Electric block heater

[Tony]

A friend of mine was peering at the usual options, asked a Chinese co about these:

http://www.preheater.net/proinfo.asp?id=10&S=2

Model S-8003A (2kW)

They are $99.56 inc shipping plus $4 for paying by paypal, which works out around £65.

Way cheaper than a Kenlowe Hotstart (£400 I think?)

[therecklessengineer]

Or use/make a JamesRL style inline heater?

[Tony]

Actually you're right, could make one quite easily with a 10mm cartridge heater, 10mm - 15mm compression reducer to hold it and and some 15mm pipe with tees in.  Would then just need a circulation pump of some description.

[greasemonkey]

Where do you get cartridge heaters from? They look quite expensive on the net. 1000W ones look around £35. At that price the chinese heater looks reasonable. I quite like the look of it.

[K.H]

My two came from here,300 and 600W

http://www.ebay.co.uk/itm/Heating-Element-Single-End-Wired-Cartridge-Heater-220V-600W-15mm-x-280mm-Qxcah-/160908547524?pt=LH_DefaultDomain_3&hash=item2576e595c4

[Tony]

9.8mm 800W for £8.54 delivered

http://www.ebay.co.uk/itm/AC-220V-800W-9-8mm-x-250mm-Cartridge-Heater-Mold-Heating-Element-/200838637022

[greasemonkey]

Not all that expensive then. Could put two in to get the Wattage up.

Not as simple as it looks though, i dont think. The water would have to flow with the length of the heater rather than across it, and they are not waterproof. Maybe two of the 9.8 mm heaters, fitted inside 10mm copper. Both tubes side by side, and fitted inside a 28mm copper tube, with inlet soldered on one end, outlet on other. Sort of like a PD condenser setup. You'd have to make allowance to change the elements if they go pop.

I wonder how much heat 1200W would put into the water over a certain time? Whats a kettle 3Kw, so a little less than half the heat of a kettle. Plenty really. Then a pump, and a cutout. Hmmm, the heater for £65 still sound cheap enough, although something made yourself is often better.

[therecklessengineer]

Actually, if my suspicions are correct, you don't need a circulation pump. The item in the original link I'm 99% sure doesn't have one.

What gives me a clue is that we have one nearly identical fitted on board the ship that I work on for preheating the emergency generator. I'll double check tomorrow, but I'm pretty certain it works by convection only.

[greasemonkey]

I think, if the heater goes in the bottom rad hose, then it should be fine without a circulation pump. I dont think it will circulate from there anyway, because the thermostat will be closed, unless it is getting it above the 80c odd that opens the 'stat.

But if its plumbed into the interior heater pipes, then its the water at the top of the engine being heated. Not sure how that would work, even with a pump.

[K.H]

Heres my homemade attempt

[Tony]

The chinese one integrates a circulation pump and is intended to fit the heater matrix part of the engine circuit (engine side of the thermostat).

But we were wondering what happens if a pipe freezes up, there is no thermostat on that particular heater to stop it boiling the pocket of water it contains.  There are more expensive ones (£110) that integrate a thermostat to stop this happening.

Keith what did you make yours out of?

Sometimes I think he's wasted as a builder, he should be inventing new stuff and running a tech company!

[K.H]

Its the sump and element from a dishwasher,a normal imm thermostat a 240v submersable mini aq pump and a washing machine inlet valve that isolates it when the power is off so that it doesnt restrict the flow,i bench tested it then gave it to RM not sure what he did with it,must be 3 years ago now

[julianf]

for a moment there, i thought that you had fitted an element to the engine sump!

[Rotary-Motion]

Its the sump and element from a dishwasher,a normal imm thermostat a 240v submersable mini aq pump and a washing machine inlet valve that isolates it when the power is off so that it doesnt restrict the flow,i bench tested it then gave it to RM not sure what he did with it,must be 3 years ago now

i still got it, not done anything with it k