Need help buying TRV

ChrisJ

Aside from my 2nd floor being warmer than the 1st on really cold days which isn't a big deal I have endless problems with my bedroom.  Its the only insulated room on the 2nd floor and has a 55EDR radiator in it which may have given me sunburn last night.  Ok, its not that bad but it really sucks...



On mild nights the room is in the low 60s and on cold nights like last night at 5F its in the mid 70s which I hate.  So I'm ready to build a TRV for it but need some help.



Radiator is 55 EDR, 2nd floor with a fairly short horizontal runout to the main.  Main is the first one on the header and very short (10ft or so) which steals steam if I vent too fast so I have a single Hoffman 4A as a main vent on it.



I'm looking at these three items but don't know if I want the Danfoss vent?  I also don't know what speed I'd want to vent this at, if it even matters.  I assume once it starts heating it will continue heating that much as a minimum until the boiler shuts off so I'm nervous about venting super fast.

<a href="http://www.pexsupply.com/Danfoss-013L8011-1-Pipe-Steam-Air-Vent">http://www.pexsupply.com/Danfoss-013L8011-1-Pipe-Steam-Air-Vent</a>



<a href="http://www.pexsupply.com/Danfoss-013G0140-Thermostatic-Rad-Valve-w-Vac-Breaker-1-Pipe-Steam-5551000-p">http://www.pexsupply.com/Danfoss-013G0140-Thermostatic-Rad-Valve-w-Vac-Breaker-1-Pipe-Steam-5551000-p</a>



<a href="http://www.pexsupply.com/Danfoss-013G8250-Direct-Mount-Operator-5558000-p">http://www.pexsupply.com/Danfoss-013G8250-Direct-Mount-Operator-5558000-p</a>



I assume this is the combination I want for a single pipe system, but want opinions before buying the most expensive vent setup by far I've done to date.



Thanks,

Mark N

Taming a Rad

Chris



There are several courses of action you could take. Rad covers can reduce the output of a rad by up to 35%. Smaller vent to slow the amount of steam that enters the rad. since this room is insulated maybe a smaller rad to go along with the lower heat loss. Don't know anything about TRV's I have never used one.

Hap_Hazzard

You don't need to buy their el cheapo vent.

That's just a USAV 881, like they sell at Home Cheapo. It may say "Danfoss" on it, but some of them say "Durst." That just shows that brands mean nothing anymore. They come from the same Chinese factory. If I were you I'd just get the TRV and the operator and stick the same vent you're using now on it. If you think it's venting too fast/slow, try a slower/faster one, but use a good vent that you trust.

ChrisJ

Ah ha!

Thanks Hap, I swore that looked like a USAV and USAV has no business on my system.



All of my radiators had those when we moved in so I've had some experience with them.





My concern about using the Gortons is they are right angle, won't that lead to drainage issues? Looks like I'll be putting together two of these for both 2nd floor bedrooms now. If I use brass elbows then the nickel plating is moot and I could just buy the gold Gortons. I was thinking of Hoffman 41s for them but I'm questioning if they are fast enough sometimes. I'm thinking, yes.



Wonder how much fuel I'll save by keeping 700sqft 5 degrees cooler.

Hap_Hazzard

You can get straight Gortons.

http://www.pexsupply.com/Gorton-G6S8-Gorton-No-6-1-8-Straight-Vapor-Equalizing-Valve-3533000-p



If you already have an angled one you can use a street elbow to mount it--do not try to straighten it! :-)



I might be imagining things, but I thought it was also possible to rotate the valve so you could mount a right angle vent on it, but I would confirm that with someone who knows what they're talking about.

ChrisJ

Gortons

Ah yes, but those arn't nickel plated and I'm not sure how the wife would like that.



You know how it is,....

David Nadle

Go for the straight vent.

Hoffman has shiny straight vents...



The Danfoss TRV setup has worked very well for me. I recommend you choose the slowest you can, but not so slow that your room is cold in fall and spring.

ChrisJ

Vent

Hi Dave,

What vent did you go with out of curiosity?



The Hoffman 41 is really the only option and I'm concerned about its speed. I have Gorton Cs on some of the 2nd floor rads as well as some 6s. Compared to those the Hoffman 41 isn't going to keep up on mild days.



