Second Water Heater

My kitchen is a LONG way from my electric water heater, which is under the floor beneath the downstairs bathroom. I'm thinking about adding a second water heater under the floor under the kitchen sink. (A tankless water heater is not being considered, and there is no inside cabinet space to accommodate another water heater.)
1. Can a short body propane water heater be installed in the crawl space? If so, does it have to be vented to the outside, or is venting into the crawl space sufficient?
2. Is there any reason that I cannot put a valve going into the hot water line at the kitchen sink that will allow me to switch between the present electric hot water heater and the new propane one?
3. My house is plumbed with 3/4" copper, but the line going to the kitchen is only 1/2". Shouldn't that line be upgraded to 3/4"?
4. What is the optimum water pressure for the house? My last plumber reduced it because it was way too high. Now it's too low.
The reasons I want to use propane are that we have a large propane tank for our gas logs. We don't use the minimum amount each month, so we can get some of the heating energy for "free". Second, if the power goes out, we'll still have hot water, and our power does go out way too often.
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It's sufficient if you don't want to live long. Your floor is not airtight and the crawlspace is likely not positively ventillated. The CO will work its way up into your living space and poison you.

What would be the point? Why keep water hot if you're not going to use it?

Most houses are only plumbed with 1/2"

Get the plumber back and make him increase the pressure.
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All codes are local, you need to call your local plumbing inspector. If it's allowed, you will almost certainly need to vent it properly.

No, but it sounds unnecessarily complex.

Not usually. Increasing the pipe size makes you waste more water and time waiting for the hot water to arrive.

Between 50 and 60 psi is considered normal. Exceed 50 and you increase the wear and tear on the valves in your house - especially the washer & dishwasher solenoid valved.
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How far is a LONG way? Fifty feet? 100 ft?

space? Yes
>>>>If so, does it have to be vented to the outside, or is venting into the crawl space sufficient?
Needs outside vent, it's a no-no to vent into the crawlspace.

water line at the kitchen sink that will allow me to switch between the present electric hot water heater and the new propane one?
Why bother? Propane usage mentioned below?

kitchen is only 1/2". Shouldn't that line be upgraded to 3/4"?
NO! A larger line will increase just increase the wait time. My kitchen faucet has 30 ft of hot water line feeding it (1/2" nominal PEX) and the wait is ~10 secs.

reduced it because it was way too high. Now it's too low.
I installed a pressuring reducing valve to bring the city water pressure ~75 psi down to less than 65 psi. Plumbing systems are suggested to have less than 65 psi to minimize water hammer...personally I prefered the higher pressure.

for our gas logs. We don't use the minimum amount each month, so we can get some of the heating energy for "free". Second, if the power goes out, we'll still have hot water, and our power does go out way too often. <<<<<
If you want to optimize your propane usage, you'd need to "start & stop" your propane heater use. I guess you could feed the one water heater with the other and turn one off depending on the propane usage. This might set up a situation for Legionaire's, something to think about.
cheers Bob
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Sounds like an ideal place for a point-of-use or tankless water heater. I've used them several times now and they work great.
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You're best bet is a 10 gallon electric. You can plug it in a standard outlet, and then feed it with the hot from the far away unit. You'll have instant hot and it won't use much energy since it will mostly be being fed with hot water.
steve

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Steve Barker wrote:

Are there any code issues with feeding a second hot water heater from a first one, as you recommend? I had heard about this configuration before, but I thought maybe I heard wrong. The tank would have to be under the house. There is not enough room under the sink.
The recirculator is a good idea, too. I had not heard of there being a switch at the faucet.
Thanks to everyone for weighing in on this question. An unvented propane hot water heater is now out of the question. The crawl space is about three feet, but I don't think that's enough to correctly install a vent. (Doesn't the vent have to point "uphill" so that the exhaust can escape?)
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Is it a heated crawl does it get below 70f, you have risks if it fails and its below 32, if its colder than the house you will waste propane, In the house is best.
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plus many propane water heaters for thru the wall type venting will need power line voltage to operate. that prevets OP idea of having hot water during power outages.
best to add the propane heater in series before electric heater in basement and re circluating pump so with push of button theres hot water. insulate both lines well to minimize loses
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as for the code question, i don't know. I don't worry about that. As for the circulator, you can also do that without a return line, you can send it back through the cold line. See:
http://www.chilipepperapp.com /
steve

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When I re-plumbed, I added an additional pipe back to the water heater from the end of the line, and a recirculating pump. At each hot water outlet is a pushbutton. Push it, and it turns on the pump for long enough to get hot water to the tap. So you walk in the room, push the button, and do whatever for 1/2 minute or so. Then, when you turn on the hot tap, you get hot within a couple seconds.
If your plumbing is in a crawl space, this could be as easy as adding another heater.
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I've seen crawspaces that are about 18'. No, it could not be used. I don't know your setup, but it must be vented properly.

No, no tif that is what you want to do.

No, the actual feed to the valve is even smaller. The more water sitting int he pipe, the longer the wait fo rh ot water.

Usually in the 50 to 60# range. The pressure regulator should have an adjustment on it.

It may pay to use a large propane in place of the electric. If it is getting old, consider a replacement and in the long run save money.
If my only concern is hot water at the sink, I'd look at a little electric under the sink. I don't know if it is sufficient to supply a dishwasher, but plenty for simple washing.
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mcp6453 wrote:

You are better off with a small tank point of use electric. A six gallon tank will give you instant hot water and by the time the hot water gets there from the big tank it will reheat the small tank so it would use minimal energy. No venting required.
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