Pumps!

[lewisericeric]

Hi guys

 

We're getting a stove fitted on the boat soon and it's going to be a boiler stove which will be connected up to 2 radiators. Do you guys know which pumps are the best for just a small circuit like that? Went to B & Q today but the pumps I saw there seemed to all be for much more complex heating systems than what we need it for!

 

Cheers guys! (and gals!)

[mrsmelly]

Hi guys

 

We're getting a stove fitted on the boat soon and it's going to be a boiler stove which will be connected up to 2 radiators. Do you guys know which pumps are the best for just a small circuit like that? Went to B & Q today but the pumps I saw there seemed to all be for much more complex heating systems than what we need it for!

 

Cheers guys! (and gals!)

 

If you plumb the two radiators in a thermo syphon system ( Dead easy ) you will not need a pump at all and it works very well.

[lewisericeric]

If you plumb the two radiators in a thermo syphon system ( Dead easy ) you will not need a pump at all and it works very well.

Can you elaborate a bit more? WIll this work with the fact the stove is at one end of the boat and the last radiator will be near the stern?

 

Cheers mate

[koukouvagia]

Can you elaborate a bit more? WIll this work with the fact the stove is at one end of the boat and the last radiator will be near the stern?

 

If you decide to do away with a pump, bear in mind that the the pipes should rise approx 5cm (2") per 100cm (39") run.

[lewisericeric]

Yes that's what I dont want - pipes half way up the walls!

[Dominic M]

Hi Lewis. If you have a sufficient rise in the top pipe from the back boiler to the furthest radiator, you wont need a pump. It will take longer for the rads to get warm, but it works very well. If you do fit a pump, 12v ones are noisy beasts. A 230v central heating pump run off the inverter that you have already received so much conflicting advice about is quiet, but it means you have to run that inverter all the time. I have a 230v pump on my system, and have never worried about the draw from the batteries via the inverter, but then I have access to a landline much of the time, and when cruising, I am running the engine to keep moving and therefore the batteries topped up, and never spend much time moored up. If I was continuously cruising rather than taking a 1 or 2 week break here and there, I think I would opt for the no pump rising pipe convection system.

[n.b.Goldie]

If you plumb the two radiators in a thermo syphon system ( Dead easy ) you will not need a pump at all and it works very well.

 

No power draw on the batteries and totally silent, as long as the stove is hot you will have circulation, the best of both worlds.

 

 

Yes that's what I dont want - pipes half way up the walls!

 

Polished copper pipes look nice and add to the heat emissions.

 

Thermo-syphon has no moving parts to go wrong!

 

Regards

Ditchdabbler

[Smelly]

If you're looking at a 12 volt CH pump Bolin are well respected; but bear in mind if your pump dies or your batteries fail then no fire... Also you need to size your radiator output to the max output of the fire otherwise if you stoke it to the max it will boil and whereever your expansion tank is that's not funny!

 

 

Thermo-syphon has no moving parts to go wrong!

 

 

 

Yup!

[DeanS]

Hi Lewis. If you have a sufficient rise in the top pipe from the back boiler to the furthest radiator, you wont need a pump.

 

My boat has the pipework and expansion tank already in place...the pipework down the length of the boat is parallel, but at the end is an elbow and it then feeds up the wall to the expansion tank. Would this meet the requirements of the "sufficiant rise" ....or does the pipe have to fitted at an angle along it's length?

[Dominic M]

Yes that's what I dont want - pipes half way up the walls!

Why not? Radiators are far more ugly than pipes I think, but you need them, so you need the pipes. I think pipes are a nice functional and utilitarian feature, and so does the architect Richard Rogers. Google the Centre Pompidou.

[lewisericeric]

Why not? Radiators are far more ugly than pipes I think, but you need them, so you need the pipes. I think pipes are a nice functional and utilitarian feature, and so does the architect Richard Rogers. Google the Centre Pompidou.

