Hot Water Donkey from Beer Keg

Submitted: Thursday, Nov 12, 2009 at 14:23

ThreadID: 73712 Views:17391 Replies:13 FollowUps:9

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Member - Norm C (QLD)

I just posted this question on the Caravanners Forum, then thought it is 'on topic' for EO (relates to camping) and there are some smart people here, so I'll ask it here also.

I've got my hands on an old beer keg that is in good condition. I am looking to make a hot water donkey from it. The keg seems to be aluminium. The idea is that it will be put on a small stand and a fire will be lit under it to heat water for showers etc when bush camping for an extended period in one place.

I'll need to connect two hoses to it, one for cold water in at the top and and one for hot water out at the bottom. For the moment, I'm assuming I'll be able to pump cold water into it under pressure, so I'll have pressurised hot water out as well.

I'm figuring the main mods I need to do are:
1. Connect (drill hole and weld) appropriate fittings to the side near the top and bottom. I'll need to connect copper pipe to both of these for the first 40 cm or so (due to heat), then convert to plastic, garden hose or other from there. My main issue is to select the right fittings. Can copper be welded direct to aluminium? Or do I need to connect brass, stainless steel or something else to the keg initially. Concerns are both physical strength of the connections and the effect of using dissimilar metals.

2. Put a pressure relief valve of some sort in the top of the keg in case I get it too hot - I don't want it to blow up!!! I'm figuring I can get a simple pressure valve of some sort from a plumbing supplies place than can be screwed into a hole drilled in the top.

Are there any issues with the ball valve in the top of the keg where the spear (?) is attached to extract the beer? I'm figuring it can be left alone and should not be concern. The keg is stamped with words to the effect of ' safe operating pressure for this container is 500 PSI'.

Anyone got any thoughts and advice on this. Not the end of the world if it does not work, but it seems a good project if I can sort it out.

Norm C

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Reply By: sandk33 - Thursday, Nov 12, 2009 at 14:31

Thursday, Nov 12, 2009 at 14:31

Give it away ...its stainless steel for a start ...and you are to matter of fact about putting maybe some sort of pressure relief valve.........if you don't know get someone who does know how to set it up otherwise you might end up killing or injuring all and sundry within 100mtres

AnswerID: 390995

Reply By: Moose - Thursday, Nov 12, 2009 at 14:41

Thursday, Nov 12, 2009 at 14:41

G'day Norm
All the donkeys I've seen have had a simple system with an inlet hole on top (into which a funnel is inserted for adding water) and an outlet piece of pipe near the top at one end. So anyone wanting water has to pour cold in to get some hot out. Not sure why you're talking about pressurising the thing - too complicated. Mate - stick with the KISS principle!
Cheers from the Moose

AnswerID: 390999

Reply By: handy - Thursday, Nov 12, 2009 at 14:46

Thursday, Nov 12, 2009 at 14:46

your hot water comes out of the top[ heat rises ] and the cold goes in at the bottom . they would all be stainless.

AnswerID: 391000

Reply By: camwill69 - Thursday, Nov 12, 2009 at 14:50

Thursday, Nov 12, 2009 at 14:50

Hi Norm,
I have a 50l keg for both hot water and water storage. I would not go down the pressured vessel path as this is just waiting for trouble. Use the KISS principle. keep it simple silly. Just put the keg next to the fire, have a filler point at the top and an outlet at the bottom, connect your pump to the outlet and presto you have hot water on tap.

It is most likly a S/S keg. Pull the spear out and get the inlet and outlet welded in with a thread to suit , most likley 3/4.

Regards,
Cam

ps, how did the ply go?

AnswerID: 391002

Follow Up By: Jethro T - Thursday, Nov 12, 2009 at 15:07

Thursday, Nov 12, 2009 at 15:07

You can put the outlet near the top of the keg at one end and put a funnell in top of the other end,

When you put cold water in it goes to the bottom and pushes the hot water out near the top at the other end.

Simple and works well.

