Add Automatic Damper to Barometric?

JackStevens

I live in a 2-family house, built in 1929. Two steam boilers' flues feed into a single 12-inch chimney flue. Each boiler has a barometric damper teed off its own flue pipe. My problem is the very healthy draft constantly pulling cold outside air into the basement, in turn cooling off the first floor.

My question is whether I can or should install two automatic dampers. In reading related threads, there seems to be some concern as to soot and high temperature reducing their reliability and safety when installed in-line. Could I, instead, extend the barometric dampers' tees and install the automatic dampers there? It would be a cleaner and cooler environment. Then, if it failed, it would either cause a constant draft (the situation I have now) or an uneven draft (partially mitigated by the other boiler's barometric damper) until it could be fixed. I don't see the much smaller amount of air pulled in through the burner when it is off as being much of a problem.

Here are a couple of photos of the setup. Thanks, everyone, for your help.

EBEBRATT-Ed

Field Controls model OVD

(oil vent damper is what you need it is made just for the purpose you are speaking of you can google it.

Also (and this is not causing your issue) your barometric (I only see one) is incorrectly installed on the run of a tee. It is supposed to be installed with the flue collar that it comes with.

I assume with the boiler you have your on oil as I can't see the burners.

Steamhead

W-M is now supplying OVD dampers with new SGO series oil boilers.

JackStevens

I added the locations of the barometric dampers to the photo for clarity.

EBEBRATT-Ed, I see what you mean about the location of one of the barometric dampers. Yes, those are Weil-McLain SGO Series 3 boilers with Beckett oil burners.

Steamhead, if W-M is supplying OVD dampers, I am persuaded that the earlier safety and reliability concerns have been laid to rest.

Thank you both for your help.

EBEBRATT-Ed

@JackStevens

I read about the OVD briefly. It looks like it can be installed between the barometric and the chimney which would alleviate your problem

Bob Harper

You could shorten that chimney connector on the right hand unit by about 10 LF. The pipe is inadequately supported. The counterweight on the RC baro. damper is on the left, which is for horizontal applications. It needs to be moved to the right side then adjusted. Where are the test holes for draft pressure? I see a hole for combustion analysis.

JackStevens

Bob Harper, I wonder if the wide-angle shot makes it looks like there is extra ducting. Here is a photo taken from the left side of the original that may be clearer.
I understand about the support for the flue (though to be fair to the installer, it has been secure for 25 years) and the lack of a hole for draft pressure testing. I will certainly talk with my heating contractor.
The weight on the Field Controls RC barometric damper is on the "H" side, so I should be okay there.

EdTheHeaterMan

When you get your OVDs and are ready to install them. Try this to shorten the connector from the boiler on the right. The first elbow can be connected directly to the boiler on both systems. or a short (up to 6” long) straight piece if you need to go around the relief valve or other obstacles. Just before both boiler vent connectors go to the common pipe increase to 9” pipe. (if not available go to 10”) as illustrated. The Barometric can be on a 45° pipe as long as the hinge is level and the face is plumb. The weight will go on the V side if the angle is less than 45 or on the H side if the angle is closer to the Horizontal.


This way, your vent connector will be much shorter with less fittings that add to the total equivalent length and its easier for service during maintenance. Be sure to provide sufficient hangers to support the vent connector pipe.

JackStevens

EdTheHeaterMan, Got it. Thanks.