TRV's for radiant floor

Brad_3

Has anyone used TRV's to control a radiant floor zone, as Siegenthaler suggests in his PM article? Is it smart enough not to overshoot and undershoot either a slab or low mass system? Does the brand of valve make any difference?

Are there any electronic modulating valves with PID as in a Tekmar 500 series thermostat?

Thanks,
Brad

jerry scharf_2

a couple options

Brad,
(edited)

The overshoot of these units should be no worse, and probably a bit better than a thermostat. Fighting overshoot in radiant situations can be very difficult in certain cases, especially with rapid passive solar gain. Outdoor reset will reduce the risk of overshoot with just about any of these systems.

Danfoss makes mechanical ones. Caleffi can build these up with their iRadiant controls and valves, which have an adaptive controllers that could reduce the overshoot.

I'm building my own, so I can play with the controls and instrument the system carefully. The controls are very much a roll your own thing, but that's what suits my system.

jerry

Mike T., Swampeast MO

The FHVs by Danfoss have a built-in adjustment for setting flow--the object is to keep the head loss in all loops as close as possible--despite differently loop lengths. Combined with a good reset curve, this reduces panel overshoot when raising temp in the space. Not sure if the other valves Siggy mentions have this additional adjustment.

Paul Pollets

UniBox

I've used the Oventrop Unibox on 5 projects and am currently doing a remodel that will use 3. They pipe off the radiator 2 pipe system and can be set up to power up to 3 loops of QuickTrac or a mud-set. I buy the unit with the built-in limiter, which makes the device bullet proof. The 1/2" supply of the UniBox means the unit should not be used with a radiant load of over 12K BTU's. Pump head may also increase, depending upon the tubing size selected for the radiant application. Purging is critical, since the UniBox may be the high point of the system. It comes with a built-in bleeder. While this is a simple device, it must be piped correctly, and the pump sized accordingly.
You can read my article mentioning the device at:
http://www.supplyhousetimes.com/CDA/ArticleInformation/features/BNP__Features__Item/0,5333,132161,00.html

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

John Cockerill

Exquisite Heat will rgulate with thermostat activity. see www.exqheat.com

Constantin

TRV's are great in radiant applications...

... I would have seriously considered the Danfoss FHV's for my home, if it wasn't for the large size of the unit that turned off my wife from that idea.

I suppose once the room is cluttered with lots of other stuff, the controllers become less noticable. However, their siting is important, and depending on the possible solar gain, you may need something that is a bit more responsive.

The new generation of controls now making its way down to the consumer level is very exciting. The i-Series from Taco has great promise, as do the Caleffi controls, etc. Soon, we'll have the instrumentation and temperature control capabilities now only commonly found in modern high-rise buildings. I look forward to variable-speed ΔP pumps, better-integrated controllers, etc.

Lastly, I would also like to comment on Mr. Cockerill's post here, which has nothing to do with TRV's and is a rather blatant attempt to use the Wall as a advertising forum for his product. At the very least, I would expect a disclosure. Thank you.