Mass installation of TRVs in 1-pipe system

NYLamb

Greetings all,

I work at a 100 building apartment complex that utilizes a vacuum system in our 2-pipe radiators. The owner of this property owns buildings elsewhere that utilize 1-pipe systems where he is looking to install TRVs en masse for the sake of meeting NYCs aggressive green/efficiency law initiative. 

He wants us to recreate a 1-pipe system in  an isolated room in order to test some of these valves. While testing a single unit is one thing, what consequences could be expected when these TRVs get installed on a mass scale (50+ units)? 

More cycling of the boiler? Excessive water hammer? Issues with steam distribution?

JUGHNE

These could not be TRV's as you put on a 2 pipe system.

Rather these would be a control on the air vents of a 1 pipe rad.

The original steam inlet valves must remain in place to allow for condensate return back thru them.

NYLamb

Sorry if not clear. These TRVs will be used on a 1-pipe system. We've tapped off a steam line at my job not located on the vacuum system in order to recreate a 1-pipe system. 

I'm more curious about what can be expected when TRVs are installed on a system that has a large quantity of units.

Mad Dog_2

TRVs should be used SPARINGLY after the steam system..both one & Two pipe, is in original proper working order.  TRVs are excellent at preventing overheating rooms and radiators but they should be a fine tuning tool...Cherry 🍒 on the Sundae 🍨. 
They are often overused and misapplied as an Energy Efficiency Panacea.  $$$ should be put in to the basics of good operation first.  Mad Dog 🐕 

Steamhead

Agreed. Think of TRVs as limiting devices. They don't call for heat like a room thermostat does.

We'd have to know how these buildings' boilers are controlled- room thermostat? Outdoor control such as a Heat-Timer or Tekmar?

First thing to do is make sure the steam mains are properly vented. This will distribute heat to all the radiators in the building quickly and evenly. Once that's done we can look at TRVs.

If a lot of TRVs close, the boiler will probably short-cycle. Some commercial burners can drop to a lower firing rate, controlled by a Vaporstat, if this happens. We've actually upgraded several PowerFlame burners to 2-stage firing, with help from their tech-support people who have been quite helpful.

There are several contractors in NYC who can help with this- @JohnNY and @Mad Dog_2 are two that I know.

Mad Dog_2

Powerflames are awesome machines...Mad Dog  🐕 

Jamie Hall

This is a two pipe system? How are the radiators connected? If the inlet is at the top, as is usual, you can't convert them to one pipe without a great deal of work. On the other hand, you could use TR VALVES on the inlets, rather than the TR VENTS you would use on one pipe. But you'd still have the same balance, size and control problems...

NYLamb

Jamie, we ordered some one-pipe radiators and built an isolated room to test out the valves. We had to run piping directly off a steam line to avoid tying into our normal heating lines which are under a vacuum. I caused some confusion stating that I normally work with a 2-pipe system. My main intent of the post was to see what issues would arise when a large quantity of 1-pipe radiators go from a standard vent to these TRV vents overnight. 

JUGHNE

For those air vents to work the PSI must cycle on and off.

And the vents need the vac breaker on them to allow the condensate to drain back.

Your 1 pipe rad will need a larger run out and supply valve than your 2 pipe system to allow for the counter flow of steam and water.

ChrisJ

While it's a baby system compared to what you're talking about I have TRVs on 5 out of 10 radiators in my house.   There's a few things I've found were needed to get them to work perfectly.

First the system must be vented and balanced reasonably well even without the TRVs.

Pressure must be kept fairly low.

More cycles is better.   The TRVs need steam pressure to drop to zero several times an hour. I'd say no less than twice an hour but 3 times may be better.  I highly recommend an outdoor reset system for this.

I have two Danfoss and three Macon TRVs. I like the Macon more.