insulated hot water lines? Do they make much difference?

Hello group.. I am in the early stages of building a house and this is my first new one..I have been going over options with my builder and hitting him with stuff I have gleaned from talking to other people..One thing I have seen a couple of references to are insulated hot water lines...I am wondering how effective these would be..My water heater will be in the garage, which is on one side of the house and the master br and one guest bath is on the opposite side of the house. The house is over 80' wide from one side to the other..One thing I have been concidering is one of those hot water circulating pumps, but seems like insulated pipes would help prevent temp loss...How do they do it, just simply wrap the pipes with foam prior to installing and pouring the slab? I have not hit him with this do don't even know if it's too expensive... Thanks in advance for any comments... John
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On Wed, 21 Jan 2004 14:54:27 -0600, "John"

There are inexpensive foam tubes (with a length-wise slit down the side) you can use to insulate the water pipes. Well worth the cost. I insulated my cold water pipes where there could be a sweat problem. Use wire to secure the insulation.
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80 ft is a long way, I have a apt bldg with maybe 80 ft . the heat loss with insulated pipes and recirculating pump is 10 degrees and the pumps cost alot to run and waiste alot of heat. Your heater should be in the middle, or better yet use 2 tankless gas Takagi heaters . one at each end . They last longer are 83% efficient and will give you a 4 yr payback. My Water heater costs are down 80% from electric tank. Yes you should insulate all hot water pipes with foam sleeve. And insulate your heating ducts
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The tankless gas water heaters consume no energy when hot water is not used (except for electronics). Unless you're interested in heating your basement year-round with water pipes, the recirculating pump system is an energy hog, insulated pipes or not. You could design a new system with a couple of tankless water heaters close to points of use (as mentioned above). However, they are more expensive than conventional water heaters and not all contractors are familiar with them.
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Actualy Bosch has 2 models that dont consume electricity at rest or 120v. One model uses 2 d cells , my batteries are going on the second year. A second model has a mini Hydro generator for spark ignition.
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I would insulate. My kitchen is about 20' (as the crow flies) from the water heater. When I 1st moved in, 30 years ago, you would wait and wait for hot water in the kitchen. And, even after getting it, 5 minutes later it was cold, really cold. I discovered that the hot water pipe went from the heater around a small basement furnace room, then down to the basement floor and eventually passed through the floor concrete to the other side of the basement. It finally emerged and went up to the kitchen above. I replumbed it on the basement ceiling, eliminating some of the loop-the-loops, insulated the pipe with foam covers and now the water stays hot for some time. For a long run in concrete, I would think insulation is a must. I would also consider a "return line" back to the heater. As it sounds like a one level construction, a small pump might be in order.
BTW, I recently discovered a similar situation in my powder room. Ironically, the sink is about 1 to 2 feet from the top of the water heater. However, the pipe goes into the concrete for about 6'. It seems to take forever to get hot water and even when you finally do, it gets cold in a few minutes. I plan on making a direct connection to the heater, however, this will have to wait until this heater dies as the connections would be impossible without removing the entire heater.
John wrote:

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I dont recomend having your pipes in a slab even if they are insulated , unless its pvc a chemical reaction can occur if any concrete touches the pipe, 2 your slab will probably be 50 to 55 degrees all year, your basement will be alot warmer, less heat loss. Id also be worried about settling and future upgrades and repairs.
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If it's still in the design stage - why not move the water heater to a central location? This seems like an odd arrangement. The water run is long; central will minimize the pipe length - and heat loss. I'd hide it in a closet closest to the room that uses the most hot water (bath, laundry, kitchen, whatever).

Insulation will not stop heat loss, it will only slow it down. If you wake up in the morning and hop in the shower, the water will have had all night to cool - I can't say how cool it will be, but it won't be hot. To determine how much insulation is needed to be effective, you'd have to consider the water temp vs temp outside the pipes and figure out how much insulation is needed to get an acceptable level of heat loss. I don't know about Texas, but where I live up here in the Great White North, it would take a lot of insulation on the exposed part of the pipe to keep the water hot overnight in winter.
You definitely want to insulate the pipe where it exits the water tank for a distance of a couple of meters (yards) to minimize the heat loss from the tank while it's sitting there.
If you use a circulating pump, you'll just spend money heating the air and slab.
Mike
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I think the pipes are usually laid in the dirt along with the drains before the slab is poured, ending up under, not inside the slab. I would definately install a return line if your 80 feet from the WH and insulate both lines as well. Copper pipe is cheap and insulation sleeves even cheaper.
While you're at it, I'd install 1 spare 3/4 pipe from the WH to the furthest bath just in case either the hot, cold, or return line ever spring a leak. These are things a contractor could care less about, but mean a lot to a homeowner.
Also - a 1/2 inch hot feed will get the hot water there more quickly than a 3/4 line, though you'll lose pressure if both the guest bath and master bath call for hot water simultaniously. (In the event you don't go the return loop method)
Also note- most return loops work on convection and gravity if plumbed right, eliminating the necessity for a circulator pump.
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Buddy,
The last part of your post intrigues me. Could you explain how convection and gravity will make the return loop run? I'm interested and clueless!
Larry
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I just insulated the copper hot water pipes in my basement about a week ago. I used the foam things that you see in the store. It made a big difference. The temperature at the tap is much hotter. I may even rip apart some of my walls to insulate more of the pipes.
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In addition to all the other good comments so far, I would suggest insulating with 1-inch (or maybe 1/2 inch) jacketed fiberglass pipe insulation if you can get it at a supply store. I used some of it many years ago, and more recently used some of the black foam stuff. The fiberglass does a better job, I think, and I trust it more than the soft foam for longevity. I am not sure about the relative R values. If you are doing new construction, then do both hot and cold lines, the hot to hold energy; the cold to minimize sweating. Gravity feed with a loop would probably not work well for the length of lines you have unless the pipes sizes were much bigger and the insulation was super. A pumped loop would also need insulation. Anyone know of any good internet accessible studies of this subject? Others have posted some great considerations. --Phil
John wrote:

--
Phil Munro Dept of Electrical & Computer Engin
mailto: snipped-for-privacy@cc.ysu.edu Youngstown State University
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