can't control radiator

r. perry

Any ideas from you seasoned professionals would be appreciated.  I have 3 radiators that overheat.  As a last ditch effort to tame the worst 2 radiators I removed the air vent and installed a simple 1/8th plug.  This has helped, but the radiators still get steam and heat up.  Any ideas?? 

Specs:  One pipe system.  Totally rebuilt.  New Weil-M boiler.  New Hoffman 75 main air vents.  New Hoffman 1A vents on the radiators.  New 0-3 psi gauge indicates the boiler NEVER goes above .75 psi, usually just cruises along at .50 psi.  Pressure limit set at 1 psi and cut-in at .50 psi.  Boiler has been skimmed weekly since installed.  Hand valves on radiators shot, so closing then not an option and very difficult to replace.  Pretty much have to cut them out along with a section of steam line and replace all of it.  Anybody think a Danfoss TRV will work???  THANKS!! for any replies.

jpf321

how many that don't?

how many rads do you have that don't overheat?

what is special about these 3? same riser? sequential on the main? closest to boiler? smallest?



how long are your cycles? rads with plugs really shouldn't be getting that much steam especially under such low pressure.



how deep is your setback?



is your t-stat in a good location?



is your system otherwise balanced so that all rads are getting hot at the same time and rate?



are your pressure control pigtails clean? my system almost never gets to 5oz (

r. perry

can't control radiators

Thanks for your reply.  A total of 14 radiators in a two storey houise.  All the rads heat evenly, except these 3 "trouble makers".  I've been able to get 1 of them to balance.(somewhat, it's the largest, 4 tube, 24 column) by setting the Hoffman 1A almost closed, and, oddly, it's the one closest to the boiler.  The other 2, smaller in size, ( 1 is 4 tube, 14 column, 1 is 3 tube, 12 column) take off at the END of the 2" main.  All 3 of these are on the first floor.  Pigtail is clean and loop has water.  Thermostat is fine.  Checked operation.  NO setback.  The 2 rooms that these rads are in overheat, but with the rads plugged, now don't get enough heat.  Ughhhhhhh!  Boiler cycles on about 35 to 40 minutes when thermostat calls for heat, then there is about a 60 to 75 minute wait until the temp drops to call for heat again.  This, of course, depends on the outside temp, etc.  It's been in the low to mid 20's here.  I've got a Danfoss RA2000 TRV unit sitting here, but don't want to install it if any of you seasoned pros don't think it will help.  These valves (Danfoss) are expensive, almost $100. each from PexSupply and once installed, that's it, I own it.  Thanks for any ideas or suggestions.......

Unknown

TRVs

Since you already have a TRV, try it out.  You can switch it between the over heating radiators and test whether it has the desired effect.  I have TRVs on about 75% of my radiators. They are ideal to stop over heating and also I use them to shut down parts of the house in the winter to save fuel. Remeber don't use them in the room that has the thermostat!

- Rod

jpf321

well....

let me start by saying that I have no experience with the TRVs ... but I hear they can be very useful .. what I can say is that it is encouraging to hear that the 2 problem rads can be tamed (plug causes no heat, vent causes overheat) and because of that, the TRV should do the trick.



ensure that you mount them properly. there is a good article on TRVs available here: BSETRVs.pdf



in giving rad measurements, always try to include the overall width (top-plug to top-plug) as well as the height. pictures help .. if you can make out any brand names or models (usually stamped near the plugs, sometimes a pencil rubbing helps) that would also be helpful.



i'm really dismayed by the fact that you can't balance the rad based soley on vent size. a proper EDR measurement of the rads would help as well on length of pipe connecting them to the mains and the diameter of that pipe.



shall I assume that your mains are all vented properly with enough vents to give "open pipe" capacity (OPC)? have you balanced the system looking at it as a whole unit? if the upper and other rads on the system are giving too much resistance, then the steam would likely head down the main where their is easiest resistance and perhaps end up in the 2 end rads.



i would recommend buying Dan's EDR book and the Gill & Pajek-Balancing Steam Systems paper (both available through the "shop" on this site) and then trying out my excel worksheet (linked below)  to balance the entire system as a whole unit.



let us know.

r. perry

TRV, etc.

Hey Rod,  Thanks for the reply and info.  I'm tempted to go ahead and try the TRV but like I wrote before, it's almost $100.00 bucks worth of valve and once installed, I can't return it if it doesn't work.  What has me stumped and what I'd like to figure out is why these rads are getting steam if they're plugged.  If a plug won't stop the steam, I doubt a TRV will ethier.  I've gone over the entire system, especially the plugged rads that are getting steam, and can't find any air leaks anywhere.  Nothing in the rads themselves, nothing in the hand valves, union, packing nuts, supply pipe etc.  All I can figure is the steam is compressing the air in the rads but at .50 to .75 psi running pressure, it doesn't seem like enough pressure to compress the air in the rads.  I'm wondering if I could lure "Steamhead" up from Maryland with the offer of a motel room and a private session with an exotic dancer to check this problem out.............HA!