Regards
Geoff

FollowupID: 658828

Reply By: Member - Pesty (SA) - Thursday, Nov 12, 2009 at 15:10

Thursday, Nov 12, 2009 at 15:10

This is how i would aproach it from experience,
Make your stand, mount your keg, drill a large hole in the side near the top, weld a delivery pipe about 6inches long into the side, find a metal funnel, or make something along those lines, and weld a pipe to it, feed through hole in top so pipe is just short of the bottom of the keg, inside.
To get hot water out, you place your bucket under delivery pipe, and pour the amount you want of cold water into the funnel, and the exact same amount will come out the delivery pipe, so HWS is always full and ready for use, NO PRESSURE is required to have good hot water.

Pesty

AnswerID: 391005

Follow Up By: Member - Norm C (QLD) - Thursday, Nov 12, 2009 at 15:30

Thursday, Nov 12, 2009 at 15:30

Yes, I've made and used 'put and take' systems many times - generally from an old 44. I'm looking to be a bit more adventurous this time if I can. Fall back is the old put and take if I can't work it out effectively and safely.

FollowupID: 658834

Reply By: Member - Norm C (QLD) - Thursday, Nov 12, 2009 at 15:20

Thursday, Nov 12, 2009 at 15:20

As suggested it is more likely the keg is SS, probably 304 stainless. In my view this makes it easier as brass and copper can be effectively brazed to SS. Or I could possibly use stainless fittings and weld.

I would have any welding done by an experienced TIG welder.

Yes, I accept that a non pressurised 'put and take' system is simpler, but I didn't get where I am today by always seeking simple solutions. I may well end up making a simple 'put and take', but doing something a bit more adventurous has got my imagination - if it can be done cheaply and safely - and I suspect it can.

I'm a bit reluctant to pump hot water out (that is, have hot water going through the pump. Doing it my way, I am only pumping cold water - the hot water being pushed out by the incoming cold. Also, at one of the places I would use it, I have pressurised bore water available, so no pump would be needed.

Norm C

AnswerID: 391008

Follow Up By: Member - John M (NSW) - Thursday, Nov 12, 2009 at 15:34

Thursday, Nov 12, 2009 at 15:34

Norm

I have had a 9 gallon s/steel keg used as a water heater for about 20 years. When my kids were young and we camped on Moreton and Stradbroke Islands it was nothing for this unit to provide hot water for 25 to 30 people.

It has removable legs, fill with cold water from the top and the hot water comes out the side at the top. Simple to make and works fantastic.

If you want it you can have it when I come to Brisbane over Xmas.
Just let me know.

Regards

John

Life isn't about how to survive the storm, but how to dance in the rain!

Lifetime Member
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FollowupID: 658835

Follow Up By: Member - Norm C (QLD) - Thursday, Nov 12, 2009 at 15:59

Thursday, Nov 12, 2009 at 15:59

Hi John, we are actually at Green Point (Gosford) at the moment. Brother-in-Law has the keg and has offered it to me. We are winding our way south on our way to Tassie, then back North to spend the winter in NT (where I would use the keg HWS).

I'll have to design and get any mods done to the keg on the way, but will have plenty of time for that.

For the moment, I'm working out if it is worth packing the keg and carrying it all the way, so we can use it in NT.

Thanks for the offer though.

Norm C

FollowupID: 658841

Follow Up By: Member - Timbo - Thursday, Nov 12, 2009 at 16:25

Thursday, Nov 12, 2009 at 16:25

Norm, why not just make a simple put-n-take donkey but put a 12v pump on the CW inlet, that way you can have the hot water with the flick of a switch (instead of having to pour cold water in to get hot water out).

If you wanted to get a bit more fancy, you could even fit a tap (or trigger nozzle to the outlet) and get a 12v pump with a pressure switch operating on the inlet - you would probably still need a pressure release in this last case (the water will expand as it heats) but if the keg is rated to a few hundred PSI, perhaps a standard domestic pressure relief valve would do the job?

FollowupID: 658844

Follow Up By: Member - Timbo - Thursday, Nov 12, 2009 at 16:37

Thursday, Nov 12, 2009 at 16:37

Sorry, should clarify: I meant "standard pressure relief valve from a domestic hot water heater/tank".

