Small radiant loop with 2 mono-flo tees?

Plumdog_2

I've gotten flow thru 80' of 1/2 pex with 2 monoflow tees, spaced not all that far apart. Put some Ultrafin on there and insulate underneath with 2" board; leaving a gap. No need for tempering down, and it works well for a little space like that. Don't overkill on the Ultrafin.

Ross_7

Small radiant loop with 2 mono-flo tess

Has anyone tried to tie-in a small (6'by 4')radiant loop by just using two mono-flo tees? Or do you think the pressure drop would be too much. I have an existing monoflo 1" main for the rest of the house, and I wanted to do some radiant in our small kitchen for the wife. Just curious, or otherwise I was going to try the "direct return" piping approach with a circuit setter to balance it out. TIA for any input!
Ross

Ross_7

Hmm

Maybe my subject is as eye catching as a friggin' icicle hangin from a concentric vent outside?

Jeff Lawrence_25

Ross

Is your current system a radiant system?

If not, what are you going to use to control the temps?

Ross_7

Jeff,
I installed a TT Prestige, so I am using the outdoor reset. So, I'll be utilizing some joist track & then insulating. Upstairs in the kitchen, is maple hardwood, but there is also a pretty thick subfloor beneath the main flooring. So, I'll only be reaching 180f on the coldest day. Like I said I'll have a small amount of 1/2" pex to use for the radiant loop. I just thought that maybe two monoflo tees wouldn't create enough pressure drop across to divert the water into radiant loop. My existing zone is a 1" monoflo loop for the entire upstairs, with Burnham Baseray cast iron baseboard.

Ross_7

Plumdog,
What size monoflo tees did you use? 1" by 3/4", and then reduce down with pex adapters or 1" by 1/2" TIA
Ross

scott markle_2

Oventrop RTL

I have never used one but this seems like a perferct application. This trv like valve is installed on the return side of the loop you describe and would essentially provide setpiont control (high limit protection) by flow regulation as opposed to mixing.

If the flow through this loop ends up strong I would have concerns about unregulated 180 deg water and your maple flooring. Is the reset strategy for the rest of the house providing constant circulation? or is is just increasing circulator on time and relying on conventional indoor thermostats? I believe that true or close to true constant circ. is much gentler on wood flooring because it minimizes thermal cycling(stress).

Calculating the flow from monoflow T's would be tricky (over my head), you might just have to use your intuition, which is safer since it's your house. If the flows are week but sufficient purging the air from this loop may also prove difficult. You might consider placing a ball valve between the mono flow t's to assist with this. Maybe consider 5/8" tubing to keep the head low, are conductor plates available for 5/8'' ?

Oventrop RTL link; http://www.oventrop.co.uk/en/index.htm

scott markle_2

ultra fin

The ultra fin is probably a simpler and more practical approach, although you may not get much effect from it when your system is running a lower temps (floor won't feel warm). The RTL and extruded plates would probably deliver perceivable heat for a broader range of operating conditions, while providing protection against over heating.

Ross_7

Mini-shunt set-up

Hi Scott,
The Oventrop set-up must be like the Roth radiant mini-shunt pump set-up for small radiant loops? I do not have constant circulation for the loop. My Prestige boiler handles the outdoor reset. With the cast iron baseboard & free standing radiators that installed last year, the supply temps rarely go to 180f. With the Joist trak installed I should be able to feel the radiant warmth even at lower temps. I'm also going through about 2" of subfloor in this particular area, because when it was remodeled the existing floor was built up a little from the existing pine subfloor.

scott markle_2

The mini shunt is more sophisticated I believe it utilizes a circulator and I think it essentially can provide a second reset temperature for a one temp system.

All the Oventrop valve does is restrict circulation based on a desired return water temperature. If 180 is entering the loop the valve will adjust (restrict) on the return side such that a set temperature is maintained. Basically it operates like a trv but based on desired return water temp instead of air temp. For a small supplemental radiant heat loop this seem to me to be a interesting device.

The more you lower the curve on the prestige the closer you will come to constant circulation, At a certain point your thermostats will be calling for heat continuously because the curve is below what is required to heat the house to that thermostat setting. The closer you come to this point the higher your condensing bonus will be. The only drawback to a carefully set (low as possible) curve is slow recovery and no upward adjustment of room temp beyond what the curve can supply. If it's a essentially a one zone set-up, your not into deep nighttime setback, and have a set it and forget it approach to thermostat adjustment I would recommend experimenting with establishing a curve that will result in near constant circ. Cast iron is especially well suited to this sort of delivery. You may find that you don't truly require 180 even in the coldest weather.

Ross_7

Siggy

I thought that Siggy had a section in his "Modern hydronic heating" about this, or was that just a micro-zoning with panel radiators? I don't have mine available, I loaned it to my boss. I gues I need to get it back from him! :-)
Ross

Plumdog_2

3/4 x 1/2

The variety with the little scoop; you would use to add a toe-kick heater. I put them in line, with the arrows facing one another. There was a fan-coil in line, too, and the darn thing got pretty good flow.

Ross_7

legend \"monoflow\" tees

I believe those are Legend brand "Monoflow" tees. Yes, I would think that you would have to use two tees with the "rings" or arrows facing inwards mainly because of the pressure drop across the coil, radiant or otherwise.
Ross