Infloor radiant issue

ChrisJ

> @ChrisJ said:
> So,
> Still no real progress on this.
>
> Except....................can anyone tell me if a slab sensor can be used with a Honeywell Prestige and the EIM? I can't imagine it not being possible, yet I didn't see it in any of my documentation. It's got 4 inputs, but I only see duct temp sensors as a listing.
>
> Also, how does a slab sensor actually work?
> Does it effect anticipation? What's the objective in such a setup?

Any responses to this?

pecmsg

I don’t think any sensor, outdoor reset, algorithm would help with sun load in Colorado. When the sun is shining your warm,when a cloud blocks it you putting on a shirt or jacket...........that quickly.

nibs

When I was designing and building our roof, calculated the sun angle in mid July and gave the south facing clerestory shade by extending the roof overhang, now the direct sunlight is just beginning to touch the living room floor, yesterday the lower 1/4 of the clerestory windows were in direct sunlight, in another two months the sun will be shining directly onto the concrete north wall, we have two rooms that have limited roof overhangs, for these we plan to use drapes if the solar gain gets too high. So far the house maintains a 65 to 70 average temp night and day through the summer and we have not had to use drapes.

Voyager

ChrisJ said:

> @ChrisJ said:

> So,

> Still no real progress on this.

>

> Except....................can anyone tell me if a slab sensor can be used with a Honeywell Prestige and the EIM? I can't imagine it not being possible, yet I didn't see it in any of my documentation. It's got 4 inputs, but I only see duct temp sensors as a listing.

>

> Also, how does a slab sensor actually work?

> Does it effect anticipation? What's the objective in such a setup?



Any responses to this?

No experience with Honeywell Prestige so can’t comment.

A slab sensor works like any other temp sensor. It will respond faster than a room air sensor since it is closer to the heat source so that can certainly help anticipate an overshoot a little.

However, I think it will be of marginal benefit in the case you are looking at as I don’t think the temperature instability you are seeing is due to overshoot of the heating system. I suspect it is due to so much solar heating that the room can’t reject the heat fast enough. If it was my house, I would consider motorized blinds that could be controlled by the automation system that could close to quickly address solar heat gain. And some form of active cooling for the cases where the solar gain might still exceed the room’s heat rejection rate.

I have motorized blinds in my log house as the “great room”, as they are called, has two prow walls that are windows from floor to ceiling and face southeast and get a lot of sun. The blinds really help the AC keep things cool.

JakeCK

> @John Ruhnke said:
> Tekmar can control this lag problem. They use a outdoor reset with indoor feed back. The Tekmar control can actually take info from the indoor sensor, measure the cycle lengths and adjust for outdoor temps. Once it learns the cycle the control actually turns on early and shuts off early to even out any temperature swings. The control handles normal solar gain well too. As for extreme cases the excess solar gain can be a problem. That could be accounted for and adjusted in some window tinting, awning or shades that automatically come down when it gets too bright
>
> Some people mentioned ducted air conditioning and ventilation. That is not the only option. Another option can be a ceiling with a combo of both radiant heating and cooling. Just put a new Messana radiant cooling ceiling up over the existing ceiling. It might be easier than jamming in some ducts.

Which tekmar control can do this? Sounds interesting and a better alternative to a nest's learning bs.

John Ruhnke

@JakeCK
Nest was developed by marketing people. They don't understand enough about the hvac industry to be competent.

Tekmar makes a great control package. In order to do what I am talking about with Tekmar you need to go with a networked system. This includes a main control, slab sensors, thermostats, indoor and out door sensors and zone controls. Find out more info at TekmarControls.com.

So you can just use just the thermostats. Tekmar Thermostats are way better as a stand alone thermostat than Nest. or you can build out a complex networked control package to control solar, snowmelt, radiant, cooling, and just about anything else. You don't need everything in there hi end package, you can build out a control package on a budget and still get good controls. Most of the time the fuel savings pays for any control upgrades.

The high end TN4 Tekmar networked system is the absolute best on the market. It is the most comfortable, energy efficient and it helps equipment last longer by optimizing boiler cycles, zone cycles, controlling return water temps and more. You need experience in hydronics and some training to accomplish this. The end result is only as good as the installer/designer and the work he does. It even controls ducted systems too.

I don't rep Tekmar. they don't pay me anything to say this.

njtommy

I know the Honeywell prestige can be set up for radiant heat, but not sure what sensor they would use. Probably just a 10k at 77f.

ChrisJ

> @njtommy said:
> I know the Honeywell prestige can be set up for radiant heat, but not sure what sensor they would use. Probably just a 10k at 77f.

What does that sensor actually do?

mikeg2015

Maybe add a kickspace heater or some baseboard or wall mount panel radiator and reduce the setpoint for the slab. You’ll get faster response to resolve the overshoot issue.

Solid_Fuel_Man

I agree that the Tekmar tn4 is a great system. I've used the house control 404 on several jobs with nothing but fantastic results.

Solar gain must be controlled, or the excess heat vented outside (wasted) if there is no way to limit it. Plain physics as has been said.