I might have to just buy gold colored Gorton 6s and hope the wife accepts it.

David Nadle

Vents

I have a straight Gorton 6 on one and a straight Varivent on the other. But.. I have radiator boxes so you can't see them. I used the remote sensor/dial version and mounted them on the side of the radiator box.



If you like the balance now in fall and spring with a Gorton C, maybe you should stick with it. I'd get a 6 and a C and try the 6 first.

BobC

If your not sure

what size air valve to use with a TRV you might want to try a Maid O Mist straight pattern air valve.



I've been using the angled version on my system for a while now and they have been quiet and trouble free. You can by the smallest one and drill it out to whatever vent rate you need. Once you know what you need you can buy whatever brand vent you like if you would rather not use MOM vents.



Bob

ChrisJ

How does a trv work?

One thing I'm not sure of is how the TRV actually controls temperature.



Is it a simple ON\OFF device or can it actually throttle air speed? I assume once it closes, the radiator will continue to throw off whatever amount of heat it already was when the TRV closes.



If the TRV actually throttles, why not use the fastest vent you can?

David Nadle

Bellows and needle valve

The actuator contains a metal bellows with an inert gas. As the room heats up the bellows expands and pushes a needle into a seat, shutting off the air flow through the vent assembly. The dial adjustment changes the preset compression on the bellows.



There is a control lag between the steam entering the radiator and the sensor experiencing the set room temperature. If you vent too fast you make it more difficult for the TRV to prevent overshoot. You'd have to compensate by choosing a lower setting on the actuator.

ChrisJ

Bellows

Hi Dave,



This sounds kind of how the temperature control works on the 1930s monitor top refrigerator.



Does this slowly happen or is it a snap action device?  Obviously with an electric thermostat its a sudden snap on or off.

David Nadle

It's gradual

...but so is the old bimetallic spring. It just seems snap action because nothing happens until the contacts make or break.

Mark N

Main Vent

Chris, you are using a Hoffman #4a main vent on your short main. But are using Gorton #6's and C as your rad vents, The vents have greater venting capacities than your main vent. The rads should have less venting capacity than your main vents. It is my understanding that the total venting capacity of all the rad vents on the same main should be less than the capacity of the main vent or vents on that main.

Hap_Hazzard

Not necessarily.

There's no reason you couldn't have a lot of long runouts and/or risers on a short main. It's not the best design, but sometimes the architecture imposes it.

Mark N

Run out

He states the rad has short run out in the first post. You shouldn't size rad vents larger than main vents.

Hap_Hazzard

You should size them both according to

how much air they need to vent in a given amount of time. Mains and radiators are independent of each other.

Mark N

Venting

What? How can they be independent when they are connected together. In order to balance the system you want the steam to favor the main. Having larger vents on the mains allows this to happen.

Rod

Danfoss TRV Animation

Hi Chris- Here's a link to some animations on the Danfoss TRVs. This is for the RA 2000 model (2 pipe steam or HW)  The 1 pipe steam model uses the same parts but with an internal vacuum breaker

- Rod

http://na.heating.danfoss.com/Content/39189D64-8455-4674-BD5D-CEB2D082F09E_MNU17504125_SIT209.html

ChrisJ

Animations

Hi Rod,



Thanks for the animations!

ChrisJ

venting

The short main currently has a Hoffman 4A main vent and 3 radiators 2 of which are on the 2nd floor. One on the first floor and second on the line is oversized for the room currently has a Hoffman 1A venting as slow as possible. The third and last on the line is on the second floor and in my bedroom and cooks me, also a Hoffman 1A as slow as I could get it. The first on that line is second floor and currently a Gorton #5, started with a #6.



I am considering changing the 4A to a Gorton #1 once I install the TRVs but not until then.



Mark, sometimes, you want to intentionally throw something out of balance. I still have not made up my mind what vent I want to use with the TRV in my bedroom, I don't think I said a #6 for sure, thats for another radiator. I'm still considering a #4 or #5 for that one.



The radiators with #6 and C vents are on the 29' main which is vented with four Gorton #1s.

Mark N

TRV

Chris there is a thread on page 4 "Possible Substitute for a radiator". This person has a rad that continues to overheat despite the fact of having a TRV on the rad. I have never used one so I have no idea how effective they are.