 

Thanks for all the advice guys- still a bit confused about the how great the rise of pipes needs to be!

 

Dominic - i'm totally NOT with you on that one! I find pipework vulgar, and it reminds me (no offence) of ill-fitted council houses! Nothing more ghastly than copper pipes all over the bleedin place!

[Smelly]

Nothing more ghastly than copper pipes all over the bleedin place!

 

I agree but...

 

There was a fella with a nice, pumped, CH system from his Squirrel who moored by us a few years ago who couldn't tell the difference between charging voltage and resting voltage. Having spent the better part of a season convinced he'd been sold crap alternators off the back of his Rutland charge controller and a Maplins ammeter he was faced with knackered batteries, little money and winter. His cheapest (only!) option to see the winter would've been to strip the backboiler out of the fire; he couldn't power the pump.

 

At the time I was planning our CH system... I was convinced to abandon the thought of relying on electricity to propel heat around the boat. Funnily I've still got his Stilsons; he moved off his boat during that winter.

 

I don't know whether you plan to live aboard, but if you do. at least to my mind, you need to compromise aesthetics against functionality and if you don't the first winter will be a leveller...

[lewisericeric]

Thanks Smelly - but what about those Bolin pumps everyone is talking about? Its only 12v and supposed to be pretty reliable?

[koukouvagia]

My boat has the pipework and expansion tank already in place...the pipework down the length of the boat is parallel, but at the end is an elbow and it then feeds up the wall to the expansion tank. Would this meet the requirements of the "sufficiant rise" ....or does the pipe have to fitted at an angle along it's length?

 

In my experience, yes the rise has to be at the same angle all the way along the run. When I added an extra radiator at the end of the run, I reduced the angle of rise simply so that I could get the last radiator under the gunwale. The themo-syphoning stopped working and I ended up repositioning the flow (top) pipe so that it was at a consistent angle thoughout its length.

 

 

 

 

 

[lewisericeric]

Can you not just have a minimum angle on the pipe though? Such as from stove to End of boat being a total of 6 or 7 inches? Surely it should still work?

[ditchcrawler]

Can you not just have a minimum angle on the pipe though? Such as from stove to End of boat being a total of 6 or 7 inches? Surely it should still work?

Remember your bow is probably a foot above your stern to start with so its not the angle of the pipes to the floor that counts but to level.

[koukouvagia]

Can you not just have a minimum angle on the pipe though? Such as from stove to End of boat being a total of 6 or 7 inches? Surely it should still work?

 

Yes, provided you've got room for a 1 in 20 gradient and as Ditchcrawler says, you take account of the slope of the boat.

Edited August 25, 2011 by koukouvagia

[DeanS]

To make it aesthetic, you can fit a criss cross wooden trellis or something similar. There are ways. Being a liveaboard, in winter....is not simple. You wont care about looking at a copper pipe when you're breathing cold air out your mouth. I have a solid fuel stove, and thinking of using an Ecofan to blow the heat down the passage......but thats 100 pounds.....so perhaps I should get a back boiler instead for 250...but then it's the cost of the radiators as well.... we shall see. Ecofan it may have to be for this winter. Another home made stove in the back engine room.

[lewisericeric]

Dean you can get rads pretty cheap - we've just bought a couple £32 each. Not a massive expense to get some heat further down the boat!

[blackrose]

Thanks for all the advice guys- still a bit confused about the how great the rise of pipes needs to be!

 

Dominic - i'm totally NOT with you on that one! I find pipework vulgar, and it reminds me (no offence) of ill-fitted council houses! Nothing more ghastly than copper pipes all over the bleedin place!

 

If you don't want exposed pipework you'll probably need a pump. Thermosyphoning without a pump requires wide bore flow & return main pipe runs which ideally run right around the radiators (flow above, return below). A well-designed thermosyphoning circuit is most definitely the best system for a boat with a stove/backboiler because as others have said, there's nothing to go wrong.

