and one or more radiators.

 

Alan

 

I think my thermal circuit must be undersized as my boiler can thump a bit when the fire's really going. I've 2 x 2500 btu rads and a 10m long (return) x 28mm dia copper circuit from a 7000 btu backboiler. Does it still corrode the boiler if it's got noise reducer/inhibitor in it?

 

If the thermal circuit is oversized I thought the rads wouldn't get hot.

 

I have 4 ports on my boiler and 2 are blanked off, so suppose I could connect a pump to the 2 blanked off ports and T into the coolant feed to my calorifier?

Edited October 20, 2011 by blackrose

[Bob18]

Will it circulate once started by the pump? Normally no, but sometimes yes. If a friend's house is anything to go by - they have to run the pump for about an hour, then they turn it off, sometimes the water keeps circulating, but most times it slows to a stand, they ten run the pump for half hour and all might be happy... I think you get the picture.

[cereal tiller]

i had a kabola old english on our boat

 

i used a 12 volt pump for circulating the water to a heated towel rail in the bathroom

 

having heard that 12 volt pumps could be worn out in just 2 winters,i installed a temp. sensor on the copper tube at the top of the stove,it enabled a 4 pin relay which switched the pump on when the water was hot enough.

 

the pump ran for 40 seconds at a time,then it was off for 2-3 minutes.

 

it worked well for 5 years,then the kabola was swapped for a solid fuel stove.

[lewisericeric]

Sorry if this is a daft question - but how can the water boiling in the back boiler "ruin it"? Its a cast iron backboiler on the back of my stove? Its supposed to have boiling water in it? Its not made of chocolate and doesn't haev any other components that Im aware of?

Edited October 21, 2011 by lewisericeric

[ditchcrawler]

Sorry if this is a daft question - but how can the water boiling in the back boiler "ruin it"? Its a cast iron backboiler on the back of my stove? Its supposed to have boiling water in it? Its not made of chocolate and doesn't haev any other components that Im aware of?

No it is not supposed to have boiling water in it, just very hot. If its boiling you risk an explosion from the rapidly expanding steam that could be superheated.

[lewisericeric]

Hmmmm OK guess that makes sense - thanks ditch

[Alan Saunders]

I think my thermal circuit must be undersized as my boiler can thump a bit when the fire's really going. I've 2 x 2500 btu rads and a 10m long (return) x 28mm dia copper circuit from a 7000 btu backboiler. Does it still corrode the boiler if it's got noise reducer/inhibitor in it?

 

If the thermal circuit is oversized I thought the rads wouldn't get hot.

 

I have 4 ports on my boiler and 2 are blanked off, so suppose I could connect a pump to the 2 blanked off ports and T into the coolant feed to my calorifier

 

Sorry if this is a daft question - but how can the water boiling in the back boiler "ruin it"? Its a cast iron backboiler on the back of my stove? Its supposed to have boiling water in it? Its not made of chocolate and doesn't haev any other components that Im aware of?

 

I am not a heating engineer I am just passing on advice given to me by the supplier and the designer of a Thermorossi Bosky multifuel central heating boiler/cooker I installed in a cottage 1984. 10 years later the sheet steel boiler sprung a leak close to the normal centre of the fire. Abuse by friends and relatives unused to solid fuel cooking probably accountd for the damage. My brother-in-law decided he must cook himself some breakfast at stupid o'clock and finding that the huge hotplate was not as hot a gas or electric stove, jammed the fire door open and ruined the stove when it was one month old. What sort of an idiot did not realise that he could fry eggs, bacon and sausages direct on the hoyplate? Later my sister-in-law opened the bottom draught to maximum, after watching a film on TV she was shocked by how hot the stove had become.

 

The system had the usual (Fernox) anti corrosion inhibitor tested annually (do iron nails corrode after a week in a sample?). With a 30' head it was pressurised more than a boat installation so the boiling temperature was higher. I think the problem is not boiling but local-boiling; superheated steam with a small oxygen content?

 

My multi-fuel boiler was output rated for seasoned oak refuelled every two hours. If I filled that large firebox with anthracite it would produce many times the 'rated output'. Worse still, I think it could (did) burn very hot at one point near to the boiler wall.

 

Radiators, properly installed. are usually rated at 70C (70C is unlikely to cause injury or corrosion) with an ambient air temperature of 20C (50C difference). Their actual output is proprotional to the temperature difference. e.g. If you can get your radiators to 100C when the air temperature is 0C they will dump twice as much heat. If your boiler is 100C+ a circulator pump could achieve the same temperature at the first radiator.

 

I would be happy if a Morso Sqirrel boiler lasts for five years of continuous use. I was dissapointed with 10 years life from a £2,500 (1984 price) boiler but, with care it may have survived for my expected 20 years.

 

Alan

[Supertramp]

I know fitting a stat wont stop it from being noisy but it would be great, for example, if it would run for 15 minutes or whatever for every hour to keep things ticking over but meaning that it doesn't haev to be on permanently!

It was the Jabsco heating pump

 

 

Thermosyphoning was off the cards when a boat fitter i mentioned it to slated it beyond belief, saying that the first rad is usually ok but any subsequent radiators are going to most likely be cold ??

 

Being perhaps a little paranoid, - I've taken the 'what happens if the pump fails' a bit further.

 

My stove feeds 3 rads and the calorifier (tho it's not hot enough for that - but that's another issue).

there are 2 pumps in circuit, one 240v Welo from screwfix as mentioned earlier in this thread, and one 12v jabesco.

 

Thermostatic sensor on the top outlet pipe from the backboiler switches the pump circuits. anything above 25c calls for pumping.

If 240v is available, the 240v pump is switched via a cheap mains fail relay (£3) from maplin. If the mains fails,- (some kind yob unplugs the shoreline, power cut, out of credit etc,) the mains relay drops out, - switching in the 12v pump as a backup.

 

Another thermostatic sensor rated at 85c switches the 12v pump on regardless of mains or not, either to assist the 240v pump, or in case the mains pump has failed.

 

A couple of neon indicators under the front step show whats happening, and a buzzer operates if the 85c sensor clicks in.