Air purging with poorly placed coin vents

garfungle

Hi all,

I'm about to take my second stab at purging the air from my boiler. I did it once last season and I remember struggling on one section that had several poorly placed coin vents (not at highest points in heating loop) on a baseboard loop. The technique I used to purge the air from this section was to effectively drain the water in the loop from one of the coin vents to remove some of the air pockets that were causing the blockage. It was difficult in that the coin vent was in a really tight space and I would get water everywhere since the vent was located above me. Can I attach an air hose line to a 1/8" npt coin vent and if so, what size would this even be or can I swap out the coin vent for a 1/8" valve type fitting that a hose can be attached to? I haven't seen any products like this.

I was originally planning on installing a purge and fill valve, but I have run out of time (cold out) and I don't want to risk messing up some bigger solder joints and having to find somewhere that stocks 1 1/4" copper pipe.

Big Ed_4

Baseboard should have a purge valve on the line by the boiler . Was the baseboard added to the system from original ?

HVACNUT

If you have the room, you can do something like this.

Just close the valve when done. Or leave one open to always eliminate air.

garfungle

@Big Ed_4 This is a converted gravity-fed system (100 year old house). The boiler services several cast iron loops in parallel. This is the only loop that is base board and it is servicing three baseboard radiators that are piped in series. The pipping on this loop goes up and down between floors, so it's challenging to purge. There is a coin vent located on the three baseboard radiators, but they get even more water everywhere, so I believe that's why I purged from the basement for this loop.

garfungle

@HVACNUT is that a 1/8" npt valve? I didn't think that existed, but I also didn't look that long. Can you draw out what you're suggesting? I'm trying to understand how you're suggesting to replace an existing coin vent with a valve and an auto air vent. What fittings would you use and how would you drain (npt → ght?)?

Big Ed_4

That section on baseboard sounds all wrong . It should be on its own zone . Would it be fair to say it does not work well when its bleed ?

garfungle

@Big Ed_4 You're 100% correct. The plumbing on this system is a hack job and I try to do my best with it before I rip it all out. It should not be plumbed with the cast iron rads, but it was. I suspect it was done some time before zones were well adopted. There are no zones on this boiler system. The air separator isn't even located in the correct spot. The balance is way off on the baseboard rads (scalding hot). An idea I had before adding zone heating was to add a trv valve to the start of the loop to balance the baseboard heat output. I currently have no ability to control the flow through the baseboard rads, so I am slightly worried with some of the changes I made this offseason (more trvs on cast iron rads that previously had no flow control) that they'll be even hotter this season. The reason I haven't completely repiped everything is because it's a massive job. Massive 100 year old cast iron piping all throughout the basement. I plan to address it, I just need a free summer…

Big Ed_4

Radiators run temperatures 120* -160* ,tube and fin run temperatures 160*-200* . I don't see an easy fix …

I would recommend zoning that section and upgrade from baseboard to panel Radiators . Size them for each room using 160* as your guide on the chart .

From here I don't see an easy fix and see a re-do .

The person that paid for the install was looking for the easy fix , like a flipper maybe ..

mattmia2

you don't have to replumb everything, you just need to pipe the baseboard loop back to the boiler and control it with a second circulator or put in 2 zone valves.

garfungle

@mattmia2 @Big Ed_4 I understand this is the ideal solution and I already have that planned. The issue right now is that it's getting cold out and I'm looking for an easier way to purge air out of the system that doesn't require me putting the boiler down for several days. I was thinking of doing something clever with one of the coin vents and I actually think @HVACNUT had a good idea. I could put a 1/8" npt valve (if it exists) in line with a hyvent. This would allow me to hot swap the hyvent with a ght / hose line adapter if the system has air in it. I also could just keep the coin vent if a 1/8" npt exists.

mattmia2

you could put something like this in the baseboard loop.

https://www.supplyhouse.com/Webstone-50613-3-4-Sweat-PRO-PAL-Full-Port-Ball-Valve-w-Drain

HydronicMike

https://www.google.com/aclk?sa=L&ai=DChsSEwipgrid5cWQAxU4gyIFHaZoM7MYACICCAEQGxoHdmlja3ZyYQ&co=1&gclid=EAIaIQobChMIqYK4neXFkAMVOIMiBR2maDOzEAQYAyABEgJgIfD_BwE&cid=CAASsAHkaHAA9rMMXyRk0WvTuJ-nHpru7GQUSTGPQSIEYuiaLx3R_7I-9-Bf7z3jaJ88_or9cj9xkBScCQicrlUyMAGtPGbHWfZn0xGJsrgmeyHu5TsPYmnMClL9nuiKF9FnK6XZB51X9zMa7mf51Wlbi1eUI2D70r2xuSdxXnjBvaSsuq486bxf6DCB0TWLy8HuijOlNsap6TLCs7V7OOGAQhUP0Jok9qOpv3vERsRnKbq4QA&cce=1&sig=AOD64_06C3pmx6eRvtwoqpzYNs-2oHZNVA&ctype=5&q=&ved=2ahUKEwidlLGd5cWQAxUprYkEHR-9MLMQ5bgDKAB6BAgKEBc&adurl=

Can’t get links to work or add photo, getting error message.

Trying to post a mini ball valve 1/8” from zoro.

hot_rod

sometimes called gauge cocks 1/8 and 1/4

Most valve manufacturers offer them

Or Home Depot

Big Ed_4

Bring up the system pressure while bleeding and lifting up the element on the bleeder end may help you out in the mean time …

garfungle

I ordered the 1/8" valve from supply house with an npt to barb adapter. I'll hook up pvc vinyl tubing to the adapter and when I feel I've purged the air from the baseboards, I'll swap out the adapter for either a plug or a coin vent. I think this will definitely help me purge air from this loop without getting water everywhere. The valve is hidden in a laundry room, so it won't be an eye sore on top of a radiator anyway.

HVACNUT

https://forum.heatinghelp.com/discussion/comment/1869555#Comment_1869555

You don't drain it. The air will vent out during the heat cycles.