Questions about procedure for installing Honeywell V8043E Zone Valves

I have a Honeywell V8043E zone valve that I need to replace. Unfortunately, it has the older style seat, so I can't just pull the motor assembly off. The Honeywell instructions say that I have to drain the system before I can remove the seat. However, I have also been told that if I have shut off valves before the zone valves that, instead, I can shut these off, install the valves and then turn the water supply back on. When I inquired about air in the system, I was told that the autovent should take care of this. I do have an autovent in my heater system.
Whose advice is correct? Any comments would be appreciated.
Thanks;
James M Wiedle
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On 22 Aug 2003 19:49:37 -0700, snipped-for-privacy@acsalaska.net (James M Wiedle) wrote:

If you have shut off valves that isolate that zone, you can just drain the one zone and do the repair. If you don't have a drain connection for each zone it will make a mess when you pull the zone valve and the water drains out of the zone piping. I usually turn off the make-up water supply as well, although not really necessary if the shut-offs work well. You will have to bleed the radiator(s) on that zone to remove the bulk of the air. The autovent can only vent air that reaches it. Generally, when you drain a zone, air will be trapped in the highest point of that zone (usually the radiator). After you do your repair, turn the make up water back on if necessary, open the isolation shut offs, and then (with the circulator off) open the bleeds on the affected radiator(s) until you get steady water flow with no hissing and bubbling. Then you're good to go. It's usually a good idea to bleed the radiator again a few days later to release any residual trapped air.
HTH,
Paul
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