How do I change a PRV on a Weil McLain boiler

[poison_1024]

I have developed a very small drip. The expansion tank appears to be fine and the pressure on the gauge is at an appropriate level. It seems these things are not the longest lasting devices. This is a WGO-3 model with the PRV at the upper left corner. Can anyone give me some pointers on how to replace this?

1) Shut off the unit and water input 2) Reduce the pressure inside the boiler (how can I do this manually?) 3) Unscrew the PRV and replace it (any particular sealant needed or just regular pipe dope?) 4) Turn on water source and turn unit back on. (Do I have to purge any air on this or is that done automatically?)

Thanks for your help.

[unitedslates]

A McCain boiler????????? Do they plan to boil Mccain now that he lost?

[Ed Pawlowski]

1 yes 2 open the drain valve 3 pipe dope or Teflon tape 4 purge if you can but minimal water should be lost

[poison_1024]

Hi thanks for your reply. A few more newbie questions. 1) Where is the drain. Unless it's hidden I do not see it. 2) In terms of purging the system how exactly do you do that? Thanks.

[Ed Pawlowski]

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The drain my not be on the boiler but on the piping in the system as it enters or leaves the loop. Every system is a bit different so look around. My system has a drain near the floor and a valve on each zone just before the circulator for the zone.

The heating system will have an air trap and should be self venting. If, however, you have a lot of air to get rid on, just slightly crack the drain valve just slightly while the circulator is running and you'll hear it sputter as air pockets pass by.

[poison_1024]

I found it, it's on the floor almost behind the burner. What is odd is that there are numerous ball valves on the hot water heater and one heating zone loops - I'm guessing they put them in in case you had a leak somewhere or had to swap the circulator out or make a repair. Plus there are three drain gate vales (in addition to the main boiler drain) - two on the hot water (indirect fired) loop plus one on the heating line. I'm not sure why there are all of these gate valves unless maybe you have to blow/flush them out for some reason. It must be fun trying to drain the boiler with no floor drain with the valve all the way down at floor level. I hope I can get enough out into a bucket. I suspect (hope) that I do not need to get all of the water out to change the PRV especially since I can close off the heating zone off. Thanks!