Questions about installing a ventfree gas heater

I have been meaning to get one of these for a few years now, and when I saw them at half price at HD I ran out of excuses. Except for installing my water heater I haven't done any gas plumbing, so I have a few questions.
1) When I had a new furnace put in a couple years ago I had them put in a T for this, but foolishly didn't think to have them put a valve on it. The only valve is one by the gas meter. Is it okay to use that? I don't see any alternative.
2) I am putting a valve just past the T. Do I have to put one just before the heater also? I suppose I could leave out the one at the T, but I like the idea of shutting the whole line off.
3) The directions show a T with a 1/8" bushing right before the valve at the heater. What is that for?
4) It specifies 4" W.C. to 10" W.C. pressure. Since my water heater and furnace work fine, is it fair to assume I have pressure in that range?
5) Can that 1/8" bushing in #3 be used for compressed air to test for leaks? How many PSI is reasonble for a compressed air test?
I know I am asking a lot of questions, but my water heater is still okay after 3 years, and this doesn't seem any more difficult.
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Toller wrote:

Put a gas-rated valve at the appliance.
Gas pressure should be OK. This article may answer some questions: http://www.frentzandsons.com/content/howto/builtingrill.htm
helpful info here too: http://www.worldmkting.com/gas_heaters1.htm
Don't know what the 1/8" bush was for but be sure to install the drip leg at the appliance.
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Toller wrote:

Put 2 manual valves at the tee, one for the furnace and one for the new heater. That way you can service one and use the other.

There should be a drip leg, also called a dirt pocket at the heater to catch any dirt, dust or rust that comes down the line. If the drip leg is not there, small debris can get into the small passages in the gas valve and screw it up. I have seen automatic gas valves do terrible things for lak of a drip leg. And, it is required by code.

Probably, but best to get a test gauge. Or use clear "U" shaped tubing 20" high (U Tube Manometer) with water in it to test inches water gauge. If the difference between the two tops of the water columns is 10", then pressure is 10 inches. (28 inches = 1 PSI)

If you do not disconnect other automatic gas valves and CAP the lines of, you may damage the automatic valves. Most are rated for just 1/2 PSI (14 inches). Be careful.

Stretch
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i bought a rinnai vented instead at:http://alsheating.com/RinnaiHeater.htm
why use a vented heater: http://alsheating.com/WhyVented.htm
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Very cool!
Have you been happy with the vented Rinnai?
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