Commercial radiant floor... How to achieve comfort

WilliamLaForge

I have a truck shop that has a radiant floor fed by a combi boiler. The shop also has 2 reznors overhead units to help it recover when something different is brought in.
My problem lies in that all are controlled by 3 separate air temp t'stats. during recover times, the Reznors shut down the radiant until air demand is met. Floor goes cold while the snow & ice melt off the truck then the radiant takes back over and all is fine again until the next project rolls in.

I think a floor temp controlled t'stat would help this problem but I am lost in the battle of too much information available to figure out what product to use ! Also how to install a temp probe in an existing concrete slab..... Or do you install more than one to get more accuracy,.... or back up if one goes south....

I am located tn the snowy part of Western NY and this is my first post after many years of lurking here...

Feel free to ask away anything that will get us where we need to go.....

Thank you for any help you may have for me...

hot_rod

Do they really need the infrareds at all?

Typically as soon as the doors close the radiant slab, with its massive flywheel covers the new load and maintaining the set point. I can see the over-heads speeding up the snow removal on the top surfaces, but it will have a tendency to compete with the radiant slab.

Slab sensors do help and thermostats with minimum slab temperature settings can help fine tune the system. Uponor and tekmar were two of my favorite T-stats that had radiant friendly functions like slab sensing. I imagine other brands have the ability to add slab sensing.

Adding a slab sensor after the pour is a bit tricky. Some installers strap the sensor on the return piping from the manifold to get some better control.

WilliamLaForge

The Reznors are forced air, not infrareds ...

hot_rod

WilliamLaForge said:

The Reznors are forced air, not infrareds ...

Probably worse as forced air units effect the air temperature quickly.

The more points of sensing the more accurately you can control. adding some slab or return sensors, dialing in an outdoor reset for example.

tekmar usually has good data and case studies on control logic for applications like that, see what you can find at their site.
www.tekmarcontrols.com

With slab sensors you could idle the slab at a not to exceed temperature and maybe still bring in the Reznors for boost, ideally controlled from a single stat with the logic to watch and control both. two stage stats may be an option with remote sensor input?

I think the unit heaters are best used in shoulder season before revving. See if you can wean them off using them in the winter months.

Assuming the radiant was designed to handle design loads for their application?

WilliamLaForge

The radiant was sized correctly & works perfectly once it gets cold enough.

Its just on low demand days when we run into the fight.

I think you are correct about the reznors.... they do fine when you don't need much heat & they do help to clean off a truck when you first bring it in.

However, in the dead of winter the radiant handles the load after the melt water is gone (evaporated) with no extra help from the reznors

I looked at Tekmar's website & Emailed them a help request.
I saw a # 557, but will wait to see what they have to offer...

Thx

hot_rod

I know Don Rathe, Rathe and Associates reps tekmar on the other side of New York, he is very knowledgable on the tekmar line, try him if you don't get any reply.

Usually the factory pushes support and application calls to the local reps, sometimes communication breaks down

That shoulder season is tough to get a handle on with high mass systems.

631 822 1200
drathe@ratheassoc.com

WilliamLaForge

OK Thanks!!

I'll give it a day or so for the chain of command to respond ....

WilliamLaForge

Tekmar Responded with this:

A floor sensing two stage thermostat would be the best controller. This thermostat would allow you to set a minimum floor temperature and then call a second stage Air Handler (Reznor or AHU). However, floor sensing is not needed on tekmar thermostats as those thermostats have settings that will always maintain radiant floor heating as the first call and AHU as second.



Your choices are:

553 or 557 tekmarNet or standalone

562 or 563 with Wi-Fi and app

Invita – 564 two wires from the hardware module to the user interface and many wires to the heating air handling.

All these thermostats are made to operate radiant floor heating first (562,563 and 564 must be set to Radiant Floor YES in the setup). Then follow up with a second or third stage of heat (depending on the model), after a delay and differential (both user settable).



All these sensors can accept one or more auxiliary sensors which can be set to floor.

Any Thoughts or experience with any of these??

Thx in advance....

hot_rod

do you need or want WiFi capability? If not the basic 553 will do all you ask.

Google all those numbers to see the features of each for comparison. tekmar does a great job with documents, buying, installing, troubleshooting.

WilliamLaForge

No Need for Wi Fi for Me...

hot_rod

KISS with controls especially in a building with potentially many t-stat twisters

Some installers mount all the stats in the mechanical room, hang an air sensor and slab sensor in the space. Keep the controls out of site and harms way.

Gordy

Shoulder seasons are tough with any type of heating. Most of it due to how our bodies adapt. Going into fall/winter 50 calls for a hoodie. Coming out of winter into spring shorts, and a t shirt......we are a complicated piece of machinery

WilliamLaForge

Ordered a 553 Tekmar & slab Sensor today.... I will let you know how it works When i get it put in & programmed...