FollowupID: 658845

Reply By: jvb1 - Thursday, Nov 12, 2009 at 15:25

Thursday, Nov 12, 2009 at 15:25

Have a look here, it is a set up similar to what you are talking about, sorry cant post picture.

http://myswag.org/forum/index.php?topic=1863.0

cheers JB1

AnswerID: 391009

Follow Up By: Member - Norm C (QLD) - Thursday, Nov 12, 2009 at 15:51

Thursday, Nov 12, 2009 at 15:51

Not quite what I had in mind, but a great set up just the same. Has given me some ideas for both my pressurised system and an alternative if I go no pressurised.

Thanks for the link.

Norm C

FollowupID: 658837

Follow Up By: Member - Norm C (QLD) - Thursday, Nov 12, 2009 at 16:00

Thursday, Nov 12, 2009 at 16:00

I wonder how he cut the lid out so neatly?

FollowupID: 658842

Follow Up By: Member No 1- Thursday, Nov 12, 2009 at 18:14

Thursday, Nov 12, 2009 at 18:14

laser?

FollowupID: 658854

Reply By: Mandrake - Thursday, Nov 12, 2009 at 19:43

Thursday, Nov 12, 2009 at 19:43

Just a thought from someone who know diddly squat about things plumbing -

Put fire under the barrel -
Put a 1/2" copper pipe coiled from top side of barrel to bottom side of barrel - several turns long inside the barrel ..
leave the top open with a loose cover and pass cold water in the top of the coil to run round and around and out the bottom possibly getting real hot as it went along the coiled tube - Could have water in the barrel boiling to keep copper coil pipe hot or maybe just hot air would do it ...

Like I said I know nuffing about plumbing ...LOL

Cheers

Mandrake

AnswerID: 391033

Reply By: Von Helga - Thursday, Nov 12, 2009 at 21:28

Thursday, Nov 12, 2009 at 21:28

For John M,

Hey John Since does not want it I'll have it.
Cheers
Trevor

AnswerID: 391048

Reply By: Richard Kovac - Friday, Nov 13, 2009 at 00:04

Friday, Nov 13, 2009 at 00:04

Norm

someone but this up in the swap files once. hill billy

someone = No. 1

cheers

Richard

AnswerID: 391067

Reply By:- Friday, Nov 13, 2009 at 00:41

Friday, Nov 13, 2009 at 00:41

G'day Norm C, the donkey systems I had experience with were gravity fed from the bottom of an overhead cold water supply with the cold water entering the donkey at the bottom and hottest part of the donkey then discharging through another pipe above but on the same end of the drum on releasing the pressure by turning on a tap which of course is the hot water tap. The cold water to the mixing manifold for the cold water tap came from the bottom of the overhead source. If my memory is serving me correctly there was another hose coming off the donkey top outlet to take overheated water back into the top of the overhead source and preventing over pressurisation of the donkey. Brilliant in its simplicity. Happy Days, Pauper.

AnswerID: 391072

Reply By: Honky - Friday, Nov 13, 2009 at 10:49

Friday, Nov 13, 2009 at 10:49

You could chase up a "Chippy" water heater.
Basically a two skinned drum that you light a fire in the inside one.
It has a funnel for air entry into the fire box which creates a bellow effect.
It has a spout at the top where the water comes out and a long funnel that chanels the water down to the bottom pushing the hot water to the top.
Very effective without using much wood ( best to use wood chips hence chippy)

Honky

AnswerID: 391102

Reply By: Hespy (NT) - Friday, Nov 13, 2009 at 14:19

Friday, Nov 13, 2009 at 14:19

This is what they use in the NT.
I use a similar one(smaller version) made out of a 50l beer keg at my property at Dundee. Also very portable and can be used for other camping trips. Unlike the 44 gallon drum which already has the threaded inlet and outlets, just drill two holes and have two nuts welded in place.

Donkey Heater

AnswerID: 391126