Single Pipe Steam Heat Radiator Vent ID and Replacement Rec

MikeC_3 · March 5

As per my previous inquiry, I replaced the non-functioning, undersized main valve on my mother's heating system with a Gorton # 2. Whether the ideal fit or not, it sped up the heating time by about a third and reduced gas consumption per week by about 25%.

The only major issue now is two runs of baseboard heat on the first floor furtherest from the boiler in rooms that were "modernized." They still take around 25 minutes to heat up end to end. One is 8 foot in length, the other is 10. They are off a main run of 1 1/2 inch pipe approximately 18 feet.

Using the formula in the G & P guide to balancing, I calculated that they would require a Gorton C or D. However, upon closer inspection (which admittedly, I should have done first), I now realize that these units are vented in a different manner. From reading up in this forum, it seems like this is the preferable way to vent long runs of baseboard - as a two pipe system, allowing the condensate to flow more freely.

So, how does the current configuration affect vent size, if at all? .

Also, the current vents are 3/4 inch and what I believe to be main line type. I haven't had the chance to remove one to inspect it more closely. Is this scenario possible - could they be main vents? Do they make 3/4 radiator vents (not that I have found)? If not, what would be appropriate?

Thanks!

Steamhead · March 5

You're right. That looks like an old Flair vent, but it's 3/4". 3/4" convector vents do exist however, and they vent more slowly than main vents.

Since Hoffman has moved production of air vents to China, with accompanying drastic reductions in venting rates (hey @gerry gill, any way you could test them?) I no longer use or recommend them. But you might try a Vent-Rite #35 or #75 on those baseboards to see how that works.

But that would still leave the problem of differing thermal behavior between those baseboards and the cast-iron radiators in the rest of the house. This can cause uneven heating.

MikeC_3 · March 5

So, there is no issue with using a main vent on a radiator?

@Steamhead - either of those Vent-Rites would work, but if my calculation is correct (BIG if) , they might be a little on the slow side. Does the method of piping have any effect on vent sizing?

As far as uneven heating, I am not shooting for absolute perfection. Just hoping for less consumption and somewhat even heating so my mother isn't shutting every door in the house. Moving in that direction with everyone's help here!

Any idea of the venting capacity of this heap one at Lowe's? Figure I could spend $16 just to see what happens before splurging.

https://www.lowes.com/pd/Durst-Silver-Hydronic-Baseboard-Heater-Accessory-3-4-in-x-1-2-in-Straight-Quick-Vent-Steam-Compatible-Large-Fixed-Vent-Easy-Installation/3535250

ethicalpaul · March 5

Don't buy vents from big box stores

MikeC_3 · March 5

Well aware but when the other option is $150+, $16 seems worth it to troubleshoot.

mattmia2 · March 5

I'd probably g o with this and a 90 and an adapter(adapt in the vertical so it doesn't trap water)

https://www.supplyhouse.com/Jacobus-Maid-O-Mist-0220-5L-1-8-Adjustable-Angle-Steam-Vent-Valve-Kit

or this and an adapter

https://www.supplyhouse.com/Jacobus-Maid-O-Mist-J5S4-5-1-4-Straight-Air-Valve-7863000-p

and this orifice kit

https://www.supplyhouse.com/Jacobus-Maid-O-Mist-JAC-ORIPAK-Orifices-for-Retrofit-Pack-of-5

MikeC_3 · March 5

@mattmia2 So a Maid-O-Mist #5 has enough venting capacity for such a long run main and baseboard?

This is why I get confused — when I ask about venting capacities everyone posts links to the Gill & Pajek bible. When I refer to it and take in consideration the length and diameter of the main along with the capacity of baseboard radiators, I come up with a much higher capacity vent.

mattmia2 · March 5

no idea, that is why i posted the link to the set of orifices that cost about as much as the vent or the vent that is an angle vent that comes with the set of orifices

mattmia2 · March 5

you can always try taking the vent off and see if it heats. i suspect your problem is elsewhere.

Steamhead · March 5

OK, is that Gorton #2 on the main feeding the baseboards? If so, how long does it take for the steam to fill the main?

Also, either of those Vent-Rites should vent considerably faster than the present vent or the one from Lowe's.

MikeC_3 · March 6

Yes, it is.

Everything on the first floor begins to get warm on the valve end within 4-5 minutes including the baseboards. The heat then just creeps along them at a snails pace, unlike the other tubular radiators .

I have Gorton # 5's on everything on the floor except for a #4 on a smaller radiator almost directly above the boiler and one on the room with the thermostat. I'll probably change that one to a #5 — it is diagonally across the building from the boiler and I think that the distance alone will slow it down sufficiently.

Gsmith · March 6

are those baseboards connected at both ends to the steam main? or are they connected only at the end with the vent?

MikeC_3 · March 6

Yes, connected at both ends to the main. That is the pipe below the vent in the picture.

Does that have any bearing on proper vent size?

BobC · March 6

Take out the 3/4 vent and use a 3/4M to 1/8F adapter so you can use a straight radiator vent there. The 3/4 to 1/8 might be tough to find, you can use a 3/4 X 1/2 and a 1/4 X 1/8 to get what you need. Then just hope you can find a vent that actually works.

Bob

Gsmith · March 6

yes having connections at both ends, while helping to drain condensate, can lead to early closure of the vent because steam comes up from the steam main and quickly gets to the vent just above that pipe connection.

Fixing the situation may be tough. Do the baseboards adequately heat the spaces they are in?

dabrakeman · March 6

Just for my own understanding if piped at both ends wouldn't you want ideally the vented low side piped into a wet return?

Would definitely go with the MoM vent with the multiple orifices.

MikeC_3 · March 6

@BobC From a quick search, it doesn't look like finding the appropriate reducer will be a huge issue. Finding a vent that actually works might be another story. As I mentioned, when I do the calculation using the formula in the Gill & Pajek document, the required vent falls between a Gorton C & D (if I am correct). Even the largest M of M orifice isn't even close to them.

@Gsmith Yes, the baseboards do heat the rooms adequately once they finally heat up - just behind the rest of the house. From everything I've read on this forum, maybe I'm too focused on having all the radiators heat up in unison?

@dabrakeman There are plenty of posts about this here. Way above my pay grade - but ideally it seems like long runs of baseboard should ideally be piped in this way. I believe because of their high steam capacity?