 

Your other issue that doesn't bode well for thermosyphoning is that your stove and rads are at opposite ends of the boat. Thermosyphoning works best over short distances, so you're probably better off with a pump and then you can just have your main pipe runs boxed in on the floor. I'm not sure B&Q is the place to go for a 12v circulation pump? You did want a 12v pump didn't you?

 

http://www.google.co.uk/search?q=12v+circulation+pump&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-GB:official&client=firefox-a#q=12v+circulation+pump&hl=en&client=firefox-a&hs=83d&rls=org.mozilla:en-GB:official&prmd=ivns&source=univ&tbm=shop&tbo=u&sa=X&ei=sHxWTqD1OMii8QO-teCeDA&ved=0CE4QrQQ&bav=on.2,or.r_gc.r_pw.&fp=e67052e80effdac3&biw=1151&bih=657

Edited August 25, 2011 by blackrose

[Ex- Member]

Hi Lewis

 

Should you end up going for a 240 volt pump, the best I found from the 240 volt range was the Wilo smart pump A rated

 

http://www.screwfix.com/p/wilo-4132507-smart-central-heating-pump-a-rated/53435#

 

I've only ever needed to run it on the lowest setting and it's very energy efficient although needs an inverter to operate if no shore line.

 

You won't find a 12 volt pump at B&Q well very unlikely, you need to use chandlry's or outlets specialising in 12 volt equipment, Maplins might supply them as well. There are also some on E-bay

[Supertramp]

Being the eternal pessimist -

If I load the fire up for the day and go off to work, - what happens if the 12v pump fails?

 

How do people cater for such a situation, it could be 6 hours or more, and the stove would go on burning....

 

??

[BEngo]

Thanks for all the advice guys- still a bit confused about the how great the rise of pipes needs to be!

 

Dominic - i'm totally NOT with you on that one! I find pipework vulgar, and it reminds me (no offence) of ill-fitted council houses! Nothing more ghastly than copper pipes all over the bleedin place!

There is a third option, which I have used successfully for over 20 years on a Squirrel and two rads over about 25 feet, but no calorifier.

 

You need physical design which thermosyphons at low stove settings and a pump for full blast. My set up has a 22mm vertical pipe from the stove rising to about 2in below the gunwhale then 22mm pipes parallel to the gunwhale running aft to each of the rads which are on TBOE connections with 15mm drops. The bottom pipe runs parallel to the floor back to the boiler, drops into the mag-drive Johnson pump on the floor then back up into the boiler. The pump is controlled by an on-off switch and, in parallel with that, a cylinder thermostat on the connection from the boiler to the vertical pipe.

 

What I normally do is light the stove and once it has warmed up the back boiler and the vertical pipe is geting warm I put the pump on for 15 secs or so. This starts the water moving and after that there is no need to do anything. If the stove gets hotter than the cylinder stat setting then it puts the pump on. If I forget to start the pump manually the stat puts it on OK anyway. If one is mad enough to open the stove up to heat the boat quickly then the pump runs continuously until the stove is shut down. Eventually, because the rads are not big enough to dissipate all the heat he system will boil if not shut down!

 

Once the boat is warm I can keep it warm enough, even with ice on the cut, without the pump coming on. I admit that I am occasionally disturbed if the wind gets up and the stove draws harder. that causes the pump to come on. A bolin pump would be quieter and might not wake me up, but I have never bothered to buy one.

 

It may be possible to replace the cyl stat with the stat from the incoming pipe on a hot-air curtain which are smaller, but I like the cyl stat because it's easy to adjust and it hides OK behind the stove..

 

N

Edited August 26, 2011 by BEngo

[Supertramp]

Thanks BEngo,

Thats another option, although my pipework is already in situ.

 

I'm looking at possibly putting a Boiln pump in now, but they seem to be over £200 ? - is that right?

[lewisericeric]

Sorry I'm a bit late on this BEngo - but thanks for the advice on this one - great help.

 

Supertramp - yes they are around £200