varivalves vs. TRVs vs. replacing (or adding) main vents

chumie

I just moved into a house with steam heat which is producing irregular results between rooms. Most bothersome is that the master bedroom gets too hot, while the childrens' room, right next door, remains too cold. The radiator in that room does get hot; just not hot enough. On the advice of the company that has been maintaining the boiler for years, I replaced almost all the vents with varivents. The one in the master bedroom (and most others) is closed and the one in the childrens' room is wide open. This might have made a small difference, but the situation remains. Next, I had a service call from someone with a lot of experience with steam heat. He told me that my piping looks good and that the only way to regulate things will be to break up my ceiling, find the ends of the mains and install new vents. I would do so if I had confidence that this will really solve the problem of the cold room, but I have a hard time getting my arms around that opinion. I can easily see it stopping the hissing (not terrible) and saving on energy costs, but will it really solve temperature differences between rooms that are next door to one another? Last but not least, someone online recommended thermostatic radiator valves, which I have not yet read much about.

So... I turn to you to ask what makes sense as my next step. I have no problem spending what I need to spend, so long as it will really do what I need it to do. I am growing tired of paying for service calls that seem to get me nowhere and need help making an intelligent decision.

Thanks in advance!

Nicole

David Nadle

ideas

The master bedroom and the child's bedroom may be served from different mains. If so and if for some reason one main vents much faster than the other, it will be nearly impossible to balance the heat at the radiators. So the guy who suggested checking the main vents was on to something. Those vents---if they exist, and I hope they do---shouldn't be buried in a ceiling anyway, in my opinion. Some day you'll have to replace them. Have access panels installed when you close the ceiling up. Once you've got that addressed, if the bedroom still gets too hot a TRV will certainly help. For some crazy reason these things are not commonly prescribed in the US. You may have to educate yourself about them and take the lead.

nicholas bonham-carter

irregular heat

main vents are definitely needed to even out the arrival of steam at all the radiators on a floor. depending on the type of system, they may be close to the boiler, or at the ends of the mains.

to make some tests, lower the setting on the thermostat to lowest for a few hours, to let all the rads get stone cold. then raise to the max and while the boiler runs non-stop to catch up, feel all the radiators to find out the order in which they get steam. do not look at the air temperature, but feel the metal. they should all get steam at the same time!

this will show you how unbalanced things are.

as steam rises, pushing the air out of the boiler, and pipes. the main vents should allow the mains to fill with steam first, before the risers and rads. as all the rads are the same distance above the mains, the air vents can regulate the air removal so that there is simultaneous arrival. if the main vents are not doing there job, the steam may go up one riser first before the others, creating a hot-spot.

trv's can only do so much to compensate for lack of main venting.--nbc

chumie

if they heat up at the same time...

I like the idea of testing the system before doing the work! If I happen to find that the rooms are heating at the same time, would that indicate that I don't need to replace the main vents? If they are uneven (which I suspect they will be), I will certainly leave access panels in the newly cut ceiling

Funny, I thought I was lucky finding a house with a fully finished basement and attic, but I am slowly discovering that it might have been better to leave a few more things exposed....

Rod

Not a Fan of VariValves

Hi Nicole- I’m not a big fan of Varivalves as I’m of the opinion that they cause more problems than they fix.  On the minimum setting they don’t shut off.  The  minimum setting has about the same venting capacity of  an adjustable vent like a  Hoffman 1A set to its middle setting.  When a Varivalve is set wide open, the orifice is huge which is why they are used as stop gap measure to make up for the lack of main venting.  You need main vents! You’re much better off getting them fixed/installed and then using adjustable radiator vents like the Hoffman 1A or the Vent- Rite to get the radiators balanced out. If there is still an overheating problem then you could consider using a TRV on the overheating radiator.

 There maybe  a possibility that main venting could be installed on your return pipes if you have them. Some 1 pipe steam systems don’t have return piping  and that maybe the case in your situation as I think the steam guy would have suggested that. However let’s check that possibility just to be sure.  If you could upload some pictures of your boiler and the piping leading we can see what you have. Take the pictures far enough away so they include the boiler and the piping connected to it. We can then trace out the piping leading to the boiler and we can blow up the pictures for more detail if necessary.

Let us know where you are located and we may be able to suggest a steam pro near you that could fix you system.  Have you checked the “Find a Contractor” section at the top of the page?  Scroll down past the zip code section to the States section and pick your state. There are some very good steam pros listed there.

Since you’re new to steam you might want to get a book that is available in the Store section at the top of this page. The book is called “We Got Steam Heat!” and is written for the homeowner new to steam heating. Here’s a link to it.

http://www.heatinghelp.com/products/Books/5/61/We-Got-Steam-Heat-A-Homeowners-Guide-to-Peaceful-Coexistence

- Rod

chumie

about a pro....

Thanks Rod. The pro who came by yesterday was listed on this site (not sure if I'm supposed to name names on this forum) but he did take a nice long look at the pipes before suggesting that we will have to go digging to find the main vents (or the right place to install them). He too mentioned not being a big fan of varivents, and I suppose that if the ones I newly installed need to be replaced, it will not be my biggest wasted expense of this venture...



I imagine that the pro who came by is good at what he does (I just wanted to get some more opinions before spending all that money), but if you have someone that you especially like in the NY metro area (I live on the Queens/Long Island border), I'm all ears!



Also, should I be playing with the valves at the bottom of my radiators? I nearly turned off the valve in the master bedroom and that seems to have alleviated the overheating, although it has not fixed the cold in the other bedroom.



Thanks!

David Nadle

no

The valve at the bottom of the radiator can't control the amount of heat. It should be all the way open or all the way closed, not in-between.

Rod

Main Vents

My house is rural Maine so I don’t know any steam pros personally in the New York area. The fact you found him in the “Find a Contractor” section speaks highly of him. My main concern was that you could find someone who was competent with steam heating and it looks like you have.  Finding mains vents when the piping is hidden isn’t easy, but someone with steam experience would have a much better idea of where to start to look. There is a saying. “Steam pros are good plumbers but very few plumbers are steam pros!” which seems to hold true in my experience. That’s why it is so important to find a real steam pro. The guys that recommended the vari-vents suggests they don’t know much about steam heating.



The purpose of the main vents is so that the air in the mains can be quickly replaced by steam. Air will pass quickly through the main vent but then the vent will shut when steam reaches it. The main vents are located on the end of the main and this allows the whole main to fill quickly with steam which means all the pipes leading off the main to each radiator receive steam at about the same time.  Without the main vents, the steam will fill the closest radiator to the boiler first and then slowly progress farther down the steam main filling each radiator as it comes to them. If you put large vents like the Vari Vent on all the radiators, the venting becomes chaotic and they all compete for what steam is available. As for now having unneeded vents, I think every steam homeowner has a shelf with steam parts which they changed out for some reason or another. I have a box full!



Radiator Inlet Valves - On a 1 pipe system the valve (tap) on the pipe going into the radiator must be fully open or fully closed. It can’t be half way as the incoming steam and outgoing condensate (water) will collide and cause problems. I’ve attached a diagram on this which might be of help to you. Another thing with radiators on 1 pipe systems is they need to be very slightly sloped towards the end of the radiator where the steam pipe is attached. This “encourages” the condensate (water) to flow back out the steam pipe and back to the boiler. I’m sure you pro will check this for you. The slope doesn’t have to be much.

- Rod

chumie

confirmation of above!

So I was planning to run the suggested test tomorrow morning (let radiators get stone cold and then watch them heat back up), but as luck would have it, the house was really quiet now and I noticed the following:

A faint hissing, squeaking noise from a radiator on the left side of the house, first floor. It was just starting to heat up. I ran to the right side and it was already going full blast. So I went upstairs where things were completely cold on the left side and just getting cranked on the right.

So, if I'm understanding everyone correctly, I've learned 2 things. First, the left side heats more slowly than the right (and that explains the difference between two bedrooms next door to one another having dramatically different temps. Second, the hissing and squeaking also suggests air that was not vented properly from the mains (I think I read this somewhere - is that correct?).

If this observation confirms the diagnosis, I will set up appointments to open my basement ceiling and (re)vent the mains right away.

If you don't mind, please post and let me know if I've got this all straight.

Happy New Years and thanks for all your help!

Nicole

Rod

Need Pictures

Hi Nicole- I wouldn’t be ripping your ceiling out just yet as it may not be necessary. I would let the pro decide first what needs to be removed.

 It’s pretty hard to give advice as we don’t have much information about your steam system.  Could you post some pictures of your boiler and the piping connected to the boiler as this would give us a better idea of about the configuration of your system. Try to take the pictures so we can see how the piping connected to the boiler and also where the piping goes above the boiler.



As for the test, all it really shows is your system is out of balance.  As for the hissing that doesn’t show you much other than a lot of air is being released through the radiator vent which indicates a problem with the main venting.

The room where the thermostat is located, is it one of the rooms which heat quickly? If that room heats more quickly than the other rooms the thermostat will reach the set temperature and turn off the burner.  That means the colder rooms will never heat up completely. This is why a steam system needs to be balanced.  

Pictures of your boiler will probably tell us more.

A very Happy, Prosperous (and warm) New Year to you too!

- Rod

David Nadle

ideas

It could be two different mains or it could just be a stuck vent on that radiator. You need to trace the system out and confirm there are two mains.



If the people you hire can bring or borrow a thermal imaging camera, they may be able to "see" the mains right through your ceiling and make nice surgical cuts at the ends. However, if your mains are not insulated I think it's worth the extra expense to expose all the mains and have them insulated.

jpf321

I'd be happy

to stop by tomorrow for a friendly "2nd pair of eyes" visit. I'm in forest hills and available anytime. drop me a line directly with your phone and availability.