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Forum Index : Other Stuff : Hot Water Thermal Losses
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Downwind Guru  Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Hot water cylinder thermal losses. I have a electric how water cylinder that is outside, and during cold periods the thermal loss through rather poor insulation is reasonably high. Here is a simple cheap way to help reduce those losses, which i have done and it works rather well. Through work we get a lot of products from China packaged in miles of bubble wrap, so for myself its a free source that normally ends up as land fill. I simply wrapped my hot water cylinder in layers upon layers of bubble wrap, using clear packing tape to secure each layer of bubble wrap. It added about 1-2 inches of insulation to the outside of the cylinder, very easy to do and it dont look that bad. I have not data logged the benefits, but i do have a picaxe controller for the solar hot water pump that records max and min temps, and by a few simple resets of max and min records and viewing the overnight differences it would appear to be about a 15-20% gain in heat retention, compared to no bubble wrap. All up its a positive gain for almost no cost (well the cost of a roll of packing tape). Just thought it might be of interest to other members, and if you can source some free bubble wrap its well worth doing. Pete. Sometimes it just works |
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| brucedownunder2 Guru Joined: 14/09/2005 Location: AustraliaPosts: 1548 |
yes Pete, I've thought of something similar, very cheap ,as your's is .. get one of those pressure foam cans and gradually fill from the bottom up ,leaving a boxed opening for the electrical/thermostat, . I used to do this with my sailing dinghy's for necessary bouyancy.. I could possibly get some of that "form-a-tube" from work sites that they fill with concrete, and then remove. Would look ok also.. Bruce Bushboy |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
There is many ways to add insulation and i have pondered over several, but it all kept getting too hard or too costly, and hence nothing got done. The bubble wrap was a no brainer for me, and within 20 minutes the job was done. I can not think of any thing easier than a wrap on insulation, like bubble wrape is. Pete. Sometimes it just works |
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norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Downwind, If your external HW is old it may suffer from moisture ingression. Especially if glass wool insulation which if you add water becomes a good thermal conductor. We come from the land downunder. Vic |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Norcold, Gee i doubt a HW service of that age would survive Adelaide water long enought to be still in service (10 years is a good life here) Mine is a expanded foam insulated HW service, but only with about 1 inch of foam between cylinder and outer casing, really a very poor design. From what i understand the current regulations demand a greater insulation for todays standards, but even then a little more added insulation can not hurt. Pete. Sometimes it just works |
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yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Mine was installed in 1963. Took it to pieces sometime in the eighties and soldered a seam that had split and while we had it apart I filled the cavity with batt insulation. There is a lot of room in the old ones. Apart from some mice pulling the glass out it has been a trouble free upgrade. 
I'm confused, no wait... maybe I'm not... |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
I can only guess you got your 60's and 90's mixed up, because it dont look to be a 60's model to me. 63 makes it as old as myself, and i doubt that is its correct date. As you say a solder repair, would deem it a low pressure unit, and not a mains pressure system, as here i often see above 80psi supply and would doubt a copper soldered cylinder would withstand that pressure. Nice paint job all the same. Pete Sometimes it just works |
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| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Those had a heat exchange coil, the outer cylinder was not exposed to mains pressure. That`s if I`m seeing right. I`d reckon there`d be probably still a few around here from that era operating, Braemars & Saxons installed by the hundreds when the "grid hit town". The local would call the plumber and in broken English, ask to have the "hot sister" installed. 
But over Easter had a good test of my 2 year old solar HW`s insulation(Solahart), Cloudy cool weather and a bunch of grandkids. No booster, no drama handled it with ease. We come from the land downunder. Vic |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Yeah Pete it is gravity fed low pressure, I have never had mains water. It pre-dates the mains power here by 7 years. I have been tempted to hook the old wetback lines up to a solar system a number of times but the amount of hot water I use doesn't justify the cost (or effort, I'm lazy). I should insulate some of the exposed pipework around the tank I suppose. I had a problem with the thermostat a while back and the plumber would not even look for a replacement (too old) so I gritted the teeth and went looking myself. Turns out, it is a standard industrial fitment and very cheap. That was a win! I purchased a roll of very heavy bubble wrap to transport some vintage TV's and radiograms a few years ago, the bubbles were about 20mm wide and thick plastic. I thought that might last a bit longer than the thinner stuff as insulation before it broke down, sadly no. I assume it is the UV that causes it, I got about 9 winters from some window inserts I made to winterize the house and keep some extra heat in, before they crumbled. It is a great idea Pete, perhaps an outer skin of corroflute and some of that plastic banding would give a heater a slick looking finish. I would not recommend the camouflage paintjob without practicing on something else first, this took me about six attempts and a lot of paint. I'm confused, no wait... maybe I'm not... |
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| M Del Senior Member  Joined: 09/04/2012 Location: AustraliaPosts: 155 |
