Danfoss Valves on Single Pipe Steam Systems

Brad White_150

are a relatively low-cost investment and worth doing. They do not need to be placed everywhere if first cost is an issue. I would prioritize them toward bedrooms, kitchens and sunny rooms which either overheat or are preferred cooler. I would not put them in bathrooms or at least have them at a lower priority because one can not get them warm enough IMHO.

A key feature of these is an integral vacuum breaker. Only Danfoss, Macon and Amaark (sp.) offer these to my understanding.

Instead of a Heat Timer, Tekmar makes a decent building wide steam control. the 269 series. Similar to the Heat Timer, these take into account the outdoor temperature and the cycle time (time from firing to hot return temperature at the boiler). It is an indirect way to heat but is surprisingly effective.

Steven Capri

Danfoss Valves on Single Pipe Steam System

I just recently purchased an 11-unit 3 story apartment building that has a single pipe gas fired steam heating system. So far this is the first heating season that I have experienced with the system. The building needs a lot of work and as part of an ongoing renovation process I would like to give each apartment as much control over their own heat and save some money in fuel in the process.

So far I've taken care of replacing main vents as well as the low limit and autofill valves on the boiler. I've also replaced air vents on the radiators in several of the apartments.

Unfortunately the boiler in the building is regulated by a thermostat that is located at the top of the central stairwell. This system has been functioning(how well and to what degree I don't know) for many years. I've already fielded some calls that it is way too hot (which I suspect is inevitable in this mild season)

I have heard that the Danfoss RA2000 thermostatic radiator valves would provide a solution to regulating heat to each individual radiator. I have several questions:

1. I am confused as to the proper application of such a valve. Is a valve like the RA2000 to be mounted in place of the steam valve on the pipe before the radiator or is the proper application to use a valve such as the RA2000 1PS which regulates the air venting out of the radiator? Keep in mind that each radiator does indeed have its own air vent.

2. I have been told (from one heating contractor) that the use of the RA2000 on the steam pipe in a one pipe system is an improper application that can cause flooding of the boiler. I don't quite understand this.As long as there is an air vent on the radiator shouldn't the valve regulating the steam into the radiator work?

3. If the RA2000 1PS (on the air vent) is a viable alternative it would seem to be far less costly both in terms of labor and material to install than using the RA2000 on the steam pipe.

4. What are the ramifications on system operation of everyone controlling their own heat?

5. Do these things work in terms of regulating heat and saving fuel? If they do as claimed it would seem to be a no-brainer.

[Deleted User]

RA2000 1PS

Because you've got a one-pipe steam system, your only option is a thermostatic valve on the radiator's vent hole, like the RA2000 1PS. If you fit an RA2000 1PS, you should use a straight-shank air vent, to guarantee that condensate drains from the vent.

You can't use a thermostatic valve in place of the supply valve, like the RA2000 non-1PS. Those won't work on a one-pipe steam radiator. They throttle the steam supply, but because the same pipe is used to drain condensate, you'll wind up with water hammer as steam blasts away the water that's in its way.

If you've got the thermostat in an unheated space, the worst case scenario is that all of the Danfoss valves close, and the thermostat keeps calling from heat. The burner will run short cycles to maintain pressure, but nothing's going to get any warmer. I like the thermostat in a heated but lightly-used space, with a smallish radiator, smallish vent, and no TRV. You want the thermostat in a heated space so it knows when to turn the system on and off, but you don't want a TRV on its radiator because if the TRV is set to maintain a lower temperature than the thermostat, the thermostat will never stop calling for heat. A heat-timer is an alternative to a thermostat that's especially attractive when you can't find a good spot for the thermostat - like when you don't want to put the 'stat for the whole building in any one tenant's apartment - but they're expensive and I've never played with one.

I really like these little valves, and so do the formerly-broiling tenants. When you use 'em properly, they work well and you will save fuel.

Mark
Another apartment building guy

Steven Capri

Thanks for the advice. I've already installed several of these RA2000 valves on the stream pipe and so far I don't think there any noise or water hammer problems - but then again I'm not there. I'll start using the RA2001PS for the remainder of the reno. So far only 3 out of 11 apartments have been retrofitted.

Also, the stairwell is in fact heated at the bottom by a single radiator. The thermostat is at the top. Some of the tenants leave the main entrance door open so that the thermostat at the top will kick in. Obvoisly not the way to regulate the boiler. I will check into the Tekmar unit.

I suppose another alternative would be to put a remote sensor in one (or more) of the apartments on the middle floor.

Barbarossa

Ice bagging

Then they will put an Ice bag on the remote sensor once they know what it is. Do not skimp on the temp. controls and the $$ they can save.

bb_7

check the library

Steven:

Check "The Library" here on this site. There are a few pieces on 1PS valves from Danfoss posted. They will help to explain in detail how they work. If you need more assitance call: 443-648-1205 for tech support.

As mentioned in another post, you may want to insvest in a Heat-Timer control for 1PS. This will control the boiler based on outdoor temp., and ensure the boiler cycles off long enough to all condensate to drain back to the boiler.

It seems like you are on the right track with what you have done so far. Make sure the pipes pitch back to the risers so the condensate may fully drain back to the boiler.

The next best thing you can do for your building is to tighen up the envelope. Less heat loss mean less BTUs need to heat the building!

Good luck.

bb