dhwc install

I have a hilcoil for my pocono I was going to install today (really get started !!!!!!) on the instructions #2 the vent elbow auto float type air vent , I had no idea what this was, so a google search found grainger had them for $100 !!!! ouch . Do I really need this can I use something else ????. I have some 90's with the little screw vent cap. I am going to use the siphon method, but with fittings, pipe , the cost of the coil , and now this $100 vent .I'm not sure it's worth it. I am going to use valves and unions so I can take it apart when not burning. It's going to be well over $400 to install myself !!!!!!!!!.Just looking for some ideas to save some money on the install. Also what type of thread sealant should I use on the coil threads that come out of the stove, the area will be very warm !!! Scotty

they are not that much!!

plumbing supply store has em for 18-25 bucks....

Just make sure your tank is within 10 feet of your stove for the thermosyphon to work properly, otherwise a pump would be needed. Yes, use a few unions and isolation valves, a Pressure Relief valve (required), etc...yes, plan on $300-500 extra for all the other stuff.

here a few
http://www.pexsupply.com/Taco-Air-Vents-Hy-Vents-305000