With having a 4A on your short main and 4 #1's on your long main does the steam arrive at the end of your mains at the same time? Do you have steam getting to the rads on the short main before it get to the end of the main?

ChrisJ

mains heating

Hi Mark,



Not sure as my whole objective has been to try and keep my bedroom and livingroom from overheating. Once I install the TRV in the bedroom I'm going to proceed to tweak. I have a feeling if I vent too fast I'm going to end up sorry though.



I do want to say, currently it still reaches the end of the short main too fast though. Its kind if frustrating being I'm venting the 29' main 10 times faster currently but the short one is first on the header so I guess, you know, early bird gets the worm.



You know, something has been bothering me regarding how we calculate main venting. Often we see how much air we must move out of a certain size main in 3 minutes. But heres what concerns me, I have a 150,000btu input boiler connected to two semi-short mains, a 29' and a 11' both 2". What about someone with the same boiler connected to much longer mains? Sure, they have more air to move but they have the same force pushing it. My 3PSI Wika never shows any real signs of back pressure during main venting so maybe its not a concern.

David Nadle

That thread

...was frustrating for me because the original poster would not brook any advice or even discussion related to TRVs, and was vague about why. In my experience TRVs work very well and solve a problem that static vents cannot.

ChrisJ

Noticed that

I don't see why TRVs wouldn't work but I can see that once you let the steam in, its not going to stop that amount until the boiler shuts off.



This is why I'm really concerned over venting them right. The way I see it I can end up with cold radiators on warmer days (ugh) , just right, or too hot.



My current concern and what confuses me is if I vent so steam hits those two oversized bedroom rads at the same time as the rad in my thermostat room this normally, without a TRV would certainly roast a turkey. I'm concerned this might be too much for the TRV to control, and yet on a warmer day I won't get steam if I vent slower.



This is really where experience pays off big time.

ChrisJ

Picture

One thing I have learned from Rod is pictures really help when your not looking at a system in person.



Here is a layout of my system currently.



The back bedroom vented with a Gorton 5 is still way too warm but I don't sleep in there so it wasn't a huge issue.  The main bedroom with the Hoffman 1A barely venting is where I sleep.  I want both rooms to end up normal so I stop throwing money away over heating them.  The main bedroom has been *OK* with the 1A barely letting air out, but obviously on more mild days its going to be freezing in there now.





All vents are Gortons unless noted to be a 1A.  They were orignally all 1As but as many know I had issues with the 1As



I'm thinking of throwing a #4 on the livingroom rad, a #5 + TRV on the main bedroom and a #6 + TRV on the back bedroom and switching the 4A to a single Gorton 1.

David Nadle

Don't be too concerned.

Buying the wrong size vent once is not going to deplete your savings...



The TRV's ability to control is not related to the size of the vent, but there are good reasons not to choose a vent faster than needed. If you remember the room getting too hot even at the start of the heating season, then get a slower vent. Otherwise, get the same size you have now. The TRV is not that sensitive to this choice.

ChrisJ

update

After thinking about it I realized by switching the 4A main vent to a Gorton #1 I would probably effect how the radiator at the top of the stairs acts as pressure would be relief (maybe).



I just switched to the Gorton #1 to see if I need to vent the rad at the top of the stairs any differently.

Mark N

Short main

Chris I have a friend who system is similar to yours, a short main and a long main. His short main might even be a bit shorter than 10ft. His short main has no main vent. There is no place to put one. He has a Gorton C on the last rad off that main. Because the main is so short it doesn't contain much air and the vent on the last rad handles it. Have you considered removing the main vent and and putting in a plug and use a bigger vent on the last rad. I might be worth a try to slow that main down a balance it against the other main.

Mark N

Required Reading

From the Library



heatinghelp.com/files/articles/1321/115.pdf



heatinghelp.com/files/articles/1294/124.pdf



heatinghelp.com/files/articles/1328/116.pdf



heatinghelp.com/files/articles/1315/123.pdf

RJ_4

Danfoss info

Check my post Feb. 9th   2012  good info

RJ

Bio

Have you tried

Have you tried boilerpros aproach, I think its worth to try it, it works for me, I almost have what you show in your picture but my smaller 12" main runs opposite of my 55" main, I vent them fast on both mains and used hoffman 40 on all radiators, except the two radiators on the short main where I have ventrite1 set at 2, no set backs and all radiators heated half way evenly on the coldest days we had last week in NJ, the system runs comfortable, no overshooting and quiet



If you are not happy with the vents the folks at pexsupply will give you a full refund, good luck

ChrisJ

Stuff

Thank you for the responses!



