Supplemental to floor question

ScottMP

poor Steve Ebels thinks I should be put out to pasture.

The question is ; I have a small bathroom that will have climate panel floor heat. I need 3700 btu's and have enough floor space for about 1600.

So we'll add a Buderus panel.

Do I out the panel on the constant criculation of the other units and let the TRV run it as supplemental when needed OR over size the panle and run it on the same temperature and Taco I-radiant valve as the floor.

Either works fine I think but I am having a brain cramp from all that 70's talk.

Scott

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Mike T., Swampeast MO

I think the first would be best. I have TRVd rads in spaces with both electric and hydronic floor heat. Works great with both. Rads only heat when the floor can't meet the load or if you intentionally turn up the TRV.

Brad White_9

I am with Mike T. on this one too.

Make the Buddha part of the larger system with a TRV and it will fill in nicely. Plus it can give a boost when you need it. Cannot do that with limited water temperatures.

Unknown

Is the bathroom running off a t-stat in another room?

If the radiant t-stat is in the bathroom, the floor will shut down as the radiator satisfies the space. If not, then you're all set with the TRV'ed radiator.

ScottMP

I'm not sure

I agree Rob. A trv will throttle open gradually to satisfy the room, so as it does it will shut-off and the floor won't have enough time cool. ITs a small bathroom so it should recovery quicky especially with climate panel which is rather quick reacting.

No ?

Scott

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Unknown

Imagine a situation where the radiant can't keep up. TRV opens and brings the room up towards the room temp.. gradually reducing output until you hit the room temp it's dialed for.

Radiant now has no reason to ever turn on again unless the radiator, for some reason, no longer meets load, right? The radiator is right there providing modulated output to maintain room temp.. when is it ever going to drop enough to trigger a thermostatic call for heat? If the TRV is doing its job, the floor will sit there waiting for a heat demand that will never arrive. Unless you guys are seeing a lack of precision of room temperature in TRV systems?

I suppose you could get around this by setting the TRV to only heat the room to a degree or two less than the radiant T-stat. And hope no one adjusts it (accidentally or on purpose) later.

Or, I suppose you could use a floor sensor for the radiant T-stat, so the radiant can get its "foot in the door" again when the floor temp gets too low. But I think that would only get you to floor minimum. Air 'stat would still never need the heat.

Maybe the precision of a TRV is not equal to whatever differential your stat requires for a heat demand? But I don't know that I'd bank on that. I'd run the bathroom floor with an adjacent zone, maybe with a floor sensor, and use that TRV'ed radiator to fine tune the bathroom temperature.

Mike T., Swampeast MO

That problem will occur only if the controller for the radiant panel is in the same space AND the radiant panel is controlled via room air temperature.

If the controller is in another room or if it's controlled via panel temperature the radiant will continue to provide output and once load drops to the point that the radiant alone can provide the heat the TRVd radiator will cease to provide heat.

My "mixed" spaces with hydronic radiant and TRVd rad have the radiant control via the boiler reset curve. The "mixed" space with electric radiant and TRVd has the radiant controlled by the temp of the floor. No conflicts and the radiant ALWAYS acts as the "base".

I do though plan on a different arrangement in the kitchen/breakfast/laundry that has three TRVd rads and will use 2 FHVs to control the panel (floor). I'm really not sure what will happen other than I expect the one rad under a bank of N windows to be significantly influenced by its location. The other two rads are on interior walls. Should be interesting but will probably be about three years before I install. Complicating matters is that this large (600 sq.ft.) radiant floor area will STILL operate via the internal circulator in the Vitodens. Long 1" "manifolds" running the length of the space at each side connected by very short runs with the manifolds in reverse return. Yes, I know the bleeding will be complicated...

Unknown

That's the situation we were talking about: radiant tstat in the bathroom with a TRV radiator.

Sounds like you are doing constant circ on the floor, with TRV radiators to fine tune room temp?

ScottMP

Maybe the difference

is who's handling the higher load.

I have a job that has been wirking fine for a few years now.

The panel is just the additonal load needed during design times. The panel can never handle the load on its own ( I suppose during spring and fall it might ) but for the most part the floor handles the larger part of the load.

I belive ME has done some jobs like this.

Scott

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Mike T., Swampeast MO

Sounds like you are doing constant circ on the floor, with TRV radiators to fine tune room temp?

Yes.

But also no conflict with electric radiant controlled via floor temp.

[Deleted User]

Pair-o-lellis radiatoritis

If you go with the radiator parallel to the rfH load, then you can decide which gets hotter. It might suprise you what the floor is actualy capable of without the radaitor.

We call it the KISS system, and I think you know what it means.

ME

Ted_9

Floor sensor?

Scott, can you add a floor sensor? You could run the radiant off of this to keep the floor warm and use the panel with a trv.

I personally have done large rooms with floor heat and used a buderus panel and towel rad off of the radiant manifold to make up the additional btus. Works like a champ.

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