Onewheeler
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Posts posted by Onewheeler
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It might be feasible if installed as an adjunct to a stove, and would make the boat feel very comfortable. Easier to fit on a new build. Maybe just fit it up the middle 1 m of the boat (assuming a narrowboat) as the edges are usually furniture. The ballast goes up the edges. Build a Celotex wall to separate the centre section from the ballast area, and line the baseplate with Celotex.
Typcial heating mat is 150 - 200 W/m^2. 50 mm Celotex has an R-value of 2.25 m^2 K / W so a deltaT of say 40 K water to heat mat would only lose about 17 W/m^2 to the water, anything left would warm your feet. 10 m^2 of 150 W/m^2 would therefore put over 1300 W into the boat. Not enough to keep it fully heated but it would certainly make the boat feel more comfortable.
Domestic underfloor relies on a low heat input over a large area. A narrowboat is only the area of a small room in a house.
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I'd try to keep it simple.
Tank H has webasto and engine
Tank V has solar (with its own pump and controller) and spare coil.
Fit the Webasto outlet with a three way valve (including midway option) to feed H, V spare coil or both.
Cold feed to V comes from hot outlet of H. DHW feed comes from V.
Normal operation has Webasto going to V or use solar in V.
Bathnight has Webasto powering H (and V if solar hasn't done much).
It sounds as if you don't use the engine much, but otherwise you could arrange a small recirculation pump from hot side of V to cold side of H (with a NRV in the cold feed to H and an expansion tank) to get hot water to V.
I don't know if you can get three-way valves for 12 V with a midway option, but otherwise take the actuator off and operate it manually (Womanually? Gender-non-specificually?)
Some clever Arduino programming with sensors could help, or get very confusing!
Martin/
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"Hardly no cavitation"??
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6 minutes ago, Tash and Bex said:
what about a collector network directly on the baseplate, a given amount of reflective insulation on top to create a thermal barrier, then run the heating matrix through those bricks with holes in them in lieu of a more conventional frog? Always good to make stuff work for a living on a boat, and it would make my ballast less "passive"!
That is the idea that's doing the rounds of the old grey matter atm, but I haven't even started adding numbers to it!
Might work if you've got enough space under the floor. However (without doing any sums) you would need a thick insulation layer as the area used over the baseplate would be large. Otherwise you'll be circulating heat from one side to t'other.
Molten salt storage? ?
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13 minutes ago, Tash and Bex said:
well I wouldn't exactly be all electric, and a decent cocooned generator should keep up with a heat pump I would have thought, particularly if i were to use ballast as a thermal store.....early days and depends on whether I take the plunge and go wide beam. but between a generator and 4kw of solar I think it's worth looking into
If you've got that much electrical power then no problem! You'll have a large bath tank as a thermal store! Water has the highest thermal capacity of anything readily available, although it would be interesting to do a conceptual design using parafin wax as a thermal store using its latent heat of fusion.
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16 minutes ago, Tash and Bex said:
do you know (unrelated to the bath) I was just looking into the use of a heat pump for heating an all electric (hybrid I guess) boat.
It's tempting, but for any reasonable heat output the electrical consumption (assuming that you go the more conventional route) gets a bit scary. A CoP of 4 would be good in practice even if the theoretical maximum is higher, you might be able to do better with a reliable heat sink like a canal and by keeping the output temperature low. Gas-fired absorption heat pumps are available, but you said somewhere that you don't want gas and you'll still need some electric for running mechanical pumps. (I'm looking at heat pumps for domestic use. Glad that I kept my old thermodynamics text book!)
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I'd bet there's no dip tube inside the tank.
Edit: ignore that, I'd missed three pages of discussion!
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One could use a heat pump to warm the tank, with the canal water as heat source (heat conducted through the base plate). It would need a compressor for a more conventional system, but that could be mechanically powered using e.g. a gym stepping machine. After a couple of hours exercise a nice hot bath would be welcome. A diesel fired absorption heat pump would also work but I don't think anyone makes them. A market opportunity?
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I slapped some Zinsser all coat exterior black on our gunwales last year. Went on easily, covered well, looks good. From Screwfix. Supposed to be satin but it's fairly glossy.
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Having towed Vanessa from Abingdon to Eynsham, I can vouch that she is (mostly!) harmless and good company! It was a pleasant voyage, aside from a minor collision with Godstow Bridge in a strong cross wind and a couple of bumps going into locks. She was alongside our nb most of the way, other than some narrow bridge 'oles and all of the locks above Iffley where we towed her behind (oo-err!) I would have been happy to help again, but other commitments in the next few weeks make it unlikely.