Mark, just spent a fair amount of time reading the links you posted.  RJ, I had seen your posts yesterday and found the check valve idea pretty interesting.  I had wondered about using a vacuum breaker on the system.  Thank you for posting it.

Bio,  I guess I've been using the Gerry Gill and Steve Pajek aproach.  Honestly I've had good results overall except for the two main bedrooms, probably because the rads are too big.



One thing I have found is calculating how much air you need to move in say 3 minutes including the runout, doesn't always work.  A good example is my 3rd bedroom and main bathroom where I now have Gorton Cs.  Apparently they actually need a Gorton 5 but even a 6 wasn't quite fast enough on mild days.

Perhaps I'm wrong, but how would all Hoffman 40s work on my system being as some rads have super short runouts and others have 20 foot run outs?

Mark N

Sizing Vents

The number that Gerry comes up with is arbitrary. He chooses 3 minutes because he is looking to heat fast. The truth is you can't heat your rad completely across in 3 minutes. The boiler makes steam at a constant rate. If the boiler is properly sized for the amount of rads it can take nearly an hour to heat the rads completely across. The main venting is determined by the open pipe method. But I think you would have to make accommodations when you have mains of different lengths but the same size vent tap. Also I would think you should leave the boiler off a certain amount of time say 1 hour to remove the variable of a hotter main venting quicker because the hotter pipes condense less steam. Therefore there is more steam available to push the air out.

ChrisJ

Done

With everyones help I made a decision and ordered two Danfoss TRVs along with two vertical; Gorton #6s.  Also ordered Gorton's to replace the last few Hoffman 1As as well as an extra Gorton #1 which I may just hold as a spare.



Call me weird but I don't feel comfortable unless I have a few spare vents on hand.



If I end up having issues with the short main after installing the TRV on that radiator I may invest in installing a zoning valve + aquastat to control the main vent on the short main.  I'm thinking with a Gorton 4 on the livignroom radiator (insulated room with 1980s windows) and with a TRV in the bedroom the short main won't be an issue but who knows.



Thank you for everyone's help and time I appreciate it.

ChrisJ

Oops

Seems pexsupply will not give a refund on vents that have been used.



Allwell, can't say I blame them.

Hap_Hazzard

Home Depot does.

As long as you have the receipt they will take them back and put them back on the shelf for some poor sucker to buy.

ChrisJ

Vents

Hi Hap,



Yea, I can't stand that nor do I think its appropriate.



Kind of stinks to be me right now though cause I went with Gorton 6s on those TRVs and, yea,  one of them may be ok but the one in my bedroom is venting WAY too fast.  Poor TRV doesn't have a prayer to try and hold that radiator back.

Ordered a Gorton 4 and 5 as I'm not sure which it needs in the end.  Either way I'm probably going to end up with two almost brand new straight Gorton 6s with no use for them.

ChrisJ

It works! Kind of...

Just wanted to update the thread, TRVs do indeed work and they do work for stopping oversized radiators from heating too much.



Right now I have two installed, one on a 19 section and one on a 18 section radiator with Gorton 6s.  Each is in the neighborhood of 50sqft of radiation.  Last night stunk, I set them to what Danfoss said were preset temperatures and one of mine is quite a bit off.  I set it to #3 and ended up way back to #1 and by that time that 19 section radiator was full of steam *ugh*,

I have a Gorton #4 and #5 coming because as David and others said, too big is no good.  That said, while I was making steam I ran up and was able to adjust the temperature by listening for the vent to make noise.  It does indeed throttle it, but slower venting is going to be better as I feel it will give the TRV more control.  My 19 section radiator heated ONE section during the last heating cycle even with a Gorton 6 on it.  I am impressed and very happy so far.

Dave in QCA

Excellent

Chris, glad to hear your TRVs are working out.