TRV on old-school single-pipe steam radiator

MJasick454

Hi everyone. Thanks so much for the help. I've made an appointment with a local pro to take a good look at the setup in the basement. In the meantime, I've been doing a bunch of research on TRVs. I understand that installing a TRV on the air valve (or vent valve) may help me control how hot a radiator in a specific room gets AND that swapping them out can be quite straightforward.

I've found this catalogue from Danfoss:
https://assets.danfoss.com/documents/99867/AF163386458944en-010101.pdf

And below are the pictures of a radiator in the house.




Is there a specific model I should get based on what you can see?

KC_Jones

What is listed in the catalogue for 1 pipe steam will work fine, I’ve got one in my bedroom.  You don’t need their vent, any straight vent will work.

I have to ask though, what size vent do you have on it now?

I'm having a hard time believing a radiator that small is a big overheating problem in the house, many times just adjusting the vent size will make the difference.

MJasick454

Thank you KCJones for the advice.

Just to clarify, this is just an example of a radiator in the house. This particular room is actually perfectly fine. The radiators in the other rooms (both overheating an underheating) are the problem, although they have decorative grilles over them, so taking a clear picture is hard. The small radiator here is just an example of what the radiators in the other rooms look like, minus the grille.

To follow up: (1) how can I tell what size vent do I have? Is it labeled somewhere? Do I need to measure it? (2) how do I “adjust the vent size”? Is that swapping out with a different vent, or with the TRV that will presumably allow me to adjust the size? (3) is swapping it out as simple as unscrewing it and rescrewing on a new one? I am doing some reading that’s made a lot of references to having to “thread it” and using some sort of teflon tape, etc.

KC_Jones

Vents do just unscrew and screw in a new one.  They are marked on the end what brand and size, both things are important.

To be clear you can control the amount they hear with venting changes even without TRV’s.  It sounds like you have a balance issue, so honestly I’d start with that first.

Venting starts in the basement with the main vents and once the main venting is squared away you can move to the radiator vents.  You size them based on relative location in the house, radiator size and with influence of what temperature you want the room.  Yes venting can keep some rooms cooler and some warmer independent of the actual thermostat settings, with exception of the room the thermostat is actually in.

See why main venting you have in the basement, and let us know how long and what size the mains are and we can recommend the proper amount of main venting.

On the TRV’s, if the radiators in question have covers you would need to get the operator with a remote sensor and that would be mounted on a wall slightly away from the radiator.  And it has a connection back to the operator head that needs to be run through the cover.

MJasick454

Here is a better picture of the vent. It appears to be a Gorton #4 equalizing valve.

So all I need to do is (1) unscrew this, and (2) screw in the proper Danfoss TRV?

KC_Jones

Yes, if you’ve got the system balanced with all proper venting and the radiator is still overheating then a TRV may be the only solution.  I want to be clear about this point, you should only consider TRV after all venting is balanced as good as it can be and you are still having issues.

For the Danfoss TRV there are three parts that need purchase, the body, operator (remote or not depending on application) and a vent.  The TRV needs a straight vent and without TRV you use angled vents.  Also keep in mind with the TRV need to make sure the vent is sized appropriately.  The TRV tends to add some resistance so it can slow things down more than just a vent and could make the room colder if you aren’t careful with the vent choice.

With all the involved components that is part of why I stress getting venting right first.  The cost of TRV and associated components is significantly more than just a vent and the expense may not be necessary.

MJasick454

Well understood. I’ve got the appointment with the pro to check on getting venting right first. My understanding is that every few years, my in laws try this and it doesnt work. Hence Im just thinking ahead.

PS. What about “underheating”. Is that a thing?

Jamie Hall

While you are at it, two very important things to keep in mind. First, a TRVent can only reduce the heat. It can't increase it. Second, it can only do so if the boiler cycles on and off (usually on pressure). Once a radiator gets hot, closing the vent (for instance, with a TRV) won't keep it from heating further.

MJasick454

KCJones. Thanks again for your advice. So for my free-standing radiators, I should get:
Body: 013G0140
Operator: 013G8250
Vent: 013L8011

For my radiators covered by a grille, I should get:
Body: 013G0140
Operator: 013G8562
Vent: 013L8011 and 013L8300 (what’s this?)