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1 hour ago, Tash and Bex said:
Maybe I will stay a while after all, at least I might be able to help a few people in a less judgemental way.
Please stay! You have a nice sense of humour. Ignore the r-soles.
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If, is suggested elsewhere, you use the bath as your heat store, you could insulate the surface with tesselating plastic ducks. Is that sufficiently out of the box?
2 minutes ago, Paul C said:Its the Poiseuille Equation, I think? That's assuming the flow remains laminar (I think it will......but you can always check by calculating the Reynolds number).
That tells you the delta P for laminar flow in a pipe. I've lost the plot as to what you're trying to calculate!
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33 minutes ago, Boater Sam said:
You would need a significant length of 10mm pipe to achieve sufficient surface area for heat transfer on the rate that a Webasto kicks it out. Nice idea but it requires more design than has been proposed. 10mm pipe is far too small for the required flow rate in the Webasto heat exchanger matrix.
I said I'd not done the heat transfer calcs. However, a flow rate through the 10 mm secondary of 2 L / min with a delta T of 40 C would take 5.6 kW of heat. Based on experience with a very differently configured heat exchanger I use for cooling wort with about 1 m of 10 mm pipe, the heat transfer rate probably isn't miles adrift.
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2 minutes ago, Boater Sam said:
Coaxial plumbing is difficult to arrange, requires special tee pieces.
Plenty of c/f heat exchangers are home-made for brewing purposes. Just needs some imagination, and Bex doesn't seem short of that ?
e.g. 10 x 15 x 15 tee at each end, with a short length of 15 mm Cu pipe into plastic fittings. Ream out the 10mm end so that the pipe will pass through.
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You could save a second Webasto by putting a small c/f h/x between your existing Webasto and calorifier coil with a switched pump that feeds secondary side water around your bathtime tank (or bath). It would have no effect on the normal operation of heating the calorifier. Without doing the heat transfer calculations, maybe a metre or so of 10 mm copper tube on the secondary inside 15 mm plastic tube carrying the primary, the whole lot insulated and coiled.
Martin/
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42 minutes ago, bizzard said:
Tinkin outside da box-boat. Mount bath upon bricks on towpath. Fill with canal water. Light a fire of sticks beneath it. Wait one hour precisely to heat up. Jump in with toy boat or duck.
When I were a lad, we had a galvanised steel bath. Filled it from kettle and saucepans on t'gas cooker every Friday night. Youth of today don't know they've been born etc...
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53 minutes ago, Tash and Bex said:
I've just looked at the capacity, which it clams is 210l, so no allowance for displacement,
Bath with a friend and double the displacement ?
210 L is a lot of water in a bath unless you want to swim lengths. I reckon we use less than 100 L in a corner bath at home.
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The location of my small exhaust leak was obvious from the transient puff of smoke on starting the engine from cold.
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It clearly says primary side max 3.5 bar and working head (presumably secondary) 10 m (1 bar). I'd take that as engine side 3 bar and domestic side 1 bar. Heat usually flows from primary to secondary.
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Look for BA15D. BA15S are single contact, BAY15D have offset bayonet pins (often found in nav lights). Loads on Ebay or the usual LED suppliers.
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They're 12 V lamps and the batteries are delivering over 13 V? If so they won't last long...
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23 hours ago, buccaneer66 said:
Try WD40 according to this website it has many uses you would never normally think of. http://www.novelodge.com/worldwide/wd40/34
Tried it with the missus. Made her smell right funny and she wouldn't let me near her for several days.
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18 hours ago, pearley said:
Nothing to do with the OPs question but Euro 5 & 6 vehicles do not like the second battery being charged via a split charge relay it diode.
Why?
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1 hour ago, Rickent said:
We too have a sunshine solar 1000w pure sine wave and are very satisfied with it, does what it says on the tin for not a lot of money.
We too. I tested it recently with the washing machine on cold wash and it ran with no problems even on the spin cycle.
Good Quality Flat Pack Kitchen Units Suitable for Boat Use.
in Boat Building & Maintenance
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That's a pity, the C&L weren't bad for the price. I've just fitted a couple in my house. We were lucky to have bought just in time. It's worth adding some PVA to the joints to make them sturdier.