Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Downsizing an Equalizer on 45: Bad?

vaporvac Member Posts: 1,520
It's recently been mentioned it's a bad thing to down size an equalizer on a 45. I know it's best to go vertical, but thought I'd read this was OK and have seen a few pro installs with this. I hope so because that's how we're piping this right now! We're coming down 3" after a 4" elbow. Please see the pic of the elbow as well as the header., although it's too late to change it without holding up the entire project.

I hope this is OK as I upsized my header to 4" and am using two 3" risiers into a high drop header. we will be further reducing it to 2" on the vertical for the Hartford loop.Thoughts? C

Here was mdnlansings reply and corroboration:

Also, your equalizer needs to reduce in the vertical plane, not on the 45. Move the reducing coupling lower to the vertical drop into the return.


I was given this advice by two people. First, the steam guy I'm working with suggests not introducing any place that can slow water in the return from the header. When the boiler first starts it will generate steam up the equalizer, this can condense and pool in the reducing coupling. When steam and condensate enters from the header you can get hammer by a wave created when it reduces. If you have to reduce it on the 45, he says to use an eccentric coupling so no water can slow.

I also have an email response from Weil-McLain. I sent them my near boiling piping design and they recommended leaving all horizontal and 45 piping the same size and only reducing with a street elbow pointing down, or in the vertical plane. They offered no explanation for this though, just the recommendation. The exact wording is as follows...

"4. Maintain consistent pipe diameter on all equalizer pipes except those that are exactly perpendicular to the water line. Reducing size with a street elbow is acceptable so long as the reduced side of the elbow is perpendicular to the water line."

I just replied to them asking for an explanation of this item. I'll post what they respond with. I'm assuming its the same reason I stated above, but it might be something different, I'm not sure.

I don't think this is a big issue though as I've seen plenty of installs that do it. I don't have enough experience to tell you what I've seen in the field but eliminating any place for water to collect makes sense to me. However, if it were a major no no I would think there would be plenty of posts talking about it. Maybe ask some other pro;
Two-pipe Trane vaporvacuum system; 1466 edr
Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF


  • MDNLansing
    MDNLansing Member Posts: 297
    Weil McLain Response

    Here is the response I received from Weil McLain today.


    As a general rule, all pipe diameter transitions need to occur in a vertical orientation, perpendicular to the water line. This is to prevent slow moving water from forming small pools around fittings inside the pipe. Small collected pools of water can often be more problematic than water ejecting into a path of steam. Pools of condensed steam will allow the steam flowing over it to cool very rapidly, causing a cold void. This void will quickly fill with either water or steam. When this void fills the resulting sound is what we call water hammer. Often times, this water hammer will can be accompanied with upwards of 900 pounds of force on the pipe and fitting. Water hammer is not just an annoying sound, the forces involved with it can also cause damage to the system. We always recommend eliminating every possible place that water can collect and pool for this reason.

    If transitions must occur on non vertical pipes, we recommend using eccentric couplings or street connections over bushings. Bushings will introduce a lip inside the fitting that can dam up small amounts of water. Street and eccentric (installed properly) fittings will allow water to flow through the fitting much easier.

    We strongly feel that these recommendations need to be followed in your particular installation. Since you're objective is to heat in the most efficient way possible, you will be running with very low pressures. This will also result in slow condensate flow rates at the beginning of cycles. We feel it's important that you avoid any place that can catch water and slow it down, being it will be flowing slow to start with anyway. Since this is a new installation requiring all new near boiler piping, this shouldn't be much of a concern. If you need further assistance piping in accordance to these recommendations, please let us know. We should be able to come up with a solution to place the transitions on vertical pipes only."

    Like I said before, I don't think this will be much of an issue with your header / equalizer. If anything, it would cause a little pooling in the end of the header, but it won't be much. Based on what they are saying, you will be fine.
  • vaporvac
    vaporvac Member Posts: 1,520
    good info...

    Thanks for that very clear description. Hopefully others can benefit. from it.

    I, too, don't think this will be a problem in this case.. We did NOT transition from 4" to 3" until AFTER the elbow and it is a steeper incline that 45. I'm sure you've seen the many installs with the transition actually on the horizontal. This is NOT the case here.

    Additionally, my drop header has been upsized, so I'm still using the recommended 3" on the equalizer until we go down to the hartford loop which is 2". The reducer we used (see above pic) has smooth transitions inside. Unfortunately, we have already hung the header and it would have been very difficult to redo and I'm not sure it will make a huge difference. 4" fittings are hard enough to get, much less on a Sunday. Since noone responded saying, " NO, no, no!!! ", I figured it

    was OK.

    We've had so many set-backs with the install (broken threader, UPS delays, etc, etc) that I'm just happy to have something to show for all the effort and time. I'm hoping today is more productive.

    p.s. After having read the Wiki description and image of eccentric reducers, seems I'll be OK, since we are not on the horizontal. Makes perfect sense for that.
    Two-pipe Trane vaporvacuum system; 1466 edr
    Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF
This discussion has been closed.