Unknown

Plugged Radiator Room Temperature

The question is: how warm does the radiator get with the plug in place? If radiator valve leaks, this means air escapes and steam will get to the radiator. If steam is able to get to the radiator, by compressing the air a bit, it can enter the radiator and condense. When the steam condenses, (1 cubic ft of steam = 1 cubic inch of water) it creates a vacuum which will bring in more steam into the radiator so you can see that the radiator probably won't remain completely cold. It's more a matter of how hot does the room get in the "plugged" condition. If it's unacceptably warm, a TRV won't do you any good. If it's cooler than you would normally feel comfortable with, a TRV will work well for you.



You're right, TRVs aren't cheap. I've added a couple at a time to my system over the years till I have approximately 75% of my radiators with TRVs.  They're great in making adjustments to  the temperature in individual rooms. We first used them in the kid's rooms so that we could turn down the temperature when they were sleeping and then turn it back up to the system's (main thermostat's) temperature during the day when the kids were playing in their rooms. As my wife and I are now alone in a big house, we go to a survival mode during the winter. We occupy a minimum number of rooms and close off all the rest. On the closed off rooms we use TRVs set to minimum temperature so the pipes in the wall won't freeze. If it wasn't for using the "survival mode" I would probably only be using on 3 or 4 TRVs in the upstairs to control overheating.

- Rod

r. perry

TRV

Hey Rod,  Thanks for your input.  Actually, the rooms with the plugged rads are now too cold and I'm concerned about condensate building up in them, since they get steam and get warm, not hot, they must be getting condensate inside.  Also, since they can't "breathe" at the end of the heat cycle, the condensate could get trapped????  Not sure about that one, but I think I'll go ahead and give this TRV a try.  What kind of TRV do you have?  I found 2 for one pipe steam.  Danfoss & Honeywell, and after reading the specs for each, went with the Danfoss.  Odd though, when I ordered it I thought it came in sections, all separate.  The valve, the actuator and the air vent.  I ordered the valve and actuator and when it arrived I realized the valve comes with a control knob.  Now the actuator looks like its a bit more complex, actually operating like a thermostat.  Is that what you have?  Thanks!  

Unknown

TRVs

Don't worry about the radiator holding condensate. Gravity isn't affected by vacuum so the condensate will return to the boiler okay. You only have to be concerned when you close the valve on the steam pipe as steam, being a gas, can leak into the radiator but condensate (water) probably wouldn't leak out.



TRVs - I have both Danfoss and Macon, mostly Danfoss. Both are well built. I like the Macon better due to a larger vacuum vent but question whether that is worth the larger price as I haven't had a problem with either in this regard. (When I bought them there was a price difference but now I understand this has evened out)



If your Danfoss TRV valve came with a gray knob, this is just a cover to protect the valve. You remove this and add the actuator knob.  Use this link for more info-

http://www.heatinghelp.com/forum-thread/129098/homeowner-questions-re-steam

 I posted some Danfoss charts on there plus there is a link to some neat videos on TRVs on the Danfoss website. The videos are on HW TRVs but the workings are basically the same.



Edit: Here's a link to Danfoss on installing/removing the actuator from the valve.

http://na.heating.danfoss.com/PCMPDF/013R9356_VI51T622_standard.pdf

- Rod

mike_in_nj

Having the same problem

I have the same problem - over heating - but I have already installed Danfoss single pipe steam TRVs on several radiators and am having only limited success.  The radiators tend to still get hot even when the room is quite hot already.



I understand high pressure could be a problem, but I don't think it's the problem here.  I have never seen the pressure gauge on my boiler move above zero as the gauge is very old and almost certainly doesn't work.  However, the last time I had a heating professional in the house, he checked the pressuretrol and replaced the pigtail, and he assured me the pressure was being kept very low.



The main reason I don't think high pressure is the problem here is because I removed the valve in one of the rooms and blew through it.  There was definitely some air getting through when it was turned off. Lots more air got through if I adjusted the thermostat to allow it, and the vacuum break allowed quite a bit more airflow under negative pressure.  But there was definitely a small amount of air getting through even when it was closed.



Is this normal?  I have posted the same question to Danfoss's website but I never know whether anyone actually responds to questions on a manufacturer's site.



Thanks,

Mike

mike_in_nj

Bump

Bump

jpf321

what are the TRVs set at?

where are the TRV's set? I have Macon units set at 5/6 and they keep rooms limited at about 69/70deg.

If you turn the TRV to very low setting do the rads still get hot?



the best way that I found to adjust the TRVs is to let them all temper in a room that you know the temp of .. and that you wish to achieve .. then as you did .. pick them up and blow through them until no air passes .. then open up very slightly to allow just a tiny amount of air to pass ... then mark them with some tape or a pen at that setting to "calibrate" them ..



if you are unable to close them completely perhaps they are defective or not properly assembled.

mike_in_nj

All the way off

I get heat even when they are all the way off. The air that is bypassing the valve acts like a slower vent, so if it isn't too cold out, the rad may not have time to heat during a steam cycle. But if it is cold outside and the boiler runs long enough, the radiator will get hot.

Charlie from wmass

Get repair kits

for your valves. How old are they? Off should be off.

mike_in_nj

6 yrs old

They are 6 years old. Danfoss one-pipe steam TRV (013G0140).  I am not sure they ever worked 100% correctly, but the one is this particular room just basically doesn't work at all.



I don't think there is a repair kit available for these.