Boiler - automatic air vent and pressure relief valve?


Old 05-27-03, 03:41 PM
Visiting Guest
Posts: n/a
Boiler - automatic air vent and pressure relief valve?

For a variety of reasons, I need to replace the pressure relief valve on the gas-fired boiler for my single-pipe hot water heating system. The old relief valve is mounted horizontally off the side of a tee attached to the pipe coming from the boiler, and an old automatic air vent is attached to the top of the tee (see attached diagram) Do I need to replace the auto air vent when I replace the pressure relief valve, or can I eliminate it and attach the new valve directly to the pipe from the boiler? I have a standard (non-bladder type) expansion tank which I drain and re-charge yearly and otherwise have had no problems with my system. If you recommend keeping the automatic air vent (I'll put in a new one), does it matter whether it is mounted horizontally or vertically? Also - any tips on refilling the partially-drained boiler once I attach the new valve (or, if necessary, the two new valves). Thanks for your help - it's a great forum!

Sponsored Links
Old 05-31-03, 08:12 AM
notuboo's Avatar
Join Date: Sep 2001
Location: Kansas City MO
Posts: 1,780
Received 0 Votes on 0 Posts
The new Pressure Relief Valve must have the ability to discharge a higher BTU rating than the boiler is capable of producing. Be sure to check the rating of the new valve, it will be on a metal tab attached to the valve. It's location on the boiler is set by the manufacturer for very specific reasons, you should not change the location of this valve because you enhance that chances of something bad happening.

The same for the auto air vent. These MUST be installed in an up position. No option for this.

The expansion tank you mentioned is for a totally different purpose. It regualtes the pressure on the system and has no real impact on air being allowed in or out of your system.

Hope this helps, more questions, ask away and someone will answer them...
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: