One-Pipe Steam-TRV or Better boiler controls?

skifaster

Hi all,



I am trying to figure out the best way to address an overheated one-pipe steam building. It is a 100 year old, 65 unit building heated with a scotch marine boiler and a one-pipe steam distribution system. From what I can gather, the apartment temperatures during the heating season are regularly close to 80 degrees throughout the building. Tenants have gone so far as to have radiators removed from their apartments because it is so hot. The current control on the boiler is an outdoor reset control with no indoor reference temperature (Heat Timer). The building is currently undergoing an energy study and the PE that is doing the study recommended TRVs on every radiator, and he dismissed the idea that an Energy Management System with wireless apartment temperature sensors would do anything to reduce overheating in a one-pipe steam system. Can anyone point me in the right direction? It seems to me that TRVs are a very expensive way to address a problem that a more sophisticated boiler control system would centrally address.

The Steam Whisperer (Formerly Boilerpro)

Both......

If the whole building is overheating, then the existing control just needs to be adjusted down.  If that doesn't work then a new control is in order.



However, not putting in TRV's will still keep the building 30 years behind the worldwide comfrot and efficiency curve.  TRV's in every room in every structure has been required for a long, long time in most countries.  Properly installed and properly designed TRV's will cut the fuel usage and increase comfort.  Just think about it this way, lots of people have separate temperature controls for each side of thier car....then why shouldn't we have separate temperature controls for each room in our homes?

JohnNY

No love for TRVs

TRVs for 65 apartments are going to cost you a fortune.

Your problem is better solved with balancing and matching steam output to the system's ability to convey and process that steam and resulting condensate.



A good steam control that learns the building's rate of heating and loss is also key in medium to larger residential systems.

I use the tekmar 279 with great success, installing 20 units or more every year of that model alone.



In what part of the world is your building?

JohnNY

Hey Steam Whisperer,

No offense in offering an opinion conflicting with yours.

TRVs are certainly a great way for much of the world to control hydronics, but the 1-pipe steam systems found here were never intended for such targeted control. Rather, they were designed as whole systems with EDR values equal to boiler output. OR vice versa if you prefer.

I'd like to hear from others on this point.



Thanks.

RJ_4

danfoss

A Danfoss RA-2000 1 pipe valve and a G-8023 operator together run about $100.00. I have used these in old multi story office bldgs. in San Fran. with some success.  The problem with this type of control is that the boiler must cycle alot and reach below 0 psig. on off cycle       Dan Foss has a 1983 memo explaining this.

Paul48

Coal

The system was probably designed for coal. The radiators were probably sized for open windows. It would probably be a good idea to do some checking of heat loss vs radiator size. I believe that if they had TRVs 100 years ago, they'd have used them. Balancing a building that size would be similar to bridge painting. Start at one end, go to the other, then start over again. My 2 cents....change due.

sreja

One-Pipe Steam-TRV or Better boiler controls?

I can't speak on one-pipe TRVs, but I can tell you that we installed TRVs on our two-pipe 14 unit apartment building with about 100 radiators, and it completely solved our overheating issues.  The improvement in comfort was astounding and it was a huge success.



People suddenly were able to regulate the temperatures in their units easily and they loved it.



We later installed a tekmar 279 controller and I would recommend that too, but my summary conclusions are: TRVs to improve comfort and eliminate overheating; tekmar 279 style boiler control to improve efficiency and reduce wasted boiler runtime.

Rod

You Probably Need Both

Like Dave Bunnell , The Steam Whisperer, mentioned ideally you probably need both, especially in older buildings lacking good insulation.  Primarily you need a good over all system control like the Tekmar 279 and TRVs to control any overheating in individual units.  

      Here in Maine we have winter days that are very cold but clear and sunny.  If you base the system temperature on the few rooms in the sunny south side of the building, the rooms on the north side are freezing and vice versa, if you base the system temperature on the rooms in the north side of the building, the rooms on the sunny side get too hot.  TRVS used on the sunny side keeps these units from overheating.  The problem is that you will then find that though you only need TRVs on some of the south facing units, the units on the north side will complain and ask why they don’t have TRVs too!  I’d start with a good system controller (like the 279) and sneak in TRVs as necessary on a case by case basis.  If you use TRVs, you need to take into consideration, as RJ mentioned, the need for a 1 pipe TRV to have an "off cycle" to operate properly.

- Rod

skifaster

Thanks

Thank you all for your comments-keep em coming!

This building is located in Brooklyn, NY.

jumper

best control

The best control for any radiator is a blanket over it. Too cold ? Use a shorter cover.

JohnNY

You're in my area.

If you think I may be able to help you, let me know. I do a fee-based Heating System Evaluation, EDR calculation and written report.



Thanks,

John Cataneo

nicholas bonham-carter

balancing the system

i would get the system balanced first, with proper main venting, and lower pressure; then see how much improvement there is. of all the outdoor reset systems out there, the tekmar seems to be most popular. none of these controls are able to compensate for imbalance or poor venting, and some controls will make the imbalance worse.

i am sure your PE is eminently qualified, but perhaps not as suitable as a real steam expert such as john to eveluate your system.

remember the desire for comfort and economy was just as strong when your building was first built, and the job is now to return it to its original excellent state of operation.--nbc

jumper

what did the PE do?

Did he check the outdoor sensor ? How old is it ? Did he calibrate the heat timer ?

What is it programmed to do ? Directly control burner based on outdoor temperature ?

Or delay cut in based on outdoor temperature ? The latter sounds like a better idea.



Sometimes those intelligent vents create new problems.

The Steam Whisperer (Formerly Boilerpro)

No offence ever taken.....

about a different opinion.  Different opinions is how we all can come up with something better than what was in the past.    Too bad so many in Washington haven't figured this out!