Andair fuel valve

I'm wanting to purchase an Andair fuel valve for my RV8, I can't quit make heads or tails which one I should be getting. My tanks have a return flow fitting. Should I use the FS20x7T or the FS20x20-3? Looks like the latter requires return lines. Is it better/safer/required to run the return line configuration?

To give some details: IO375 precision silver hawk fuel injection, efii boost pump and I'd like some way to purge fuel into the tank for hot starts if needed.

Brian--We helped a builder in Ohio plumb a purge return into the right tank with a branch female swivel fitting at his Andair valve. Male -6 on both sides of the run, branch was female -6 swivel to connect the Andair males.
Purge hose was -4, with a -6 hose ends at the valve, the wing hose connected to the other male port on the tee.
Tom

AFP and Andair solution

FlynBrian said:

I'm wanting to purchase an Andair fuel valve for my RV8, I can't quit make heads or tails which one I should be getting. My tanks have a return flow fitting. Should I use the FS20x7T or the FS20x20-3? Looks like the latter requires return lines. Is it better/safer/required to run the return line configuration?

To give some details: IO375 precision silver hawk fuel injection, efii boost pump and I'd like some way to purge fuel into the tank for hot starts if needed.

Click to expand...

I used the Andair FS20x7T with a swivel-T (Vans AN fitting) with a AFP Boost Pump/Filter assembly. For an AFP FM-150 fuel injection system. Not flying yet ... but here's the view. NOTE: The attach tabs on this version are fabricated to install nutplates making it a clean fastener, too. (nutplates not on mine in photo)

Thanks! It sounds like the fs20x-7t is what I'm looking for. The Andair and a swivel T setup will accomplish what I'm trying to achieve. Is the AFP purge valve the go-to choice or are there other purge valves I should also consider?

The AFP purge valve is the only one I have ever seen discussed here on VAF. I have installed one myself and like it a lot.

Now I'm not sure how that's going to work with the swivel T in your picture. I cannot see how you're going to get fuel pumping back to the tank and cold fuel into the lines. Maybe that's a benefit you don't care about. If you run the fuel pump with the purge valve open (pre-start with a hot engine), you're just going to circulate the fuel in a big loop warming is as it goes through the engine area.

FWIW, I installed the duplex andair valve with a return to each tank (fuel always goes back to the tank where it's being drawn from.) I can circulate cold fuel through the system prior to starting a hot engine, and more.

Bevan

I've been reading a bunch of posts on this as well as the great advice from all of the posts above. I think its becoming more clear. It sounds like there are two popular installation methods.

1. A full duplex setup that Bevan has described above which is very nice.
2. Running a line from the purge valve back to a swivel T fitting plumbed into one of the fuel lines just before the fuel selector switch. It sounds like you can purge warm fuel into a tank using this setup by selecting the opposite fuel tank from where the T is installed prior to purging. This would seem to allow the fuel to go to the purge valve back to the T fitting and back into the non-selected fuel tank. The downfall with this approach appears to be only having the ability to purge back into one tank and its one more check list item to verify in an emergency situation.

Am I understanding this correctly?

Well, the swivel T in the picture appears to be connected to the output of the fuel valve. Unless I am misunderstanding that particular valve configuration. See

http://www.mykitlog.com/users/display_log.php?user=garyc&project=757&category=6392&log=178164&row=26

Bevan

3rd option

You can also plumb the return line to before the valve to one tank only. (Let's say right for this discussion, but it could be either). When you want to purge, switch to the left tank, and draw cool fuel from there while returning warm fuel to the right.

Just another opinion-

That's a lot of money and system complexity to address the "hot start issue". Proper hot start technique is equally effective, and adds no cost or system complexity.