Long Beach Ed

Sounds like you have other problems you are seeking to solve the wrong way. The only way you would be "overheating" is if you are "underheating" elsewhere. That's a balance problem or the radiators are improperly sized. Fix the problems and you'll save money. Patch them up with thermostatic valves will cost you...

KC_Jones

MJasick454 said:

Well understood. I’ve got the appointment with the pro to check on getting venting right first. My understanding is that every few years, my in laws try this and it doesnt work. Hence Im just thinking ahead. PS. What about “underheating”. Is that a thing?

Not surprising, people come here all the time after pros have been there and venting is a common issue because it’s either ignored, or not understood.

The TRV is really not a fix all that many want it to be, that’s why I’m emphasizing caution here.  Also Jamie’s point is valid as it only does one thing and everything needs to be running properly for that one thing to work properly.

In addition adding them without having all the venting right can have an impact on other areas of the home, so other rooms that were fine could end up hotter, balance is the key here.

Where are you located?  We may know someone capable of handling this in your area.

ethicalpaul

That number 4 Gorton is a nice small vent. If I had a radiator with a #4 on it that was still heating more than I wanted, I would just put a blanket over the radiator.

ChrisJ

ethicalpaul said:

That number 4 Gorton is a nice small vent. If I had a radiator with a #4 on it that was still heating more than I wanted, I would just put a blanket over the radiator.

I would increase the venting on all of the other radiators in the house.

ethicalpaul

Carefully, one or two at a time with gentle increases I assume!

(although if the rest of the house is comfortable, I still stick by my "put a blanket on it" advice)

JUGHNE

If you go with the TRV, you want to get the vacuum breaker feature included.

Once the air vent closes and the boiler shuts down the rad may not drain back and eventually become water logged.

ChrisJ

JUGHNE said:

If you go with the TRV, you want to get the vacuum breaker feature included.

Once the air vent closes and the boiler shuts down the rad may not drain back and eventually become water logged.

It would be pretty incredible for a wide open 1" - 1 1/4" pipe to somehow allow a radiator to hold a vacuum and stop water from leaving via gravity when the rest of the system is open to atmosphere. Wouldn't it?

JUGHNE

Yes, it seems incredible. I would have never thought it could happen.
However in our schoolhouse, the second floor rads would hold water and then eventually let go when the boiler shut down.

In the basement it sounded like a WC flushing, 2" risers up 2 floors, 1 1/2" valves on rads.
Connected to a 3" main. Pretty well a straight shot up 2 floors, a few 90's.

Also there is an extra rad connected with the 100 year old valve shut off (as will as one would expect).
I would unhook it and cap the pipe, but the valve is the only thing securing the rad in place.
Huge and top heavy.
No vent on it, just an 1/8" pet cock. (closed as an air vent would be when hot)
Occasionally I open the pet cock and let the air in and have the same down rush of water I have heard before

And why, pray tell, do they offer vac breakers with the 1 pipe steam TRV's?

Gordo

https://youtu.be/hjS5slMqtuA

PC7060

Wow, amazing floors @MJasick454

gfrbrookline

I have had first hand experience with Honeywell TRV's on my up stairs tenants radiators retaining water. Danfoss and Macom make much better units that let the water drain.

ChrisJ

gfrbrookline said:

I have had first hand experience with Honeywell TRV's on my up stairs tenants radiators retaining water. Danfoss and Macom make much better units that let the water drain.

What were the symptoms?

EBEBRATT-Ed

@MJasick454

Just to stress what the others have posted above. A TRV is not a fix all but work well in the right. application.

As @KC_Jones mentioned the venting in the basement has to be up to snuff. And as @Jamie Hall mentioned a trv can reduce the heat from an overheating radiator but cannot increase the heat from a cold rad

JUGHNE

Gfrbrookline, do you mean the radiator itself retained water or the TRV control was water logged?

gfrbrookline

@ChrisJ and @JUGHNE radiators retained water with the Honeywell units. My system tends to cycle twice with each call for heat. The radiator with the TRV heats and closes on the first cycle and then opens and bangs on the second cycle before closing again. When I removed it and installed the Danfoss units the hammering went away completely.

JUGHNE

Pretty incredible.......huh

mattmia2

I wonder if the trapped water has to do with a slug of water getting shoved around at some point such that it can fill the crossection of the runnout and prevent air and water from moving past eachother.