Zoned Radiator Control

Will_6

I've got a 1930s gravity hot water system that I'd like to add a circulating pump to. This site hase been very helpful in preparing me for that job. While I'm at it though, I plan to add thermostatic radiator valves (TRVs) at each radiator. I've seen them advertised with stand-alone mechanical thermostats.

What I'd really rather be able to do is connect each one to its own programmable time-of-day system so that every room (or radiator or zone) can have its own independent schedule. For example, I'd love to be able to turn off most of the house while I'm sleeping, turn off the bedrooms when I'm not in them, etc. Does such a thing exist? Is there an affordable option that would allow me to install many of these guys into a single (large) house?

---Will

jerry scharf_3

Not with the ones I know

Will,

The TRVs i know are purely mechanical in construction. Anything electronic would cost many times more, and that's what you need when you talk about time of day...

Now my opinion. The common logic is to set them and not worry about the time of day stuff. While there is some savings to be had with setbacks, it rarely seems worth the complexity it adds to a control system which delivers on comfort. When compared to TRVs, the digital setback thermostats seem like a comfort optional solution.

jerry

steve_86

zone valves

I'm just a homeowner, so I'm throwing this out as a response/question.

How about using a programmable thermostat in each room with a 24v valve controlling flow to the radiator(s) in the room ?

Danfoss has a couple of electronically controlled valves: http://www.danfoss.ca/products/hydronic/ZONE VALVES.htm

There might not be a worthwhile energy savings from such a system, and I can see how it might be expensive to implement, but could it be made to work?

Mike T., Swampeast MO

Danfoss also makes a programmable operator for standard RA-2000 TRV valve bodies.

Code No: 013G2750 Believe that these are dual function--either completely self-contained operation or linked to a centralized control system. Nearly triple the cost of a standard self-contained actuator; about double the cost of operator with remote sensing unit.

You can mix the programmable and non-programmable in the same system without problem.

I have their earlier TRV setback system that put a tiny, dual element heater in contact with the sensing bulb. You get three setback levels and literally hundreds can be powered by a single doorbell transformer. Unsure if they're still available. Cost was higher than standard operators, but not as expensive as the newer system.

My experience regarding setback of TRVd standing iron radiators has been a bit mixed. With an original gravity system your radiators are probably greatly oversized (and likely poorly balanced if you've insulated/weatherized). With the TRVs and constant circulation you'll find that the radiators run amazingly cool providing very even and extremely gentle heat rivaling large radiant panels like floors or ceilings.

For highest comfort and efficiency I've found it best to find the lowest setting suitable for each space and leave it there--it will probably be lower than you think. Daily setback seems to decrease comfort without a corresponding decrease in fuel consumption. Unused spaces can of course be set back as far as you like.

One great feature of TRVs is their ability to recover rapidly from setback. Unlike digital control devices like thermostats or zone valves, the more you turn up a TRV operator the faster the space heats so those greatly oversized radiators really shine and you can recover nearly as rapidly as forced air systems.

DWood

In addition

Danfoss also makes a battery operated TRV that can be set up with two programs for set back purposes, part #013G2750, called the RA Plus. I've tried to attach the pdf, we'll see if it works.
DWood

Will_6

Thanks!

That looks like just what I was looking for.