Along the same lines as above I used foil backed fibreglass insulation on my old square water heater many years ago, to support & protect the foil I used the white plastic coroflute(?) sheets they make advertising signs out of. It cut my power usage in half for hot water, 8kwhr a day down to 4.5kwhr a day. When that heater died in 2006 I replaced it with a round one that uses 4kwhr on average without extra insulation. Time to do some more temp readings and source some ally bubble wrap insulation roll ends to cover the plastic bubble wrap. Some extra wrap may cut power usage down some more. Mark |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Yes UV breakdown of the wrap crossed my mine too, along with water getting between the many layers. My intention was to make a canvas cover (condom) to go over the outside and velcro closed around the plumbing side. like a canvas blanket with a top on it. Or even a canvas blanket with a draw string canvas hat to go over the top and down onto the blanket. Part of my work is making canvas awings so a canvas cover should not be too hard. I had thought of using Panda film plastic, white on one side and black on the other, as the white handles UV rather well, and again a simple wrap around solution with a good optic result. I see water between the layers a bigger problem than UV, moisture negates the advantage of the bubble wrap insulation. Then i might just be lazy and replace the bubble wrap in a year or 2 for the cost of a $2.00 roll of packing tape. Pete. Sometimes it just works |
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| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Another option would be wrapping with plastic UV resistant dam liner and plastic welding joints to keep moisture out, but as HW cylinders don`t have a long life down your way, guess replacing bubble wrap would be cheapest. I now know the insulation solahart uses seems far superior to what they once used, note the closed system I have uses steel tubes in the solar collector protected by the "hartguard" solution. We come from the land downunder. Vic |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
I think the insulation on older tanks was less to save energy and more to stop you burning yourself if you touched it. Last winter I wrapped my tank in packing foam, and a layer of builders insulation foil. I was surprised how warm it was if I put my hand up under the foil. This year I've done as Pete suggested, wrapped a couple of layers of bubble wrap around the tank, all taped down to keep water out and stop air flow under the bubble wrap. I still want to add a couple more layers of bubble wrap, and then a layer of the builders foil to finish it off. It's important to wrap up any exposed pipes too. Anything that feels warm will be loosing heat. Also with cold nights, a wrapped up pipe is less likely to freeze. So wrap it, wrap it good  The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Good point Glenn, i didnt think to use bubble wrap to do the pipes with, most of my outer plumbing is insulated with the black skins you buy, about $2.00 a meter. The skins work well, as long as you install them before joining the pipe work up. As i have several long runs in the house roof with no insulation, its a pain in the butt to add skins to, where strips of bubble wrap would be somewhat easy to wrap the pipes in. The plan now is to roll up sone bubble wrap and run it through the bandsaw and cut it into about 4 inch strips, which i can easy wrap the pipework in. Pete. Sometimes it just works |
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| M Del Senior Member Joined: 09/04/2012 Location: AustraliaPosts: 155 |
Pete, depending on how easy it is to access your roof and the position of the pipes in question (also personal preference), it may be easier (not cheaper) to overlay your pipes with half width insulation mats/batts. When I insulated my roof years ago I just laid extra batts (R2.5) over the top of the exposed pipes in the roof. You do however need to be careful of any high load electrical wires or fittings in the vicinity. I had a couple of remote thermometers sitting next the pipes under the batts for a while and it took many hours for the temp to drop from 60C to 45C. It still takes a few hours for the water to get to the point where it feels cool now. These were fibreglass batts not the polyester ones, so the warm pipes came with a little itching for a while. Mark |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Mark, Thats a rather easy solution too. The main problem line is to the kitchen, because it was once a in roof gravity feed system, that i tapped into and put a mains pressure heater outside, which is close to the bathroom and laundry, but now a long run to the kitchen, and as the old plumbing was in 3/4 inch copper for gravity feed, it now means over 10m of large copper tube to feed the kitchen, it wastes a lot of water waiting for the hot water to come through, and looses heat fast through the large copper diameter. So running the tap with a trickle to rinse dishes means the water is almost cold after a short while. The best solution would be to replace the copper with 1/2 inch and add skins to it, but its a reasonable cost and like all things a pain in the ass to get around to doing. I did think to use the plastic plumbing that all new homes are plumbed with nowdays, but without the right gear to crimp the conections it could be a right failure with in roof leaks, i think dragging the oxy torch up there would be safer, or even doing the welds on the ground and use compression fittings for the final connections would be the simplest. Its been on the "to do list" for several years but not yet done. Pete. Sometimes it just works |
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| Georgen Guru Joined: 13/09/2011 Location: AustraliaPosts: 462 |
For a while I try to think of some kind of glue that will glue pieces of stereo-foam. I would like to make custom made thermal insulator box out of pieces of otherwise waste, throw away packing material. I noticed that acetone dissolves and seen expanding foam used to fill in gaps between larger pieces. But am bit worried that expanding foam simply disappears after a while in service. Not sure if all of them do that or some? Does anybody have some working permanent solution, for what I am trying to do? George |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
As long as "space invader" aka poly urethane is kept out of the weather, it should last for years. I used to make 600mm x 300mm PU floats covered in a thin skin (300GSM) of fibreglass mat for controlling windmills (water pumping type). They sat out in all sorts of weather for many years without degradation. Perhaps you could cover with the Styrofoam, fill with PU expanding foam and apply a layer of F/glass to keep it all together? The PU and poly styrene foams both shape well using very coarse sandpaper. David M. |
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| Georgen Guru Joined: 13/09/2011 Location: AustraliaPosts: 462 |
Don't they disintegrate with time, irrespectively of Sun exposure or not? Remember of filling in hole in the wall with expanding foam, to see it comple gone in few years. George |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
That largely depends on the "free rise density" of the PU being used. The floats used about 32kg/cuMtr. The "space invader" PU in a pressure pack can is a bit less than that but still should last a long time. About 12 years ago I filled all the corrugated iron roof flutes on my f'glass workshop with the can stuff to keep the spoggies out. It is still as good as the day I did the job. David M. |
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